Get Our Extension
Select Wikiz in another Language
DeutschEspañolSuomiFrançaisItalianoNederlands
Settings
A
A
Text Highlights
Notes/Citations
Edit on Wikipedia

Share This Article

About Wikiz About Us Cookies Policy Terms & Services Privacy Policy Contact Contact us Enjoying Wikipedia Content? DONATE TO WIKIPEDIA
Enjoying Wikipedia Content? DONATE TO WIKIPEDIA

Cilium

From Wikipedia, in a visual modern way
Cilium
Bronchiolar epithelium 3 - SEM.jpg
SEM micrograph of motile cilia projecting from respiratory epithelium in the trachea
Details
Identifiers
LatinCilium
MeSHD002923
THH1.00.01.1.01014
FMA67181
Anatomical terms of microanatomy
This article is about organelles. For fine hairs on insect wings, see Cilium (entomology).
Not to be confused with Psyllium.

The cilium, plural cilia (from Latin 'eyelash'), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates.[1] Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projection that extends from the surface of the much larger cell body.[2] Eukaryotic flagella found on sperm cells and many protozoans have a similar structure to motile cilia that enables swimming through liquids; they are longer than cilia and have a different undulating motion.[3][4]

There are two major classes of cilia: motile and non-motile cilia, each with a subtype, giving four types in all.[5] A cell will typically have one primary cilium or many motile cilia.[6] The structure of the cilium core called the axoneme determines the cilium class. Most motile cilia have a central pair of single microtubules surrounded by nine pairs of double microtubules called a 9+2 axoneme. Most non-motile cilia have a 9+0 axoneme that lacks the central pair of microtubules. Also lacking are the associated components that enable motility including the outer and inner dynein arms, and radial spokes.[7] Some motile cilia lack the central pair, and some non-motile cilia have the central pair, hence the four types.[5][7]

Most non-motile cilia are termed primary cilia or sensory cilia and serve solely as sensory organelles.[8][9] Most vertebrate cell types possess a single non-motile primary cilium, which functions as a cellular antenna.[10][11] Olfactory neurons possess a great many non-motile cilia. Non-motile cilia that have a central pair of microtubules are the kinocilia present on hair cells.[5]

Motile cilia are found in large numbers on respiratory epithelial cells – around 200 cilia per cell, where they function in mucociliary clearance, and also have mechanosensory and chemosensory functions.[12][13][14] Motile cilia on ependymal cells move the cerebrospinal fluid through the ventricular system of the brain. Motile cilia are also present in the fallopian tubes of female mammals where they function in moving the egg cell from the ovary to the uterus.[13][15] Motile cilia that lack the central pair of microtubules are the cells of the embryonic primitive node termed nodal cells and these nodal cilia are responsible for the left-right asymmetry in bilateral animals.[16]

Discover more about Cilium related topics

Eyelash

Eyelash

An eyelash is one of the hairs that grows at the edge of the eyelids. It grows in one layer on the edge of the upper and lower eyelids. Eyelashes protect the eye from debris, dust, and small particles and perform some of the same functions as whiskers do on a cat or a mouse in the sense that they are sensitive to being touched, thus providing a warning that an object is near the eye.

Eukaryote

Eukaryote

Eukaryota, whose members are known as eukaryotes, is a diverse domain of organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea make up the other two domains.

Cell (biology)

Cell (biology)

The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites. The term comes from the Latin word cellula meaning 'small room'.

Ciliate

Ciliate

The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different undulating pattern than flagella. Cilia occur in all members of the group and are variously used in swimming, crawling, attachment, feeding, and sensation.

Bacteria

Bacteria

Bacteria are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised and there are many species that cannot be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.

Archaea

Archaea

Archaea is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria, but this term has fallen out of use.

Axoneme

Axoneme

An axoneme, also called an axial filament is the microtubule-based cytoskeletal structure that forms the core of a cilium or flagellum. Cilia and flagella are found on many cells, organisms, and microorganisms, to provide motility. The axoneme serves as the "skeleton" of these organelles, both giving support to the structure and, in some cases, the ability to bend. Though distinctions of function and length may be made between cilia and flagella, the internal structure of the axoneme is common to both.

Chemoreceptor

Chemoreceptor

A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance to generate a biological signal. This signal may be in the form of an action potential, if the chemoreceptor is a neuron, or in the form of a neurotransmitter that can activate a nerve fiber if the chemoreceptor is a specialized cell, such as taste receptors, or an internal peripheral chemoreceptor, such as the carotid bodies. In physiology, a chemoreceptor detects changes in the normal environment, such as an increase in blood levels of carbon dioxide (hypercapnia) or a decrease in blood levels of oxygen (hypoxia), and transmits that information to the central nervous system which engages body responses to restore homeostasis.

Cerebrospinal fluid

Cerebrospinal fluid

Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.

Brain

Brain

A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.

Fallopian tube

Fallopian tube

The fallopian tubes, also known as uterine tubes, oviducts or salpinges, are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In other mammals they are only called oviducts.

Egg cell

Egg cell

The egg cell, or ovum, is the female reproductive cell, or gamete, in most anisogamous organisms. The term is used when the female gamete is not capable of movement (non-motile). If the male gamete (sperm) is capable of movement, the type of sexual reproduction is also classified as oogamous. A nonmotile female gamete formed in the oogonium of some algae, fungi, oomycetes, or bryophytes is an oosphere. When fertilized the oosphere becomes the oospore.

Structure

Eukaryotic motile cilium
Eukaryotic motile cilium

A cilium is assembled and built from a basal body on the cell surface. From the basal body the ciliary rootlet forms ahead of the transition plate and transition zone where the earlier microtubule triplets change to the microtubule doublets of the axoneme.

Basal body

The foundation of the cilium is the basal body, a term applied to the mother centriole when it is associated with a cilium. Mammalian basal bodies consist of a barrel of nine triplet microtubules, subdistal appendages and nine strut-like structures, known as distal appendages, which attach the basal body to the membrane at the base of the cilium. Two of each of the basal body's triplet microtubules extend during growth of the axoneme to become the doublet microtubules.

Ciliary rootlet

The ciliary rootlet is a cytoskeleton-like structure that originates from the basal body at the proximal end of a cilium. Rootlets are typically 80-100 nm in diameter and contain cross striae distributed at regular intervals of approximately 55-70 nm. A prominent component of the rootlet is rootletin a coiled coil rootlet protein coded for by the CROCC gene.[17]

Transition zone

To achieve its distinct composition, the proximal-most region of the cilium consists of a transition zone, also known as the ciliary gate, that controls the entry and exit of proteins to and from the cilium.[18][19][20] At the transition zone, Y-shaped structures connect the ciliary membrane to the underlying axoneme. Control of selective entry into cilia may involve a sieve-like function of transition zone. Inherited defects in components of the transition zone cause ciliopathies, such as Joubert syndrome. Transition zone structure and function is conserved across diverse organisms, including vertebrates, Caenorhabditis elegans, Drosophila melanogaster and Chlamydomonas reinhardtii. In mammals, disruption of the transition zone reduces the ciliary abundance of membrane-associated ciliary proteins, such as those involved in Hedgehog signal transduction, compromising Hedgehog-dependent embryonic development of digit number and central nervous system patterning.

Axoneme

Inside a cilium, is a microtubule-based cytoskeletal core called the axoneme. The axoneme of a primary cilium typically has a ring of nine outer microtubule doublets (called a 9+0 axoneme), and the axoneme of a motile cilium has, in addition to the nine outer doublets, two central microtubule singlets (called a 9+2 axoneme). This is the same axoneme type of the flagellum. The axoneme in a motile cilium acts as a scaffold for the inner and outer dynein arms that move the cilium, and provides tracks for the microtubule motor proteins of kinesin and dynein.[2][21][22] The transport of ciliary components is carried out by intraflagellar transport (IFT) which is similar to the axonal transport in a nerve fibre. Transport is bidirectional and cytoskeletal motor proteins kinesin and dynein transport ciliary components along the microtubule tracks; kinesin in an anterograde movement towards the ciliary tip and dynein in a retrograde movement towards the cell body. The cilium has its own ciliary membrane enclosed within the surrounding cell membrane.[23]

Discover more about Structure related topics

Basal body

Basal body

A basal body is a protein structure found at the base of a eukaryotic undulipodium. The basal body was named by Theodor Wilhelm Engelmann in 1880 It is formed from a centriole and several additional protein structures, and is, essentially, a modified centriole. The basal body serves as a nucleation site for the growth of the axoneme microtubules. Centrioles, from which basal bodies are derived, act as anchoring sites for proteins that in turn anchor microtubules, and are known as the microtubule organizing center (MTOC). These microtubules provide structure and facilitate movement of vesicles and organelles within many eukaryotic cells.

Caenorhabditis elegans

Caenorhabditis elegans

Caenorhabditis elegans is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek caeno- (recent), rhabditis (rod-like) and Latin elegans (elegant). In 1900, Maupas initially named it Rhabditides elegans. Osche placed it in the subgenus Caenorhabditis in 1952, and in 1955, Dougherty raised Caenorhabditis to the status of genus.

Drosophila melanogaster

Drosophila melanogaster

Drosophila melanogaster is a species of fly in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, D. melanogaster continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, five Nobel Prizes have been awarded to drosophilists for their work using the insect.

Chlamydomonas reinhardtii

Chlamydomonas reinhardtii

Chlamydomonas reinhardtii is a single-cell green alga about 10 micrometres in diameter that swims with two flagella. It has a cell wall made of hydroxyproline-rich glycoproteins, a large cup-shaped chloroplast, a large pyrenoid, and an eyespot that senses light.

Hedgehog signaling pathway

Hedgehog signaling pathway

The Hedgehog signaling pathway is a signaling pathway that transmits information to embryonic cells required for proper cell differentiation. Different parts of the embryo have different concentrations of hedgehog signaling proteins. The pathway also has roles in the adult. Diseases associated with the malfunction of this pathway include cancer.

Microtubule

Microtubule

Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement.

Cytoskeleton

Cytoskeleton

The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. It is composed of three main components, microfilaments, intermediate filaments and microtubules, and these are all capable of rapid growth or disassembly dependent on the cell's requirements.

Axoneme

Axoneme

An axoneme, also called an axial filament is the microtubule-based cytoskeletal structure that forms the core of a cilium or flagellum. Cilia and flagella are found on many cells, organisms, and microorganisms, to provide motility. The axoneme serves as the "skeleton" of these organelles, both giving support to the structure and, in some cases, the ability to bend. Though distinctions of function and length may be made between cilia and flagella, the internal structure of the axoneme is common to both.

Flagellum

Flagellum

A flagellum is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates.

Intraflagellar transport

Intraflagellar transport

Intraflagellar transport (IFT) is a bidirectional motility along axoneme microtubules that is essential for the formation (ciliogenesis) and maintenance of most eukaryotic cilia and flagella. It is thought to be required to build all cilia that assemble within a membrane projection from the cell surface. Plasmodium falciparum cilia and the sperm flagella of Drosophila are examples of cilia that assemble in the cytoplasm and do not require IFT. The process of IFT involves movement of large protein complexes called IFT particles or trains from the cell body to the ciliary tip and followed by their return to the cell body. The outward or anterograde movement is powered by kinesin-2 while the inward or retrograde movement is powered by cytoplasmic dynein 2/1b. The IFT particles are composed of about 20 proteins organized in two subcomplexes called complex A and B.

Axonal transport

Axonal transport

Axonal transport, also called axoplasmic transport or axoplasmic flow, is a cellular process responsible for movement of mitochondria, lipids, synaptic vesicles, proteins, and other organelles to and from a neuron's cell body, through the cytoplasm of its axon called the axoplasm. Since some axons are on the order of meters long, neurons cannot rely on diffusion to carry products of the nucleus and organelles to the end of their axons. Axonal transport is also responsible for moving molecules destined for degradation from the axon back to the cell body, where they are broken down by lysosomes.

Axon

Axon

An axon, or nerve fiber, is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons, such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired neurological disorders that affect both the peripheral and central neurons. Nerve fibers are classed into three types – group A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are unmyelinated. These groups include both sensory fibers and motor fibers. Another classification groups only the sensory fibers as Type I, Type II, Type III, and Type IV.

Types

Non-motile cilia

In animals, non-motile primary cilia are found on nearly every type of cell, blood cells being a prominent exception.[2] Most cells only possess one, in contrast to cells with motile cilia, an exception being olfactory sensory neurons, where the odorant receptors are located, which each possess about ten cilia. Some cell types, such as retinal photoreceptor cells, possess highly specialized primary cilia.[24]

Although the primary cilium was discovered in 1898, it was largely ignored for a century and considered a vestigial organelle without important function.[25][2] Recent findings regarding its physiological roles in chemosensation, signal transduction, and cell growth control, have revealed its importance in cell function. Its importance to human biology has been underscored by the discovery of its role in a diverse group of diseases caused by the dysgenesis or dysfunction of cilia, such as polycystic kidney disease,[26] congenital heart disease,[27] mitral valve prolapse,[28] and retinal degeneration,[29] called ciliopathies.[30][31] The primary cilium is now known to play an important role in the function of many human organs.[2][10] Primary cilia on pancreatic beta cells regulate their function and energy metabolism. Cilia deletion can lead to islet dysfunction and type 2 diabetes.[32]

Cilia are assembled during the G1 phase and are disassembled before mitosis occurs.[33][11] Disassembly of cilia requires the action of aurora kinase A.[34] The current scientific understanding of primary cilia views them as "sensory cellular antennae that coordinate many cellular signaling pathways, sometimes coupling the signaling to ciliary motility or alternatively to cell division and differentiation."[35] The cilium is composed of subdomains and enclosed by a plasma membrane continuous with the plasma membrane of the cell. For many cilia, the basal body, where the cilium originates, is located within a membrane invagination called the ciliary pocket. The cilium membrane and the basal body microtubules are connected by distal appendages (also called transition fibers). Vesicles carrying molecules for the cilia dock at the distal appendages. Distal to the transition fibers form a transition zone where entry and exit of molecules is regulated to and from the cilia. Some of the signaling with these cilia occur through ligand binding such as Hedgehog signaling.[36] Other forms of signaling include G protein-coupled receptors including the somatostatin receptor 3 in neurons.[37]

Illustration depicting motile cilia on respiratory epithelium.
Illustration depicting motile cilia on respiratory epithelium.

Modified non-motile cilia

Kinocilia that are found on hair cells in the inner ear are termed as specialized primary cilia, or modified non-motile cilia. They possess the 9+2 axoneme of the motile cilia but lack the inner dynein arms that give movement. They do move passively following the detection of sound, allowed by the outer dynein arms.[38][39]

Motile cilia

Tracheal respiratory epithelium showing cilia and much smaller microvilli on non-ciliated cells in scanning electron micrograph.
Tracheal respiratory epithelium showing cilia and much smaller microvilli on non-ciliated cells in scanning electron micrograph.

Mammals also have motile cilia or secondary cilia that are usually present on a cell's surface in large numbers (multiciliate), and beat in coordinated metachronal waves.[40] Multiciliated cells are found lining the respiratory tract where they function in mucociliary clearance sweeping mucus containing debris away from the lungs.[13] Each cell in the respiratory epithelium has around 200 motile cilia.[12]

In the reproductive tract, smooth muscle contractions help the beating of the cilia in moving the egg cell from the ovary to the uterus.[13][15] In the ventricles of the brain ciliated ependymal cells circulate the cerebrospinal fluid.

The functioning of motile cilia is strongly dependent on the maintenance of optimal levels of periciliary fluid bathing the cilia. Epithelial sodium channels (ENaCs) are specifically expressed along the entire length of cilia in the respiratory tract, and Fallopian tube or oviduct that apparently serve as sensors to regulate the periciliary fluid.[13][41]

Modified motile cilia

Motile cilia without the central pair of singlets (9+0) are found in early embryonic development. They are present as nodal cilia on the nodal cells of the primitive node. Nodal cells are responsible for the left-right asymmetry in bilateral animals.[16] While lacking the central apparatus there are dynein arms present that allow the nodal cilia to move in a spinning fashion. The movement creates a current flow of the extraembryonic fluid across the nodal surface in a leftward direction that initiates the left-right asymmetry in the developing embryo. [12][42]

Motile, multiple, 9+0 cilia are found on the epithelial cells of the choroid plexus. Cilia also can change structure when introduced to hot temperatures and become sharp. They are present in large numbers on each cell and move relatively slowly, making them intermediate between motile and primary cilia. In addition to 9+0 cilia that are mobile, there are also solitary 9+2 cilia that stay immobile found in hair cells.[39]

Nodal cilia

Scanning electron micrograph of nodal cilia on a mouse embryo
Scanning electron micrograph of nodal cilia on a mouse embryo

Nodal cells have a single cilium called a monocilium. They are present in the very early development of the embryo on the primitive node. There are two areas of the node with different types of nodal cilia. On the central node are motile cilia, and on the peripheral area of the node the nodal cilia are modified motile.[42]

The motile cilia on the central cells rotate to generate the leftward flow of extracellular fluid needed to initiate the left-right asymmetry.[42]

Cilia versus flagella

See also: Flagellum § Terminology

The motile cilia on sperm cells and many protozoans enables swimming through liquids and are traditionally referred to as "flagella".[3] As these protrusions are structurally identical to motile cilia, attempts at preserving this terminology include making a distinction by morphology ("flagella" are typically longer than ordinary cilia and have a different undulating motion)[4] and by number.[43]

Microorganisms

Ciliates are eukaryotic microorganisms that possess motile cilia exclusively and use them for either locomotion or to simply move liquid over their surface. A Paramecium for example is covered in thousands of cilia that enable its swimming. These motile cilia have been shown to be also sensory.[44]

Discover more about Types related topics

Polycystic kidney disease

Polycystic kidney disease

Polycystic kidney disease is a genetic disorder in which the renal tubules become structurally abnormal, resulting in the development and growth of multiple cysts within the kidney. These cysts may begin to develop in utero, in infancy, in childhood, or in adulthood. Cysts are non-functioning tubules filled with fluid pumped into them, which range in size from microscopic to enormous, crushing adjacent normal tubules and eventually rendering them non-functional as well.

Mitral valve prolapse

Mitral valve prolapse

Mitral valve prolapse (MVP) is a valvular heart disease characterized by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. It is the primary form of myxomatous degeneration of the valve. There are various types of MVP, broadly classified as classic and nonclassic. In severe cases of classic MVP, complications include mitral regurgitation, infective endocarditis, congestive heart failure, and, in rare circumstances, cardiac arrest.

Ciliopathy

Ciliopathy

A ciliopathy is any genetic disorder that affects the cellular cilia or the cilia anchoring structures, the basal bodies, or ciliary function. Primary cilia are important in guiding the process of development, so abnormal ciliary function while an embryo is developing can lead to a set of malformations that can occur regardless of the particular genetic problem. The similarity of the clinical features of these developmental disorders means that they form a recognizable cluster of syndromes, loosely attributed to abnormal ciliary function and hence called ciliopathies. Regardless of the actual genetic cause, it is clustering of a set of characteristic physiological features which define whether a syndrome is a ciliopathy.

Beta cell

Beta cell

Beta cells (β-cells) are a type of cell found in pancreatic islets that synthesize and secrete insulin and amylin. Beta cells make up 50–70% of the cells in human islets. In patients with Type 1 diabetes, beta-cell mass and function are diminished, leading to insufficient insulin secretion and hyperglycemia.

G1 phase

G1 phase

The G1 phase, gap 1 phase, or growth 1 phase, is the first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis. G1 phase ends when the cell moves into the S phase of interphase. Around 30 to 40 percent of cell cycle time is spent in the G1 phase.

Aurora kinase A

Aurora kinase A

Aurora kinase A also known as serine/threonine-protein kinase 6 is an enzyme that in humans is encoded by the AURKA gene.

Cell (biology)

Cell (biology)

The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites. The term comes from the Latin word cellula meaning 'small room'.

Basal body

Basal body

A basal body is a protein structure found at the base of a eukaryotic undulipodium. The basal body was named by Theodor Wilhelm Engelmann in 1880 It is formed from a centriole and several additional protein structures, and is, essentially, a modified centriole. The basal body serves as a nucleation site for the growth of the axoneme microtubules. Centrioles, from which basal bodies are derived, act as anchoring sites for proteins that in turn anchor microtubules, and are known as the microtubule organizing center (MTOC). These microtubules provide structure and facilitate movement of vesicles and organelles within many eukaryotic cells.

G protein-coupled receptor

G protein-coupled receptor

G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. Since they are coupled with G proteins, they pass through the cell membrane seven times in form of six loops of amino acid residues, which is why they are sometimes referred to as seven-transmembrane receptors. Ligands can bind either to the extracellular N-terminus and loops or to the binding site within transmembrane helices. They are all activated by agonists, although a spontaneous auto-activation of an empty receptor has also been observed.

Somatostatin receptor 3

Somatostatin receptor 3

Shekel Somatostatin receptor type 3 is a protein that in humans is encoded by the SSTR3 gene.

Respiratory epithelium

Respiratory epithelium

Respiratory epithelium, or airway epithelium, is a type of ciliated columnar epithelium found lining most of the respiratory tract as respiratory mucosa, where it serves to moisten and protect the airways. It is not present in the vocal cords of the larynx, or the oropharynx and laryngopharynx, where instead the epithelium is stratified squamous. It also functions as a barrier to potential pathogens and foreign particles, preventing infection and tissue injury by the secretion of mucus and the action of mucociliary clearance.

Trachea

Trachea

The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends from the larynx and branches into the two primary bronchi. At the top of the trachea the cricoid cartilage attaches it to the larynx. The trachea is formed by a number of horseshoe-shaped rings, joined together vertically by overlying ligaments, and by the trachealis muscle at their ends. The epiglottis closes the opening to the larynx during swallowing.

Ciliogenesis

Main article: Ciliogenesis

Cilia are formed through the process of ciliogenesis. An early step is docking of the basal body to the growing ciliary membrane, after which the transition zone forms. The building blocks of the ciliary axoneme, such as tubulins, are added at the ciliary tips through a process that depends partly on intraflagellar transport (IFT).[45][46] Exceptions include Drosophila sperm and Plasmodium falciparum flagella formation, in which cilia assemble in the cytoplasm.[47]

At the base of the cilium where it attaches to the cell body is the microtubule organizing center, the basal body. Some basal body proteins as CEP164, ODF2[48] and CEP170,[49] are required for the formation and the stability of the cilium.

In effect, the cilium is a nanomachine composed of perhaps over 600 proteins in molecular complexes, many of which also function independently as nanomachines. Flexible linkers allow the mobile protein domains connected by them to recruit their binding partners and induce long-range allostery via protein domain dynamics.[35]

Discover more about Ciliogenesis related topics

Ciliogenesis

Ciliogenesis

Ciliogenesis is defined as the building of the cell's antenna or extracellular fluid mediation mechanism. It includes the assembly and disassembly of the cilia during the cell cycle. Cilia are important organelles of cells and are involved in numerous activities such as cell signaling, processing developmental signals, and directing the flow of fluids such as mucus over and around cells. Due to the importance of these cell processes, defects in ciliogenesis can lead to numerous human diseases related to non-functioning cilia. Ciliogenesis may also play a role in the development of left/right handedness in humans.

Intraflagellar transport

Intraflagellar transport

Intraflagellar transport (IFT) is a bidirectional motility along axoneme microtubules that is essential for the formation (ciliogenesis) and maintenance of most eukaryotic cilia and flagella. It is thought to be required to build all cilia that assemble within a membrane projection from the cell surface. Plasmodium falciparum cilia and the sperm flagella of Drosophila are examples of cilia that assemble in the cytoplasm and do not require IFT. The process of IFT involves movement of large protein complexes called IFT particles or trains from the cell body to the ciliary tip and followed by their return to the cell body. The outward or anterograde movement is powered by kinesin-2 while the inward or retrograde movement is powered by cytoplasmic dynein 2/1b. The IFT particles are composed of about 20 proteins organized in two subcomplexes called complex A and B.

Plasmodium falciparum

Plasmodium falciparum

Plasmodium falciparum is a unicellular protozoan parasite of humans, and the deadliest species of Plasmodium that causes malaria in humans. The parasite is transmitted through the bite of a female Anopheles mosquito and causes the disease's most dangerous form, falciparum malaria. It is responsible for around 50% of all malaria cases. P. falciparum is therefore regarded as the deadliest parasite in humans. It is also associated with the development of blood cancer and is classified as a Group 2A (probable) carcinogen.

Microtubule organizing center

Microtubule organizing center

The microtubule-organizing center (MTOC) is a structure found in eukaryotic cells from which microtubules emerge. MTOCs have two main functions: the organization of eukaryotic flagella and cilia and the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division. The MTOC is a major site of microtubule nucleation and can be visualized in cells by immunohistochemical detection of γ-tubulin. The morphological characteristics of MTOCs vary between the different phyla and kingdoms. In animals, the two most important types of MTOCs are 1) the basal bodies associated with cilia and flagella and 2) the centrosome associated with spindle formation.

Basal body

Basal body

A basal body is a protein structure found at the base of a eukaryotic undulipodium. The basal body was named by Theodor Wilhelm Engelmann in 1880 It is formed from a centriole and several additional protein structures, and is, essentially, a modified centriole. The basal body serves as a nucleation site for the growth of the axoneme microtubules. Centrioles, from which basal bodies are derived, act as anchoring sites for proteins that in turn anchor microtubules, and are known as the microtubule organizing center (MTOC). These microtubules provide structure and facilitate movement of vesicles and organelles within many eukaryotic cells.

CEP164

CEP164

Centrosomal protein of 164 kDa, also known as CEP164, is a protein that in humans is encoded by the CEP164 gene. Its function appears two be twofold: CEP164 is required for primary cilium formation. Furthermore, it is an important component in the response to DNA damage by UV light.

ODF2

ODF2

Outer dense fiber protein 2, also known as cenexin, is a protein that in humans is encoded by the ODF2 gene.

CEP170

CEP170

Centrosomal protein 170kDa, also known as CEP170, is a protein that in humans is encoded by the CEP170 gene.

Molecular machine

Molecular machine

A molecular machine, nanite, or nanomachine is a molecular component that produces quasi-mechanical movements (output) in response to specific stimuli (input). In cellular biology, macromolecular machines frequently perform tasks essential for life, such as DNA replication and ATP synthesis. The expression is often more generally applied to molecules that simply mimic functions that occur at the macroscopic level. The term is also common in nanotechnology where a number of highly complex molecular machines have been proposed that are aimed at the goal of constructing a molecular assembler.

Function

The dynein in the axoneme – axonemal dynein forms bridges between neighbouring microtubule doublets. When ATP activates the motor domain of dynein, it attempts to walk along the adjoining microtubule doublet. This would force the adjacent doublets to slide over one another if not for the presence of nexin between the microtubule doublets. And thus the force generated by dynein is instead converted into a bending motion.[50][51]

Sensing the extracellular environment

Some primary cilia on epithelial cells in eukaryotes act as cellular antennae, providing chemosensation, thermosensation and mechanosensation of the extracellular environment.[52][10] These cilia then play a role in mediating specific signalling cues, including soluble factors in the external cell environment, a secretory role in which a soluble protein is released to have an effect downstream of the fluid flow, and mediation of fluid flow if the cilia are motile.[52]

Some epithelial cells are ciliated, and they commonly exist as a sheet of polarized cells forming a tube or tubule with cilia projecting into the lumen. This sensory and signalling role puts cilia in a central role for maintaining the local cellular environment and may be why ciliary defects cause such a wide range of human diseases.[31]

In the embryo, nodal cilia are used to direct the flow of extracellular fluid. This leftward movement is to generate left-right asymmetry across the midline of the embryo. Central cilia coordinate their rotational beating while the immotile cilia on the sides sense the direction of the flow.[42][53][54] Studies in mice suggest a biophysical mechanism by which the direction of flow is sensed.[55]

Axo-ciliary synapse

With axo-ciliary synapses, there is communication between serotonergic axons and primary cilia of CA1 pyramidal neurons that alters the neuron's epigenetic state in the nucleus – "a way to change what is being transcribed or made in the nucleus" via this signalling distinct from that at the plasma membrane which also is longer-term.[56][57]

Discover more about Function related topics

Dynein

Dynein

Dyneins are a family of cytoskeletal motor proteins that move along microtubules in cells. They convert the chemical energy stored in ATP to mechanical work. Dynein transports various cellular cargos, provides forces and displacements important in mitosis, and drives the beat of eukaryotic cilia and flagella. All of these functions rely on dynein's ability to move towards the minus-end of the microtubules, known as retrograde transport; thus, they are called "minus-end directed motors". In contrast, most kinesin motor proteins move toward the microtubules' plus-end, in what is called anterograde transport.

Adenosine triphosphate

Adenosine triphosphate

Adenosine triphosphate (ATP) is an organic compound that provides energy to drive and support many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer. When consumed in metabolic processes, it converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP. The human body recycles its own body weight equivalent in ATP each day. It is also a precursor to DNA and RNA, and is used as a coenzyme.

Nexin

Nexin

Nexin is a proteinous inter-doublet linkage that prevents microtubules in the outer layer of axonemes from moving with respect to one another; otherwise, vesicular transport proteins such as dynein would dissolve the whole structure.

Molecular sensor

Molecular sensor

A molecular sensor or chemosensor is a molecular structure that is used for sensing of an analyte to produce a detectable change or a signal. The action of a chemosensor, relies on an interaction occurring at the molecular level, usually involves the continuous monitoring of the activity of a chemical species in a given matrix such as solution, air, blood, tissue, waste effluents, drinking water, etc. The application of chemosensors is referred to as chemosensing, which is a form of molecular recognition. All chemosensors are designed to contain a signalling moiety and a recognition moiety, that is connected either directly to each other or through a some kind of connector or a spacer. The signalling is often optically based electromagnetic radiation, giving rise to changes in either the ultraviolet and visible absorption or the emission properties of the sensors. Chemosensors may also be electrochemically based. Small molecule sensors are related to chemosensors. These are traditionally, however, considered as being structurally simple molecules and reflect the need to form chelating molecules for complexing ions in analytical chemistry. Chemosensors are synthetic analogues of biosensors, the difference being that biosensors incorporate biological receptors such as antibodies, aptamers or large biopolymers.

Mechanosensation

Mechanosensation

Mechanosensation is the transduction of mechanical stimuli into neural signals. Mechanosensation provides the basis for the senses of light touch, hearing, proprioception, and pain. Mechanoreceptors found in the skin, called cutaneous mechanoreceptors, are responsible for the sense of touch. Tiny cells in the inner ear, called hair cells, are responsible for hearing and balance. States of neuropathic pain, such as hyperalgesia and allodynia, are also directly related to mechanosensation. A wide array of elements are involved in the process of mechanosensation, many of which are still not fully understood.

Secretion

Secretion

Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical mechanism of cell secretion is via secretory portals at the plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structures embedded in the cell membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell.

Motility

Motility

Motility is the ability of an organism to move independently, using metabolic energy.

Lumen (anatomy)

Lumen (anatomy)

In biology, a lumen is the inside space of a tubular structure, such as an artery or intestine. It comes from Latin lumen 'an opening'.

Ciliopathy

Ciliopathy

A ciliopathy is any genetic disorder that affects the cellular cilia or the cilia anchoring structures, the basal bodies, or ciliary function. Primary cilia are important in guiding the process of development, so abnormal ciliary function while an embryo is developing can lead to a set of malformations that can occur regardless of the particular genetic problem. The similarity of the clinical features of these developmental disorders means that they form a recognizable cluster of syndromes, loosely attributed to abnormal ciliary function and hence called ciliopathies. Regardless of the actual genetic cause, it is clustering of a set of characteristic physiological features which define whether a syndrome is a ciliopathy.

Left-right asymmetry

Left-right asymmetry

Left-right asymmetry is the process in early embryonic development that breaks the normal symmetry in the bilateral embryo. In vertebrates, left-right asymmetry is established early in development at a structure called the left-right organizer and leads to activation of different signalling pathways on the left and right of the embryo. This in turn cause several organs in adults to develop LR asymmetry, such as the tilt of the heart, the different number lung lobes on each side of the body and the position of the stomach and spleen on the right side of the body. If this process does not occur correctly in humans it can result in the syndromes heterotaxy or situs inversus.

Axon

Axon

An axon, or nerve fiber, is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons, such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired neurological disorders that affect both the peripheral and central neurons. Nerve fibers are classed into three types – group A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are unmyelinated. These groups include both sensory fibers and motor fibers. Another classification groups only the sensory fibers as Type I, Type II, Type III, and Type IV.

Pyramidal cell

Pyramidal cell

Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons are also one of two cell types where the characteristic sign, Negri bodies, are found in post-mortem rabies infection. Pyramidal neurons were first discovered and studied by Santiago Ramón y Cajal. Since then, studies on pyramidal neurons have focused on topics ranging from neuroplasticity to cognition.

Clinical significance

Main article: Ciliopathy

Ciliary defects can lead to a number of human diseases.[31][58] Defects in cilia adversely affect many critical signaling pathways essential to embryonic development and to adult physiology, and thus offer a plausible hypothesis for the often multi-symptom nature of diverse ciliopathies.[30][31] Known ciliopathies include primary ciliary dyskinesia, Bardet–Biedl syndrome, polycystic kidney and liver disease, nephronophthisis, Alström syndrome, Meckel–Gruber syndrome, Sensenbrenner syndrome and some forms of retinal degeneration.[30][52] Genetic mutations compromising the proper functioning of cilia, ciliopathies, can cause chronic disorders such as primary ciliary dyskinesia (PCD), nephronophthisis, and Senior–Løken syndrome. In addition, a defect of the primary cilium in the renal tubule cells can lead to polycystic kidney disease (PKD). In another genetic disorder called Bardet–Biedl syndrome (BBS), the mutant gene products are the components in the basal body and cilia.[30] Defects in cilia cells are linked to obesity and often pronounced in type 2 diabetes. Several studies already showed impaired glucose tolerance and reduction in the insulin secretion in the ciliopathy models. Moreover, the number and length of cilia was decreased in the type 2 diabetes models.[59]

Epithelial sodium channels (ENaCs) that are expressed along the length of cilia regulate periciliary fluid level. Mutations that decrease the activity of ENaCs result in multisystem pseudohypoaldosteronism, that is associated with fertility problems.[13] In cystic fibrosis that results from mutations in the chloride channel CFTR, ENaC activity is enhanced leading to a severe reduction of the fluid level that causes complications and infections in the respiratory airways.[41]

Since the flagellum of human sperm has the same internal structure of a cilium, ciliary dysfunction can also be responsible for male infertility.[60]

There is an association of primary ciliary dyskinesia with left-right anatomic abnormalities such as situs inversus (a combination of findings is known as Kartagener syndrome), and situs ambiguus (also known as Heterotaxy syndrome).[61] These left-right anatomic abnormalities can also result in congenital heart disease.[62] It has been shown that proper cilial function is responsible for the normal left-right asymmetry in mammals.[63]

The diverse outcomes caused by ciliary dysfunction may result from alleles of different strengths that compromise ciliary functions in different ways or to different extents. Many ciliopathies are inherited in a Mendelian manner, but specific genetic interactions between distinct functional ciliary complexes, such as transition zone and BBS complexes, can alter the phenotypic manifestations of recessive ciliopathies.[64][65] Some mutations in transition zone proteins can cause specific serious ciliopathies.[66]

Extracellular changes

Reduction of cilia function can also result from infection. Research into biofilms has shown that bacteria can alter cilia. A biofilm is a community of bacteria of either the same or multiple species of bacteria. The cluster of cells secretes different factors which form an extracellular matrix. Cilia in the respiratory system is known to move mucus and pathogens out of the airways. It has been found that patients with biofilm positive infections have impaired cilia function. The impairment may present as decreased motion or reduction in the number of cilia. Though these changes result from an external source, they still effect the pathogenicity of the bacteria, progression of infection, and how it is treated.[67]

The transportation of the immature egg cell, and the embryo to the uterus for implantation depends on the combination of regulated smooth muscle contractions, and ciliary beating. Dysfunction in this transportation can result in an ectopic pregnancy where the embryo is implanted (usually) in the Fallopian tube before reaching its proper destination of the uterus. Many factors can affect this stage including infection and menstrual cycle hormones. Smoking (causing inflammation), and infection can reduce the numbers of cilia, and the ciliary beat can be affected by hormonal changes.[15][68]

Primary cilia in pancreatic cells

The pancreas is a mixture of highly differentiated exocrine and endocrine cells. Primary cilia are present in exocrine cells which are centroacinar, duct cells.[69][32] Endocrine tissue is composed of different hormone secreting cells. Insulin secreting beta cells and glucagon secreting alpha cells which are highly ciliated.[70][71]

Discover more about Clinical significance related topics

Ciliopathy

Ciliopathy

A ciliopathy is any genetic disorder that affects the cellular cilia or the cilia anchoring structures, the basal bodies, or ciliary function. Primary cilia are important in guiding the process of development, so abnormal ciliary function while an embryo is developing can lead to a set of malformations that can occur regardless of the particular genetic problem. The similarity of the clinical features of these developmental disorders means that they form a recognizable cluster of syndromes, loosely attributed to abnormal ciliary function and hence called ciliopathies. Regardless of the actual genetic cause, it is clustering of a set of characteristic physiological features which define whether a syndrome is a ciliopathy.

Primary ciliary dyskinesia

Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare, autosomal recessive genetic ciliopathy, that causes defects in the action of cilia lining the upper and lower respiratory tract, sinuses, Eustachian tube, middle ear, Fallopian tube, and flagella of sperm cells. The alternative name of "immotile ciliary syndrome" is no longer favored as the cilia do have movement, but are merely inefficient or unsynchronized. When accompanied by situs inversus the condition is known as Kartagener syndrome.

Bardet–Biedl syndrome

Bardet–Biedl syndrome

Bardet–Biedl syndrome (BBS) is a ciliopathic human genetic disorder that produces many effects and affects many body systems. It is characterized by rod/cone dystrophy, polydactyly, central obesity, hypogonadism, and kidney dysfunction in some cases. Historically, slower mental processing has also been considered a principal symptom but is now not regarded as such.

Polycystic kidney disease

Polycystic kidney disease

Polycystic kidney disease is a genetic disorder in which the renal tubules become structurally abnormal, resulting in the development and growth of multiple cysts within the kidney. These cysts may begin to develop in utero, in infancy, in childhood, or in adulthood. Cysts are non-functioning tubules filled with fluid pumped into them, which range in size from microscopic to enormous, crushing adjacent normal tubules and eventually rendering them non-functional as well.

Polycystic liver disease

Polycystic liver disease

Polycystic liver disease (PLD) usually describes the presence of multiple cysts scattered throughout normal liver tissue. PLD is commonly seen in association with autosomal-dominant polycystic kidney disease, with a prevalence of 1 in 400 to 1000, and accounts for 8–10% of all cases of end-stage renal disease. The much rarer autosomal-dominant polycystic liver disease will progress without any kidney involvement.

Nephronophthisis

Nephronophthisis

Nephronophthisis is a genetic disorder of the kidneys which affects children. It is classified as a medullary cystic kidney disease. The disorder is inherited in an autosomal recessive fashion and, although rare, is the most common genetic cause of childhood kidney failure. It is a form of ciliopathy. Its incidence has been estimated to be 0.9 cases per million people in the United States, and 1 in 50,000 births in Canada.

Alström syndrome

Alström syndrome

Alström syndrome (AS), also called Alström–Hallgren syndrome, is a very rare autosomal recessive genetic disorder characterised by childhood obesity and multiple organ dysfunction. Symptoms include early-onset type 2 diabetes, cone-rod dystrophy resulting in blindness, sensorineural hearing loss and dilated cardiomyopathy. Endocrine disorders typically also occur, such as hypergonadotrophic hypogonadism and hypothyroidism, as well as acanthosis nigricans resulting from hyperinsulinemia. Developmental delay is seen in almost half of people with Alström syndrome.

Meckel–Gruber syndrome

Meckel–Gruber syndrome

Meckel-Gruber syndrome is a rare, lethal ciliopathic genetic disorder, characterized by renal cystic dysplasia, central nervous system malformations, polydactyly (postaxial), hepatic developmental defects, and pulmonary hypoplasia due to oligohydramnios. Meckel–Gruber syndrome is named for Johann Meckel and Georg Gruber.

Sensenbrenner syndrome

Sensenbrenner syndrome

Sensenbrenner syndrome is a rare multisystem disease first described by Judith A. Sensenbrenner in 1975. It is inherited in an autosomal recessive fashion, and a number of genes appear to be responsible. Three genes responsible have been identified: intraflagellar transport (IFT)122 (WDR10), IFT43—a subunit of the IFT complex A machinery of primary cilia, and WDR35

Retinopathy

Retinopathy

Retinopathy is any damage to the retina of the eyes, which may cause vision impairment. Retinopathy often refers to retinal vascular disease, or damage to the retina caused by abnormal blood flow. Age-related macular degeneration is technically included under the umbrella term retinopathy but is often discussed as a separate entity. Retinopathy, or retinal vascular disease, can be broadly categorized into proliferative and non-proliferative types. Frequently, retinopathy is an ocular manifestation of systemic disease as seen in diabetes or hypertension. Diabetes is the most common cause of retinopathy in the U.S. as of 2008. Diabetic retinopathy is the leading cause of blindness in working-aged people. It accounts for about 5% of blindness worldwide and is designated a priority eye disease by the World Health Organization.

Senior–Løken syndrome

Senior–Løken syndrome

Senior–Løken syndrome is a congenital eye disorder, first characterized in 1961. It is a rare, ciliopathic, autosomal recessive disorder characterized by juvenile nephronophthis and progressive eye disease.

Type 2 diabetes

Type 2 diabetes

Type 2 diabetes, formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urination, and unexplained weight loss. Symptoms may also include increased hunger, feeling tired, and sores (wounds) that do not heal. Often symptoms come on slowly. Long-term complications from high blood sugar include heart disease, strokes, diabetic retinopathy which can result in blindness, kidney failure, and poor blood flow in the limbs which may lead to amputations. The sudden onset of hyperosmolar hyperglycemic state may occur; however, ketoacidosis is uncommon.

Source: "Cilium", Wikipedia, Wikimedia Foundation, (2023, January 30th), https://en.wikipedia.org/wiki/Cilium.

Enjoying Wikiz?

Enjoying Wikiz?

Get our FREE extension now!

Download Extension

Further Reading

Flagellum

Cytoskeleton

Dynein

Primary ciliary dyskinesia

Basal body

Axoneme

Intraflagellar transport

Undulipodium

CEP290

Kinesin-like protein KIF3A

DNAI1

IFT20

Ciliopathy

Hydrolethalus syndrome

MORM syndrome
See also
References
  1. ^ "Definition of CILIUM". www.merriam-webster.com. Retrieved 15 April 2022.
  2. ^ a b c d e Gardiner MB (September 2005). "The Importance of Being Cilia" (PDF). HHMI Bulletin. 18 (2). Retrieved 26 July 2008.
  3. ^ a b Haimo LT, Rosenbaum JL (December 1981). "Cilia, flagella, and microtubules". The Journal of Cell Biology. 91 (3 Pt 2): 125s–130s. doi:10.1083/jcb.91.3.125s. PMC 2112827. PMID 6459327.
  4. ^ a b Alberts, Bruce (2015). Molecular biology of the cell (Sixth ed.). New York, NY. pp. 941–942. ISBN 9780815344643.
  5. ^ a b c Falk, N; Lösl, M; Schröder, N; Gießl, A (11 September 2015). "Specialized Cilia in Mammalian Sensory Systems". Cells. 4 (3): 500–19. doi:10.3390/cells4030500. PMC 4588048. PMID 26378583.
  6. ^ Wheatley, DN (September 2021). "Primary cilia: turning points in establishing their ubiquity, sensory role and the pathological consequences of dysfunction". Journal of Cell Communication and Signaling. 15 (3): 291–297. doi:10.1007/s12079-021-00615-5. PMC 8222448. PMID 33970456.
  7. ^ a b Fisch, C; Dupuis-Williams, P (June 2011). "Ultrastructure of cilia and flagella - back to the future!". Biology of the Cell. 103 (6): 249–70. doi:10.1042/BC20100139. PMID 21728999. S2CID 7636387.
  8. ^ Prevo, B; Scholey, JM; Peterman, EJG (September 2017). "Intraflagellar transport: mechanisms of motor action, cooperation, and cargo delivery". The FEBS Journal. 284 (18): 2905–2931. doi:10.1111/febs.14068. PMC 5603355. PMID 28342295.
  9. ^ Elliott, Kelsey H.; Brugmann, Samantha A. (1 March 2019). "Sending mixed signals: Cilia-dependent signaling during development and disease". Developmental Biology. 447 (1): 28–41. doi:10.1016/j.ydbio.2018.03.007. ISSN 1095-564X. PMC 6136992. PMID 29548942.
  10. ^ a b c Singla, Veena; Reiter, Jeremy F. (4 August 2006). "The primary cilium as the cell's antenna: signaling at a sensory organelle". Science. 313 (5787): 629–633. Bibcode:2006Sci...313..629S. doi:10.1126/science.1124534. ISSN 1095-9203. PMID 16888132. S2CID 29885142.
  11. ^ a b Patel, MM; Tsiokas, L (1 November 2021). "Insights into the Regulation of Ciliary Disassembly". Cells. 10 (11): 2977. doi:10.3390/cells10112977. PMC 8616418. PMID 34831200.
  12. ^ a b c Horani, A; Ferkol, T (May 2018). "Advances in the Genetics of Primary Ciliary Dyskinesia". Chest. 154 (3): 645–652. doi:10.1016/j.chest.2018.05.007. PMC 6130327. PMID 29800551.
  13. ^ a b c d e f Enuka Y, Hanukoglu I, Edelheit O, Vaknine H, Hanukoglu A (March 2012). "Epithelial sodium channels (ENaC) are uniformly distributed on motile cilia in the oviduct and the respiratory airways". Histochemistry and Cell Biology. 137 (3): 339–53. doi:10.1007/s00418-011-0904-1. PMID 22207244. S2CID 15178940.
  14. ^ Bloodgood, RA (15 February 2010). "Sensory reception is an attribute of both primary cilia and motile cilia". Journal of Cell Science. 123 (Pt 4): 505–9. doi:10.1242/jcs.066308. PMID 20144998. S2CID 207165576.
  15. ^ a b c Panelli, DM; Phillips, CH; Brady, PC (2015). "Incidence, diagnosis and management of tubal and nontubal ectopic pregnancies: a review". Fertility Research and Practice. 1: 15. doi:10.1186/s40738-015-0008-z. PMC 5424401. PMID 28620520.
  16. ^ a b Desgrange, A; Le Garrec, JF; Meilhac, SM (22 November 2018). "Left-right asymmetry in heart development and disease: forming the right loop" (PDF). Development. 145 (22). doi:10.1242/dev.162776. PMID 30467108. S2CID 53719458. Archived (PDF) from the original on 9 October 2022.
  17. ^ "Rootelin". Retrieved 28 March 2022.
  18. ^ Garcia, Galo; Raleigh, David R.; Reiter, Jeremy F. (23 April 2018). "How the Ciliary Membrane Is Organized Inside-Out to Communicate Outside-In". Current Biology. 28 (8): R421–R434. doi:10.1016/j.cub.2018.03.010. ISSN 1879-0445. PMC 6434934. PMID 29689227.
  19. ^ Garcia-Gonzalo, Francesc R.; Reiter, Jeremy F. (1 February 2017). "Open Sesame: How Transition Fibers and the Transition Zone Control Ciliary Composition". Cold Spring Harbor Perspectives in Biology. 9 (2): a028134. doi:10.1101/cshperspect.a028134. ISSN 1943-0264. PMC 5287074. PMID 27770015.
  20. ^ Gonçalves, João; Pelletier, Laurence (April 2017). "The Ciliary Transition Zone: Finding the Pieces and Assembling the Gate". Molecules and Cells. 40 (4): 243–253. doi:10.14348/molcells.2017.0054. ISSN 0219-1032. PMC 5424270. PMID 28401750.
  21. ^ Rosenbaum JL, Witman GB (November 2002). "Intraflagellar transport". Nature Reviews. Molecular Cell Biology. 3 (11): 813–25. doi:10.1038/nrm952. PMID 12415299. S2CID 12130216.
  22. ^ Scholey JM (January 2008). "Intraflagellar transport motors in cilia: moving along the cell's antenna". The Journal of Cell Biology. 180 (1): 23–29. doi:10.1083/jcb.200709133. PMC 2213603. PMID 18180368.
  23. ^ Rohatgi R, Snell WJ (August 2010). "The ciliary membrane". Current Opinion in Cell Biology. 22 (4): 541–46. doi:10.1016/j.ceb.2010.03.010. PMC 2910237. PMID 20399632.
  24. ^ Wolfrum, U; Schmitt, A (June 2000). "Rhodopsin transport in the membrane of the connecting cilium of mammalian photoreceptor cells". Cell Motility and the Cytoskeleton. 46 (2): 95–107. doi:10.1002/1097-0169(200006)46:23.0.CO;2-Q. PMID 10891855.
  25. ^ Satir, Peter (2017). "CILIA: before and after". Cilia. 6: 1. doi:10.1186/s13630-017-0046-8. ISSN 2046-2530. PMC 5343305. PMID 28293419.
  26. ^ Wagner CA (2008). "News from the cyst: insights into polycystic kidney disease". Journal of Nephrology. 21 (1): 14–16. PMID 18264930.
  27. ^ Brueckner M (June 2007). "Heterotaxia, congenital heart disease, and primary ciliary dyskinesia". Circulation. 115 (22): 2793–95. doi:10.1161/CIRCULATIONAHA.107.699256. PMID 17548739.
  28. ^ Toomer KA, et al. (2019). "Primary cilia defects causing mitral valve prolapse". Sci. Transl. Med. 11 (493): eaax0290. doi:10.1126/scitranslmed.aax0290. PMC 7331025. PMID 31118289.
  29. ^ Chen, Holly Y.; Kelley, Ryan A.; Li, Tiansen; Swaroop, Anand (31 July 2020). "Primary cilia biogenesis and associated retinal ciliopathies". Seminars in Cell & Developmental Biology. 110: 70–88. doi:10.1016/j.semcdb.2020.07.013. ISSN 1096-3634. PMC 7855621. PMID 32747192.
  30. ^ a b c d Badano JL, Mitsuma N, Beales PL, Katsanis N (2006). "The ciliopathies: an emerging class of human genetic disorders". Annual Review of Genomics and Human Genetics. 7: 125–48. doi:10.1146/annurev.genom.7.080505.115610. PMID 16722803.
  31. ^ a b c d Reiter, Jeremy F.; Leroux, Michel R. (September 2017). "Genes and molecular pathways underpinning ciliopathies". Nature Reviews. Molecular Cell Biology. 18 (9): 533–547. doi:10.1038/nrm.2017.60. ISSN 1471-0080. PMC 5851292. PMID 28698599.
  32. ^ a b Hegyi, P; Petersen, OH (2013). "The exocrine pancreas: the acinar-ductal tango in physiology and pathophysiology". Reviews of Physiology, Biochemistry and Pharmacology. 165: 1–30. doi:10.1007/112_2013_14. ISBN 978-3-319-00998-8. PMID 23881310.
  33. ^ Pan J, Snell W (June 2007). "The primary cilium: keeper of the key to cell division". Cell. 129 (7): 1255–57. doi:10.1016/j.cell.2007.06.018. PMID 17604715. S2CID 17712155.
  34. ^ Pugacheva EN, Jablonski SA, Hartman TR, Henske EP, Golemis EA (June 2007). "HEF1-dependent Aurora A activation induces disassembly of the primary cilium". Cell. 129 (7): 1351–63. doi:10.1016/j.cell.2007.04.035. PMC 2504417. PMID 17604723.
  35. ^ a b Satir P, Christensen ST (June 2008). "Structure and function of mammalian cilia". Histochemistry and Cell Biology. 129 (6): 687–93. doi:10.1007/s00418-008-0416-9. PMC 2386530. PMID 18365235.
  36. ^ Wong, Sunny Y.; Reiter, Jeremy F. (2008). "The primary cilium at the crossroads of mammalian hedgehog signaling". Current Topics in Developmental Biology. 85: 225–260. doi:10.1016/S0070-2153(08)00809-0. ISSN 0070-2153. PMC 2653622. PMID 19147008.
  37. ^ Wheway G, Nazlamova L, Hancock JT (2018). "Signaling through the Primary Cilium". Frontiers in Cell and Developmental Biology. 6: 8. doi:10.3389/fcell.2018.00008. PMC 5809511. PMID 29473038.
  38. ^ Wang, D; Zhou, J (2021). "The Kinocilia of Cochlear Hair Cells: Structures, Functions, and Diseases". Frontiers in Cell and Developmental Biology. 9: 715037. doi:10.3389/fcell.2021.715037. PMC 8374625. PMID 34422834.
  39. ^ a b Takeda, Sen; Narita, Keishi (February 2012). "Structure and function of vertebrate cilia, towards a new taxonomy". Differentiation. 83 (2): S4–S11. doi:10.1016/j.diff.2011.11.002. PMID 22118931.
  40. ^ Benjamin Lewin (2007). Cells. Jones & Bartlett Learning. p. 359. ISBN 978-0-7637-3905-8.
  41. ^ a b Hanukoglu I, Hanukoglu A (April 2016). "Epithelial sodium channel (ENaC) family: Phylogeny, structure-function, tissue distribution, and associated inherited diseases". Gene. 579 (2): 95–132. doi:10.1016/j.gene.2015.12.061. PMC 4756657. PMID 26772908.
  42. ^ a b c d Schoenwolf, Gary C. (2015). Larsen's human embryology (Fifth ed.). Philadelphia, PA. p. 64. ISBN 9781455706846.
  43. ^ Lindemann, CB; Lesich, KA (15 February 2010). "Flagellar and ciliary beating: the proven and the possible". Journal of Cell Science. 123 (Pt 4): 519–28. doi:10.1242/jcs.051326. PMID 20145000.
  44. ^ Valentine, M; Van Houten, J (24 September 2021). "Using Paramecium as a Model for Ciliopathies". Genes. 12 (10): 1493. doi:10.3390/genes12101493. PMC 8535419. PMID 34680887.
  45. ^ Johnson KA, Rosenbaum JL (December 1992). "Polarity of flagellar assembly in Chlamydomonas". The Journal of Cell Biology. 119 (6): 1605–11. doi:10.1083/jcb.119.6.1605. PMC 2289744. PMID 1281816.
  46. ^ Hao L, Thein M, Brust-Mascher I, Civelekoglu-Scholey G, Lu Y, Acar S, Prevo B, Shaham S, Scholey JM (June 2011). "Intraflagellar transport delivers tubulin isotypes to sensory cilium middle and distal segments". Nature Cell Biology. 13 (7): 790–98. doi:10.1038/ncb2268. PMC 3129367. PMID 21642982.
  47. ^ Of cilia and silliness (more on Behe) – The Panda's Thumb Archived 17 October 2007 at the Wayback Machine
  48. ^ Ishikawa H, Kubo A, Tsukita S, Tsukita S (May 2005). "Odf2-deficient mother centrioles lack distal/subdistal appendages and the ability to generate primary cilia". Nature Cell Biology. 7 (5): 517–24. doi:10.1038/ncb1251. PMID 15852003. S2CID 35443570.
  49. ^ Lamla S (22 January 2009). Functional characterisation of the centrosomal protein Cep170 (Ph.D.). Ludwig-Maximilians-Universität München.
  50. ^ Alberts, Bruce (2002). Molecular Biology of the Cell.
  51. ^ King, SM (1 November 2016). "Axonemal Dynein Arms". Cold Spring Harbor Perspectives in Biology. 8 (11): a028100. doi:10.1101/cshperspect.a028100. PMC 5088525. PMID 27527589.
  52. ^ a b c Adams M, Smith UM, Logan CV, Johnson CA (May 2008). "Recent advances in the molecular pathology, cell biology and genetics of ciliopathies". Journal of Medical Genetics. 45 (5): 257–67. doi:10.1136/jmg.2007.054999. PMID 18178628.
  53. ^ Wolpert, Lewis; Tickle, Cheryll; Martinez Arias, Alfonso (2015). Principles of Development (5th ed.). Oxford University Press. p. 227.
  54. ^ Cilia function as calcium-mediated mechanosensors that instruct left-right asymmetry, Science, 5 January 2023, Vol 379, Issue 6627, pp. 71-78 ; DOI: 10.1126/science.abq7317
  55. ^ Immotile cilia mechanically sense the direction of fluid flow for left-right determination, Science, 5 January 2023, Vol 379, Issue 6627, pp. 66-71 ; DOI: 10.1126/science.abq8148
  56. ^ Tamim, Baba (4 September 2022). "New discovery: Synapse hiding in the mice brain may advance our understanding of neuronal communication". interestingengineering.com. Retrieved 19 October 2022.
  57. ^ Sheu, Shu-Hsien; Upadhyayula, Srigokul; Dupuy, Vincent; Pang, Song; Deng, Fei; Wan, Jinxia; Walpita, Deepika; Pasolli, H. Amalia; Houser, Justin; Sanchez-Martinez, Silvia; Brauchi, Sebastian E.; Banala, Sambashiva; Freeman, Melanie; Xu, C. Shan; Kirchhausen, Tom; Hess, Harald F.; Lavis, Luke; Li, Yulong; Chaumont-Dubel, Séverine; Clapham, David E. (1 September 2022). "A serotonergic axon-cilium synapse drives nuclear signaling to alter chromatin accessibility". Cell. 185 (18): 3390–3407.e18. doi:10.1016/j.cell.2022.07.026. ISSN 0092-8674. PMC 9789380. PMID 36055200. S2CID 251958800.
  58. ^ Braun, Daniela A.; Hildebrandt, Friedhelm (1 March 2017). "Ciliopathies". Cold Spring Harbor Perspectives in Biology. 9 (3): a028191. doi:10.1101/cshperspect.a028191. ISSN 1943-0264. PMC 5334254. PMID 27793968.
  59. ^ Gerdes, J., Christou-Savina, S., Xiong, Y. et al. Ciliary dysfunction impairs beta-cell insulin secretion and promotes development of type 2 diabetes in rodents. Nat Commun 5, 5308 (2014). https://doi.org/10.1038/ncomms6308
  60. ^ Ichioka K, Kohei N, Okubo K, Nishiyama H, Terai A (July 2006). "Obstructive azoospermia associated with chronic sinopulmonary infection and situs inversus totalis". Urology. 68 (1): 204.e5–7. doi:10.1016/j.urology.2006.01.072. PMID 16850538.
  61. ^ Worsley, Calum; Weerakkody, Yuranga (1 November 2009). "Heterotaxy syndrome". Radiopaedia.org. Radiopaedia.org. doi:10.53347/rID-7420. Retrieved 10 June 2022.
  62. ^ Kennedy MP, Omran H, Leigh MW, Dell S, Morgan L, Molina PL, Robinson BV, Minnix SL, Olbrich H, Severin T, Ahrens P, Lange L, Morillas HN, Noone PG, Zariwala MA, Knowles MR (June 2007). "Congenital heart disease and other heterotaxic defects in a large cohort of patients with primary ciliary dyskinesia". Circulation. 115 (22): 2814–21. doi:10.1161/CIRCULATIONAHA.106.649038. PMID 17515466.
  63. ^ McGrath J, Brueckner M (August 2003). "Cilia are at the heart of vertebrate left-right asymmetry". Current Opinion in Genetics & Development. 13 (4): 385–92. doi:10.1016/S0959-437X(03)00091-1. PMID 12888012.
  64. ^ Leitch, Carmen C.; Zaghloul, Norann A.; Davis, Erica E.; Stoetzel, Corinne; Diaz-Font, Anna; Rix, Suzanne; Alfadhel, Majid; Al-Fadhel, Majid; Lewis, Richard Alan; Eyaid, Wafaa; Banin, Eyal (April 2008). "Hypomorphic mutations in syndromic encephalocele genes are associated with Bardet-Biedl syndrome". Nature Genetics. 40 (4): 443–448. doi:10.1038/ng.97. ISSN 1546-1718. PMID 18327255. S2CID 5282929.
  65. ^ Yee, Laura E.; Garcia-Gonzalo, Francesc R.; Bowie, Rachel V.; Li, Chunmei; Kennedy, Julie K.; Ashrafi, Kaveh; Blacque, Oliver E.; Leroux, Michel R.; Reiter, Jeremy F. (November 2015). "Conserved Genetic Interactions between Ciliopathy Complexes Cooperatively Support Ciliogenesis and Ciliary Signaling". PLOS Genetics. 11 (11): e1005627. doi:10.1371/journal.pgen.1005627. ISSN 1553-7404. PMC 4635004. PMID 26540106.
  66. ^ Cavalier-Smith, T (May 2022). "Ciliary transition zone evolution and the root of the eukaryote tree: implications for opisthokont origin and classification of kingdoms Protozoa, Plantae, and Fungi". Protoplasma. 259 (3): 487–593. doi:10.1007/s00709-021-01665-7. PMC 9010356. PMID 34940909.
  67. ^ Fastenberg JH, Hsueh WD, Mustafa A, Akbar NA, Abuzeid WM (December 2016). "Biofilms in chronic rhinosinusitis: Pathophysiology and therapeutic strategies". World Journal of Otorhinolaryngology – Head and Neck Surgery. 2 (4): 219–29. doi:10.1016/j.wjorl.2016.03.002. PMC 5698538. PMID 29204570.
  68. ^ Horne AW, Critchley HO (March 2012). "Mechanisms of disease: the endocrinology of ectopic pregnancy". Expert Reviews in Molecular Medicine. 14: e7. doi:10.1017/erm.2011.2. PMID 22380790. S2CID 10039212.
  69. ^ Cano DA, Murcia NS, Pazour GJ, Hebrok M. 2004. Orpk mouse model of polycystic kidney disease reveals essential role of pri- mary cilia in pancreatic tissue organization. Development 131: 3457–3467
  70. ^ Zhang Q, Davenport JR, Croyle MJ, et al. 2005.  Disruption of IFT results in both exocrine and endocrine abnormalities in the pancreas of Tg737orpk mutant mice. Lab Invest  85: 45– 64
  71. ^ Yamamoto M, Kataoka K. 1986. Electron microscopic observation of the primary cilia in the pancreatic islets. Arch Histol Jpn 49: 449–457
External links
Categories

The content of this page is based on the Wikipedia article written by contributors..
The text is available under the Creative Commons Attribution-ShareAlike Licence & the media files are available under their respective licenses; additional terms may apply.
By using this site, you agree to the Terms of Use & Privacy Policy.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization & is not affiliated to WikiZ.com.