Compartmentalized ciliogenesis is the most common type of ciliogenesis where the cilium axoneme is formed separated from the cytoplasm by the ciliary membrane and a ciliary gate known as the transition zone. [1]
The cilium is a membrane-bound organelle found on most types of eukaryotic cell. The cilium has the shape of a slender threadlike projection that extends from the surface of the much larger cell body. 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.
The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliary body. The ciliary body is part of the uvea, the layer of tissue that delivers oxygen and nutrients to the eye tissues. The ciliary body joins the ora serrata of the choroid to the root of the iris.
The ciliary muscle is an intrinsic muscle of the eye formed as a ring of smooth muscle in the eye's middle layer, the uvea. It controls accommodation for viewing objects at varying distances and regulates the flow of aqueous humor into Schlemm's canal. It also changes the shape of the lens within the eye but not the size of the pupil which is carried out by the sphincter pupillae muscle and dilator pupillae.
In molecular biology, 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.
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.
Centrosomal protein of 290 kDa is a protein that in humans is encoded by the CEP290 gene. CEP290 is located on the Q arm of chromosome 12.
Afadin- and alpha-actinin-binding protein is a protein that in humans is encoded by the SSX2IP gene. It has been shown that it functions together with WDR8 in centrosome maturation, ensuring proper spindle length and orientation. The SSX2IP-WDR8 complex additionally promotes ciliary vesicle docking during ciliogenesis.
Dynein heavy chain 9, axonemal is a protein that in humans is encoded by the DNAH9 gene.
Mitogen-activated protein kinase 15, also known as MAPK15, ERK7, or ERK8, is an enzyme that in humans is encoded by the MAPK15 gene.
Tetratricopeptide repeat domain 8 (TTC8) also known as Bardet–Biedl syndrome 8 is a protein that in humans is encoded by the TTC8 gene.
Bardet–Biedl syndrome 10, also known as BBS10 is a human gene.
Transmembrane protein 216 is a protein in humans that is encoded by the TMEM216 gene.
Serine/threonine-protein kinase Nek8, also known as never in mitosis A-related kinase 8, is an enzyme that in humans is encoded by the NEK8 gene.
Kintoun, is a protein that is encoded by the DNAAF2 gene.
A BBSome is a protein complex that operates in primary cilia biogenesis, homeostasis, and intraflagellar transport (IFT). The BBSome recognizes cargo proteins and signaling molecules like G-protein coupled receptors (GPCRs) on the ciliary membrane and helps transport them to and from the primary cilia. Primary cilia are nonmotile microtubule projections that function like antennae and are found in many types of cells. They receive various environmental signals to aid the cell in survival. They can detect photons by concentrating rhodopsin, a light receptor that converts photons into chemical signals, or odorants by concentrating olfactory receptors on the primary cilia surface. Primary cilia are also meaningful in cell development and signaling. They do not contain any way to make proteins within the primary cilia, so the BBSome aids in transporting essential proteins to, from, and within the cilia. Examples of cargo proteins that the BBSome is responsible for ferrying include smoothened, polycystic-1 (PC1), and several G-Protein coupled receptors (GPCRs) like somatostatin receptors (Sstr3), melanin-concentrating hormone receptor 1 (Mchr1), and neuropeptide Y2 receptor.
Forkhead box protein J1 is a protein that in humans is encoded by the FOXJ1 gene. It is a member of the Forkhead/winged helix (FOX) family of transcription factors that is involved in ciliogenesis. FOXJ1 is expressed in ciliated cells of the lung, choroid plexus, reproductive tract, embryonic kidney and pre-somite embryo stage.
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 appendages 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 known as ciliopathies.
Cytosolic ciliogenesis, otherwise cytoplasmic ciliogenesis, is a type of ciliogenesis where the cilium axoneme is formed in the cytoplasm or becomes exposed to the cytoplasm.
The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit. Three types of axons enter the ciliary ganglion but only the preganglionic parasympathetic axons synapse there. The entering axons are arranged into three roots of the ciliary ganglion, which join enter the posterior surface of the ganglion.
Jeremy Reiter is an American developmental geneticist who is the chair of the Department of Biochemistry and Biophysics at the University of California, San Francisco (UCSF). He is holder of the Albert Bowers Endowed Chair. His research focuses on the cilium, particularly in understanding its role in cell signaling and its involvement in human diseases such as cancer, congenital disorders and obesity.