PCNT | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | PCNT , KEN, MOPD2, PCN, PCNT2, PCNTB, PCTN2, SCKL4, pericentrin | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 605925 HomoloGene: 86942 GeneCards: PCNT | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Pericentrin (kendrin), also known as PCNT and pericentrin-B (PCNTB), is a protein which in humans is encoded by the PCNT gene on chromosome 21. [3] [4] [5] [6] This protein localizes to the centrosome and recruits proteins to the pericentriolar matrix (PCM) to ensure proper centrosome and mitotic spindle formation, and thus, uninterrupted cell cycle progression. [3] [7] [8] [9] [10] This gene is implicated in many diseases and disorders, including congenital disorders such as microcephalic osteodysplastic primordial dwarfism type II (MOPDII) and Seckel syndrome. [7] [8]
PCNT is a 360 kDa protein which contains a series of coiled coil domains and a highly conserved PCM targeting motif called the PACT domain near its C-terminus. [3] [6] [7] [8] [9] [11] [12] The PACT domain is responsible for targeting the protein to the centrosomes and attaching it to the centriole walls during interphase. [7] [8] In addition, PCNT possesses five nuclear export sequences which all contribute to its nuclear export into the cytoplasm, as well as one nuclear localization signal composed of three clusters of basic amino acids, all of which contribute to the protein's nuclear localization. [7]
PCNTB, a cDNA homolog of PCNT, was identified and described by Li et al. to share a sequence identity of 61% and similarity of 75%. However, compared to PCNT, PCNTB contains an additional coiled coil domain and unique 1000-residue C-terminus, suggesting that these two may be separate proteins in a new CPM superfamily. [6] As with PCNT, the C-terminus of PCNTB contains functional domains for centriole localization and CEP215 binding. The N-terminus may also contain a functional domain that associates with the C-terminus domain, and this association is required for engagement with the centriole. [13]
The protein encoded by this gene is expressed in the cytoplasm and centrosome throughout the cell cycle, and to a lesser extent, in the nucleus. It is an integral component of the PCM, which is a centrosome scaffold that anchors microtubule nucleating complexes and other centrosomal proteins. [3] [6] [7] [9] [13] [14] In one model, PCNT complexes with CEP215 and is phosphorylated by PLK1, leading to PCM component recruitment and organization, centrosome maturation, and spindle formation. [8] [13] The protein controls the nucleation of microtubules by interacting with the microtubule nucleation component γ-tubulin, thus anchoring the γ-tubulin ring complex to the centrosome, which is essential for bipolar spindle formation and chromosome assembly in early mitosis. [3] [7] [8] [9] [10] This ensures normal function and organization of the centrosomes, mitotic spindles, and cytoskeleton, and by extension, regulation over cell cycle progression and checkpoints. [3] [7] [8] [9] [14] Downregulation of PCNT disrupted mitotic checkpoints and arrested the cell at the G2/M checkpoint, leading to cell death. [12] [14] Moreover, microtubule functioning was also disrupted, resulting in mono- or multipolar spindles, chromosomal misalignment, premature sister chromatid separation, and aneuploidy. [8] [14]
PCNT is highly abundant in skeletal muscle, indicating that it may be involved in muscle insulin action. [9] PCNT is also involved in neuronal development through its interaction with DISC1 to regulate microtubule organization. [10]
Mutations in the PCNT gene have been linked to Down syndrome (DS); two types of primordial dwarfism, MOPDII and Seckel syndrome; intrauterine growth retardation; cardiomyopathy; early onset type 2 diabetes; chronic myeloid leukemia (CML); bipolar affective disorder; and other congenital disorders. [7] [8] [10] [12] [13] [14] In particular, the short stature and small brain size characteristic of MOPDII and Seckel syndrome have been attributed to centrosome dysfunction and cell growth disruption as a result of PCNT malfunction. [7] Additionally, premature aging, cerebral involution, inflammatory and immune responses are linked to DS associated with PCNT mutations, while severe insulin resistance, diabetes, and dyslipidemia are featured in MOPDII associated with PCNT mutations. [9] [12]
PCNT has been shown to interact with:
In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle progression. The centrosome provides structure for the cell. The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells. Fungi and plants lack centrosomes and therefore use other structures to organize their microtubules. Although the centrosome has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species.
In cell biology, the spindle apparatus is the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell.
Aurora kinase A also known as serine/threonine-protein kinase 6 is an enzyme that in humans is encoded by the AURKA gene.
Pericentriolar material 1, also known as PCM1, is a protein which in humans is encoded by the PCM1 gene.
Centrins, also known as caltractins, are a family of calcium-binding phosphoproteins found in the centrosome of eukaryotes. Centrins are small calcium binding proteins that are ubiquitous centrosome components. There are about 350 “signature” proteins that are unique to eukaryotic cells but have no significant homology to proteins in archaea and bacteria. They are a type of protein that is essential and present in almost all eukaryotic cells and are found in the centrioles and pericentriolar lattice. Human centrin genes are CETN1, CETN2 and CETN3.
A-kinase anchor protein 9 is a protein that in humans is encoded by the AKAP9 gene. AKAP9 is also known as Centrosome- and Golgi-localized protein kinase N-associated protein (CG-NAP) or AKAP350 or AKAP450
Transforming acidic coiled-coil-containing protein 2 is a protein that in humans is encoded by the TACC2 gene.
Centrosome-associated protein 350 is a protein that in humans is encoded by the CEP350 gene.
Centrosome-associated protein CEP250 is a protein that in humans is encoded by the CEP250 gene. This gene encodes a core centrosomal protein required for centriole-centriole cohesion during interphase of the cell cycle. The encoded protein dissociates from the centrosomes when parental centrioles separate at the beginning of mitosis. The protein associates with and is phosphorylated by NIMA-related kinase 2, which is also associated with the centrosome. Furthermore, CEP135 is also required for the centriolar localization of CEP250.
Centrosomal protein 170kDa, also known as CEP170, is a protein that in humans is encoded by the CEP170 gene.
Centrosomal protein of 63 kDa is a protein that in humans is encoded by the CEP63 gene. Several alternatively spliced transcript variants have been found, but their biological validity has not been determined.
Centrosomal protein of 70 kDa is a protein that in humans is encoded by the CEP70 gene. The protein interacts with γ-tubulin through its coiled coil domains to localize at the centrosome. CEP70 is involved in organizing microtubules in interphase cells and is required for proper organization and orientation of the mitotic spindle.
Neural precursor cell expressed, developmentally down-regulated 1, also known as Nedd1, is a human gene and encodes the protein NEDD1.
Centrosomal protein of 192 kDa, also known as Cep192, is a protein that in humans is encoded by the CEP192 gene. It is the homolog of the C. elegans and D. melanogaster gene SPD-2.
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.
Centrosomal protein of 76 kDa, also known as CEP76, is a protein that in humans is encoded by the CEP76 gene.
Centrosomal protein of 78 kDa, also known as Cep78, is a protein that in humans is encoded by the CEP78 gene.
Centrosomal protein of 152 kDa, also known as Cep152, is a protein that in humans is encoded by the CEP152 gene. It is the ortholog of the Drosophila melanogaster gene asterless (asl) and both are required for centriole duplication.
Centrosomes are the major microtubule organizing centers (MTOC) in mammalian cells. Failure of centrosome regulation can cause mistakes in chromosome segregation and is associated with aneuploidy. A centrosome is composed of two orthogonal cylindrical protein assemblies, called centrioles, which are surrounded by a protein dense amorphous cloud of pericentriolar material (PCM). The PCM is essential for nucleation and organization of microtubules. The centrosome cycle is important to ensure that daughter cells receive a centrosome after cell division. As the cell cycle progresses, the centrosome undergoes a series of morphological and functional changes. Initiation of the centrosome cycle occurs early in the cell cycle in order to have two centrosomes by the time mitosis occurs.
Sfi1 homolog, spindle assembly associated (yeast) is a protein that in humans is encoded by the SFI1 gene. It localizes to the centriole, and its S. pombe ortholog has been shown to be involved in spindle pole body duplication. SFI1 forms a complex with centrin 2.