CD99 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | CD99 , HBA71, MIC2, MIC2X, MIC2Y, MSK5X, CD99 molecule, CD99 molecule (Xg blood group) | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 313470, 450000; HomoloGene: 48107; GeneCards: CD99; OMA:CD99 - orthologs | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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CD99 antigen (Cluster of differentiation 99), also known as MIC2 or single-chain type-1 glycoprotein , is a heavily O-glycosylated transmembrane protein that is encoded by the CD99 gene in humans. [3] [4] [5] The protein has a mass of 32 kD. Unusually for a gene present on the X chromosome, the CD99 gene does not undergo X inactivation, and it was the first such pseudoautosomal gene to be discovered in humans. [6]
It is expressed on all leukocytes but highest on thymocytes [7] [8] [9] and is believed to augment T-cell adhesion [10] [11] and apoptosis of double positive T cells. [12] It has been found in endothelial cells and in the periodontium, including gingival fibroblasts and gingival epithelial cells. [5] It also participates in migration and activation. [13] There is also experimental evidence that it binds to cyclophilin A. [14]
It is found on the cell surface of Ewing's sarcoma tumors [15] and is positive in granulosa cell tumors. [16] It is more expressed in malignant gliomas than in the brain, and such overexpression results in higher levels of invasiveness and lower rates of survival. [17] Antibodies to CD99 are used in diagnostic immunohistochemistry to distinguish Ewing's sarcoma from other tumours of similar histological appearance, as well as for the identification of thymic tumours, and of spindle cell tumours, such as synovial sarcoma, haemangiopericytoma, and meningioma. [6] EWS/FLI is thought to regulate CD99, but knockdown of EWS/FLI results in only a modest reduction in CD99. When CD99 expression is knocked down in human cells with Ewing's sarcoma and those cells are grafted onto mice, tumor and bone metastasis development is reduced. [15]
Reducing CD99 expression results in higher β-III tubulin expression and more neurite outgrowth. [15]
Upregulating CD99 expression in the cell line L428, a Hodgkin's lymphoma line, resulted in those cells redifferentiating towards B cells. Consequently, the loss of B-cell differentiation in Hodgkin's lymphoma may be due to CD99 downregulation. [18]
Men appear to express higher levels of CD99 than women. [19] [20]
In patients with diffuse large B-cell lymphoma (DLBCL) with the germinal center B-cell (GCB, classified according to the Muris algorithm) subtype, positive expression of CD99 resulted in better 2-year event free survival (EFS) and 2-year overall survival (OS) compared to negative expression of CD99. In patients with DLBCL with non-GCB, however, negative expression of CD99 resulted in better 2-year EFS and 2-year OS. [21] In patients with non-small cell lung cancer (NSCLC), higher CD99 expression in the stroma results in better prognosis. [22]
There is evidence that through suppressing β1 integrin affinity, CD99 inhibits cell-extracellular matrix adhesion. [23]
CD137, a member of the tumor necrosis factor (TNF) receptor family, is a type 1 transmembrane protein, expressed on surfaces of leukocytes and non-immune cells. Its alternative names are tumor necrosis factor receptor superfamily member 9 (TNFRSF9), 4-1BB, and induced by lymphocyte activation (ILA). It is of interest to immunologists as a co-stimulatory immune checkpoint molecule, and as a potential target in cancer immunotherapy.
Phospholipase D2 is an enzyme that in humans is encoded by the PLD2 gene.
Intercellular adhesion molecule 2 (ICAM2), also known as CD102, is a human gene, and the protein resulting from it.
Cytoplasmic protein NCK1 is a protein that in humans is encoded by the NCK1 gene.
Brain-specific angiogenesis inhibitor 1 is a protein that in humans is encoded by the BAI1 gene. It is a member of the adhesion-GPCR family of receptors.
Psychosine receptor is a G protein-coupled receptor (GPCR) protein that in humans is encoded by the GPR65 gene. GPR65 is also referred to as TDAG8.
Homeobox protein Hox-A5 is a protein that in humans is encoded by the HOXA5 gene.
Growth arrest and DNA-damage-inducible, beta, also known as GADD45B, is a protein which in humans is encoded by the GADD45B gene.
Deleted in Liver Cancer 1 also known as DLC1 and StAR-related lipid transfer protein 12 (STARD12) is a protein which in humans is encoded by the DLC1 gene.
N-alpha-acetyltransferase 10 (NAA10) also known as NatA catalytic subunit Naa10 and arrest-defective protein 1 homolog A (ARD1A) is an enzyme subunit that in humans is encoded NAA10 gene. Together with its auxiliary subunit Naa15, Naa10 constitutes the NatA complex that specifically catalyzes the transfer of an acetyl group from acetyl-CoA to the N-terminal primary amino group of certain proteins. In higher eukaryotes, 5 other N-acetyltransferase (NAT) complexes, NatB-NatF, have been described that differ both in substrate specificity and subunit composition.
Serine/threonine-protein kinase PLK2 is an enzyme that in humans is encoded by the PLK2 gene.
NCK-interacting protein with SH3 domain is a protein that in humans is encoded by the NCKIPSD gene.
The human gene API5 encodes the protein Apoptosis inhibitor 5.
Zinc finger and BTB domain-containing protein 32 is a protein that in humans is encoded by the 1960 bp ZBTB32 gene. The 52 kDa protein is a transcriptional repressor and the gene is expressed in T and B cells upon activation, but also significantly in testis cells. It is a member of the Poxviruses and Zinc-finger (POZ) and Krüppel (POK) family of proteins, and was identified in multiple screens involving either immune cell tumorigenesis or immune cell development.
Growth arrest and DNA-damage-inducible proteins-interacting protein 1 is a protein that in humans is encoded by the GADD45GIP1 gene.
CD8a, is a human gene.
Capicua transcriptional repressor is a protein that in humans is encoded by the CIC gene. Capicua functions as a transcriptional repressor in a way that ensures its impact on the progression of cancer, and plays a significant role in the operation of the central nervous system through its interaction with ataxin 1. The name of the protein derives from the Catalan expression cap-i-cua which literally translates to "head-and-tail".
CXXC-type zinc finger protein 5 is a protein that is encoded by the CXXC5 gene in humans.
Gintonin is a glycolipoprotein fraction isolated from Panax ginseng. The non-saponin ingredient was designated as gintonin, where gin was derived from ginseng, ton from the tonic effects of ginseng, and in from protein. The main component of gintonin is a complex of lysophosphatidic acids (LPA) and ginseng proteins such as ginseng major latex-like protein151 (GLP151) and ginseng ribonuclease-like storage protein.
Seong Hoe Park is a Korean immunologist and pathologist and a distinguished professor of pathology at the Seoul National University College of Medicine. He served as the chair of the Department of Pathology (2000–2004), the chair of the Graduate Program of Immunology (2002–2006), the president of Center for Animal Resource Development (2004–2006) at Seoul National University. He was the president of the Korean Association of Immunologists (2000–2001). Throughout his career as a T cell immunologist, Park established the theory of T cell-T cell interaction in human thymus, in which T cells expressing MHC class II drive previously unrecognized types of T cells and provide another significant developmental mechanism of T cells.