The CYLD lysine 63 deubiquitinase gene, also termed the CYLD gene, [5] CYLD is an evolutionary ancient gene found to be present as far back on the evolutionary scale as in sponges. [6] In humans, this gene is located in band 12.1 on the long (or "q") arm of chromosome 16 [7] and is known to code (i.e. direct the production of) multiple proteins through the process of alternative splicing. [8]
The CYLD gene in known to code for a cytoplasmic protein, termed CYLD lysine 63 deubiquitinase (here termed CYLD protein), which has three cytoskeletal-associated protein-glycine-conserved (CAP-GLY) domains (areas or the protein controlling critical functions [9] ). CYLD protein is a deubiquitinating enzyme, i.e. a protease that removes ubiquitin from certain proteins and thereby regulates these proteins' activities. CYLD protein removes ubiquitin from proteins involved in regulating the NF-κB, Wnt, notch, TGF-β, [10] and JNK [11] cell signaling pathways; these pathways normally act to regulate hair formation, cell growth, cell survival, inflammatory responses, and/or tumor development. [10] [11]
The CYLD gene is classified as a tumor suppressor gene, i.e. a gene that regulates cell growth and when inactivated by a mutation leads to uncontrolled cell growth and the formation of tumors. [12] Inactivating mutations in this gene occur in essentially all cases of the CYLD cutaneous syndrome, a hereditary disorder in which individuals develop multiple skin tumors. The CYLD cutaneous syndrome includes three somewhat different forms of the disease: the multiple familial trichoepithelioma-type, Brooke–Spiegler syndrome-type, and familial cylindromatosis-type. [10] CYLD gene mutations are also associated with T-Cell Acute Lymphoblastic Leukemia, [12] multiple myeloma, hepatocellular carcinoma, neuroblastoma, pancreatic cancer, [13] uterine cancer, stomach cancer, colon cancer, lung cancer, and human papillomavirus-associated cancers. [11]
p53, also known as Tumor protein P53, cellular tumor antigen p53, or transformation-related protein 53 (TRP53) is a regulatory protein that is often mutated in human cancers. The p53 proteins are crucial in vertebrates, where they prevent cancer formation. As such, p53 has been described as "the guardian of the genome" because of its role in conserving stability by preventing genome mutation. Hence TP53 is classified as a tumor suppressor gene.
FOXP3, also known as scurfin, is a protein involved in immune system responses. A member of the FOX protein family, FOXP3 appears to function as a master regulator of the regulatory pathway in the development and function of regulatory T cells. Regulatory T cells generally turn the immune response down. In cancer, an excess of regulatory T cell activity can prevent the immune system from destroying cancer cells. In autoimmune disease, a deficiency of regulatory T cell activity can allow other autoimmune cells to attack the body's own tissues.
Phosphatase and tensin homolog (PTEN) is a phosphatase in humans and is encoded by the PTEN gene. Mutations of this gene are a step in the development of many cancers, specifically glioblastoma, lung cancer, breast cancer, and prostate cancer. Genes corresponding to PTEN (orthologs) have been identified in most mammals for which complete genome data are available.
Adenomatous polyposis coli (APC) also known as deleted in polyposis 2.5 (DP2.5) is a protein that in humans is encoded by the APC gene. The APC protein is a negative regulator that controls beta-catenin concentrations and interacts with E-cadherin, which are involved in cell adhesion. Mutations in the APC gene may result in colorectal cancer and desmoid tumors.
Menin is a protein that in humans is encoded by the MEN1 gene. Menin is a putative tumor suppressor associated with multiple endocrine neoplasia type 1 and has autosomal dominant inheritance. Variations in the MEN1 gene can cause pituitary adenomas, hyperparathyroidism, pancreatic neuroendocrine tumors, gastrinoma, and adrenocortical cancers.
The tumor suppressor gene FLCN encodes the protein folliculin, also known as Birt–Hogg–Dubé syndrome protein, which functions as an inhibitor of Lactate Dehydrogenase-A and a regulator of the Warburg effect. Folliculin (FLCN) is also associated with Birt–Hogg–Dubé syndrome, which is an autosomal dominant inherited cancer syndrome in which affected individuals are at risk for the development of benign cutaneous tumors (folliculomas), pulmonary cysts, and kidney tumors.
Tumor protein p63, typically referred to as p63, also known as transformation-related protein 63 is a protein that in humans is encoded by the TP63 gene.
Transcription factor p65 also known as nuclear factor NF-kappa-B p65 subunit is a protein that in humans is encoded by the RELA gene.
Inhibitor of nuclear factor kappa-B kinase subunit alpha (IKK-α) also known as IKK1 or conserved helix-loop-helix ubiquitous kinase (CHUK) is a protein kinase that in humans is encoded by the CHUK gene. IKK-α is part of the IκB kinase complex that plays an important role in regulating the NF-κB transcription factor. However, IKK-α has many additional cellular targets, and is thought to function independently of the NF-κB pathway to regulate epidermal differentiation.
Serine/threonine kinase 11 (STK11) also known as liver kinase B1 (LKB1) or renal carcinoma antigen NY-REN-19 is a protein kinase that in humans is encoded by the STK11 gene.
Inhibitor of growth protein 1 is a protein that in humans is encoded by the ING1 gene.
Mitogen-activated protein kinase kinase kinase 8 is an enzyme that in humans is encoded by the MAP3K8 gene.
Hypermethylated in cancer 1 protein is a protein that in humans is encoded by the HIC1 gene.
ID4 is a protein coding gene. In humans, it encodes for the protein known as DNA-binding protein inhibitor ID-4. This protein is known to be involved in the regulation of many cellular processes during both prenatal development and tumorigenesis. This is inclusive of embryonic cellular growth, senescence, cellular differentiation, apoptosis, and as an oncogene in angiogenesis.
Inhibitor of growth protein 2 is a protein that in humans is encoded by the ING2 gene.
BRCA1 associated protein-1 is a deubiquitinating enzyme that in humans is encoded by the BAP1 gene. BAP1 encodes an 80.4 kDa nuclear-localizing protein with a ubiquitin carboxy-terminal hydrolase (UCH) domain that gives BAP1 its deubiquitinase activity. Recent studies have shown that BAP1 and its fruit fly homolog, Calypso, are members of the polycomb-group proteins (PcG) of highly conserved transcriptional repressors required for long-term silencing of genes that regulate cell fate determination, stem cell pluripotency, and other developmental processes.
Trichoepithelioma is a neoplasm of the adnexa of the skin. Its appearance is similar to basal cell carcinoma.
Spiradenomas (SA) are rare, benign cutaneous adnexal tumors that may progress to become their malignant counterparts, i.e. spiradenocarcinomas (SAC). Cutaneous adnexal tumors are a group of skin tumors consisting of tissues that have differentiated towards one of the four primary adnexal structures found in normal skin: hair follicles, sebaceous sweat glands, apocrine sweat glands, and eccrine sweat glands. SA and SAC tumors were regarded as eccrine gland tumors and termed eccrine spiradenomas and eccrine spiradenocarcinomas, respectively. However, more recent studies have found them to be hair follicle tumors and commonly term them spiradenomas and spiradenocarcinomas, respectively. Further confusing the situation, SA-like and SAC-like tumors are also 1) manifestations of the inherited disorder, CYLD cutaneous syndrome (CCS), and 2) have repeatedly been confused with an entirely different tumor, adenoid cystic carcinomas of the salivary gland. Here, SA and SAC are strictly defined as sporadic hair follicle tumors that do not include the hereditary CCS spiradenomas and heridtary spiradenocarcinoms of CCS or the adenoid cystic carcinomas.
Patched 2 is a protein that in humans is encoded by the PTCH2 gene.
CYLD cutaneous syndrome (CCS) encompasses three rare inherited cutaneous adnexal tumor syndromes: multiple familial trichoepithelioma (MFT1), Brooke–Spiegler syndrome (BSS), and familial cylindromatosis (FC). Cutaneous adnexal tumors are a large group of skin tumors that consist of tissues that have differentiated towards one of the four primary adnexal structures found in normal skin: hair follicles, sebaceous sweat glands, apocrine sweat glands, and eccrine sweat glands. CCS tumors are hair follicle tumors.