Collagen alpha-1(XVIII) chain (COL18A1) (COL18A1)

Collagen alpha-1(XVIII) chain is a specialized extracellular matrix protein and a member of the multiplexin family, characterized by multiple triple-helical domains (UniProt P39060). It is a major component of basement membranes, particularly in the vascular system and the eye, where it provides structural support and modulates cell-matrix interactions (PubMed: 11518714). The protein is most notable for its C-terminal fragment, Endostatin, which is released through proteolytic cleavage and acts as a powerful endogenous inhibitor of angiogenesis by blocking endothelial cell migration and inducing apoptosis (NCBI Gene: 1310). In clinical practice, recombinant forms of Endostatin, such as Endostar, are utilized in combination with chemotherapy to treat non-small cell lung cancer by targeting the tumor's blood supply (PubMed: 16542500). Beyond cancer, mutations in the COL18A1 gene are the primary cause of Knobloch syndrome, highlighting its essential role in ocular development and maintenance (NIH: Genetic and Rare Diseases Information Center). Research also suggests its involvement in other pathological processes, including liver fibrosis and Alzheimer's disease, where it may influence amyloid-beta deposition (PubMed: 11518714).

Other names

Collagen type XVIIIEndostatinCOL18A1Multi-domain proteoglycan

Endostatin, the C-terminal fragment of Collagen XVIII, inhibits angiogenesis by binding to cell surface receptors such as alpha-5 beta-1 integrins and glypicans on endothelial cells, leading to the inhibition of VEGF-induced signaling and induction of apoptosis in endothelial cells (PubMed: 11518714, 16542500).