NG2 Chondroitin Sulfate Proteoglycan, also known as neuron-glial antigen 2 (NG2) or chondroitin sulfate proteoglycan 4 (CSPG4), is a cell surface molecule that is involved in a variety of cellular processes. It is a type I transmembrane core proteoglycan that is crucial for cell survival, migration, and angiogenesis. The regulation of NG2 expression is influenced by factors such as inflammation and hypoxia and is mediated by methyltransferases, transcription factors including Sp1, Pax3, Egr-1, and the microRNA miR129-2. These regulatory elements are essential in determining cellular processes mediated by NG2, such as glial scar formation in the central nervous system (CNS) or tumor growth and metastasis. NG2 has been implicated in the progression of several tumor types, with elevated NG2 expression found predominantly in glioblastoma, correlating with poor prognosis due to increased chemo- and radioresistance of tumor cells. It is also a key intermediate of tumor cells with extracellular matrix molecules, determining metastatic formation in soft-tissue sarcoma and melanoma patients. In addition to its role in tumorigenesis, NG2 is expressed in certain benign cell types, such as NG2-glia in the CNS, mesenchymal stem cells, osteoblasts, melanocytes, smooth muscle cells, and macrophages. It is also a typical marker for pericytes, which contribute to the stabilization of microvessels, regulation of capillary blood flow, and angiogenesis. In the context of inflammation, NG2 expression is induced in activated microglial cells, and it mediates the induction of inducible nitric oxide synthase (iNOS) and inflammatory cytokine expression, but not chemokine expression in activated microglia. This suggests that NG2 plays a role in the inflammatory response of these cells.
中文
