Chemerin (Tezarotene induced gene 2, TIG2, Retinoic acid receptor responder 2, RERRES2)

Chemerin is a novel chemoattractant protein secreted as an 18-kDa inactive pro-protein. Active chemerin is abundant in ascetic fluid from ovariam cancer patients and synovial fluid from patients with arthritis. Signaling by chemerin is mediated by the seven-transmembrane-spanning G protein-coupled receptor, chemokine like receptor-1 (CMKLR1, ChemR23,) or chemerinR. Both chemerin and chemerinR mRNA expression dramatically increased during the differentiation of preadipocytes into adipocytes. Chemerin induced the phosphorylation of extracellular signal – regulated kinase 1/2 (ERK 1/2) and lipolysis in differentiated adipocytes and 3T3-L1 cells, stimulated intracellular calcium release and inhibited cAMP accumulation. Chemerin disruption has some effect on adipogenesis in vitro, but regulation of gene expression and lipolysis in mature adipocytes suggests a wider role in lipid and carbohydrate metabolisms, and perhaps insulin sensitivity. Local production of chemerin regulates adipogenesis and through its receptor or possible other receptor can modulate a variety of functions in mature adipocytes. Adipocytes purified from adipose tissue contain high levels of chemerin mRNA; however, substantial expression in stromal vascular cells suggest that production in nonadipocytes may also be important. Chemerin is essential in early differentiation processes and may contribute or regulate critical early events in adipogenesis. Results also indicate that chemerin and ChemerinR could have an important biological role in the formation of white adipose tissue during normal or in pathological states.