FRP-5, soluble

Secreted Frizzled Related Proteins (sFRPs) are a family of glycosylated Wnt antagonists that inhibit Wnt signaling, either by directly binding to Wnt proteins to prevent their binding to Frizzled (Fz) family receptor proteins or by forming non‐functional interactions with Frizzled receptors. sFRPs share homology with the cysteine‐rich, extracellular domain of Frizzled proteins. sFRP‐5 is secreted in a variety of embryonic and adult tissues. During embryonic development, sFRP‐5 regulates formation of the retina, brain, trunk, foregut, anterior visceral endoderm, and epithelial structures through Wnt and BMP inhibition. In adults, sFRP‐5 is expressed by adipocytes, particularly in white adipose tissue, and acts as an anti‐inflammatory adipokine. Shown to improve metabolic function and reduce adipose tissue inflammation, sFRP‐5 also acts in a cardio‐protective manner after ischemia and reperfusion injury in the heart, suppressing the non‐canonical Wnt5a/JNK signaling pathway in macrophages and myocytes. sFRP‐5 levels are negatively correlated with obesity‐related disorders including insulin resistance, type 2 diabetes, dyslipidemia, atherosclerosis, and coronary artery disease. Downregulation by promoter hypermethylation is observed in numerous cancers including gastric, cervical, hepatocellular carcinoma, pancreatic, oral squamous cell, breast, colon, bladder, and renal. sFRP‐5 inhibits melanogenesis when expressed in vitiligo melanocytes. CHO cell‐derived Recombinant Human sFRP5 is a 288‐amino‐acid length glycoprotein with a calculated molecular weight of 32.7 kDa; however, due to glycosylation, protein migration occurs at an apparent molecular weight of approximately 33‐35 kDa by SDS‐PAGE analysis under both reducing and non‐reducing conditions.