Vitamin D regulation of chemerin in human bone marrow adipogenesis

Abstract

Osteoporosis is a skeletal disorder characterized by low bone mass and deterioration of bone tissue that ultimately leads to an increase in susceptibility to fracture. One cause of bone loss in osteoporosis is a decrease in the number of bone forming osteoblasts. This can occur due to a shift in the differentiation of mesenchymal stem cells (MSCs) within the bone marrow to favour the formation of adipocytes at the expense of forming osteoblasts. Therefore, manipulation of MSC differentiation to favour osteoblast formation over adipocyte formation may offer a novel target for the treatment of osteoporosis. Recently, our laboratory identified chemerin as an adipokine that regulates adipogenesis by activation of chemokine like receptor‐1(CMKLR1). The purpose of this study was to characterize the expression of chemerin and CMKLR1 in human bone marrow MSC adipogenesis and to identify regulators of chemerin within bone. Results indicate that chemerin mRNA and protein expression are altered during adipogenesis. We have also demonstrated that treatment of adipocyte/osteoblast precursors with Vitamin D causes a significant induction in chemerin expression that is mediated through the Vitamin D receptor. These results suggest one mechanism whereby chemerin may be regulated to alter bone formation.