Vitamin D Inhibition of TRPV5 Expression During Osteoclast Differentiation

Vitamin D is an important steroid that can regulate bone metabolism including osteoclast (OC) differentiation. Transient receptor potential cation channel subfamily V member 5 (TRPV5), is a calcium channel protein involved in OC differentiation. However, the impact of vitamin D on TRPV5 expression during OC differentiation is not clear.

To determine if 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) regulates the expression of TRPV5 during OC differentiation.

Bone marrow mononuclear macrophage (BMMs) were induced to differentiate intoOCwith or without treatment with 10 nM1,25(OH)2D3. The expression levels of vitamin D receptor (VDR) and TRPV5 were examined. The expression of several OC markers, including tartrate resistant acid phosphatase (TRAP), carbonic anhydrase II (Ca II), cathepsin K (CTSK), and vacuolar-type H+-ATPase (V-ATPase) were also detected.

We found that theVDRwas expressed in murine bonemarrow-derived macrophages at the early stage of OCdifferentiation. TRPV5 expression was increased during OC differentiation, which was down-regulated by 1,25(OH)2D3 after a prolonged exposure. The 1,25(OH)2D3 and TRPV5 inhibitors inhibited OC differentiation.

1,25(OH)2D3 can inhibit TRPV5 expression as well as TRPV5 inhibitors during OC differentiation. This suggests that
1,25(OH)2D3 may suppress OC differentiation by inhibiting TRPV5 expression.