THE ROLE OF VITAMIN D IN THE FUNCTIONING OF BONE CELLS

The review summarizes current literature data on the importance of vitamin D in bone cell function. An analytical search was conducted in the PubMed, MEDLINE, Embase, Scopus, and Web of Science databases from January 1, 2018, to June 01, 2023. The vitamin D metabolite 1α,25(OH)2D3 plays an important role in the regulation of mineral homeostasis and bone metabolism. It has catabolic and anabolic actions on osteoblasts, osteocytes and mature osteoclasts. In this review, we describe the direct and indirect effects of 1α,25(OH)2D3 on the function of mesenchymal stromal cells (MSCs), osteoblasts, osteocytes, and osteoclasts. Among the targets of vitamin D action in bone cells are vitamin D receptor (VDR) and cytochrome P450 Family 27 Subfamily B Member 1 (CYP27B1). In osteoblasts and MSCs with CYP27B1 knockout, cell proliferation and differentiation are impaired, and in osteoclasts, the resorption activity and lifespan of these cells are increased. The role of VDR in bone cells was demonstrated in normal and VDR-knockout animal models. The relationship between 1α,25(OH)2D3 – VDR signal transduction by bone cells and calcium balance was analyzed. In osteocytes, as well as in osteoblasts, 1α,25(OH)2D3 regulates the expression of RANKL (receptor activator of nuclear factor kappa-B ligand)), and additionally in osteocytes regulates the expression of FGF-23. The interaction of many other factors in bone cells has been shown to control the biological activity of 1α,25(OH)2D3. Thus, the effect of vitamin D on bone cells is in the phase of active research and requires an in-depth study of the features of its autocrine and paracrine effects. Identification of the molecular links of the mechanism of action of 1α,25(OH)2D3 on bone metabolism will provide a fundamental basis for approaches to the treatment of vitamin D deficiency diseases.