a1 Obesity Biology Research Group, Department of Obesity and Endocrinology, Institute of Ageing and Chronic Disease, University of Liverpool, Duncan Building, Liverpool L69 3GA, UK
a2 Clore Laboratory, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
Vitamin D deficiency and the rapid increase in the prevalence of obesity are both considered important public health issues. The classical role of vitamin D is in Ca homoeostasis and bone metabolism. Growing evidence suggests that the vitamin D system has a range of physiological functions, with vitamin D deficiency contributing to the pathogenesis of several major diseases, including obesity and the metabolic syndrome. Clinical studies have shown that obese individuals tend to have a low vitamin D status, which may link to the dysregulation of white adipose tissue. Recent studies suggest that adipose tissue may be a direct target of vitamin D. The expression of both the vitamin D receptor and 25-hydroxyvitamin D 1α-hydroxylase (CYP27B1) genes has been shown in murine and human adipocytes. There is evidence that vitamin D affects body fat mass by inhibiting adipogenic transcription factors and lipid accumulation during adipocyte differentiation. Some recent studies demonstrate that vitamin D metabolites also influence adipokine production and the inflammatory response in adipose tissue. Therefore, vitamin D deficiency may compromise the normal metabolic functioning of adipose tissue. Given the importance of the tissue in energy balance, lipid metabolism and inflammation in obesity, understanding the mechanisms of vitamin D action in adipocytes may have a significant impact on the maintenance of metabolic health. In the present review, we focus on the signalling role of vitamin D in adipocytes, particularly the potential mechanisms through which vitamin D may influence adipose tissue development and function.
(Received April 03 2012)
(Revised June 12 2012)
(Accepted June 27 2012)
(Online publication October 09 2012)
Abbreviations: 1,25(OH)2D3, 1α,25-dihydroxycholecalciferol; 25(OH)D3, 25-hydroxycholecalciferol; C/EBP, CCAAT/enhancer-binding protein; MCP-1, monocyte chemoattractant protein-1; VDR, vitamin D receptor