The Emerging Role of Vitamin D and Vitamin D Receptor in Diabetic Nephropathy

Diabetic nephropathy (DN), one of the most common and severe microvascular complications of diabetes mellitus (DM), is an important risk factor for DM patient's death. Nowadays, DN has become the leading cause of end-stage renal disease (ESRD) in most countries without effective therapeutic methods. Recently, the renoprotective effects mediated by vitamin D (VD) and vitamin D receptor (VDR) have been evidenced. VD, a kind of steroid with the active form 1,25(OH)(2)D-3, has been known for the crucial roles in the modulation of serum calcium and phosphorus concentrations. It exerts important functions by binding with its receptor VDR.VDR, a transcription factor located at chromosome 12 containing 9 exons, is one of the nonsteroid nuclear hormone receptor superfamily, which participates in transcriptional regulation of genes in tissue- and cell-specific ways. Increasing evidences have demonstrated that VD/VDR signaling pathway possesses a variety of kidney-protective effects in DN patients, such as antiproteinuria, antifibrosis, anti-inflammatory, and preventing podocyte damage. Although there are many studies on the role of the VD/VDR signaling pathway in DN, the effects and mechanisms still need to be further explained. This review summarized the multiple roles of VD/VDR in podocyte injury, tubule lesions, interstitial fibrosis, and inflammation, as well as the clinical applications about DN to explore much more and effective therapeutic methods for DN.