RAGE Deletion Confers Renoprotection by Reducing Responsiveness to Transforming Growth Factor-β and Increasing Resistance to Apoptosis

Signalling via the receptor of advanced glycation end-products (RAGE) although complex and not fully elucidated in the setting of diabetes, is considered a key injurious pathway in the development of diabetic nephropathy (DN). We report here that RAGE deletion resulted in increased expression of fibrotic (collagen I and IV, fibronectin) and the inflammatory marker, MCP-1 in primary mouse mesangial cells (MC) and in kidney cortex. RNA-seq analysis in MCs from RAGE -/- and wild type mice confirmed these observations. Nevertheless, despite these gene expression changes a decreased responsiveness to transforming growth factor-β was identified in RAGE -/- mice. Furthermore, RAGE deletion conferred a more proliferative phenotype in MCs and reduced susceptibility to staurosporine-induced apoptosis. RAGE restoration experiments in RAGE -/- MCs largely reversed these gene expression changes resulting in reduced expression of fibrotic and inflammatory markers. This study highlights that protection against DN in RAGE KO mice is likely in part to be due the result of decreased responsiveness to growth factor stimulation and an anti-apoptotic phenotype in mesangial cells. Furthermore, it extends our understanding of the role of RAGE in the progression of DN since RAGE appears to play a key role in modulating the sensitivity of the kidney to injurious stimuli such as prosclerotic cytokines.