Molecular Mechanisms of Apoptosis of Glomerular Podocytes in Diabetic Nephropathy

Dysfunctions of glomerular podocytes and triggering of apoptotic processes in them are the main molecular causes of diabetic nephropathy and other kidney diseases. Pathogenetic factors causing these dysfunctions of podocytes are hyperglycemia, increased levels of advanced glycation end-products, oxidative stress, increased activity of inflammatory factors, and endoplasmic reticulum stress. These factors and their combinations result in the triggering of a number of intracellular signaling pathways that cause activation of apoptosis and reduce the survival of podocytes. Among these pathways are: (1) the Wnt/beta-catenin pathway, which is activated by the Wnt-proteins when they bind to the complex of Frizzled receptors and LRP co-receptors; (2) the mTOR-dependent signaling pathway, including the mTORC1 and mTORC2 complexes, which are involved in the regulation of autophagy and endoplasmic reticulum stress and are regulated by various stimuli and effectors, the AMP-activated protein kinase in particular; (3) the Rho/ROCK signaling pathway, including GTPases of the Rho family and Rho-associated protein kinase ROCK1; (4) calcium-dependent signaling pathways triggered by an increase in the concentration of intracellular Ca2+, primarily through the activation of calcium channels of the TRPC family. The review provides a detailed analysis of the current state of knowledge about the molecular mechanisms responsible for the regulation of apoptotic processes in glomerular podocytes and also considers hormonal and other factors that regulate them both in norm and in lesions induced by hyperglycemia and diabetic nephropathy.