Novel role of TrkC in diabetic nephropathy and cross-talk of TrkC with insulin-related signaling

Diabetic nephropathy is a major cause of end-stage renal disease. Kidney podocytes play a central role in the pathogenesis of diabetic nephropathy. With their intercellular contacts they assemble part of the kidney filter. Many molecular mechanisms of the pathogenesis of diabetic nephropathy are not elucidated and targeted therapies are lacking. Nephron-specific TrkCknockout (TrkC-KO) and TrkC overexpressing mice exhibit features of diabetic nephropathy such as enlarged glomeruli with mesangial proliferation, basement membrane thickening, albuminuria and podocyte loss when aging. Insulin-like growth factor 1 receptor (Igf1R)- associated gene expression was regulated in TrkC-KO mice glomeruli by qPCR. Phosphoproteins associated with insulin, erb-b2 receptor tyrosine kinase (Erbb) and Toll-like receptor signaling were enriched in lysates of podocytes treated with the TrkC ligand neurotrophin-3(Nt-3) in a mass spectrometry analysis. Activation of TrkC by Nt-3 resulted in phosphorylation of the Igf1R on activating tyrosine residues in podocytes. Our results identify TrkC to be a potentially targetable mediator of diabetic nephropathy.