High glucose-altered gene expression in mesangial cells - Actin-regulatory protein gene expression is triggered by oxidative stress and cytoskeletal disassembly

High extracellular glucose plays a pivotal role in the pathophysiology of diabetic nephropathy. Here we report 200 genes, identified using suppression-subtractive hybridization, that are differentially expressed when human mesangial cells are propagated in high ambient glucose in vitro. The major functional classes of genes identified included modulators and products of extracellular matrix protein metabolism, regulators of cell growth and turnover, and a cohort of actin cytoskeleton regulatory proteins. Actin cytoskeletal disassembly is a prominent feature of diabetic nephropathy. The induction of actin cytoskeleton regulatory gene expression by high glucose was attenuated by the inhibitor of reactive oxygen species generation, carbonyl cyanide m-chlorophenylhydrazone but not by the protein kinase C inhibitor GF 109203X and was not mimicked by the addition of transforming growth factor beta. Enhanced expression of actin cytoskeleton regulatory genes was also observed following disruption of the mesangial cell actin cytoskeleton by cytochalasin D. In aggregate, these results suggest that the induction of genes encoding actin cytoskeleton regulatory proteins (a) is a prominent component of the mesangial cell transcriptomic response in diabetic nephropathy and (b) is dependent on oxidative stress, is independent of protein kinase C and transforming growth factor-beta, and represents an adaptive response to actin cytoskeleton disassembly.