Translocation of H-Ras and its implications in the development of diabetic retinopathy.
H-Ras, a small molecular weight G-protein, undergoes post-translational modifications enabling its translocation from cytosol to the membrane. Hyperglycemia increases apoptosis of retinal capillary cells via activation of H-Ras, which can be ameliorated by farnesylation inhibitors. Our aim is to investigate the mechanism of retinal H-Ras activation in diabetes. H-Ras and Raf-1 were quantified in the retinal membrane and cytosol fractions obtained from streptozotocin-induced diabetes rats, and the role of post-translation modification was determined by investigating the effect of simvastatin on diabetes-induced alterations. The effect of H-Ras-siRNA on membrane translocation and apoptosis was also determined in bovine retinal endothelial cells (BRECs). Diabetes increased expressions of H-Ras and Raf-1 in the retinal membranes, and simvastatin prevented such translocation. Glucose-exposure of BRECs increased membrane H-Ras expression and H-Ras-siRNA prevented this translocation, and also decreased their apoptosis. Thus, membrane translocation of H-Ras is a plausible mechanism responsible for accelerated apoptosis of retinal capillary cells in diabetes.
Kowluru
Renu A
RA
Department of Ophthalmology, Kresge Eye Institute, Wayne State University, 4717 St. Antoine, Detroit, MI 48201, USA. rkowluru@med.wayne.edu
Kanwar
Mamta
M
D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D003930:Diabetic Retinopathy / Q000201:enzymology* / Q000235:genetics; D008297:Male; D021381:Protein Transport; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000201:enzymology*
D019908:Proto-Oncogene Proteins c-raf; D016283:Proto-Oncogene Proteins p21(ras)