Small molecular weight G-protein, H-Ras, and retinal endothelial cell apoptosis in diabetes

We have demonstrated that the expressions of small molecular weight G-protein, H-Ras, and its effector protein, Raf-1, are increased in the retina in diabetes, and the specific inhibitors of Ras function inhibit glucose-induced apoptosis of retinal capillary cells. This study is to examine the contr...

Full description

Saved in:
Bibliographic Details
Published in:Molecular and cellular biochemistry 2007-02, Vol.296 (1-2), p.69-76
Main Authors: Kowluru, Renu A, Kowluru, Anjan, Kanwar, Mamta
Format: Article
Language:English
Subjects:
Animals
Apoptosis
Apoptosis - physiology
Caspase 3 - metabolism
Cattle
Cells
Cells, Cultured
Diabetes
Diabetes Mellitus - pathology
Diabetic retinopathy
endothelial cells
Endothelial Cells - cytology
Endothelial Cells - physiology
Enzyme Activation
Glucose - metabolism
H-Ras
Humans
NF-kappa B - metabolism
Nitric Oxide - metabolism
Proto-Oncogene Proteins c-raf - genetics
Proto-Oncogene Proteins c-raf - metabolism
Proto-Oncogene Proteins p21(ras) - antagonists & inhibitors
Proto-Oncogene Proteins p21(ras) - genetics
Proto-Oncogene Proteins p21(ras) - metabolism
Retina - cytology
Retina - metabolism
Signal Transduction - physiology
small molecular weight G-protein
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We have demonstrated that the expressions of small molecular weight G-protein, H-Ras, and its effector protein, Raf-1, are increased in the retina in diabetes, and the specific inhibitors of Ras function inhibit glucose-induced apoptosis of retinal capillary cells. This study is to examine the contributory roles for H-Ras in glucose-induced apoptosis of retinal endothelial cells by genetic manipulation of functionally active H-Ras levels. Bovine retinal endothelial cells were transfected with the plasmids of either wild type (WT), constitutively active (V12) or dominant-negative (N17) H-Ras. Glucose-induced increase in apoptosis, nitric oxide (NO) levels and activation of NF-κB and caspase-3 were determined in these genetically manipulated cells. Exposure of bovine retinal endothelial cells to 20 mM glucose significantly increased H-Ras activation as determined by Raf-1 binding assay. Overexpression of V12 in the endothelial cells further increased their glucose-induced apoptosis by 40%, NO levels by about 50%, and activated NF-κB and caspase-3 by about 30-40% compared to the untransfected cells incubated in 20 mM glucose. In contrast, overexpression of the inactive mutant, N17, inhibited glucose-mediated increases in apoptotic cell death, NO levels and NF-κB and caspase-3 activation; the values were significantly different (p < 0.02) compared to those obtained from the untransfected cells incubated under similar conditions. Our findings demonstrate that H-Ras activation is important in the activation of the specific signaling events leading to the accelerated retinal capillary cell apoptosis in hyperglycemic conditions, suggesting the possible use of H-Ras inhibitors to inhibit the pathogenesis of diabetic retinopathy.
ISSN:0300-8177
1573-4919
DOI:10.1007/s11010-006-9299-z