Aldose Reductase Genotypes and Cardiorenal Complications: An 8-year prospective analysis of 1,074 type 2 diabetic patients

OBJECTIVE—We report the independent risk association of type 2 diabetic nephropathy with the z−2 allele of the 5′-(CA)n microsatellite and C-106T promoter polymorphisms of the aldose reductase gene (ALR2) using a case-control design. In this expanded cohort, we examined their predictive roles on new onset of cardiorenal complications using a prospective design

Genetic deficiency of aldose reductase counteracts the development of diabetic nephropathy in C57BL/6 mice

National Science Foundation of China [30770490]; 973 Program of China [2009CB941601]; Science Planning Program of Fujian Province [2009J1010]; Natural Science Foundation of Fujian Province [2009J01180]; Fujian Provincial Department of Science and TechnoloThe aim of the study was to investigate the effects of genetic deficiency of aldose reductase in mice on the development of key endpoints of diabetic nephropathy. A line of Ar (also known as Akr1b3)-knockout (KO) mice, a line of Ar-bitransgenic mice and control C57BL/6 mice were used in the study. The KO and bitransgenic mice were deficient for Ar in the renal glomeruli and all other tissues, with the exception of, in the bitransgenic mice, a human AR cDNA knockin-transgene that directed collecting-tubule epithelial-cell-specific AR expression. Diabetes was induced in 8-week-old male mice with streptozotocin. Mice were further maintained for 17 weeks then killed. A number of serum and urinary variables were determined for these 25-week-old mice. Periodic acid-Schiff staining, western blots, immunohistochemistry and protein kinase C (PKC) activity assays were performed for histological analyses, and to determine the levels of collagen IV and TGF-beta 1 and PKC activities in renal cortical tissues. Diabetes-induced extracellular matrix accumulation and collagen IV overproduction were completely prevented in diabetic Ar-KO and bitransgenic mice. Ar deficiency also completely or partially prevented diabetes-induced activation of renal cortical PKC, TGF-beta 1 and glomerular hypertrophy. Loss of Ar results in a 43% reduction in urine albumin excretion in the diabetic Ar-KO mice and a 48% reduction in the diabetic bitransgenic mice (p < 0.01). Genetic deficiency of Ar significantly ameliorated development of key endpoints linked with early diabetic nephropathy in vivo. Robust and specific inhibition of aldose reductase might be an effective strategy for the prevention and treatment of diabetic nephropathy

High glucose alters mesangial cell protein kinase C activity and isoform cellular content and localization, role of the polyol pathway

grantor: University of TorontoHigh glucose causes diacylglycerol (DAG) accumulation and protein kinase C (PKC) activation in mesangial cells. Our purpose was to determine which of the DAG-sensitive PKC isoforms are affected by high glucose, and whether the polyol pathway plays a role. Primary cultured rat mesangial cells were growth-arrested and cultured in glucose 5.6 mM (NG) or 30 mM glucose (HG) for 48 h, with or without the aldose reductase inhibitor tolrestat or ARI-509. Total PKC activity was measured by an in situ phosphorylation assay. Activation of specific PKC isoforms was inferred by translocation from the cytosol to other cellular compartments, determined by immunoblotting and confocal immunofluorescence microscopy. HG increased total PKC activity; total levels of PKC-$\alpha$, -\beta\sb2, and -$\varepsilon ;$ membrane and particulate PKC-$\alpha ,$ membrane PKC-$\delta$ and PKC-$\varepsilon .$ These HG effects were not due to the increase in osmolality, demonstrated by the L-glucose control. In HG, confocal imaging confirmed an increase in all four PKC isoforms and indicated translocation to the plasma membrane and nucleus of PKC-$\alpha ,$ -$\delta ,$ and -$\varepsilon .$ ARI-509, but not tolrestat, normalized total PKC activity in HG. In HG, both drugs prevented the increase in total PKC-$\varepsilon$ and membrane PKC-$\alpha ,$ -$\delta ,$ and -$\varepsilon .$ In conclusion, we found that HG causes an increase in total PKC activity, accumulation and cellular redistribution of DAG-sensitive PKC isoforms. HG-induced changes in PKC-$\varepsilon$ content and membrane-association of PKC-$\delta ,$ and -$\varepsilon ,$ and possibly PKC-$\alpha ,$ are polyol pathway-dependent.M.Sc