Altered endothelial nitric oxide synthase targeting and conformation and caveolin-1 expression in the diabetic kidney.
Experimental diabetes is associated with complex changes in renal nitric oxide (NO) bioavailability. We explored the effect of diabetes on renal cortical protein expression of endothelial NO synthase (eNOS) with respect to several determinants of its enzymatic function, such as eNOS expression, membrane localization, phosphorylation, and dimerization, in moderately hyperglycemic streptozotocin-induced diabetic rats compared with nondiabetic control rats and diabetic rats with intensive insulin treatment to achieve near-normal metabolic control. We studied renal cortical expression and localization of caveolin-1 (CAV-1), an endogenous modulator of eNOS function. Despite similar whole-cell eNOS expression in all groups, eNOS monomer and dimer in membrane fractions were reduced in moderately hyperglycemic diabetic rats compared with control rats; the opposite trend was apparent in the cytosol. Stimulatory phosphorylation of eNOS (Ser1177) was also reduced in moderately hyperglycemic diabetic rats. eNOS colocalized and interacted with CAV-1 in endothelial cells throughout the renal vascular tree both in control and moderately hyperglycemic diabetic rats. However, the abundance of membrane-localized CAV-1 was decreased in diabetic kidneys. Intensive insulin treatment reversed the effects of diabetes on each of these parameters. In summary, we observed diabetes-mediated alterations in eNOS and CAV-1 expression that are consistent with the view of decreased bioavailability of renal eNOS-derived NO.
Komers
Radko
R
Division of NephrologyHypertension PP262, Oregon Health and Science University, 3314 SW US Veterans Hospital Rd., Portland, OR 97239, USA. komersr@ohsu.edu
Schutzer
William E
WE
Reed
John F
JF
Lindsley
Jessie N
JN
Oyama
Terry T
TT
Buck
David C
DC
Mader
Scott L
SL
Anderson
Sharon
S
D000818:Animals; D015153:Blotting, Western; D051242:Caveolin 1 / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D007328:Insulin / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D052250:Nitric Oxide Synthase Type III / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013311:Streptozocin
D051242:Caveolin 1; D007004:Hypoglycemic Agents; D007328:Insulin; D013311:Streptozocin; D052250:Nitric Oxide Synthase Type III