Blocking VEGF/Caveolin-1 signaling contributes to renal protection of fasudil in streptozotocin-induced diabetic rats.
OBJECTIVE
RhoA/ROCK signaling plays an important role in diabetic nephropathy, and ROCK inhibitor fasudil exerts nephroprotection in experimental diabetic nephropathy. In this study we investigated the molecular mechanisms underlying the protective actions of fasudil in a rat model of diabetic nephropathy.


METHODS
Streptozotocin (STZ)-induced diabetic rats, to which fasudil or a positive control drug enalapril were orally administered for 8 months. Metabolic parameters and blood pressure were assessed during the treatments. After the rats were euthanized, kidney samples were collected for histological and molecular biological studies. VEGF, VEGFR1, VEGFR2 and fibronectin expression, and Src and caveolin-1 phosphorylation in the kidneys were assessed using RT-PCR, Western blot and immunohistochemistry assays. The association between VEGFR2 and caveolin-1 was analyzed with immunoprecipitation.


RESULTS
Chronic administration of fasudil (30 and 100 mg·kg(-1)·d(-1)) or enalapril (10 mg/kg, bid) significantly attenuated the glomerular sclerosis and albuminuria in the diabetic rats. Furthermore, fasudil treatment prevented the upregulation of VEGF, VEGFR1, VEGFR2 and fibronectin, and the increased association between VEGFR2 and caveolin-1 in the renal cortices, and partially blocked Src activation and caveolin-1 phosphorylation on tyrosine 14 in the kidneys, whereas enalapril treatment had no effects on the VEGFR2/Src/caveolin-1 signaling pathway.


CONCLUSIONS
Fasudil exerts protective actions in STZ-induced diabetic nephropathy by blocking the VEGFR2/Src/caveolin-1 signaling pathway and fibronectin upregulation. Thus, VEGFR2 may be a potential therapeutic target for the treatment of diabetic nephropathy.
Department of Biochemistry, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China.
Jing
J
Jin
Department of Biochemistry, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China.
Chao
C
Peng
Department of Biochemistry, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China.
Su-zhen
SZ
Wu
Department of Biochemistry, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China.
Hong-min
HM
Chen
1] Department of Biochemistry, Wuhan University School of Basic Medical Sciences, Wuhan 430071, China [2] Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China.
Bai-fang
BF
Zhang
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D051242:Caveolin 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013311:Streptozocin; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000378:metabolism
C495537:Cav1 protein, rat; D051242:Caveolin 1; D047428:Protein Kinase Inhibitors; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D013311:Streptozocin; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C049347:fasudil