title: RhoA/Rho-kinase suppresses endothelial nitric oxide synthase in the penis: a mechanism for diabetes-associated erectile dysfunction.
abstract: Significant impairment in endothelial-derived nitric oxide is present in the diabetic corpus cavernosum. RhoA/Rho-kinase may suppress endothelial nitric oxide synthase (eNOS). Here, we tested the hypothesis that RhoA/Rho-kinase contributes to diabetes-related erectile dysfunction and down-regulation of eNOS in the streptozotocin (STZ)-diabetic rat penis. Colocalization of Rho-kinase and eNOS protein was present in the endothelium of the corpus cavernosum. RhoA/Rho-kinase protein abundance and MYPT-1 phosphorylation at Thr-696 were elevated in the STZ-diabetic rat penis. In addition, eNOS protein expression, cavernosal constitutive NOS activity, and cGMP levels were reduced in the STZ-diabetic penis. To assess the functional role of RhoA/Rho-kinase in the penis, we evaluated the effects of an adeno-associated virus encoding the dominant-negative RhoA mutant (AAVTCMV19NRhoA) on RhoA/Rho-kinase and eNOS and erectile function in vivo in the STZ-diabetic rat. STZ-diabetic rats transfected with AAVCMVT19NRhoA had a reduction in RhoA/Rho-kinase and MYPT-1 phosphorylation at a time when cavernosal eNOS protein, constitutive NOS activity, and cGMP levels were restored to levels found in the control rats. There was a significant decrease in erectile response to cavernosal nerve stimulation in the STZ-diabetic rat. AAVT19NRhoA gene transfer improved erectile responses in the STZ-diabetic rat to values similar to control. These data demonstrate a previously undescribed mechanism for the down-regulation of penile eNOS in diabetes mediated by activation of the RhoA/Rho-kinase pathway. Importantly, these data imply that inhibition of RhoA/Rho-kinase improves eNOS protein content and activity thus restoring erectile function in diabetes.
authors.affiliation: Department of Urology, Tulane Health Sciences Center, New Orleans, LA 70112, USA.
authors.forename: Trinity J
authors.initials: TJ
authors.lastname: Bivalacqua
authors.forename: Hunter C
authors.initials: HC
authors.lastname: Champion
authors.forename: Mustafa F
authors.initials: MF
authors.lastname: Usta
authors.forename: Selim
authors.initials: S
authors.lastname: Cellek
authors.forename: Kanchan
authors.initials: K
authors.lastname: Chitaley
authors.forename: R Clinton
authors.initials: RC
authors.lastname: Webb
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Lewis
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Mills
authors.forename: Wayne J G
authors.initials: WJ
authors.lastname: Hellstrom
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Kadowitz
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000577:Amides / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D006152:Cyclic GMP / Q000096:biosynthesis; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000150:complications* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000378:metabolism; D007172:Erectile Dysfunction / Q000201:enzymology* / Q000209:etiology; D015870:Gene Expression; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D043263:Myosin-Light-Chain Phosphatase / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D010413:Penis / Q000187:drug effects / Q000201:enzymology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014162:Transfection; D054460:rho-Associated Kinases
chemical_list: D000577:Amides; D001786:Blood Glucose; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D009125:Muscle Relaxants, Central; D011725:Pyridines; C108830:Y 27632; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496316:Nos3 protein, rat; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D043263:Myosin-Light-Chain Phosphatase; D006152:Cyclic GMP