Transnitrosylation: A Factor in Nitric Oxide-Mediated Penile Erection.
Nitric oxide (NO) signaling can be mediated not only through classic 3',5'-cyclic guanosine monophosphate but also through S-nitrosylation. However, the impact of S-nitrosylation on erectile function and in NO regulation and oxidative stress in the penis remains poorly understood.



To characterize the role of S-nitrosoglutathione reductase (GSNOR), a major regulator of S-nitrosylation homeostasis, on erection physiology and on endothelial NO synthase (eNOS) function and oxidative-nitrosative stress in the penis.



Adult GSNOR-deficient and wild-type (WT) mice were used. Erectile function was assessed in response to electrical stimulation of the cavernous nerve. Total NO in penile homogenates was measured by Griess reaction. Protein S-nitrosylation, eNOS phosphorylation on Ser-1177 (positive regulatory site), eNOS uncoupling, and markers of oxidative stress (4-hydroxy-2-nonenal, malondialdehyde, and nitrotyrosine) in the penis were measured by western blot.



Erectile function, eNOS function, and oxidative stress in the penis of GSNOR-deficient mice.



Erectile function was intact in GSNOR-deficient mice. Total S-nitrosylated proteins were increased (P < .05) in the GSNOR(-/-) compared with WT mouse penis. Although eNOS phosphorylation on Ser-1177 did not differ between the GSNOR(-/-) and WT mouse penises at baseline, electrical stimulation of the cavernous nerve increased (P < .05) phosphorylated eNOS in the WT mouse penis but failed to increase phosphorylated eNOS in the GSNOR(-/-) mouse penis. Total NO production was decreased (P < .05), whereas eNOS uncoupling, 4-hydroxy-2-nonenal, malondialdehyde, and nitrotyrosine were increased (P < .05) in the GSNOR-deficient mouse penis compared with the WT mouse penis.



Transnitrosylation mechanisms play an important role in regulating NO bioactivity in the penis. Deficiency of GSNOR leads to eNOS dysfunction and increased oxidative damage, suggesting that homeostatic eNOS function in the penis is governed by transnitrosylation.
The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
Biljana
B
Musicki
The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
Gwen
G
Lagoda
The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
Tabitha
T
Goetz
The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
Justin D
JD
La Favor
The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
Arthur L
AL
Burnett
D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D000818:Animals; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism*; D008297:Male; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010410:Penile Erection / Q000502:physiology*; D010413:Penis / Q000294:innervation; D010766:Phosphorylation
D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent
Endothelial Nitric Oxide Synthase; Endothelial Nitric Oxide Synthase Uncoupling; Erectile Function; Mouse; Oxidative-Nitrosative Stress; S-Nitrosoglutathione Reductase; S-Nitrosylation