title: cGMP-dependent activation of protein kinase G precludes disulfide activation: implications for blood pressure control.
abstract: Protein kinase G (PKG) is activated by nitric oxide (NO)-induced cGMP binding or alternatively by oxidant-induced interprotein disulfide formation. We found preactivation with cGMP attenuated PKG oxidation. 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) blockade of cGMP production increased disulfide PKG to 13 ± 2% and 29±4% of total in aorta and mesenteries, respectively. This was potentially anomalous, because we observed 2.7-fold higher NO levels in aorta than mesenteries; consequently, we had anticipated that ODQ would induce more disulfide in the conduit vessel. ODQ also constricted aorta, whereas it had no effect on mesenteries. Thus, mesenteries, but not aorta, can compensate for loss of NO-cGMP by recruiting disulfide activation of PKG. Mechanistically, this is explained by loss of cGMP allowing disulfide formation in response to basal oxidant production. Why aorta treated with ODQ generated less PKG disulfide that is insufficient to induce vasoconstriction was unclear. One potential explanation, especially because aorta were much less sensitive than mesenteries to exogenous H(2)O(2)-induced relaxation (EC(50)=205 ± 24 and 33 ± 2 µmol/L, respectively) was that conduit vessels may have higher peroxidase capacity. Indeed, we found that aorta express 49 ± 22% and 80 ± 25% more peroxiredoxin and thioredoxin, respectively, than mesenteries, and their 2-Cys peroxiredoxin peroxidatic cysteines were also less sensitive to hyperoxidation. The higher peroxidase capacity of aortas would explain their constriction during cGMP removal and their insensitivity to H(2)O(2)-induced relaxation compared with mesenteries. In summary, cGMP binding to PKG induces a state that is resistant to disulfide formation. Consequently, cGMP depletion sensitizes PKG to oxidation; this happens to a lesser extent in aortas than in mesenteries, because the conduit vessels generate more NO and express more peroxiredoxin.
authors.affiliation: Cardiovascular Division, King's College London, Rayne Institute, St Thomas' Hospital, London SE1 7EH, United Kingdom.
authors.forename: Joseph Robert
authors.initials: JR
authors.lastname: Burgoyne
authors.forename: Oleksandra
authors.initials: O
authors.lastname: Prysyazhna
authors.forename: Olena
authors.initials: O
authors.lastname: Rudyk
authors.forename: Philip
authors.initials: P
authors.lastname: Eaton
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D001665:Binding Sites / Q000235:genetics; D001794:Blood Pressure / Q000187:drug effects; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism* / Q000494:pharmacology; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015151:Immunoblotting; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects
chemical_list: C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D004220:Disulfides; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D016877:Oxidants; D011810:Quinoxalines; C091861:spermine nitric oxide complex; D013096:Spermine; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D006152:Cyclic GMP