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Alteration of the soluble guanylate cyclase system in coronary arteries of high cholesterol diet-fed rabbits.

ABSTRACT: This study aimed to investigate how atherosclerosis affects the soluble guanylate cyclase (sGC) system in coronary arteries. Rabbits were fed a normal diet for 12 weeks (N group) or a diet containing high cholesterol (1%) for 4 weeks (S-HC group) and 12 weeks (L-HC group). Cholesterol deposition in the intima of coronary arteries was observed in the S-HC group, but the formation of an atherosclerotic plaque was not observed. In contrast, a major plaque developed in the L-HC group. The relaxant response of isolated coronary arteries to sodium nitroprusside (SNP, nitric oxide donor) was not different between the N and S-HC groups, whereas the response in the L-HC group was markedly attenuated. The relaxation induced by BAY 60-2770 (sGC activator) tended to be augmented in the S-HC group, but it was significantly impaired in the L-HC group compared to that in the N group. sGC β1 immunostaining was equally detected in the medial layer of the arteries among the N, S-HC, and L-HC groups. In addition, a strong staining was observed in the plaque region of the L-HC group. cGMP levels in the arteries stimulated with SNP were identical in the N and S-HC groups and slightly lower in the L-HC group than the other groups. BAY 60-2770-stimulated cGMP formation tended to be increased in the S-HC and L-HC groups. These findings suggest that the sGC system was not normal in atherosclerotic coronary arteries. The redox state of sGC and the distribution pattern are likely to change with the progression of atherosclerosis.

SUBMITTER: Tawa M

PROVIDER: S-EPMC8294056 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Heme oxygenase-1 knockout, H(mox)1(-/-), mice exhibit exacerbated vascular lesions after ischemia-reperfusion and mechanical injury. Surprisingly, we found no studies that reported contractile responses and sensitivity to vasorelaxants in H(mox)1(-/-) mice. The contractile responses [superior mesenteric arteries (SMA), from female H(mox)1(-/-) mice] exhibited increased sensitivity to phenylephrine (p < 0.001). Cumulative addition of acetylcholine relaxed SMA, with the residual contraction remaining 2 times higher in H(mox)1(-/-) mice (p < 0.001). Sodium nitroprusside (SNP, an NO donor) and 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole [YC-1; acts directly on soluble guanylate cyclase (sGC)] led to further relaxation, yet the residual contraction remained 2 to 3 times higher in H(mox)1(-/-) than H(mox)1(+/+) mice (p < 0.001). Branches from H(mox)1(-/-) mesenteric and renal arteries also showed reduced relaxation (p < 0.025). Relaxation of SMA was measured to 4-({(4-carboxybutyl) [2-(5-fluoro-2-{[4'-(trifluoromethyl) biphenyl-4-yl] methoxy}phenyl)ethyl]amino}benzoic acid (BAY 60-2770), which is a more effective activator of oxidized/heme-free sGC; and to 5-cyclopropyl-2-{1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl}-pyrimidin-4-ylamine (BAY 41-2272), a more effective stimulator of reduced sGC. H(mox)1(-/-) arteries were 15 times more sensitive to BAY 60-2770 (p < 0.025) than were H(mox)1(+/+) arteries. Pretreatment with 1H-[1,2,4]oxadiazolo[3,4-a]quinoxalin-1-one (ODQ), an oxidizer of sGC, predictably shifted the BAY 60-2770 response of H(mox)1(+/+) to the left (p < 0.01) and BAY 41-2272 response to the right (p < 0.01). ODQ had little effect on the responses of H(mox)1(-/-) arteries, indicating that much of sGC was oxidized/heme-free. Western analyses of sGC in SMA indicated that both ?1 and ?1 subunit levels were reduced to <50% of H(mox)1(+/+) level (p < 0.025). These findings support the hypothesis that the antioxidant function of H(mox)1 plays a significant role in the maintenance of sGC in a reduced state, which is resistant to degradation and is sensitive to NO. This function may be especially important in reducing vascular damage during ischemia-reperfusion injury.

Project description:Eukaryotic nitric oxide (NO) signaling involves modulation of cyclic GMP (cGMP) levels through activation of the soluble isoform of guanylate cyclase (sGC). sGC is a heterodimeric hemoprotein that contains a Heme-Nitric oxide and OXygen binding (H-NOX) domain, a Per/ARNT/Sim (PAS) domain, a coiled-coil (CC) domain, and a catalytic domain. To evaluate the role of these domains in regulating the ligand binding properties of the heme cofactor of NO-sensitive sGC, we constructed chimeras by swapping the rat ?1 H-NOX domain with the homologous region of H-NOX domain-containing proteins from Thermoanaerobacter tengcongensis, Vibrio cholerae, and Caenorhabditis elegans (TtTar4H, VCA0720, and Gcy-33, respectively). Characterization of ligand binding by electronic absorption and resonance Raman spectroscopy indicates that the other rat sGC domains influence the bacterial and worm H-NOX domains. Analysis of cGMP production in these proteins reveals that the chimeras containing bacterial H-NOX domains exhibit guanylate cyclase activity, but this activity is not influenced by gaseous ligand binding to the heme cofactor. The rat-worm chimera containing the atypical sGC Gcy-33 H-NOX domain was weakly activated by NO, CO, and O(2), suggesting that atypical guanylate cyclases and NO-sensitive guanylate cyclases have a common molecular mechanism for enzyme activation. To probe the influence of the other sGC domains on the mammalian sGC heme environment, we generated heme pocket mutants (Pro118Ala and Ile145Tyr) in the ?1 H-NOX construct (residues 1-194), the ?1 H-NOX-PAS-CC construct (residues 1-385), and the full-length ?1?1 sGC heterodimer (?1 residues 1-619). Spectroscopic characterization of these proteins shows that interdomain communication modulates the coordination state of the heme-NO complex and the heme oxidation rate. Taken together, these findings have important implications for the allosteric mechanism of regulation within H-NOX domain-containing proteins.

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Alteration of the soluble guanylate cyclase system in coronary arteries of high cholesterol diet-fed rabbits.

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