Nitroxyl Donor CXL-1020 Lowers Blood Pressure by Targeting C195 in Cyclic Guanosine-3’,5’-Monophosphate-Dependent Protein Kinase I

Abstract

Background: We previously demonstrated that nitroxyl causes vasodilation, at least in part, by inducing the formation of an intradisulfide bond between C117 and C195 in the high affinity cyclic guanosine monophosphate-binding site of PKGI (cyclic guanosine monophosphate-dependent protein kinase I). The aim of this study was to determine whether nitroxyl donors lower blood pressure via this novel PKGI activation mechanism in vivo. Methods: To determine this, a C195S PKGI knock-in mouse model was generated that ubiquitously and constitutively expresses a mutant kinase resistant to nitroxyl-induced intradisulfide activation. Results: Knock-in and wild-type littermates did not differ in appearance, body weight, in PKGI protein expression or blood gas content. Organ weight was similar between genotypes apart from the cecum that was significantly enlarged in knock-in animals. Mean arterial pressure and heart rate monitored in vivo over 24 hours by radio-telemetry revealed neither a significant difference between genotypes at baseline nor during angiotensin II–induced hypertension or sepsis. CXL-1020, a clinically relevant nitroxyl donor, did not lower blood pressure in normotensive animals. In contrast, administering CXL-1020 to hypertensive wild-type mice reduced their blood pressure by 10±4 mm Hg ( P =0.0184), whereas the knock-in littermates were unaffected. Conclusions: Oxidation of C195 in PKGI contributes to the antihypertensive effects observed in response to nitroxyl donors, emphasising the potential importance of nitroxyl donors in pathological scenarios when cyclic guanosine monophosphate levels are reduced and insufficient to activate PKGI.

The 10th International Conference on cGMP 2022: recent trends in cGMP research and development—meeting report

“…On the contrary, micromolar concentrations of CXL-1020 induced transient relaxation of isolated mesenteric arteries in both genotypes; inhibition of the relaxation by the NO-GC inhibitor ODQ indicated activation of NO-GC rather than direct targeting cGKI as underlying mechanism. Interestingly, angiotensin II treatment increased blood pressure in WT and KI in a similar way; however, CXL-1020 induced a reduction in blood pressure by 10 mmHg only in WT (Kamynina et al 2022 ). Thus, intra-disulfide formation within cGKI subunits is capable of differentially reducing blood pressure in hypertensive but not healthy animals (Friederike Cuello, Hamburg).…”

Update on Endogenous HNO Production: An Exploration of Unanswered Questions and Challenges

“…[1][2][3][4][5][6][7] The available information has revealed enormous potential for its application in medicine. [6,[8][9][10] HNO initially emerged as a biologically active component in studies involving cyanamide (H 2 NCN), a drug used to treat alcoholism. [11][12][13] Further investigations revealed that the release of HNO via cyanamide induced vasorelaxation in the rabbit thoracic aorta.…”

“…[23] Additionally, HNO has been shown to lower blood pressure. [9] The positive inotropic and lusitropic effects of HNO are heightened in severely diabetic myocardium. [24] On the whole, HNO has demonstrated beneficial effects in both healthy hearts [25] and heart failure.…”

“…Over the last decades, extensive studies have been conducted on azanone due to its high biological significance [1–7] . The available information has revealed enormous potential for its application in medicine [6,8–10] . HNO initially emerged as a biologically active component in studies involving cyanamide (H 2 NCN), a drug used to treat alcoholism [11–13] .…”

PKG, CXL, and HNO. Relax!

“…In this issue of Hypertension, another piece of the PKGIα-puzzle is slotted into place. Kamynima et al 6 found evidence for a role of PGKIα-C195 in the nitroxyl (HNO)-mediated reduction of AngII-induced hypertension in mice treated with the HNO donor CXL1020. Interestingly, HNO was observed to have no effect in normotensive mice or in mice with sepsis-induced hypotension, indicating that the role of PGKIα-C195 in HNO treated mice was selectively unmasked in AngII-induced hypertension.…”