Volume overload induces differential spatiotemporal regulation of myocardial soluble guanylyl cyclase in eccentric hypertrophy and heart failure

Abstract

Nitric oxide activation of soluble guanylyl cyclase (sGC) blunts the cardiac stress response, including cardiomyocyte hypertrophy. In the concentric hypertrophied heart, oxidation and re-localization of myocardial sGC diminish cyclase activity, thus aggravating depressed nitric oxide–cyclic guanosine monophosphate (NO–cGMP) signaling in the pressure-overloaded failing heart. Here, we hypothesized that volume-overload differentially disrupts myocardial sGC activity during early compensated and late decompensated stages of eccentric hypertrophy. To this end, we studied the expression, redox state, subcellular localization, and activity of sGC in the left ventricle of dogs subjected to chordal rupture-induced mitral regurgitation (MR). Unoperated dogs were used as Controls. Animals were studied at 4 weeks and 12 months post chordal rupture, corresponding with early (4wkMR) and late stages (12moMR) of eccentric hypertrophy. We found that the sGC heterodimer subunits relocalized away from caveolae-enriched lipid raft microdomains at different stages; sGCβ1 at 4wkMR, followed by sGCα1 at 12moMR. Moreover, expression of both sGC subunits fell at 12moMR. Using the heme-dependent NO donor DEA/NO and NO-/heme-independent sGC activator BAY 60-2770, we determined the redox state and inducible activity of sGC in the myocardium, within caveolae and non-lipid raft microdomains. sGC was oxidized in non-lipid raft microdomains at 4wkMR and 12moMR. While overall DEA/NO-responsiveness remained intact in MR hearts, DEA/NO responsiveness of sGC in non-lipid raft microdomains was depressed at 12moMR. Caveolae-localization protected sGC against oxidation. Further studies revealed that these modifications of sGC were also reflected in caveolae-localized cGMP-dependent protein kinase (PKG) and MAPK signaling. In MR hearts, PKG-mediated phosphorylation of vasodilator-stimulated phosphoprotein (VASP) disappeared from caveolae whereas caveolae-localization of phosphorylated ERK5 increased. These findings show that differential oxidation, re-localization, and expression of sGC subunits distinguish eccentric from concentric hypertrophy as well as compensated from decompensated heart failure.

Crosstalk between mitogen-activated protein kinases and mitochondria in cardiac diseases: Therapeutic perspectives

“…Similar to other MAPKs, in vivo and in vitro studies demonstrated that various hypertrophic stimuli and growth factors rapidly and transiently enhanced ERK5 activity in cultured cardiomyocytes (Ikeda et al, 2005, Nicol et al, 2001) and intact hearts (Takeishi et al, 2001, Kacimi and Gerdes, 2003). Recent studies in dogs demonstrated that volume overload-induced eccentric hypertrophy increased the localization of p-ERK5 in caveolae and selectively activated ERK5 signaling (Liu et al, 2013). However, the progression of hypertrophy to HF reduced ERK5 activity to normal levels (Kacimi and Gerdes, 2003), or even lower levels (Takeishi et al, 2002).…”

Chronic β1-adrenergic blockade enhances myocardial β3-adrenergic coupling with nitric oxide-cGMP signaling in a canine model of chronic volume overload: new insight into mechanisms of cardiac benefit with selective β1-blocker therapy

“…Mitral regurgitation (MR) was induced in conditioned mongrel dogs (19–26 kg) by rupturing a papillary chord under fluoroscopy, as previously described [25, 29, 46]. Sixteen dogs underwent chordal rupture and ten unoperated dogs served as controls.…”

“…Caveolae-enriched lipid raft fractions (Cav3 + LR) were prepared from snap-frozen LV tissue, using a discontinuous 35–5 % sucrose density gradient ultracentrifugation method as previously described [29, 57]. LV tissue homogenization was carried out on ice, in detergent-free buffer (50 mmol/L Tris–HCl, pH 7.6, 1 mmol/L EDTA, 1 mmol/L DTT, 2 mmol/L PMSF, 50 mmol/L NaF, 1 mmol/L Na Vanadate) with protease inhibitors (Mammalian Cocktail, Sigma-Aldrich).…”

“…Yet how the interaction between βAR and NO signaling differs in the stressed and pathologically remodeled heart is not fully understood. We previously demonstrated that NO-sGC-cGMP signaling is dysregulated in animal models of concentric and eccentric cardiac hypertrophy with respect to myocardial expression, subcellular localization, and oxidation of sGC heterodimer subunits [29, 57]. …”

Guidelines for Translational Research in Heart Failure

“…Sheep, pigs, and dogs all have been used for modeling HF [17]. In these models, HF can be induced by tachycardia (i.e., pacing) [33,34], ischemia provoked by either coronary artery occlusion [35,36] or microembolization [37], or volume overload [38,39]. They differ in their pathological characteristics and offer distinct advantages and disadvantages for testing therapies.…”