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MIALET-PEREZ, Jeanne/0000-0002-1765-0283; O, Lairez/0000-0001-8141-6582; Sicard, Pierre/0000-0001-5837-3916; Vindis, Cecile/0000-0003-2421-1155; Schiltz, Odile/0000-0002-3606-2356; Santin, Yohan/0000-0002-9229-1161 WOS:000534930000012 PubMed: 31819159 Chronic remodeling postmyocardial infarction consists in various maladaptive changes including interstitial fibrosis, cardiomyocyte death and mitochondrial dysfunction that lead to heart failure (HF). Reactive aldehydes such as 4-hydroxynonenal (4-HNE) are critical mediators of mitochondrial dysfunction but the sources of mitochondrial 4-HNE in cardiac diseases together with its mechanisms of action remain poorly understood. Here, we evaluated whether the mitochondrial enzyme monoamine oxidase-A (MAO-A), which generates H2O2 as a by-product of catecholamine metabolism, is a source of deleterious 4-HNE in HF. We found that MAO-A activation increased mitochondrial ROS and promoted local 4-HNE production inside the mitochondria through cardiolipin peroxidation in primary cardiomyocytes. Deleterious effects of MAO-A/4-HNE on cardiac dysfunction were prevented by activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2), the main enzyme for 4-HNE metabolism. Mechanistically, MAO-A-derived 4-HNE bound to newly identified targets VDAC and MCU to promote ER-mitochondria contact sites and MCU higher-order complex formation. The resulting mitochondrial Ca2+ accumulation participated in mitochondrial respiratory dysfunction and loss of membrane potential, as shown with the protective effects of the MCU inhibitor, RU360. Most interestingly, these findings were recapitulated in a chronic model of ischemic remodeling where pharmacological or genetic inhibition of MAO-A protected the mice from 4-HNE accumulation, MCU oligomer formation and Ca2+ overload, thus mitigating ventricular dysfunction. To our knowledge, these are the first evidences linking MAO-A activation to mitoCa(2+) mishandling through local 4-HNE production, contributing to energetic failure and postischemic remodeling.

Exercise training has been demonstrated to have beneficial effects in patients with heart failure (HF) or diabetes. However, it is unknown whether diabetic patients with HF will benefit from exercise training. Male Wistar rats were fed either a standard (Sham, n = 53) or high-fat, high-sucrose diet ( n = 66) for 6 mo. After 2 mo of diet, the rats were already diabetic. Rats were then randomly subjected to either myocardial infarction by coronary artery ligation (MI) or sham operation. Two months later, heart failure was documented by echocardiography and animals were randomly subjected to exercise training with treadmill for an additional 8 wk or remained sedentary. At the end, rats were euthanized and tissues were assayed by RT-PCR, immunoblotting, spectrophotometry, and immunohistology. MI induced a similar decrease in ejection fraction in diabetic and lean animals but a higher premature mortality in the diabetic group. Exercise for 8 wk resulted in a higher working power developed by MI animals with diabetes and improved glycaemia but not ejection fraction or pathological phenotype. In contrast, exercise improved the ejection fraction and increased adaptive hypertrophy after MI in the lean group. Trained diabetic rats with MI were nevertheless able to develop cardiomyocyte hypertrophy but without angiogenic responses. Exercise improved stress markers and cardiac energy metabolism in lean but not diabetic-MI rats. Hence, following HF, the benefits of exercise training on cardiac function are blunted in diabetic animals. In conclusion, exercise training only improved the myocardial profile of infarcted lean rats fed the standard diet.NEW & NOTEWORTHY Exercise training is beneficial in patients with heart failure (HF) or diabetes. However, less is known of the possible benefit of exercise training for HF patients with diabetes. Using a rat model where both diabetes and MI had been induced, we showed that 2 mo after MI, 8 wk of exercise training failed to improve cardiac function and metabolism in diabetic animals in contrast to lean animals.

International audience; Aims: Recent studies reported that cAMP-binding protein Epac1-deficient mice were protected against various forms of cardiac stress, suggesting that pharmacological inhibition of Epac1 could be beneficial for the treatment of cardiac diseases. To test this assumption, we characterized an Epac1-selective inhibitory compound and investigated its potential cardioprotective properties.Methods and results: We used the Epac1-BRET (bioluminescence resonance energy transfer) for searching for non-cyclic nucleotide Epac1 modulators. A thieno[2,3-b]pyridine derivative, designated as AM-001 was identified as a non-competitive inhibitor of Epac1. AM-001 has no antagonist effect on Epac2 or protein kinase A activity. This small molecule prevents the activation of the Epac1 downstream effector Rap1 in cultured cells, in response to the Epac1 preferential agonist, 8-CPT-AM. In addition, we found that AM-001 inhibited Epac1-dependent deleterious effects such as cardiomyocyte hypertrophy and death. Importantly, AM-001-mediated inhibition of Epac1 reduces infarct size after mouse myocardial ischaemia/reperfusion injury. Finally, AM-001 attenuates cardiac hypertrophy, inflammation and fibrosis, and improves cardiac function during chronic β-adrenergic receptor activation with isoprenaline (ISO) in mice. At the molecular level, ISO increased Epac1-G protein-coupled receptor kinase 5 (GRK5) interaction and induced GRK5 nuclear import and histone deacetylase type 5 (HDAC5) nuclear export to promote the activity of the prohypertrophic transcription factor, myocyte enhancer factor 2 (MEF2). Inversely, AM-001 prevented the non-canonical action of GRK5 on HDAC5 cytoplasmic shuttle to down-regulate MEF2 transcriptional activity.Conclusion: Our study represents a ‘proof-of-concept’ for the therapeutic effectiveness of inhibiting Epac1 activity in cardiac disease using small-molecule pharmacotherapy.

Rationale: Although the second messenger cyclic AMP (cAMP) is physiologically beneficial in the heart, it largely contributes to cardiac disease progression when dysregulated. Current evidence suggests that cAMP is produced within mitochondria. However, mitochondrial cAMP signaling and its involvement in cardiac pathophysiology are far from being understood. Objective: To investigate the role of MitEpac1 (mitochondrial exchange protein directly activated by cAMP 1) in ischemia/reperfusion injury. Methods and Results: We show that Epac1 (exchange protein directly activated by cAMP 1) genetic ablation ( Epac1 −/− ) protects against experimental myocardial ischemia/reperfusion injury with reduced infarct size and cardiomyocyte apoptosis. As observed in vivo, Epac1 inhibition prevents hypoxia/reoxygenation–induced adult cardiomyocyte apoptosis. Interestingly, a deleted form of Epac1 in its mitochondrial-targeting sequence protects against hypoxia/reoxygenation–induced cell death. Mechanistically, Epac1 favors Ca 2+ exchange between the endoplasmic reticulum and the mitochondrion, by increasing interaction with a macromolecular complex composed of the VDAC1 (voltage-dependent anion channel 1), the GRP75 (chaperone glucose-regulated protein 75), and the IP3R1 (inositol-1,4,5-triphosphate receptor 1), leading to mitochondrial Ca 2+ overload and opening of the mitochondrial permeability transition pore. In addition, our findings demonstrate that MitEpac1 inhibits isocitrate dehydrogenase 2 via the mitochondrial recruitment of CaMKII (Ca 2+ /calmodulin-dependent protein kinase II), which decreases nicotinamide adenine dinucleotide phosphate hydrogen synthesis, thereby, reducing the antioxidant capabilities of the cardiomyocyte. Conclusions: Our results reveal the existence, within mitochondria, of different cAMP–Epac1 microdomains that control myocardial cell death. In addition, our findings suggest Epac1 as a promising target for the treatment of ischemia-induced myocardial damage.

Background: Concentrations of the anti-angiogenic factor soluble fms-like tyrosine kinase-1 (sFlt-1) are altered in peripartum cardiomyopathy (PPCM). In this study we investigated changes in the angiogenesis balance in PPCM. Methods and Results: Plasma concentrations of sFlt-1 and the pro-angiogenic placenta growth factor (PlGF) were determined in patients with PPCM during the post-partum phase (n=83), in healthy women at delivery (n=30), and in patients with acute heart failure (AHF; n=65). Women with cardiac failure prepartum or associated with any form of hypertension, including pre-eclampsia, were excluded. Compared with non-pregnant women, in women with AHF and PPCM, median PlGF concentrations were greater (19 [IQR 16–22] and 98 [IQR 78–126] ng/mL, respectively; P0.94. Median plasma concentrations of the anti-angiogenic factor relaxin-2 were lower in PPCM and AHF (0.3 [IQR 0.3–1.7] and 0.3 [IQR 0.3–1] ng/mL, respectively) compared with normal deliveries (1,807 [IQR 1,101–4,050] ng/mL; P

Hypertension, which is a risk factor of heart failure, provokes adaptive changes at the vasculature and cardiac levels. Notch3 signaling plays an important role in resistance arteries by controlling the maturation of vascular smooth muscle cells. Notch3 deletion is protective in pulmonary hypertension while deleterious in arterial hypertension. Although this latter phenotype was attributed to renal and cardiac alterations, the underlying mechanisms remained unknown. To investigate the role of Notch3 signaling in the cardiac adaptation to hypertension, we used mice with either constitutive Notch3 or smooth muscle cell–specific conditional RBPJκ knockout. At baseline, both genotypes exhibited a cardiac arteriolar rarefaction associated with oxidative stress. In response to angiotensin II–induced hypertension, the heart of Notch3 knockout and SM- RBPJκ knockout mice did not adapt to pressure overload and developed heart failure, which could lead to an early and fatal acute decompensation of heart failure. This cardiac maladaptation was characterized by an absence of media hypertrophy of the media arteries, the transition of smooth muscle cells toward a synthetic phenotype, and an alteration of angiogenic pathways. A subset of mice exhibited an early fatal acute decompensated heart failure, in which the same alterations were observed, although in a more rapid timeframe. Altogether, these observations indicate that Notch3 plays a major role in coronary adaptation to pressure overload. These data also show that the hypertrophy of coronary arterial media on pressure overload is mandatory to initially maintain a normal cardiac function and is regulated by the Notch3/RBPJκ pathway.

Introduction Des donnees in vitro suggerent que l’inhibition pharmacologique des proteines EPAC, des regulateurs du signal cytoplasmique de l’AMPc, s’accompagne d’anomalies quantitatives et qualitatives de l’expression de l’aquaporine-2 (AQP2) dans les cellules principales du canal collecteur, en particulier lors d’une stimulation prolongee des recepteurs AVPR2 par l’ADH. EPAC1 ou EPAC2 pourraient etre de nouvelles cibles therapeutiques dans les pathologies impliquant la voie de signalisation ADH/AVPR2/AMPc/AQP2 (SIADH, diabete insipide, polykystose renale). Patients et methodes Dans des souris invalidees pour Epac1 (Epac1-/-) et des souris sauvages (wt), les parametres suivants ont ete mesures a l’etat basal, apres injection de ddAVP ou de furosemide, et apres restriction hydrique prolongee (RH30) : osmolarite, sodium, potassium, magnesium, calcium, uree, creatinine (sang et urine) ; histologie renale ; expression d’AQP2 (qPCR, WB et microscopie confocale) et d’Avpr2, Nkcc, Nkcc2, UT-1, Aqp1, Aqp8 (qPCR). Resultats A l’etat basal, l’osmolarite urinaire et serique des souris Epac1-/- et wt ne different pas, tout comme les concentrations d’electrolytes. L’expression des autres acteurs de l’homeostasie hydrique n’est pas modifiee. De meme, apres stimulation aigue (ddAVP) ou prolongee (RH30) du recepteur AVPR2, les capacites de reabsorption hydrique des souris Epac1-/- et wt sont identiques. La reponse au furosemide est egalement conservee (diurese, osmolarite). De fait, l’expression (ARNm et proteine) d’AQP2, tout comme son adressage a la membrane apicale chez les souris Epac1-/- sont identiques aux controles. En revanche, on note chez les souris wt une augmentation significative de l’expression d’EPAC1 sans modification d’EPAC2 apres RH30 (WB). Chez les souris Epac1-/-, l’expression d’EPAC2 est significativement diminuee apres RH30 (WB). Discussion Contrairement aux donnees in vitro utilisant un blocage pharmacologique visant EPAC1 et EPAC2, les souris Epac1-/- ne presentent pas de trouble franc de concentration des urines, suggerant une redondance des voies de signalisation et/ou une action combinee d’EPAC1 et EPAC2. Conclusion Chez la souris, l’invalidation isolee d’EPAC1 ne s’accompagne pas d’anomalie de l’expression d’AQP2 et de la reabsorption d’eau.

5 Epac1 deletion prevents cardiomyocyte apoptosis during ischemia/reperfusion {#article-title-2} Introduction: Early coronary reperfusion has been established as the best therapeutic strategy to limit infarct size and improve prognosis. Therefore, elucidating the mechanisms underlying cardiomyocyte death may yield novel therapeutic targets to limit ischemia reperfusion (I/R) injury. I/R is accompanied and influenced by perturbations of the β-adrenergic receptor pathway which acts through cAMP dependent signaling cascade to modulate cardiac function and remodeling. Purpose: Although the involvement of the cAMP-binding protein Epac1 in cardiac hypertrophy and arrhythmia has been recently described, its role in I/R induced-cardiomyocyte death has not yet been investigated. Methods: Isolated adult cardiomyocytes from Epac1 knock-out (Epac1-/-) mice or wild-type (WT) littermates were exposed to hypoxia (HX) for 4h and 2h of reoxygenation period (HX+R). Cell death was determined by Trypan blue staining and LDH release. The mitochondrial permeability transition pore (mPTP) opening was monitored by the calcein loading CoCl(2)-quenching technique. The area at risk was examined by Evans blue and infarct size was evaluated by TTC staining. Results: Our data showed that HX+R-induced cardiomyocyte death were significantly prevented in adult cardiomyocytes isolated from Epac1-/- mice. In addition, we found that the increased expression of apoptotic markers (Bax, cleaved Caspase-9,Caspase-3) during HX+R conditions were also inhibited in Epac1-/- cardiomyocytes compared to WT cells. Interestingly, HX+R induced a decrease in calcein fluorescence corresponding to mPTP opening (56%±1.1 vs control cells set at 100%) in WT cardiomyocytes while genetic deletion of Epac1 prevented mPTP opening in HX+R conditions. Concomitantly, we found that the infarct size was significantly reduced in the Epac1-/- mice compared to the WT animals (53±4 % vs 33±4%, p