Activation of NF-kappa B is required for hypertrophic growth of primary rat neonatal ventricular cardiomyocytes

Increased PHLPP1 expression through ERK-4E-BP1 signaling axis drives nicotine induced oxidative stress related damage of cardiomyocytes

Nicotine, a key constituent of tobacco/electronic cigarettes causes cardiovascular injury and mortality. Nicotine is known to induce oxidative stress and mitochondrial dysfunction in cardiomyocytes leading to cell death. However, the underlying mechanisms remain unclear. Pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) is a member of metal-dependent protein phosphatase (PPM) family and is known to dephosphorylate several AGC family kinases and thereby regulate a diverse set of cellular functions including cell growth, survival, and death. Our lab has previously demonstrated that PHLPP1 removal reduced cardiomyocyte death and cardiac dysfunction following injury. Here, we present a novel finding that nicotine exposure significantly increased PHLPP1 protein expression in the adolescent rodent heart. Building upon our in vivo finding, we determined the mechanism of PHLPP1 expression in cardiomyocytes. Nicotine significantly increased PHLPP1 protein expression without altering PHLPP2 in cardiomyocytes. In cardiomyocytes, nicotine significantly increased NADPH oxidase 4 (NOX4), which coincided with increased reactive oxygen species (ROS) and increased cardiomyocyte apoptosis which were dependent on PHLPP1 expression. PHLPP1 expression was both necessary and sufficient for nicotine induced mitochondrial dysfunction. Mechanistically, nicotine activated extracellular signal-regulated protein kinases (ERK1/2) and subsequent eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) to increase PHLPP1 protein expression. Inhibition of protein synthesis with cycloheximide (CHX) and 4EGI-1 abolished nicotine induced PHLPP1 protein expression. Moreover, inhibition of ERK1/2 activity by U0126 significantly blocked nicotine induced PHLPP1 expression. Overall, this study reveals a novel mechanism by which nicotine regulates PHLPP1 expression through ERK-4E-BP1 signaling axis to drive cardiomyocyte injury.

Human Gut Microbiota in Heart Failure: Trying to Unmask an Emerging Organ

There is a bidirectional relationship between the heart and the gut. The gut microbiota, the community of gut micro-organisms themselves, is an excellent gut-homeostasis keeper since it controls the growth of potentially harmful bacteria and protects the microbiota environment. There is evidence suggesting that a diet rich in fatty acids can be metabolized and converted by gut microbiota and hepatic enzymes to trimethyl-amine N-oxide (TMAO), a product that is associated with atherogenesis, platelet dysfunction, thrombotic events, coronary artery disease, stroke, heart failure (HF), and, ultimately, death. HF, by inducing gut ischemia, congestion, and, consequently, gut barrier dysfunction, promotes the intestinal leaking of micro-organisms and their products, facilitating their entrance into circulation and thus stimulating a low-grade inflammation associated with an immune response. Drugs used for HF may alter the gut microbiota, and, conversely, gut microbiota may modify the pharmacokinetic properties of the drugs. The modification of lifestyle based mainly on exercise and a Mediterranean diet, along with the use of pre- or probiotics, may be beneficial for the gut microbiota environment. The potential role of gut microbiota in HF development and progression is the subject of this review.

JMJD6 protects against isoproterenol-induced cardiac hypertrophy via inhibition of NF-κB activation by demethylating R149 of the p65 subunit

Histone modification plays an important role in pathological cardiac hypertrophy and heart failure. In this study we investigated the role of a histone arginine demethylase, Jumonji C domain-containing protein 6 (JMJD6) in pathological cardiac hypertrophy. Cardiac hypertrophy was induced in rats by subcutaneous injection of isoproterenol (ISO, 1.2 mg·kg-1·d-1) for a week. At the end of the experiment, the rats underwent echocardiography, followed by euthanasia and heart collection. We found that JMJD6 levels were compensatorily increased in ISO-induced hypertrophic cardiac tissues, but reduced in patients with heart failure with reduced ejection fraction (HFrEF). Furthermore, we demonstrated that JMJD6 overexpression significantly attenuated ISO-induced hypertrophy in neonatal rat cardiomyocytes (NRCMs) evidenced by the decreased cardiomyocyte surface area and hypertrophic genes expression. Cardiac-specific JMJD6 overexpression in rats protected the hearts against ISO-induced cardiac hypertrophy and fibrosis, and rescued cardiac function. Conversely, depletion of JMJD6 by single-guide RNA (sgRNA) exacerbated ISO-induced hypertrophic responses in NRCMs. We revealed that JMJD6 interacted with NF-κB p65 in cytoplasm and reduced nuclear levels of p65 under hypertrophic stimulation in vivo and in vitro. Mechanistically, JMJD6 bound to p65 and demethylated p65 at the R149 residue to inhibit the nuclear translocation of p65, thus inactivating NF-κB signaling and protecting against pathological cardiac hypertrophy. In addition, we found that JMJD6 demethylated histone H3R8, which might be a new histone substrate of JMJD6. These results suggest that JMJD6 may be a potential target for therapeutic interventions in cardiac hypertrophy and heart failure.

Recent Advances in Microbiota-Associated Metabolites in Heart Failure

Heart failure is a risk factor for adverse events such as sudden cardiac arrest, liver and kidney failure and death. The gut microbiota and its metabolites are directly linked to the pathogenesis of heart failure. As emerging studies have increased in the literature on the role of specific gut microbiota metabolites in heart failure development, this review highlights and summarizes the current evidence and underlying mechanisms associated with the pathogenesis of heart failure. We found that gut microbiota-derived metabolites such as short chain fatty acids, bile acids, branched-chain amino acids, tryptophan and indole derivatives as well as trimethylamine-derived metabolite, trimethylamine N-oxide, play critical roles in promoting heart failure through various mechanisms. Mainly, they modulate complex signaling pathways such as nuclear factor kappa-light-chain-enhancer of activated B cells, Bcl-2 interacting protein 3, NLR Family Pyrin Domain Containing inflammasome, and Protein kinase RNA-like endoplasmic reticulum kinase. We have also highlighted the beneficial role of other gut metabolites in heart failure and other cardiovascular and metabolic diseases.

PARP1 Inhibition and Effect on Burn Injury-Induced Inflammatory Response and Cardiac Function

BACKGROUND

Burn injury induces multiple signaling pathways leading to a significant inflammatory storm that adversely affects multiple organs, including the heart. Poly (ADP-ribose) polymerase inhibitor 1 (PARP1) inhibition, with specific agents such as N-(5,6-Dihydro-6-oxo-2-phenanthridinyl)-2-acetamide (PJ34), is effective in reducing oxidative stress and cytokine expression in the heart. We hypothesized that PARP1 inhibition would reduce inflammatory signaling and protect against burn injury-induced cardiac dysfunction.

STUDY DESIGN

Male Sprague-Dawley rats (8 weeks old, 300 to 350 g) were randomly assigned to sham injury (Sham), 60% total body surface area burn (24 hours post burn), or 60% total body surface area burn with intraperitoneal administration of PJ34 (20 mg/kg, 24 hours post burn + PJ34) and sacrificed 24 hours after injury. Cardiac function was determined using Vevo 2100 echocardiography. Genetic expression of 84 specific toll-like receptor-mediated signal transduction and innate immunity genes were examined using microarray to evaluate cardiac tissue. Qiagen GeneGlobe Data Analysis Center was used to analyze expression, and genetic clustering was performed using TreeView V2.0.8 software. Real-time quantitative polymerase chain reaction was used to validate identified differentially expressed genes.

RESULTS

Burn injury significantly altered multiple genes in the toll-like receptor signaling, interleukin-17 signaling, tumor necrosis factor signaling, and nuclear factor-κB signaling pathways and led to significant cardiac dysfunction. PARP1 inhibition with PJ34 normalized these signaling pathways to sham levels as well as improved cardiac function to sham levels.

CONCLUSIONS

PARP1 inhibition normalizes multiple inflammatory pathways that are altered after burn injury and improves cardiac dysfunction. PARP1 pathway inhibition may provide a novel methodology to normalize multiple burn injury-induced inflammatory pathways in the heart.

The Role of Intestinal Flora and Its Metabolites in Heart Failure

Intestinal flora is a complex collection of microbial communities that participate in the physiological and pathological activities of the human body through various pathways. In recent years, numerous studies have reported that intestinal flora are involved in the occurrence and development of heart failure (HF) and its metabolic products could play an important role in this progression, suggesting a great value in the clinical treatment of this condition. This study reported the interaction between intestinal flora and HF, and with intestinal flora metabolites, such as short-chain fatty acids, trimethylamine N-oxide and bile acids and urotoxins, considered as the starting point, the mechanism of the roles in HF was summarized. Additionally, the current research status and the development prospects of applying flora and metabolites to the clinical therapeutic decision of HF were discussed.

Changes in nuclear pore numbers control nuclear import and stress response of mouse hearts

Nuclear pores are essential for nuclear-cytoplasmic transport. Whether and how cells change nuclear pores to alter nuclear transport and cellular function is unknown. Here, we show that rat heart muscle cells (cardiomyocytes) undergo a 63% decrease in nuclear pore numbers during maturation, and this changes their responses to extracellular signals. The maturation-associated decline in nuclear pore numbers is associated with lower nuclear import of signaling proteins such as mitogen-activated protein kinase (MAPK). Experimental reduction of nuclear pore numbers decreased nuclear import of signaling proteins, resulting in decreased expression of immediate-early genes. In a mouse model of high blood pressure, reduction of nuclear pore numbers improved adverse heart remodeling and reduced progression to lethal heart failure. The decrease in nuclear pore numbers in cardiomyocyte maturation and resulting functional changes demonstrate how terminally differentiated cells permanently alter their handling of information flux across the nuclear envelope and, with that, their behavior.

NF-κB, A Potential Therapeutic Target in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death globally. Atherosclerosis is the basis of major CVDs - myocardial ischemia, heart failure, and stroke. Among numerous functional molecules, the transcription factor nuclear factor κB (NF-κB) has been linked to downstream target genes involved in atherosclerosis. The activation of the NF-κB family and its downstream target genes in response to environmental and cellular stress, hypoxia, and ischemia initiate different pathological events such as innate and adaptive immunity, and cell survival, differentiation, and proliferation. Thus, NF-κB is a potential therapeutic target in the treatment of atherosclerosis and related CVDs. Several biologics and small molecules as well as peptide/proteins have been shown to regulate NF-κB dependent signaling pathways. In this review, we will focus on the function of NF-κB in CVDs and the role of NF-κB inhibitors in the treatment of CVDs.

An Injectable Dual-Function Hydrogel Protects Against Myocardial Ischemia/Reperfusion Injury by Modulating ROS/NO Disequilibrium

Acute myocardial infarction (MI) is the leading cause of death worldwide. Exogenous delivery of nitric oxide (NO) to the infarcted myocardium has proven to be an effective strategy for treating MI due to the multiple physiological functions of NO. However, reperfusion of blood flow to the ischemic tissues is accompanied by the overproduction of toxic reactive oxygen species (ROS), which can further exacerbate tissue damage and compromise the therapeutic efficacy. Here, an injectable hydrogel is synthesized from the chitosan modified by boronate-protected diazeniumdiolate (CS-B-NO) that can release NO in response to ROS stimulation and thereby modulate ROS/NO disequilibrium after ischemia/reperfusion (I/R) injury. Furthermore, administration of CS-B-NO efficiently attenuated cardiac damage and adverse cardiac remodeling, promoted repair of the heart, and ameliorated cardiac function, unlike a hydrogel that only released NO, in a mouse model of myocardial I/R injury. Mechanistically, regulation of the ROS/NO balance activated the antioxidant defense system and protected against oxidative stress induced by I/R injury via adaptive regulation of the Nrf2-Keap1 pathway. Inflammation is then reduced by inhibition of the activation of NF-κB signaling. Collectively, these results show that this dual-function hydrogel may be a promising candidate for the protection of tissues and organs after I/R injury.

Trans-cinnamaldehyde protects against phenylephrine-induced cardiomyocyte hypertrophy through the CaMKII/ERK pathway

BACKGROUND

Trans-cinnamaldehyde (TCA) is one of the main pharmaceutical ingredients of Cinnamomum cassia Presl, which has been shown to have therapeutic effects on a variety of cardiovascular diseases. This study was carried out to characterize and reveal the underlying mechanisms of the protective effects of TCA against cardiac hypertrophy.

METHODS

We used phenylephrine (PE) to induce cardiac hypertrophy and treated with TCA in vivo and in vitro. In neonatal rat cardiomyocytes (NRCMs), RNA sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were carried out to identify potential pathways of TCA. Then, the phosphorylation and nuclear localization of calcium/calmodulin-dependent protein kinase II (CaMKII) and extracellular signal-related kinase (ERK) were detected. In adult mouse cardiomyocytes (AMCMs), calcium transients, calcium sparks, sarcomere shortening and the phosphorylation of several key proteins for calcium handling were evaluated. For mouse in vivo experiments, cardiac hypertrophy was evaluated by assessing morphological changes, echocardiographic parameters, and the expression of hypertrophic genes and proteins.

RESULTS

TCA suppressed PE-induced cardiac hypertrophy and the phosphorylation and nuclear localization of CaMKII and ERK in NRCMs. Our data also demonstrate that TCA blocked the hyperphosphorylation of ryanodine receptor type 2 (RyR2) and phospholamban (PLN) and restored Ca2+ handling and sarcomere shortening in AMCMs. Moreover, our data revealed that TCA alleviated PE-induced cardiac hypertrophy in adult mice and downregulated the phosphorylation of CaMKII and ERK.

CONCLUSION

TCA has a protective effect against PE-induced cardiac hypertrophy that may be associated with the inhibition of the CaMKII/ERK pathway.

Slc39a2-Mediated Zinc Homeostasis Modulates Innate Immune Signaling in Phenylephrine-Induced Cardiomyocyte Hypertrophy

Zinc dyshomeostasis has been involved in the pathogenesis of cardiac hypertrophy; however, the dynamic regulation of intracellular zinc and its downstream signaling in cardiac hypertrophy remain largely unknown. Using Zincpyr1 staining, we found a significant decrease of intracellular Zinc concentration in phenylephrine (PE)-induced hypertrophy of neonatal rat ventricular myocytes (NRVMs). We then screened SLC39 family members responsible for zinc uptake and identified Slc39a2 as the only one altered by PE treatment. Slc39a2 knockdown in NRVMs reduced the intracellular Zinc level, and exacerbated the hypertrophic responses to PE treatment. In contrast, adenovirus-mediated Slc39a2 overexpression enhanced zinc uptake and suppressed PE-induced Nppb expression. RNA sequencing analysis showed a pro-hypertrophic transcriptome reprogramming after Slc39a2 knockdown. Interestingly, the innate immune signaling pathways, including NOD signaling, TOLL-like receptor, NFκB, and IRFs, were remarkably enriched in the Slc39a2-regulated genes. Slc39a2 deficiency enhanced the phosphorylation of P65 NFκB and STAT3, and reduced the expression of IκBα. Finally, the expression of IRF7 was significantly increased by Slc39a2 knockdown, which was in turn suppressed by IRF7 knockdown. Our data demonstrate that zinc homeostasis mediated by a Slc39a2/IRF7 regulatory circuit contributes to the alteration of innate immune signaling in cardiomyocyte hypertrophy.

Attenuating persistent sodium current-induced atrial myopathy and fibrillation by preventing mitochondrial oxidative stress

Mechanistically driven therapies for atrial fibrillation (AF), the most common cardiac arrhythmia, are urgently needed, the development of which requires improved understanding of the cellular signaling pathways that facilitate the structural and electrophysiological remodeling that occurs in the atria. Similar to humans, increased persistent Na+ current leads to the development of an atrial myopathy and spontaneous and long-lasting episodes of AF in mice. How increased persistent Na+ current causes both structural and electrophysiological remodeling in the atria is unknown. We crossbred mice expressing human F1759A-NaV1.5 channels with mice expressing human mitochondrial catalase (mCAT). Increased expression of mCAT attenuated mitochondrial and cellular reactive oxygen species (ROS) and the structural remodeling that was induced by persistent F1759A-Na+ current. Despite the heterogeneously prolonged atrial action potential, which was unaffected by the reduction in ROS, the incidences of spontaneous AF, pacing-induced after-depolarizations, and AF were substantially reduced. Expression of mCAT markedly reduced persistent Na+ current-induced ryanodine receptor oxidation and dysfunction. In summary, increased persistent Na+ current in atrial cardiomyocytes, which is observed in patients with AF, induced atrial enlargement, fibrosis, mitochondrial dysmorphology, early after-depolarizations, and AF, all of which can be attenuated by resolving mitochondrial oxidative stress.

Integrins in cardiac hypertrophy: lessons learned from culture systems

Heart growth and pathological changes are accompanied by extracellular matrix‐dependent alterations in integrins and integrin‐associated proteins, suggesting their role in heart development and disease. Most of our knowledge on the involvement of integrins in heart pathology is provided by the in vivo experiments, including cardiac hypertrophy models. However, in vivo studies are limited by the complex organization of heart tissue and fail to discern cell types and particular integrins implicated in hypertrophic signalling. This problem is being addressed by isolated cardiomyocyte primary cultures, which have been successfully used in different in vitro disease models. This review aimed to analyse the general approaches to studying integrins and integrin‐associated signalling pathways in cardiac hypertrophy focusing on the in vitro systems. The lessons learned from culture experiments on the models of hypertrophy induced by stretch, stimulating factors, and/or extracellular matrix components are summarized, demonstrating the major involvement of integrin‐mediated signalling in cardiac hypertrophic response and its apparent crosstalk with signal pathways induced by stretch or hypertrophy stimulating factors. The benefits and perspectives of using cardiomyocyte primary culture as a hypertrophy model are discussed.

RhoA Signaling in Immune Cell Response and Cardiac Disease

Chronic inflammation, the activation of immune cells and their cross-talk with cardiomyocytes in the pathogenesis and progression of heart diseases has long been overlooked. However, with the latest research developments, it is increasingly accepted that a vicious cycle exists where cardiomyocytes release cardiocrine signaling molecules that spiral down to immune cell activation and chronic state of low-level inflammation. For example, cardiocrine molecules released from injured or stressed cardiomyocytes can stimulate macrophages, dendritic cells, neutrophils and even T-cells, which then subsequently increase cardiac inflammation by co-stimulation and positive feedback loops. One of the key proteins involved in stress-mediated cardiomyocyte signal transduction is a small GTPase RhoA. Importantly, the regulation of RhoA activation is critical for effective immune cell response and is being considered as one of the potential therapeutic targets in many immune-cell-mediated inflammatory diseases. In this review we provide an update on the role of RhoA at the juncture of immune cell activation, inflammation and cardiac disease.

Empagliflozin Disrupts a Tnfrsf12a-Mediated Feed Forward Loop That Promotes Left Ventricular Hypertrophy

PURPOSE

Although the cardioprotective benefits of sodium-glucose cotransporter 2 (SGLT2) inhibitors are now widely appreciated, the mechanisms underlying these benefits remain unresolved. Tumor necrosis factor receptor superfamily member 12a (Tnfrsf12a) is a receptor for tumor necrosis factor superfamily member 12 (Tnfsf12). Tnfrsf12a is highly inducible and plays a key role in the development of cardiac hypertrophy and heart failure. Here we set out to determine if SGLT2 inhibition affects the Tnfsf12/Tnfrsf12a system in the stressed myocardium.

METHODS

C57BL/6N mice that had undergone sham or transverse aortic constriction (TAC) surgery were treated with either the SGLT2 inhibitor empagliflozin (400 mg/kg diet; 60-65 mg/kg/day) or standard chow alone and were followed for 8 weeks. Tnfrsf12a expression in mouse hearts was assessed by in situ hybridization, qRT-PCR, and immunoblotting.

RESULTS

Left ventricular (LV) mass, end-systolic volume, and end-diastolic volume were all increased in TAC mice and were significantly lower with empagliflozin. Myocyte hypertrophy and interstitial fibrosis in TAC hearts were similarly attenuated with empagliflozin. Tnfrsf12a expression was upregulated in mouse hearts following TAC surgery but not in the hearts of empagliflozin-treated mice. In cultured cardiomyocytes, Tnfrsf12a antagonism attenuated the increase in cardiomyocyte size that was induced by phenylephrine.

CONCLUSION

Empagliflozin attenuates LV enlargement in mice with hypertrophic heart failure. This effect may be mediated, at least in part, by a reduction in loading conditions which limits upregulation of the inducible, proinflammatory, and prohypertrophic TNF superfamily receptor, Tnfrsf12a. Disruption of the Tnfsf12/Tnfrsf12a feed forward system may contribute to the cardioprotective benefits of SGLT2 inhibition.

Butterfly Pea Flower (Clitoria ternatea Linn.) Extract Ameliorates Cardiovascular Dysfunction and Oxidative Stress in Nitric Oxide-Deficient Hypertensive Rats

In this study, we examine whether Clitoria ternatea Linn. (CT) can prevent Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced cardiac and vascular dysfunction in rats. Male Sprague Dawley rats were given L-NAME (40 mg/kg, drinking water) and orally administered with CT extract (300 mg/kg/day) or lisinopril (2.5 mg/kg/day) for 5 weeks. The main phytochemical components of the CT extract were found to be flavonoids. The CT extract alleviated the high blood pressure in rats receiving L-NAME. Decreased vasorelaxation responses to acetylcholine and enhanced contractile responses to sympathetic nerve stimulation in aortic rings and mesenteric vascular beds of L-NAME treated rats were ameliorated by CT extract supplementation. Left ventricular hypertrophy and dysfunction were developed in L-NAME rats, which were partially prevented by CT extract treatment. The CT extract alleviated upregulated endothelial nitric oxide synthase expression, decreased plasma nitrate/nitrite levels, and increased oxidative stress in L-NAME rats. It suppressed high levels of serum angiotensin-converting enzyme activity, plasma angiotensin II, and cardiac angiotensin II type 1 receptor, NADPH oxidases 2, nuclear factor-kappa B, and tumor necrosis factor-alpha expression. The CT extract, therefore, partially prevented L-NAME-induced hypertension and cardiovascular alterations in rats. These effects might be related to a reduction in the oxidative stress and renin-angiotensin system activation due to L-NAME in rats.

Divergent and Overlapping Roles for Selected Phytochemicals in the Regulation of Pathological Cardiac Hypertrophy

Plant-based foods, like fruits, vegetables, whole grains, legumes, nuts, seeds and other foodstuffs, have been deemed as heart healthy. The chemicals within these plant-based foods, i.e., phytochemicals, are credited with protecting the heart. However, the mechanistic actions of phytochemicals, which prevent clinical endpoints, such as pathological cardiac hypertrophy, are still being elucidated. We sought to characterize the overlapping and divergent mechanisms by which 18 selected phytochemicals prevent phenylephrine- and phorbol 12-myristate 13-acetate-mediated cardiomyocyte enlargement. Of the tested 18 compounds, six attenuated PE- and PMA-mediated enlargement of neonatal rat ventricular myocytes. Cell viability assays showed that apigenin, baicalein, berberine hydrochloride, emodin, luteolin and quercetin dihydrate did not reduce cell size through cytotoxicity. Four of the six phytochemicals, apigenin, baicalein, berberine hydrochloride and emodin, robustly inhibited stress-induced hypertrophy and were analyzed further against intracellular signaling and genome-wide changes in mRNA expression. The four phytochemicals differentially regulated mitogen-activated protein kinases and protein kinase D. RNA-sequencing further showed divergence in gene regulation, while pathway analysis demonstrated overlap in the regulation of inflammatory pathways. Combined, this study provided a comprehensive analysis of cardioprotective phytochemicals. These data highlight two defining observations: (1) that these compounds predominantly target divergent gene pathways within cardiac myocytes and (2) that regulation of overlapping signaling and gene pathways may be of particular importance for the anti-hypertrophic actions of these phytochemicals. Despite these new findings, future works investigating rodent models of heart failure are still needed to understand the roles for these compounds in the heart.

YQWY Decoction Improves Myocardial Remodeling via Activating the IL-10/Stat3 Signaling Pathway

Heart failure (HF) has been known as a global health problem, and cardiac remodeling plays an essential role in the development of HF. We hypothesized that YQWY decoction might exert a cardioprotective effect against myocardium inflammation, fibrosis, and apoptosis via activating the interleukin-10 (IL-10)/Stat3 signaling pathway. To test this hypothesis, the HF model in rats was established by pressure overload through the minimally invasive transverse aortic constriction (MTAC). Echocardiography was performed to assess the left ventricular function of rats. Myocardial fibrosis in rats was observed by Masson and Picrosirius red staining, and the degree of myocardial apoptosis was detected via TUNEL staining. In addition, expression levels of IL-10, tumor necrosis factor-α (TNF-α), Stat3 (P-Stat3), P65 (P-P65), CD68, collagen I, TGF-β, CTGF, Bax, Bcl-2, cleaved caspase-3, and PARP in rat serum and myocardium samples were examined by ELISA, western blot, and immunohistochemistry, respectively. YQWY decoction treatment significantly improved left ventricular function in HF rats, especially in those of the high-dose group (LVEF%: 51.29 ± 5.876 vs. 66.02 ± 1.264, P < 0.01;, LVFS%: 27.75 ± 3.757 vs. 37.76 ± 1.137, P < 0.01). Furthermore, YQWY decoction markedly inhibited MTAC-induced myocardial fibrosis as evidenced by downregulated collagen I, TGF-β, and CTGF in myocardium and alleviated apoptosis (downregulated caspase-3 and PARP and increased Bcl-2/Bax ratio in cardiomyocytes). In addition, YQWY decoction decreased the level of the proinflammatory cytokine TNF-α in both circulating blood and myocardium and attenuated infiltration of inflammatory cells in heart tissue from HF rats. Most importantly, YQWY decoction suppressed MTAC-induced NF-κB activation and phosphorylated Stat3 by upregulating IL-10 in rat heart tissues. Our study showed that YQWY decoction could attenuate MTAC-induced myocardial inflammation, fibrosis, apoptosis, and reverse the impairment of cardiac function in rats by activating the IL-10/Stat3 signaling pathway and improving myocardium remodeling. Our findings suggested a therapeutic potential of YQWY decoction in HF.

The endocrinological component and signaling pathways associated to cardiac hypertrophy

Although myocardial growth corresponds to an adaptive response to maintain cardiac contractile function, the cardiac hypertrophy is a condition that occurs in many cardiovascular diseases and typically precedes the onset of heart failure. Different endocrine factors such as thyroid hormones, insulin, insulin-like growth factor 1 (IGF-1), angiotensin II (Ang II), endothelin (ET-1), catecholamines, estrogen, among others represent important stimuli to cardiomyocyte hypertrophy. Thus, numerous endocrine disorders manifested as changes in the local environment or multiple organ systems are especially important in the context of progression from cardiac hypertrophy to heart failure. Based on that information, this review summarizes experimental findings regarding the influence of such hormones upon signalling pathways associated with cardiac hypertrophy. Understanding mechanisms through which hormones differentially regulate cardiac hypertrophy could open ways to obtain therapeutic approaches that contribute to prevent or delay the onset of heart failure related to endocrine diseases.

Prostaglandin E1 protects cardiomyocytes against hypoxia-reperfusion induced injury via the miR-21-5p/FASLG axis

Background: Prostaglandin-E1 (PGE1) is a potent vasodilator with anti-inflammatory and antiplatelet effects. However, the mechanism by which PGE1 contributes to the amelioration of cardiac injury remains unclear.

Methods: The present study was designed to investigate how PGE1 protects against hypoxia/reoxygenation (H/R)-induced injuries by regulating microRNA-21-5p (miR-21-5p) and fas ligand (FASLG). Rat H9C2 cells and isolated primary cardiomyocytes were cultured under hypoxic conditions for 6 h (6H, hypoxia for 6 h), and reoxygenated for periods of 6 (6R, reoxygenation for 6 h), 12, and 24 h, respectively. Cells from the 6H/6R group were treated with various doses of PGE1; after which, their levels of viability and apoptosis were detected.

Results: The 6H/6R treatment regimen induced the maximum level of H9C2 cell apoptosis, which was accompanied by the highest levels of Bcl-2-associated X protein (Bax) and cleaved-caspase-3 expression and the lowest level of B-cell lymphoma 2 (Bcl-2) expression. Treatment with PGE1 significantly diminished the cell cytotoxicity and apoptosis induced by the 6H/6R regimen, and also decreased expression of IL-2, IL-6, P-p65, TNF-α, and cleaved-caspase-3. In addition, we proved that PGE1 up-regulated miR-21-5p expression in rat cardiomyocytes exposed to conditions that produce H/R injury. FASLG was a direct target of miR-21-5p, and PGE1 reduced the ability of H/R-injured rat cardiomyocytes to undergo apoptosis by affecting the miR-21-5p/FASLG axis. In addition, we proved that PGE1 could protect primary cardiomyocytes against H/R-induced injuries.

Conclusions: These results indicate that PGE1 exerts cardioprotective effects in H9C2 cells during H/R by regulating the miR-21-5p/FASLG axis.

FGF13 Is a Novel Regulator of NF-κB and Potentiates Pathological Cardiac Hypertrophy

FGF13 is an intracellular FGF factor. Its role in cardiomyopathies has been rarely investigated. We revealed that endogenous FGF13 is up-regulated in cardiac hypertrophy accompanied by increased nuclear localization. The upregulation of FGF13 plays a deteriorating role both in hypertrophic cardiomyocytes and mouse hearts. Mechanistically, FGF13 directly interacts with p65 by its nuclear localization sequence and co-localizes with p65 in the nucleus in cardiac hypertrophy. FGF13 deficiency inhibits NF-κB activation in ISO-treated NRCMs and TAC-surgery mouse hearts, whereas FGF13 overexpression shows the opposite trend. Moreover, FGF13 overexpression alone is sufficient to activate NF-κB in cardiomyocytes. The interaction between FGF13 and p65 or the effects of FGF13 on NF-κB have nothing to do with IκB. Together, an IκB-independent mechanism for NF-κB regulation has been revealed in cardiomyocytes both under basal and stressful conditions, suggesting the promising application of FGF13 as a therapeutic target for pathological cardiac hypertrophy and heart failure.

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Endogenous FGF13 is up-regulated in cardiomyocytes under pressure overload

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FGF13 directly interacts with p65

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Forced FGF13 overexpression activates NF-κB in cardiomyocytes

Arbutin Attenuates Isoproterenol-Induced Cardiac Hypertrophy by Inhibiting TLR-4/NF-κB Pathway in Mice

Arbutin is a glycoside reported for its anti-oxidant, anti-inflammatory and anti-tumor properties. However, the cardioprotective effect of Arbutin is not well established. The study aims to understand the effect of arbutin on isoproterenol (ISO)-induced cardiac hypertrophy in mice. The animals were pretreated with Arbutin for a week and ISO was administered for 10 days and then sacrificed. Cardiac injury markers such as creatinine kinase and lactate dehydrogenase concentrations were measured in the serum. The mRNA expression of cardiac hypertrophy markers namely atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were measured using qRT-PCR. The levels of pro-inflammatory cytokines TNF-α and IL-6 were quantified by ELISA in isolated tissues and serum. Other tissue anti-oxidant parameters such as GST, GSH, SOD and TBARS were also measured. TUNEL assay was performed to detect apoptosis. Histology studies were performed using H & E and Masson trichome staining. Immunoblot analysis was used to quantify the protein expression of TLR-4 and NF-κB. ISO-alone-treated group showed significant increase in CK-MB, LDH along with increase in hypertrophic markers ANP and BNP, TNF-α and IL-6 levels in serum and tissues and increased cardiomyocyte apoptosis. Anti-oxidant parameters were significantly decreased and TLR-4 and NF-κB protein expression was found to be upregulated in comparison to the control group. Pretreatment with Arbutin-exhibited significant inhibition of TLR-4/NF-κB pathway with decreased levels of pro-inflammatory cytokines and enhanced myocardial anti-oxidant status. Our study demonstrated that pretreatment with Arbutin exhibits marked protective effects on ISO-induced cardiac hypertrophy in mice. Thus, Arbutin may be used as potential pharmacological interventions in the management of cardiac hypertrophy.

Altered proteasome function in right ventricular hypertrophy

AIMS

In patients with pulmonary hypertension, right ventricular hypertrophy (RVH) is a detrimental condition that ultimately results in right heart failure and death. The ubiquitin proteasome system has been identified as a major protein degradation system to regulate cardiac remodelling in the left heart. Its role in right heart hypertrophy, however, is still ambiguous.

METHODS AND RESULTS

RVH was induced in mice by pulmonary artery banding (PAB). Both, expression and activity of the proteasome was found to be up-regulated in the hypertrophied right ventricle (RV) compared to healthy controls. Catalytic inhibition of the proteasome by the two proteasome inhibitors Bortezomib (BTZ) and ONX-0912 partially improved RVH both in preventive and therapeutic applications. Native gel analysis revealed that specifically the 26S proteasome complexes were activated in experimental RVH. Increased assembly of 26S proteasomes was accompanied by elevated expression of Rpn6, a rate-limiting subunit of 26S proteasome assembly, in hypertrophied cardiomyocytes of the right heart. Intriguingly, patients with RVH also showed increased expression of Rpn6 in hypertrophied cardiomyocytes of the RV as identified by immunohistochemical staining.

CONCLUSION

Our data demonstrate that alterations in expression and activity of proteasomal subunits play a critical role in the development of RVH. Moreover, this study provides an improved understanding on the selective activation of the 26S proteasome in RVH that might be driven by the rate-limiting subunit Rpn6. In RVH, Rpn6 therefore represents a more specific target to interfere with proteasome function than the commonly used catalytic proteasome inhibitors.

Differential Activation of P-TEFb Complexes in the Development of Cardiomyocyte Hypertrophy following Activation of Distinct G Protein-Coupled Receptors

Pathological cardiac hypertrophy is driven by neurohormonal activation of specific G protein-coupled receptors (GPCRs) in cardiomyocytes and is accompanied by large-scale changes in cardiomyocyte gene expression. These transcriptional changes require activity of positive transcription elongation factor b (P-TEFb), which is recruited to target genes by the bromodomain protein Brd4 or the super elongation complex (SEC). Here, we describe GPCR-specific regulation of these P-TEFb complexes and a novel mechanism for activating Brd4 in primary neonatal rat cardiomyocytes. The SEC was required for the hypertrophic response downstream of either the α₁-adrenergic receptor (α₁-AR) or the endothelin receptor (ETR). In contrast, Brd4 inhibition selectively impaired the α₁-AR response. This was corroborated by the finding that the activation of α₁-AR, but not ETR, increased Brd4 occupancy at promoters and superenhancers of hypertrophic genes. Transcriptome analysis demonstrated that the activation of both receptors initiated similar gene expression programs, but that Brd4 inhibition attenuated hypertrophic genes more robustly following α₁-AR activation. Finally, we show that protein kinase A (PKA) is required for α₁-AR stimulation of Brd4 chromatin occupancy. The differential role of the Brd4/P-TEFb complex in response to distinct GPCR pathways has potential clinical implications, as therapies targeting this complex are currently being explored for heart failure.

Deconstructing sarcomeric structure-function relations in titin-BioID knock-in mice

Proximity proteomics has greatly advanced the analysis of native protein complexes and subcellular structures in culture, but has not been amenable to study development and disease in vivo. Here, we have generated a knock-in mouse with the biotin ligase (BioID) inserted at titin’s Z-disc region to identify protein networks that connect the sarcomere to signal transduction and metabolism. Our census of the sarcomeric proteome from neonatal to adult heart and quadriceps reveals how perinatal signaling, protein homeostasis and the shift to adult energy metabolism shape the properties of striated muscle cells. Mapping biotinylation sites to sarcomere structures refines our understanding of myofilament dynamics and supports the hypothesis that myosin filaments penetrate Z-discs to dampen contraction. Extending this proof of concept study to BioID fusion proteins generated with Crispr/CAS9 in animal models recapitulating human pathology will facilitate the future analysis of molecular machines and signaling hubs in physiological, pharmacological, and disease context.

Titin determines the elasticity of the sarcomere and integrates into both the Z-disc and the M-band. Here, the authors generate a BioID mouse to study the titin interactome at the Z-disc region in neonatal and adult heart and skeletal muscle.

Extracellular heat shock protein HSC70 protects against lipopolysaccharide-induced hypertrophic responses in rat cardiomyocytes

We have recently shown that exogenous administration of extracellular heat shock protein HSC70, a previously recognized intracellular chaperone protein, can protect against LPS-induced cardiac dysfunction through anti-inflammatory actions. However, whether it can also exert anti-hypertrophic effect is unknown. The present study was aimed to investigate the efficacy of HSC70 against cardiac hypertrophy and its underlying molecular mechanisms. Cardiomyocytes were isolated from the cardiac ventricles of neonatal Wistar rats and LPS (1 μg/mL) was used to induce the hypertrophic responses. We found that HSC70 (0.1, 1 and 5 μg/mL) pretreatment attenuated LPS-induced cardiomyocyte hypertrophy dose-dependently. In addition, HSC70 mitigated LPS-induced inflammatory mediators including TNF-α, IL-6, NO, iNOS and COX-2, with down-regulated protein expression of MMP-2 and MMP-9. Moreover, HSC70 repressed LPS-induced signaling of MAPK and Akt. Finally, HSC70 inhibited NF-κB subunit p65, and the DNA binding activity of NF-κB. Taken together, these findings suggest that in vitro HSC70 can exert anti-hypertrophic effects through inhibition of pro-inflammatory mediators, which are potential mediated by the down-regulation of MAPK, Akt and NF-κB signaling pathways. In conclusion, extracellular HSC70 may be a novel pharmacologic strategy in the management of cardiac hypertrophy.

Leukocyte immunoglobulin-like receptor B4 protects against cardiac hypertrophy via SHP-2-dependent inhibition of the NF-κB pathway

Cardiac hypertrophy is a complex pathological process, and the molecular mechanisms underlying hypertrophic remodeling have not been clearly elucidated. Leukocyte immunoglobulin-like receptor B4 (lilrb4) is an inhibitory transmembrane protein that is necessary for the regulation of various cellular signaling pathways. To investigate whether lilrb4 plays a role in cardiac hypertrophy, we performed aortic banding in lilrb4 knockout mice, lilrb4 cardiac-specific transgenic mice, and their wild-type littermates. Cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. We found that lilrb4 was expressed both in myocardial tissue and on cultured cardiomyocytes under basal conditions, but the expression was obviously decreased in mouse hearts following aortic banding and in cardiomyocytes treated with angiotensin II. Lilrb4 disruption aggravated cardiac hypertrophy, fibrosis, and dysfunction in response to pressure overload. Conversely, the cardiac overexpression of lilrb4 led to the opposite effects. Moreover, lilrb4 overexpression inhibited angiotensin II-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we determined that the cardioprotective effect of lilrb4 was mediated through an interaction with SHP-2, the preservation of phosphorylated SHP-2, and the inhibition of the NF-κB pathway. In addition, SHP-2 knockdown in cardiomyocytes eliminated the inhibitory effects of lilrb4 on angiotensin II-induced hypertrophy and NF-κB activation. Our results suggest that lilrb4 protects against pathological cardiac hypertrophy via the SHP-2-dependent inhibition of the NF-κB pathway and may act as a potential therapeutic target for cardiac hypertrophy. KEY MESSAGES: Lilrb4 expression is decreased by hypertrophic stimuli. Lilrb4 protects against pathological cardiac hypertrophy. Lilrb4 interacts with SHP-2 and inhibits NF-κB pathway.

Signals for cardiomyocyte proliferation during zebrafish heart regeneration

The common laboratory zebrafish can regenerate functional cardiac muscle after cataclysmic damage or loss, by activating programs that direct the division of spared cardiomyocytes. Heart regeneration is not a linear series of molecular steps and synchronized cellular progressions, but rather an imperfect, relentless process that proceeds in an advantaged competition with scarring until recovery of the lost heart function. In this review, we summarize recent advances in our understanding of signaling events that have formative roles in injury-induced cardiomyocyte proliferation in zebrafish, and we forecast advances in the field that are needed to decipher heart regeneration.

Dietary metabolism, the gut microbiome, and heart failure

Advances in our understanding of how the gut microbiota contributes to human health and diseases have expanded our insight into how microbial composition and function affect the human host. Heart failure is associated with splanchnic circulation congestion, leading to bowel wall oedema and impaired intestinal barrier function. This situation is thought to heighten the overall inflammatory state via increased bacterial translocation and the presence of bacterial products in the systemic blood circulation. Several metabolites produced by gut microorganisms from dietary metabolism have been linked to pathologies such as atherosclerosis, hypertension, heart failure, chronic kidney disease, obesity, and type 2 diabetes mellitus. These findings suggest that the gut microbiome functions like an endocrine organ by generating bioactive metabolites that can directly or indirectly affect host physiology. In this Review, we discuss several newly discovered gut microbial metabolic pathways, including the production of trimethylamine and trimethylamine N-oxide, short-chain fatty acids, and secondary bile acids, that seem to participate in the development and progression of cardiovascular diseases, including heart failure. We also discuss the gut microbiome as a novel therapeutic target for the treatment of cardiovascular disease, and potential strategies for targeting intestinal microbial processes.

Distinct Circulating Expression Profiles of Long Noncoding RNAs in Heart Failure Patients With Ischemic and Nonischemic Dilated Cardiomyopathy

Ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM), with distinct long-term prognosis and responses to treatment, are two major problems that lead to heart failure (HF) ultimately. In this study, we investigated the long noncoding RNA (lncRNA) and messenger RNA (mRNA) expressions in the plasma of patients with DCM and ICM and analyzed the different lncRNA profile between the two groups. The microarray analysis identified 3,222 and 1,911 significantly differentially expressed lncRNAs and mRNAs between DCM and ICM group. The most enriched upregulated functional terms included positive regulation of I-kappaB kinase/nuclear factor-kappaB signaling and regulation of cellular localization, while the top 10 downregulated genes mainly consisted of acid secretion and myosin heavy chain binding. Furthermore, the Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that the differentially expressed lncRNA-coexpressed mRNAs between DCM and ICM group were significantly enriched in the natural killer cell mediated cytotoxicity and ras signaling pathway respectively. Quantitative real-time PCR confirmed 8 of 12 lncRNAs were upregulated in DCM group compared to ICM group which was consistent with the initial microarray results. The lncRNA/mRNA coexpression network indicated the possible functions of the validated lncRNAs. These findings revealed for the first time the specific expression pattern of both protein-coding RNAs and lncRNAs in plasma of HF patients due to DCM and ICM which may provide some important evidence to conveniently identify the etiology of myocardial dysfunctions and help to explore a better strategy for future HF prognosis evaluation.

Nelumbo nucifera Receptaculum Extract Suppresses Angiotensin II-Induced Cardiomyocyte Hypertrophy

Nelumbo nucifera Gaertn. (lotus) is an important medicinal plant, and many parts of the plant have been investigated for their therapeutic effects. However, the therapeutic effect of receptacles of lotuses on pathological cardiomyocyte hypertrophy has not been investigated yet. Therefore, the current study aimed to determine the protective effect of lotus against angiotensin II (Ang II)-induced cardiomyocyte hypertrophy in vitro. Ang II was used to induce hypertrophy of H9c2 cells. The lotus receptacle powder (MeOH extract of receptaculum Nelumbinis; MRN) used in the experiments was prepared by MeOH extraction and subsequent evaporation. To evaluate the effect of MRN on cardiomyocyte hypertrophy, cell size, protein synthesis, and hypertrophic marker expressions were examined. The antioxidant ability of MRN was determined by using CM-H₂DCFDA, a general oxidative stress indicator. Ang II-induced cardiomyocyte hypertrophy was significantly attenuated by 5 µg/mL of MRN, as confirmed by the reductions in cell size, protein synthesis, and hypertrophic marker expression. MRN also attenuated Ang II-induced excessive intracellular reactive oxygen species (ROS) production through the suppression of protein kinase C (PKC), extracellular-signal-regulated kinase (ERK), and NF-κB activation and subsequent type I angiotensin receptor (AT1R), receptor for advanced glycation end products (RAGE), and NADPH oxidase (NOX) expression. MRN exerted a significant protective effect against Ang II-induced cardiomyocyte hypertrophy through suppression of PKC–ERK signaling, and this subsequently led to attenuation of intracellular ROS production.

Innate Immune Signaling and Its Role in Metabolic and Cardiovascular Diseases

The innate immune system is an evolutionarily conserved system that senses and defends against infection and irritation. Innate immune signaling is a complex cascade that quickly recognizes infectious threats through multiple germline-encoded cell surface or cytoplasmic receptors and transmits signals for the deployment of proper countermeasures through adaptors, kinases, and transcription factors, resulting in the production of cytokines. As the first response of the innate immune system to pathogenic signals, inflammatory responses must be rapid and specific to establish a physical barrier against the spread of infection and must subsequently be terminated once the pathogens have been cleared. Long-lasting and low-grade chronic inflammation is a distinguishing feature of type 2 diabetes and cardiovascular diseases, which are currently major public health problems. Cardiometabolic stress-induced inflammatory responses activate innate immune signaling, which directly contributes to the development of cardiometabolic diseases. Additionally, although the innate immune elements are highly conserved in higher-order jawed vertebrates, lower-grade jawless vertebrates lack several transcription factors and inflammatory cytokine genes downstream of the Toll-like receptors (TLRs) and retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) pathways, suggesting that innate immune signaling components may additionally function in an immune-independent way. Notably, recent studies from our group and others have revealed that innate immune signaling can function as a vital regulator of cardiometabolic homeostasis independent of its immune function. Therefore, further investigation of innate immune signaling in cardiometabolic systems may facilitate the discovery of new strategies to manage the initiation and progression of cardiometabolic disorders, leading to better treatments for these diseases. In this review, we summarize the current progress in innate immune signaling studies and the regulatory function of innate immunity in cardiometabolic diseases. Notably, we highlight the immune-independent effects of innate immune signaling components on the development of cardiometabolic disorders.

Cardiolipotoxicity, Inflammation, and Arrhythmias: Role for Interleukin-6 Molecular Mechanisms

Fatty acid infiltration of the myocardium, acquired in metabolic disorders (obesity, type-2 diabetes, insulin resistance, and hyperglycemia) is critically associated with the development of lipotoxic cardiomyopathy. According to a recent Presidential Advisory from the American Heart Association published in 2017, the current average dietary intake of saturated free-fatty acid (SFFA) in the US is 11–12%, which is significantly above the recommended <10%. Increased levels of circulating SFFAs (or lipotoxicity) may represent an unappreciated link that underlies increased vulnerability to cardiac dysfunction. Thus, an important objective is to identify novel targets that will inform pharmacological and genetic interventions for cardiomyopathies acquired through excessive consumption of diets rich in SFFAs. However, the molecular mechanisms involved are poorly understood. The increasing epidemic of metabolic disorders strongly implies an undeniable and critical need to further investigate SFFA mechanisms. A rapidly emerging and promising target for modulation by lipotoxicity is cytokine secretion and activation of pro-inflammatory signaling pathways. This objective can be advanced through fundamental mechanisms of cardiac electrical remodeling. In this review, we discuss cardiac ion channel modulation by SFFAs. We further highlight the contribution of downstream signaling pathways involving toll-like receptors and pathological increases in pro-inflammatory cytokines. Our expectation is that if we understand pathological remodeling of major cardiac ion channels from a perspective of lipotoxicity and inflammation, we may be able to develop safer and more effective therapies that will be beneficial to patients.

Heat-shock protein 90 modulates cardiac ventricular hypertrophy via activation of MAPK pathway

The Raf/MAPK/ERK kinase (Mek)/extracellular signal-regulated kinases (Erk) pathway is activated in cardiac hypertrophy after a myocardial infarction. Although heat-shock protein 90 (Hsp90) may regulate the Raf/Mek/Erk signal pathway, the role of Hsp90 in pathophysiological cardiac hypertrophy remains unclear. In this study, we examined the role of Hsp90 in this pathway in cardiac hypertrophy under in vivo and in vitro experimental conditions. Cultured rat cardiomyocytes were treated with the Hsp90 inhibitor 17-(allylamino)-17-dimethoxy-geldanamycin (17-AAG) and proteasome inhibitor MG-132, and then incubated with endothelin-1 (ET) to induce hypertrophy of the cells. The ET-induced increase in the cell size was attenuated by 17-AAG pretreatment. Immunoblot analysis revealed that the c-Raf content of ET-treated cardiomyocytes was decreased in the presence of 17-AAG. An increase in phosphorylation levels of Erk1/2 and GATA4 in ET-treated cardiomyocytes was also attenuated by the 17-AAG pretreatment. Myocardial infarction was produced by ligation of the left ventricular coronary artery in rats, and then 17-AAG was intraperitoneally administered to the animals starting from the 2ndweek after coronary artery ligation (CAL). CAL-induced increases in the heart weight and cross-sectional area were attenuated by 17-AAG treatment. CAL rats showed signs of chronic heart failure with cardiac hypertrophy, whereas cardiac function in CAL rats treated with 17-AAG was not reduced. Treatment of CAL rats with 17-AAG caused a decrease in the c-Raf content and Erk1/2 and GATA4 phosphorylation levels. These findings suggest that Hsp90 is involved in the activation of the Raf/Mek/Erk pathway via stabilization of c-Raf in cardiomyocytes, resulting in the development of cardiac hypertrophy following myocardial infarction.

Emergence of Members of TRAF and DUB of Ubiquitin Proteasome System in the Regulation of Hypertrophic Cardiomyopathy

The ubiquitin proteasome system (UPS) plays an imperative role in many critical cellular processes, frequently by mediating the selective degradation of misfolded and damaged proteins and also by playing a non-degradative role especially important as in many signaling pathways. Over the last three decades, accumulated evidence indicated that UPS proteins are primal modulators of cell cycle progression, DNA replication, and repair, transcription, immune responses, and apoptosis. Comparatively, latest studies have demonstrated a substantial complexity by the UPS regulation in the heart. In addition, various UPS proteins especially ubiquitin ligases and proteasome have been identified to play a significant role in the cardiac development and dynamic physiology of cardiac pathologies such as ischemia/reperfusion injury, hypertrophy, and heart failure. However, our understanding of the contribution of UPS dysfunction in the plausible development of cardiac pathophysiology and the complete list of UPS proteins regulating these afflictions is still in infancy. The recent emergence of the roles of TNF receptor-associated factor (TRAFs) and deubiquitinating enzymes (DUBs) superfamily in hypertrophic cardiomyopathy has enhanced our knowledge. In this review, we have mainly compiled the TRAF superfamily of E3 ligases and few DUBs proteins with other well-documented E3 ligases such as MDM2, MuRF-1, Atrogin-I, and TRIM 32 that are specific to myocardial hypertrophy. In this review, we also aim to highlight their expression profile following physiological and pathological stimulation leading to the onset of hypertrophic phenotype in the heart that can serve as biomarkers and the opportunity for the development of novel therapies.

Oleanonic acid ameliorates pressure overload-induced cardiac hypertrophy in rats: The role of PKCζ-NF-κB pathway

It has been reported that inflammation is closely related with cardiac hypertrophy. Some inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, and interleukin-6 directly induce cardiac hypertrophy, which is associated with the activation of nuclear factorkappa B (NF-κB). Thus, NF-κB is an attractive target for cardiac hypertrophy. In the present study, oleanonic acid inhibited the elevation of transcriptional activity of NF-κB and reduced the mRNA expressions of hypertrophic genes such as atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) in a concentration-dependent manner in phenylephrine (PE)-treated cardiomyocytes. Furthermore, we found that oleanonic acid inhibited the phosphorylation of protein kinase C ζ (PKCζ) at Thr410 site and then reduced the activation of NF-κB using gain- and loss-of-function approaches in PE-treated cardiomyocytes. In vivo, similar results were observed in abdominal aortic constriction (AAC) rats that were intragastrically administered with oleanonic acid, and the pathological changes accompanying cardiac hypertrophy were relieved. In conclusion, oleanonic acid can effectively ameliorate cardiac hypertrophy by inhibiting PKCζ-NF-κB signaling pathway.

Inhibition of Mid-chain HETEs Protects Against Angiotensin II-induced Cardiac Hypertrophy

Recent data demonstrated the role of CYP1B1 in cardiovascular disease. It was, therefore, necessary to examine whether the inhibition of CYP1B1 and hence inhibiting the formation of its metabolites, using 2,4,3',5'-tetramethoxystilbene (TMS), would have a cardioprotective effect against angiotensin II (Ang II)-induced cardiac hypertrophy. For this purpose, male Sprague Dawley rats were treated with Ang II with or without TMS (300 μg/kg every third day i.p.). Thereafter, cardiac hypertrophy and the formation of mid-chain HETEs and arachidonic acid were assessed. In vitro, RL-14 cells were treated with Ang II (10 μM) in the presence and absence of TMS (0.5 μM). Then, reactive oxygen species, mitogen-activated protein kinase phosphorylation levels, and nuclear factor-kappa B-binding activity were determined. Our results demonstrated that TMS protects against Ang II-induced cardiac hypertrophy as indicated by the improvement in cardiac functions shown by the echocardiography as well as by reversing the increase in heart weight to tibial length ratio caused by Ang II. In addition, the cardioprotective effect of TMS was associated with a significant decrease in cardiac mid-chain HETEs levels. Mechanistically, TMS inhibited reactive oxygen species formation, the phosphorylation of ERK1/2, p38 mitogen-activated protein kinase, and the binding of p65 NF-κB.

Nitrated fatty acids in cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of death and accounts for one third of disease-related mortality worldwide. Dysregulated redox mechanisms, in particular the formation of reactive oxygen species (ROS) play a pivotal pathogenetic role in CVD. Nitro-fatty acids (NO2-FAs) are electrophilic molecules which have a NO2-group bound to one of their olefinic carbons. They are endogenously formed by the reaction of reactive nitrogen species with unsaturated fatty acids. Basal levels of NO2-FAs are in the low nanomolar range and higher concentrations can be encountered under acidic (stomach) and inflammatory (e.g. ischemia/reperfusion) conditions. Dietary intake of polyunsaturated fatty acids in combination with nitrites raises circulating NO2-FAs to a clinically relevant level in mice. NO2-FAs undergo reversible covalent binding to cysteine residues and by virtue of these posttranslational protein modifications act as potent anti-inflammatory signaling mediators via modulation of various critical pathways like nuclear factor E2-related factor 2 (Nrf2)- and peroxisome proliferator-activated receptor γ (PPARγ) activation, nuclear factor-kappa B (NF-κB) inhibition and hem oxygenase-1 (HO-1)- and heat shock protein (HSP) induction. In this review article, we summarize recent findings about the effects and underlying molecular mechanisms of NO2-FAs from a variety of pre-clinical cardiovascular disease models. The described findings suggest the potential of NO2-FAs to emerge as therapeutic agents with a broad range of potential clinical applications for CVD.

Short-Term Treatment with Esmolol Reverses Left Ventricular Hypertrophy in Adult Spontaneously Hypertensive Rats via Inhibition of Akt/NF-κB and NFATc4

Our group has previously demonstrated that short-term treatment with esmolol reduces left ventricular hypertrophy (LVH) in spontaneously hypertensive rats (SHRs). The present study aimed to assess the molecular mechanisms related to this effect. Fourteen-month-old male SHR_s were treated intravenously with saline as vehicle (SHR) or esmolol (SHR-E) (300 μg/kg/min). Age-matched vehicle-treated male Wistar-Kyoto (WKY) rats served as controls. After 48 hours of treatment, the hearts were harvested and left ventricular tissue was separated and processed for Western blot analysis to determine the levels of Akt, NF-κB, NFATc4, Creb1, Serca2a, Erk1/2, and Sapk/Jnk. Biomarkers of oxidative stress, such as catalase, protein carbonyls, total thiols, and total antioxidant capacity were evaluated. Esmolol reversed the levels of p-NFATc4, p-Akt, and p-NF-κB in SHRs to the phospholevels of these proteins in WKY rats without modifying p-Erk1/2, p-Sapk/Jnk, p-Creb1, or Serca2a in SHR. Compared with SHR, esmolol increased catalase activity and reduced protein carbonyls without modifying total thiols or total antioxidant capacity. Short-term treatment with esmolol reverses LVH in aged SHRs by downregulation of Akt/NF-κB and NFATc4 activity. Esmolol treatment also increases catalase activity and reduces oxidative stress in SHRs with LVH.

Vinpocetine Attenuates Pathological Cardiac Remodeling by Inhibiting Cardiac Hypertrophy and Fibrosis

PURPOSE

Pathological cardiac remodeling, characterized by cardiac hypertrophy and fibrosis, is a pathological feature of many cardiac disorders that leads to heart failure and cardiac arrest. Vinpocetine, a derivative of the alkaloid vincamine, has been used for enhancing cerebral blood flow to treat cognitive impairment. However, its role in pathological cardiac remodeling remains unknown. The aim of this study is to examine the effect of vinpocetine on pathological cardiac remodeling induced by chronic stimulation with angiotensin II (Ang II).

METHODS

Mice received Ang II infusion via osmotic pumps in the presence of vehicle or vinpocetine. Cardiac hypertrophy and fibrosis were assessed by morphological, histological, and biochemical analyses. Mechanistic studies were carried out in vitro with isolated mouse adult cardiac myocytes and fibroblasts.

RESULTS

We showed that chronic Ang II infusion caused cardiac hypertrophy and fibrosis, which were all significantly attenuated by systemic administration of vinpocetine. In isolated adult mouse cardiomyocytes, vinpocetine suppressed Ang II-stimulated myocyte hypertrophic growth. In cultured cardiac fibroblasts, vinpocetine suppressed TGFβ-induced fibroblast activation and matrix gene expression, consistent with its effect in attenuating cardiac fibrosis. The effects of vinpocetine on cardiac myocyte hypertrophy and fibroblast activation are likely mediated by targeting cyclic nucleotide phosphodiesterase 1 (PDE1).

CONCLUSIONS

Our results reveal a novel protective effect of vinpocetine in attenuating pathological cardiac remodeling through suppressing cardiac myocyte hypertrophic growth and fibroblast activation and fibrotic gene expression. These studies may also shed light on developing novel therapeutic agents for antagonizing pathological cardiac remodeling.

Fibroblast growth factor 9 subfamily and the heart

The fibroblast growth factor (FGF) 9 subfamily is a member of the FGF family, including FGF9, 16, and 20, potentially sharing similar biochemical functions due to their high degree of sequence homology. Unlike other secreted proteins which have a cleavable N-terminal secreted signal peptide, FGF9/16/20 have non-cleaved N-terminal signal peptides. As an intercellular signaling molecule, they are involved in a variety of complex responses in animal development. Cardiogenesis is controlled by many members of the transcription factor family. Evidence suggests that FGF signaling, including the FGF9 subfamily, has a pretty close association with these cardiac-specific genes. In addition, recent studies have shown that the FGF9 subfamily maintains functional adaptation and survival after myocardial infarction in adult myocardium. Since FGF9/16/20 are secreted proteins, their function characterization in cardiac regeneration can promote their potential to be developed for the treatment of cardioprotection and revascularization. Here, we conclude that the FGF9 subfamily roles in cardiac development and maintenance of postnatal cardiac homeostasis, especially cardiac function maturation and functional maintenance of the heart after injury.

Nanocurcumin-pyrroloquinoline formulation prevents hypertrophy-induced pathological damage by relieving mitochondrial stress in cardiomyocytes under hypoxic conditions

This study investigates the therapeutic effect of a nanocurcumin formulation (NCF) containing nanocurcumin (NC) and pyrroloquinoline quinone (PQQ) on ameliorating hypoxia-induced stress in hypertrophied primary human ventricular cardiomyocytes (HVCM) under hypoxic conditions, as validated in a Sprague-Dawley rat model of chronic hypobaric hypoxia (cHH)-induced right ventricular hypertrophy (RVH). Based on our previous findings, here, we analyzed the improvement in the protective efficacy of NCF against mitochondrial damage. The electron transport chain Complexes’ activities were analyzed as a chief operational center for mitochondrial homeostasis, along with key gene and protein markers for mitochondrial biogenesis, redox function, fatty acid oxidation, bio-energetic deficit and cell survival. NCF supplementation imparts cyto-protection from hypoxia-induced hypertrophy and damage in both in vitro and in vivo models while maintaining mitochondrial homeostasis better than NC and PQQ alone. This study proposes the use of NCF as a potential candidate molecule for imparting protection from high altitude-induced maladies in ascendants.

Effects of Ginkgo biloba leaf extract on local renin-angiotensin system through TLR4/NF-κB pathway in cardiac myocyte

The present study investigated the effects of Ginkgo biloba leaf extract (GBE50) on lipopolysaccharide (LPS) induced Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway and its effects on angiotensinogen (ATG) and AT_1a receptor, so as to explore the mechanism of GBE50 in prevention and treatment of left ventricular remodeling. In vitro cultured neonatal rat ventricular myocytes (NRVMs) were divided into 4 groups including i) control group: DMEM medium; ii) LPS group: iii) LPS + GBE50 group; iv) LPS + caffeic acid phenethyl ester (CAPE, specific inhibitor of NF-κB) group. Nuclear translocation of NF-κB p65 was detected by immunocytochemical method after intervention for 24 h. Expression of TLR4, ATG, AT_1a receptors and β-myosin heavy chain (β-MHC) mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR). Protein content of cardiomyocytes was measured by Coomassie Brilliant Blue method. Under LPS stimulation, expression level of TLR4 mRNA in NRVMs was significantly increased (P<0.01), nuclear translocation of NF-κB p65 was increased, expression levels of ATG, AT_1a receptor and β-MHC mRNA and the protein content in cells were also increased significantly (P<0.01). GBE50 and CAPE significantly inhibited nuclear translocation of NF-κB p65. GBE50 and CAPE treatments also reduced the increased mRNA levels of TLR4, ATG, AT_1a receptor and β-MHC and protein content in cell caused by LPS stimulation. We concluded that, GBE50 can inhibit the activation of local renin-angiotensin system by inhibiting the activation of TLR4/NF-κB and TLR4/NF-κB, signaling pathway inhibition may be one of the mechanisms of the role of Ginkgo biloba leaf extract in preventing myocardial remodeling.

Knockout of the ATPase inhibitory factor 1 protects the heart from pressure overload-induced cardiac hypertrophy

Mitochondrial ATP synthase catalyzes the coupling of oxidative phosphorylation. Under pathological conditions, ATP synthase hydrolyzes ATP to replenish protons from the matrix into the intermembrane space, sustaining mitochondrial membrane potential. ATPase inhibitory factor 1 (IF1) is a nuclear-encoded, ATP synthase-interacting protein that selectively inhibits the hydrolysis activity of ATP synthase, which may render the protective role of IF1 in ischemic hearts. However, the in vivo cardiac function of IF1 and the potential therapeutic application targeting IF1 remain obscure. In the present study, we uncovered that IF1 is upregulated in mouse hearts with pressure overload-induced hypertrophy and in human hearts with dilated cardiomyopathy. IF1 knockout (KO) mice were protected against cardiac dysfunction and pathological development induced by transverse aortic constriction (TAC) or isoproterenol infusion. The reduced ATP hydrolysis activated AMPK activity in IF1 KO hearts, which together facilitated autophagy. These results suggest that IF1 upregulation in the failing heart may be a maladaptive response. Inhibiting IF1 in the hypertrophied heart not only prevents cell death from excessive mitochondrial depolarization but also activates AMPK signaling and increases autophagy. Therefore, IF1 inhibition may serve as a potential therapeutic target in treating pathological cardiac hypertrophy and heart failure.

A unique microRNA profile in end-stage heart failure indicates alterations in specific cardiovascular signaling networks

It is well established that the gene expression patterns are substantially altered in cardiac hypertrophy and heart failure, however, less is known about the reasons behind such global differences. MicroRNAs (miRNAs) are short non-coding RNAs that can target multiple molecules to regulate wide array of proteins in diverse pathways. The goal of the study was to profile alterations in miRNA expression using end-stage human heart failure samples with an aim to build signaling network pathways using predicted targets for the altered miRNA and to determine nodal molecules regulating individual networks. Profiling of miRNAs using custom designed microarray and validation with an independent set of samples identified eight miRNAs that are altered in human heart failure including one novel miRNA yet to be implicated in cardiac pathology. To gain an unbiased perspective on global regulation by top eight altered miRNAs, functional relationship of predicted targets for these eight miRNAs were examined by network analysis. Ingenuity Pathways Analysis network algorithm was used to build global signaling networks based on the targets of altered miRNAs which allowed us to identify participating networks and nodal molecules that could contribute to cardiac pathophysiology. Majority of the nodal molecules identified in our analysis are targets of altered miRNAs and known regulators of cardiovascular signaling. Cardio-genomics heart failure gene expression public data base was used to analyze trends in expression pattern for target nodal molecules and indeed changes in expression of nodal molecules inversely correlated to miRNA alterations. We have used NF kappa B network as an example to show that targeting other molecules in the network could alter the nodal NF kappa B despite not being a miRNA target suggesting an integrated network response. Thus, using network analysis we show that altering key functional target proteins may regulate expression of the myriad signaling pathways underlying the cardiac pathology.