Omaveloxolone ameliorates isoproterenol-induced pathological cardiac hypertrophy in mice

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important transcriptional regulator that plays a protective role against various cardiovascular diseases. Omaveloxolone is a newly discovered potent activator of Nrf2 that has a variety of cytoprotective functions. However, the potential role of omaveloxolone in the process of pathological cardiac hypertrophy and heart failure are still unknown. In this study, an isoproterenol (ISO)-induced pathological cardiac hypertrophy model was established to investigate the protective effect of omaveloxolone in vivo and in vitro. Our study first confirmed that omaveloxolone administration improved ISO-induced pathological cardiac hypertrophy in mice and neonatal cardiomyocytes. Omaveloxolone administration also diminished ISO-induced cardiac oxidative stress, inflammation and cardiomyocyte apoptosis. In addition, omaveloxolone administration activated the Nrf2 signaling pathway, and Nrf2 knockdown almost completely abolished the cardioprotective effect of omaveloxolone, indicated that the cardioprotective effect of omaveloxolone was directly related to the activation of the Nrf2 signaling. In summary, our study identified that omaveloxolone may be a promising therapeutic agent to mitigate pathological cardiac hypertrophy.

PKD knockdown mitigates Ang II-induced cardiac hypertrophy and ferroptosis via the JNK/P53 signaling pathway

BACKGROUND

Cardiac hypertrophy is studied in relation to energy metabolism, autophagy, and ferroptosis, which are associated with cardiovascular adverse events and chronic heart failure. Protein kinase D (PKD) has been shown to play a degenerative role in cardiac hypertrophy. However, the role of ferroptosis in PKD-involved cardiac hypertrophy remains unclear.

METHODS

A cardiac hypertrophy model was induced by a subcutaneous injection of angiotensin II (Ang II) for 4 weeks. Adeno-associated virus serotype 9 (AAV9)-PKD or AAV9-Negative control were injected through the caudal vein 2 weeks prior to the injection of Ang II. The degree of cardiac hypertrophy was assessed using echocardiography and by observing cardiomyocyte morphology. Levels of ferroptosis and protein expression in the Jun N-terminal kinase (JNK)/P53 signaling pathway were measured both in vivo and in vitro.

RESULTS

The results indicated that PKD knockdown reduces Ang II-induced cardiac hypertrophy, enhances cardiac function and inhibits ferroptosis. The involvement of the JNK/P53 pathway in this process was further confirmed by in vivo and in vitro experiments.

CONCLUSION

In conclusion, our findings suggest that PKD knockdown mitigates Ang II-induced cardiac hypertrophy and ferroptosis via the JNK/P53 signaling pathway.

LncRNA MIR217HG aggravates pressure-overload induced cardiac remodeling by activating miR-138/THBS1 pathway

AIM

Cardiac hypertrophy and fibrosis are associated with cardiac remodeling and heart failure. We have previously shown that miRNA-217, embedded within the third intron of MIR217HG, aggravates pressure overload-induced cardiac hypertrophy by targeting phosphatase and tensin homolog. However, whether the MIR217HG transcript itself plays a role in cardiac remodeling remains unknown.

METHODS

Real-time PCR assays and RNA in situ hybridization were performed to detect MIR217HG expression. Lentiviruses and adeno-associated viruses with a cardiac-specific promoter (cTnT) were used to control MIR217HG expression in vitro and in vivo. Transverse aortic constriction (TAC) surgery was performed to develop cardiac remodeling models. Cardiac structure and function were analyzed using echocardiography and invasive pressure-volume analysis.

KEY FINDINGS

MIR217HG expression was increased in patients with heart failure. MIR217HG overexpression aggravated pressure-overload-induced myocyte hypertrophy and fibrosis both in vivo and in vitro, whereas MIR217HG knockdown reversed these phenotypes. Mechanistically, MIR217HG increased THBS1 expression by sponging miR-138. MiR-138 recognized the 3'UTR of THBS1 and repressed THBS1 expression in the absence of MIR217HG. Silencing THBS1 expression reversed MIR217HG-induced cardiac hypertrophy and remodeling.

CONCLUSION

MIR217HG acts as a potent inducer of cardiac remodeling that may contribute to heart failure by activating the miR-138/THBS1 pathway.

GSDMD-mediated pyroptosis promotes cardiac remodeling in pressure overload

BACKGROUND

Gasdermin D (GSDMD) forms membrane pores to execute pyroptosis. But the mechanism of how cardiomyocyte pyroptosis induces cardiac remodeling in pressure overload remains unclear. We investigated the role of GSDMD-mediated pyroptosis in the pathogenesis of cardiac remodeling in pressure overload.

METHODS

Wild-type (WT) and cardiomyocyte-specific GSDMD-deficient (GSDMD-CKO) mice were subjected to transverse aortic constriction (TAC) to induce pressure overload. Four weeks after surgery, left ventricular structure and function were evaluated by echocardiographic, invasive hemodynamic and histological analysis. Pertinent signaling pathways related to pyroptosis, hypertrophy and fibrosis were investigated by histochemistry, RT-PCR and western blotting. The serum levels of GSDMD and IL-18 collected from healthy volunteers or hypertensive patients were measured by ELISA.

RESULTS

We found TAC induced cardiomyocyte pyroptosis and release of pro-inflammatory cytokines IL-18. The serum GSDMD level was significantly higher in hypertensive patients than in healthy volunteers, and induced more dramatic release of mature IL-18. GSDMD deletion remarkably mitigated TAC-induced cardiomyocyte pyroptosis. Furthermore, GSDMD deficiency in cardiomyocytes significantly reduced myocardial hypertrophy and fibrosis. The deterioration of cardiac remodeling by GSDMD-mediated pyroptosis was associated with activating JNK and p38 signaling pathways, but not ERK or Akt signaling pathway.

CONCLUSION

In conclusion, our results demonstrate that GSDMD serves as a key executioner of pyroptosis in cardiac remodeling induced by pressure overload. GSDMD-mediated pyroptosis activates JNK and p38 signaling pathways, and this may provide a new therapeutic target for cardiac remodeling induced by pressure overload.

Exercise-induced circular RNA circUtrn is required for cardiac physiological hypertrophy and prevents myocardial ischaemia-reperfusion injury

AIMS

Regular exercise training benefits cardiovascular health and effectively reduces the risk for cardiovascular disease. Circular RNAs (circRNAs) play important roles in cardiac pathophysiology. However, the role of circRNAs in response to exercise training and biological mechanisms responsible for exercise-induced cardiac protection remain largely unknown.

METHODS AND RESULTS

RNA sequencing was used to profile circRNA expression in adult mouse cardiomyocytes that were isolated from mice with or without exercise training. Exercise-induced circRNA circUtrn was significantly increased in swimming-trained adult mouse cardiomyocytes. In vivo, circUtrn was found to be required for exercise-induced physiological cardiac hypertrophy. circUtrn inhibition abolished the protective effects of exercise on myocardial ischaemia-reperfusion remodelling. circUtrn overexpression prevented myocardial ischaemia-reperfusion-induced acute injury and pathological cardiac remodelling. In vitro, overexpression of circUtrn promoted H9 human embryonic stem cell-induced cardiomyocyte growth and survival via protein phosphatase 5 (PP5). Mechanistically, circUtrn directly bound to PP5 and regulated the stability of PP5 in a ubiquitin-proteasome-dependent manner. Hypoxia-inducible factor 1α-dependent splicing factor SF3B1 acted as an upstream regulator of circUtrn in cardiomyocytes.

CONCLUSION

The circRNA circUtrn is upregulated upon exercise training in the heart. Overexpression of circUtrn can prevent myocardial I/R-induced injury and pathological cardiac remodelling.

Ovarian Tumor Domain-Containing 7B Attenuates Pathological Cardiac Hypertrophy by Inhibiting Ubiquitination and Degradation of Krüppel-Like Factor 4

BACKGROUND

Cardiac hypertrophy (CH) is a well-established risk factor for many cardiovascular diseases and a primary cause of mortality and morbidity among older adults. Currently, no pharmacological interventions have been specifically tailored to treat CH. OTUD7B (ovarian tumor domain-containing 7B) is a member of the ovarian tumor-related protease (OTU) family that regulates many important cell signaling pathways. However, the role of OTUD7B in the development of CH is unclear. Therefore, we investigated the role of OTUD7B in CH.

METHODS AND RESULTS

OTUD7B knockout mice were used to assay the role of OTUD7B in CH after transverse aortic coarctation surgery. We further assayed the specific functions of OTUD7B in isolated neonatal rat cardiomyocytes. We found that OTUD7B expression decreased in hypertrophic mice hearts and phenylephrine-stimulated neonatal rat cardiomyocytes. Furthermore, OTUD7B deficiency exacerbated transverse aortic coarctation surgery-induced myocardial hypertrophy, abnormal cardiac function, and fibrosis. In cardiac myocytes, OTUD7B knockdown promoted phenylephrine stimulation-induced myocardial hypertrophy, whereas OTUD7B overexpression had the opposite effect. An immunoprecipitation-mass spectrometry analysis showed that OTUD7B directly binds to KLF4 (Krüppel-like factor 4). Additional molecular experiments showed that OTUD7B impedes KLF4 degradation by inhibiting lysine residue at 48 site-linked ubiquitination and suppressing myocardial hypertrophy by activating the serine/threonine kinase pathway.

CONCLUSIONS

These results demonstrate that the OTUD7B-KLF4 axis is a novel molecular target for CH treatment.

Toll-like Receptor 4 Differentially Modulates Cardiac Function in Response to Chronic Exposure to High-Fat Diet and Pressure Overload

BACKGROUND/AIM

The impact of myocardial stressors such as high-fat diet (HFD) and pressure overload has been extensively studied. Toll-like receptor 4 (TLR4) deficiency has been suggested to have a protective role in response to these stressors, although some conflicting data exist. Furthermore, there is limited information about the role of TLR4 on cardiac remodeling in response to long-term exposure to stressors. This study aims to investigate the effects of TLR4 deficiency on cardiac histology and physiology in response to chronic stressors.

METHODS

TLR4-deficient (TLR4-/-) and wild-type (WT) mice were subjected to either HFD or a normal diet (ND) for 28 weeks. Another group underwent abdominal aortic constriction (AAC) or a sham procedure and was monitored for 12 weeks. Inflammatory markers, histology, and echocardiography were used to assess the effects of these interventions.

RESULTS

TLR4-/- mice exhibited reduced cardiac hypertrophy and fibrosis after long-term HFD exposure compared to ND without affecting cardiac function. On the other hand, TLR4 deficiency worsened cardiac function in response to AAC, leading to decreased ejection fraction (EF%) and increased end-systolic volume (ESV).

CONCLUSIONS

TLR4 deficiency provided protection against HFD-induced myocardial inflammation but impaired hemodynamic cardiac function under pressure overload conditions. These findings highlight the crucial role of TLR4 and its downstream signaling pathway in maintaining cardiac output during physiologic cardiac hypertrophy in response to pressure overload.

Early-life exposure to lead changes cardiac development and compromises long-term cardiac function

Lead (Pb) is widely used in industrial and daily-use consumer products. Early-life exposure may increase the risk of lead-related heart problems in childhood. However, the effects of early-life lead exposure on fetal heart development and long-term cardiac outcomes are unknown. In this study, pregnant ICR mice were exposed to lead acetate trihydrate (50 mg/kg/d) via oral gavage from gestation day 1.5 until offspring weaning. Thereafter, the second hit model was established, two groups of offspring (4 weeks old) were either administered sterile saline or Angiotensin II (Ang II) for 4 weeks until euthanasia. We investigated lead-induced offspring heart damage from embryonic period to adulthood by echocardiographic analysis, pathological H&E staining, and ultrastructural examination, as well as mitochondrial function detection. The results showed early-life lead exposure predisposed offspring mice to decreased ejection fraction, increased left ventricular volume, accompanied by hypertrophy and dilation, cardiomyocyte sarcomere dysplasia, abnormal mitochondrial structure, mitochondrial dysfunction, and decreased expression of key sarcomeric and mitochondrial genes, rendering them more susceptible to cardiac hypertrophy, vascular wall thickening, cardiac fibrosis, apoptosis, and heart failure induced by Ang II infusion. This study elucidates early-life low dose lead exposure compromises cardiac development and exacerbates second hit-induced cardiac pathological responses in adulthood, which furnishes crucial scientific evidence pertaining to the cardiac toxicity and risk evaluation associated with early-life exposure to lead.

Cardioprotective Effects of the GRK2 Inhibitor Paroxetine on Isoproterenol-Induced Cardiac Remodeling by Modulating NF-κB Mediated Prohypertrophic and Profibrotic Gene Expression

Pathological cardiac remodeling is associated with cardiovascular disease and can lead to heart failure. Nuclear factor-kappa B (NF-κB) is upregulated in the hypertrophic heart. Moreover, the expression of the G-protein-coupled receptor kinase 2 (GRK2) is increased and linked to the progression of heart failure. The inhibitory effects of paroxetine on GRK2 have been established. However, its protective effect on IκBα/NFκB signaling has not been elucidated. This study investigated the cardioprotective effect of paroxetine in an animal model of cardiac hypertrophy (CH), focusing on its effect on GRK2-mediated NF-κB-regulated expression of prohypertrophic and profibrotic genes. Wistar albino rats were administered normal saline, paroxetine, or fluoxetine, followed by isoproterenol to induce CH. The cardioprotective effects of the treatments were determined by assessing cardiac injury, inflammatory biomarker levels, histopathological changes, and hypertrophic and fibrotic genes in cardiomyocytes. Paroxetine pre-treatment significantly decreased the HW/BW ratio (p < 0.001), and the expression of prohypertrophic and profibrotic genes Troponin-I (p < 0.001), BNP (p < 0.01), ANP (p < 0.001), hydroxyproline (p < 0.05), TGF-β1 (p < 0.05), and αSMA (p < 0.01) as well as inflammatory markers. It also markedly decreased pIκBα, NFκB(p105) subunit expression (p < 0.05) and phosphorylation. The findings suggest that paroxetine prevents pathological cardiac remodeling by inhibiting the GRK2-mediated IκBα/NF-κB signaling pathway.

NAT10 Is Involved in Cardiac Remodeling Through ac4C-Mediated Transcriptomic Regulation

BACKGROUND

Heart failure, characterized by cardiac remodeling, is associated with abnormal epigenetic processes and aberrant gene expression. Here, we aimed to elucidate the effects and mechanisms of NAT10 (N-acetyltransferase 10)-mediated N4-acetylcytidine (ac4C) acetylation during cardiac remodeling.

METHODS

NAT10 and ac4C expression were detected in both human and mouse subjects with cardiac remodeling through multiple assays. Subsequently, acetylated RNA immunoprecipitation and sequencing, thiol-linked alkylation for the metabolic sequencing of RNA (SLAM-seq), and ribosome sequencing (Ribo-seq) were employed to elucidate the role of ac4C-modified posttranscriptional regulation in cardiac remodeling. Additionally, functional experiments involving the overexpression or knockdown of NAT10 were conducted in mice models challenged with Ang II (angiotensin II) and transverse aortic constriction.

RESULTS

NAT10 expression and RNA ac4C levels were increased in in vitro and in vivo cardiac remodeling models, as well as in patients with cardiac hypertrophy. Silencing and inhibiting NAT10 attenuated Ang II-induced cardiomyocyte hypertrophy and cardiofibroblast activation. Next-generation sequencing revealed ac4C changes in both mice and humans with cardiac hypertrophy were associated with changes in global mRNA abundance, stability, and translation efficiency. Mechanistically, NAT10 could enhance the stability and translation efficiency of CD47 and ROCK2 transcripts by upregulating their mRNA ac4C modification, thereby resulting in an increase in their protein expression during cardiac remodeling. Furthermore, the administration of Remodelin, a NAT10 inhibitor, has been shown to prevent cardiac functional impairments in mice subjected to transverse aortic constriction by suppressing cardiac fibrosis, hypertrophy, and inflammatory responses, while also regulating the expression levels of CD47 and ROCK2 (Rho associated coiled-coil containing protein kinase 2).

CONCLUSIONS

Therefore, our data suggest that modulating epitranscriptomic processes, such as ac4C acetylation through NAT10, may be a promising therapeutic target against cardiac remodeling.

Effects of Long-Term Administration of Bovine Bone Gelatin Peptides on Myocardial Hypertrophy in Spontaneously Hypertensive Rats

The research purpose was to investigate the effects and the underlying molecular mechanisms of bovine bone gelatin peptides (BGP) on myocardial hypertrophy in spontaneously hypertensive rats (SHR). BGP relieved myocardial hypertrophy and fibrosis in SHR rats in a dose-dependent manner by reducing the left ventricular mass index, myocardial cell diameter, myocardial fibrosis area, and levels of myocardial hypertrophy markers (atrial natriuretic and brain natriuretic peptide). Label-free quantitative proteomics analysis showed that long-term administration of BGP changed the left ventricle proteomes of SHR. The 37 differentially expressed proteins in the high-dose BGP group participated in multiple signaling pathways associated with cardiac hypertrophy and fibrosis indicating that BGP could play a cardioprotective effect on SHR rats by targeting multiple signaling pathways. Further validation experiments showed that a high dose of BGP inhibited the expression of phosphoinositide 3-kinase (Pi3k), phosphorylated protein kinase B (p-Akt), and transforming growth factor-beta 1 (TGF-β1) in the myocardial tissue of SHR rats. Together, BGP could be an effective candidate for functional nutritional supplements to inhibit myocardial hypertrophy and fibrosis by negatively regulating the TGF-β1 and Pi3k/Akt signaling pathways.

Knockout of M-LP/Mpv17L, a newly identified atypical PDE, induces physiological afferent cardiac hypertrophy in mice

M-LP/Mpv17L (Mpv17-like protein) is an atypical cyclic nucleotide phosphodiesterase (PDE) without the molecular structure characteristic of the PDE family. Deficiency of M-LP/Mpv17L in mice has been found to result in development of β-cell hyperplasia and improved glucose tolerance. Here, we report another phenotype observed in M-LP/Mpv17L-knockout (KO) mice: afferent cardiac hypertrophy. Although the hearts of M-LP/Mpv17L-KO mice did not differ in size from those of wild-type mice, there was marked narrowing of the left ventricular lumen and thickening of the ventricular wall. The diameter and cross-sectional area of cardiomyocytes in 8-month-old M-LP/Mpv17L-KO mice were increased 1.16-fold and 1.35-fold, respectively, relative to control mice, but showed no obvious abnormalities of cell structure, fibrosis or impaired cardiac function. In 80-day-old KO mice, the expression of hypertrophic marker genes, brain natriuretic peptide (BNF), actin alpha cardiac muscle 1 (ACTC1) and actin alpha 1 skeletal muscle (ACTA1), as well as the Wnt/β-catenin pathway target genes, lymphoid enhancer-binding factor-1 (LEF1), axis inhibition protein 2 (AXIN2) and transcription factor 7 (TCF7), was significantly up-regulated relative to control mice, whereas fibrosis-related genes such as fibronectin 1 (FN1) and connective tissue growth factor (CTGF) were down-regulated. Western blot analysis revealed increased phosphorylation of molecules downstream of the cAMP/PKA signaling pathway, such as β-catenin, ryanodine receptor 2 (RyR2), phospholamban (PLN) and troponin I (cTnI), as well as members of the MEK1-ERK1/2 signaling pathway, which is strongly involved in afferent cardiac hypertrophy. Taken together, these findings indicate that M-LP/Mpv17L is one of the PDEs actively functioning in the heart and that deficiency of M-LP/Mpv17L in mice promotes physiological cardiac hypertrophy.

Transcriptional cofactor dyxin mediates hypertrophic response in the heart during angiotensin II-induced hypertension

Dyxin is a LIM-domain containing transcriptional regulator protein shown to play a role in a hypertrophic response in the heart. Here, the effect of adenoviral dyxin overexpression was studied on cardiac function and gene expression in the normal heart and in angiotensin II (Ang II)-induced hypertension in rats. The adenovirus-mediated intramyocardial gene transfer of dyxin (1.5x109 infectious units/animal) was performed into the left ventricle (LV) of Sprague-Dawley rats with and without the Ang II (33 μg/kg/h) infusion, administered via osmotic minipumps for 1 and 2 weeks. Echocardiography was used to assess the structural and functional changes. Dyxin expression and localization in the heart was analyzed with quantitative RT-PCR and immunohistochemistry, respectively. In the normal rat heart, the adenoviral overexpression of dyxin did not alter LV function in normal hearts as assessed by echocardiography. Dyxin was found to be localized in the cardiomyocytes as shown by the immunohistochemical staining. In Ang II-induced hypertrophy, echocardiographic data revealed a significant increase in the posterior wall diameter both in systole (21%, P<0.05) and diastole (21%, P<0.01) as well as in the diameter of the interventricular septum in systole (19%, P<0.05) in the dyxin-injected group compared with the LacZ-injected animals after two weeks of Ang II infusion. Interestingly, a significant decrease in the levels of both atrial natriuretic peptide (ANP) mRNA (55%, P<0.01) and B-type natriuretic peptide (BNP) mRNA (68%, P<0.05) was observed in the dyxin-injected group compared with the LacZ control group after one week of Ang II infusion. These results indicate that dyxin overexpression was deteriorative against pressure overload by inducing structural changes in the LV in rats. Interestingly, simultaneous adenoviral overexpression of dyxin suppressed the Ang II-induced changes of ANP and BNP genes suggesting that dyxin might have a role as a regulator of the cardiac hypertrophic gene program.

Exogenous NADPH exerts a positive inotropic effect and enhances energy metabolism via SIRT3 in pathological cardiac hypertrophy and heart failure

BACKGROUND

Therapies are urgently required to ameliorate pathological cardiac hypertrophy and enhance cardiac function in heart failure. Our preliminary experiments have demonstrated that exogenous NADPH exhibits a positive inotropic effect on isolated heart. This study aims to investigate the positive inotropic effects of NADPH in pathological cardiac hypertrophy and heart failure, as well as the underlying mechanisms involved.

METHODS

Endogenous plasma NADPH contents were determined in patients with chronic heart failure and control adults. The positive inotropic effects of NADPH were investigated in isolated toad heart or rat heart. The effects of NADPH were investigated in isoproterenol (ISO)-induced cardiac hypertrophy or transverse aortic constriction (TAC)-induced heart failure. The underlying mechanisms of NADPH were studied using SIRT3 knockout mice, echocardiography, Western blotting, transmission electron microscopy, and immunoprecipitation.

FINDINGS

The endogenous NADPH content in the blood of patients and animals with pathological cardiac hypertrophy or heart failure was significantly reduced compared with age-sex matched control subjects. Exogenous NADPH showed positive inotropic effects on the isolated normal and failing hearts, while antagonism of ATP receptor partially abolished the positive inotropic effect of NADPH. Exogenous NADPH administration significantly reduced heart weight indices, and improved cardiac function in the mice with pathological cardiac hypertrophy or heart failure. NADPH increased SIRT3 expression and activity, deacetylated target proteins, improved mitochondrial function and facilitated ATP production in the hypertrophic myocardium. Importantly, inhibition of SIRT3 abolished the positive inotropic effect of NADPH, and the anti-heart failure effect of NADPH was significantly reduced in the SIRT3 Knockout mice.

INTERPRETATION

Exogenous NADPH shows positive inotropic effect and improves energy metabolism via SIRT3 in pathological cardiac hypertrophy and heart failure. NADPH thus may be one of the potential candidates for the treatment of pathological cardiac hypertrophy or heart failure.

FUNDING

This work was supported by grants from the National Natural Science Foundation of China (No. 81973315, 82173811, 81730092), Natural Science Foundation of Jiangsu Higher Education (20KJA310008), Jiangsu Key Laboratory of Neuropsychiatric Diseases (BM2013003) and the Priority Academic Program Development of the Jiangsu Higher Education Institutes (PAPD).

Metabolic mechanisms in physiological and pathological cardiac hypertrophy: new paradigms and challenges

Cardiac metabolism is vital for heart function. Given that cardiac contraction requires a continuous supply of ATP in large quantities, the role of fuel metabolism in the heart has been mostly considered from the perspective of energy production. However, the consequence of metabolic remodelling in the failing heart is not limited to a compromised energy supply. The rewired metabolic network generates metabolites that can directly regulate signalling cascades, protein function, gene transcription and epigenetic modifications, thereby affecting the overall stress response of the heart. In addition, metabolic changes in both cardiomyocytes and non-cardiomyocytes contribute to the development of cardiac pathologies. In this Review, we first summarize how energy metabolism is altered in cardiac hypertrophy and heart failure of different aetiologies, followed by a discussion of emerging concepts in cardiac metabolic remodelling, that is, the non-energy-generating function of metabolism. We highlight challenges and open questions in these areas and finish with a brief perspective on how mechanistic research can be translated into therapies for heart failure.

Loss of USP22 alleviates cardiac hypertrophy induced by pressure overload through HiF1-α-TAK1 signaling pathway

Ubiquitin-specific protease 22 (USP22) is a member of the ubiquitin specific protease family (ubiquitin-specific protease, USPs), the largest subfamily of deubiquitinating enzymes, and plays an important role in the treatment of tumors. USP22 is also expressed in the heart. However, the role of USP22 in heart disease remains unclear. In this study, we found that USP22 was elevated in hypertrophic mouse hearts and in angiotensin II (Ang II)-induced cardiomyocytes. The inhibition of USP22 expression with adenovirus significantly rescued hypertrophic phenotype and cardiac dysfunction induced by pressure overloaded. Consistent with in vivo study, silencing by USP22 shRNA expression in vitro had similar results. Molecular analysis revealed that transforming growth factor-β-activating protein 1 (TAK1)-(JNK1/2)/P38 signaling pathway and HIF-1α was activated in the Ang II-induced hypertrophic cardiomyocytes, whereas HIF-1α expression was decreased after the inhibition of USP22. Inhibition of HIF-1α expression reduces TAK1 expression. Co-immunoprecipitation and ubiquitination studies revealed the regulatory mechanism between USP22 and HIF1α.Under hypertrophic stress conditions, USP22 enhances the stability of HIF-1α through its deubiquitination activity, which further activates the TAK1-(JNK1/2)/P38 signaling pathway to lead to cardiac hypertrophy. Inhibition of HIF-1α expression further potentiates the in vivo pathological effects caused by USP22 deficiency. In summary, this study suggests that USP22, through HIF-1α-TAK1-(JNK1/2)/P38 signaling pathway, may be potential targets for inhibiting pathological cardiac hypertrophy induced by pressure overload.

Palmitoylation-dependent regulation of cardiomyocyte Rac1 signaling activity and minor effects on cardiac hypertrophy

S-palmitoylation is a reversible lipid modification catalyzed by 23 S-acyltransferases with a conserved zinc finger aspartate-histidine-histidine-cysteine (zDHHC) domain that facilitates targeting of proteins to specific intracellular membranes. Here we performed a gain-of-function screen in the mouse and identified the Golgi-localized enzymes zDHHC3 and zDHHC7 as regulators of cardiac hypertrophy. Cardiomyocyte-specific transgenic mice overexpressing zDHHC3 show cardiac disease, and S-acyl proteomics identified the small GTPase Rac1 as a novel substrate of zDHHC3. Notably, cardiomyopathy and congestive heart failure in zDHHC3 transgenic mice is preceded by enhanced Rac1 S-palmitoylation, membrane localization, activity, downstream hypertrophic signaling, and concomitant induction of all Rho family small GTPases whereas mice overexpressing an enzymatically dead zDHHC3 mutant show no discernible effect. However, loss of Rac1 or other identified zDHHC3 targets Gαq/11 or galectin-1 does not diminish zDHHC3-induced cardiomyopathy, suggesting multiple effectors and pathways promoting decompensation with sustained zDHHC3 activity. Genetic deletion of Zdhhc3 in combination with Zdhhc7 reduces cardiac hypertrophy during the early response to pressure overload stimulation but not over longer time periods. Indeed, cardiac hypertrophy in response to 2 weeks of angiotensin-II infusion is not diminished by Zdhhc3/7 deletion, again suggesting other S-acyltransferases or signaling mechanisms compensate to promote hypertrophic signaling. Taken together, these data indicate that the activity of zDHHC3 and zDHHC7 at the cardiomyocyte Golgi promote Rac1 signaling and maladaptive cardiac remodeling, but redundant signaling effectors compensate to maintain cardiac hypertrophy with sustained pathological stimulation in the absence of zDHHC3/7.

Inhibition of lncRNA DANCR Prevents Heart Failure by Ameliorating Cardiac Hypertrophy and Fibrosis Via Regulation of the miR-758-3p/PRG4/Smad Axis

The current work was developed to explore the functions and possible mechanism of PRG4 in cardiac hypertrophy and heart failure. Ang II-stimulated H9c2 cells and AC16 cells were used as in vitro cell models. The binding relation between genes in cells was explored using luciferase reporter assays and RNA immunoprecipitation assay. The cardiac functions of rats received transverse-ascending aortic constriction (TAC) surgery and adeno-associated virus (AAV) injection were examined with echocardiography. The myocardial histological changes were observed using H&E, wheat germ agglutinin, and sirius red staining. It was discovered that PRG4 silencing attenuated cell hypertrophy and fibrosis and inactivated the Smad pathway under Ang II treatment. PRG4 was targeted by miR-758-3p, and miR-758-3p interacted with long noncoding RNA DANCR. DANCR silencing inhibited cardiac dysfunction, fibrosis, and TGFβ1/Smad pathway. In addition, DANCR was highly expressed in myocardial extracellular vesicles. Overall, DANCR depletion prevents heart failure by inhibiting cardiac hypertrophy and fibrosis via the miR-758-3p/PRG4/Smad pathway.

Bicyclol Attenuates Obesity-Induced Cardiomyopathy via Inhibiting NF-κB and MAPK Signaling Pathways

PURPOSE

Schisandra is a well-known traditional Chinese medicine in East Asia. As a traditional Chinese medicine derivative with Schisandra chinensis as raw material, bicyclol is well known for its significant anti-inflammatory effect. Chronic inflammation plays a significant part in obesity-induced cardiomyopathy. Our purpose was to explore the effect and mechanism of bicyclol on obesity-induced cardiomyopathy.

METHODS

Mice fed with a high-fat diet (HFD) and cardiomyocytes stimulated by palmitic acid (PA) were used as models of obesity-related cardiomyopathy in vivo and in vitro, respectively. The therapeutic effect of bicyclol on pathological changes such as myocardial hypertrophy and fibrosis was evaluated by staining cardiac tissue sections. PCR was used to detect inflammatory factors in H9c2 cells and animal heart tissue after bicyclol treatment. Then, we used western blotting to detect the expression levels of the myocardial hypertrophy related protein, myocardial fibrosis related protein, NF-κB and MAPK pathways.

RESULTS

Our results indicated that bicyclol treatment significantly alleviates HFD-induced myocardial inflammation, fibrosis, and hypertrophy by inhibiting the MAPK and NF-κB pathways. Similar to animal level results, bicyclol could significantly inhibit PA-induced inflammation and prevent NF-κB and MAPK pathways from being activated.

CONCLUSION

Our results showed that bicyclol has potential as a drug to treat obesity-induced cardiomyopathy.

ESCRT-III Component CHMP4C Attenuates Cardiac Hypertrophy by Targeting the Endo-Lysosomal Degradation of EGFR

BACKGROUND

Cardiac hypertrophy and subsequent heart failure impose a considerable burden on public health worldwide. Impaired protein degradation, especially endo-lysosome-mediated degradation of membrane proteins, is associated with cardiac hypertrophy progression. CHMP4C (charged multivesicular body protein 4C), a critical constituent of multivesicular bodies, is involved in cellular trafficking and signaling. However, the specific role of CHMP4C in the progression of cardiac hypertrophy remains largely unknown.

METHODS

Mouse models with CHMP4C knockout or cardiadc-specific overexpression were subjected to transverse aortic constriction surgery for 4 weeks. Cardiac morphology and function were assessed through histological staining and echocardiography. Confocal imaging and coimmunoprecipitation assays were performed to identify the direct target of CHMP4C. An EGFR (epidermal growth factor receptor) inhibitor was administrated to determine whether effects of CHMP4C on cardiac hypertrophy were EGFR dependent.

RESULTS

CHMP4C was significantly upregulated in both pressure-overloaded mice and spontaneously hypertensive rats. Compared with wild-type mice, CHMP4C deficiency exacerbated transverse aortic constriction-induced cardiac hypertrophy, whereas CHMP4C overexpression in cardiomyocytes attenuated cardiac dysfunction. Mechanistically, the effect of CHMP4C on cardiac hypertrophy relied on the EGFR signaling pathway. Fluorescent staining and coimmunoprecipitation assays confirmed that CHMP4C interacts directly with EGFR and promotes lysosome-mediated degradation of activated EGFR, thus attenuating cardiac hypertrophy. Notably, an EGFR inhibitor canertinib counteracted the exacerbation of cardiac hypertrophy induced by CHMP4C knockdown in vitro and in vivo.

CONCLUSIONS

CHMP4C represses cardiac hypertrophy by modulating lysosomal degradation of EGFR and is a potential therapeutic candidate for cardiac hypertrophy.

Single-nuclear transcriptome profiling identifies persistent fibroblast activation in hypertrophic and failing human hearts of patients with longstanding disease

AIMS

Cardiac fibrosis drives the progression of heart failure in ischaemic and hypertrophic cardiomyopathy. Therefore, the development of specific anti-fibrotic treatment regimens to counteract cardiac fibrosis is of high clinical relevance. Hence, this study examined the presence of persistent fibroblast activation during longstanding human heart disease at a single-cell resolution to identify putative therapeutic targets to counteract pathological cardiac fibrosis in patients.

METHODS AND RESULTS

We used single-nuclei RNA sequencing with human tissues from two samples of one healthy donor, and five hypertrophic and two failing hearts. Unsupervised sub-clustering of 7110 nuclei led to the identification of 7 distinct fibroblast clusters. De-convolution of cardiac fibroblast heterogeneity revealed a distinct population of human cardiac fibroblasts with a molecular signature of persistent fibroblast activation and a transcriptional switch towards a pro-fibrotic extra-cellular matrix composition in patients with established cardiac hypertrophy and heart failure. This sub-cluster was characterized by high expression of POSTN, RUNX1, CILP, and a target gene adipocyte enhancer-binding protein 1 (AEBP1) (all P < 0.001). Strikingly, elevated circulating AEBP1 blood level were also detected in a validation cohort of patients with confirmed cardiac fibrosis and hypertrophic cardiomyopathy by cardiac magnetic resonance imaging (P < 0.01). Since endogenous AEBP1 expression was increased in patients with established cardiac hypertrophy and heart failure, we assessed the functional consequence of siRNA-mediated AEBP1 silencing in human cardiac fibroblasts. Indeed, AEBP1 silencing reduced proliferation, migration, and fibroblast contractile capacity and α-SMA gene expression, which is a hallmark of fibroblast activation (all P < 0.05). Mechanistically, the anti-fibrotic effects of AEBP1 silencing were linked to transforming growth factor-beta pathway modulation.

CONCLUSION

Together, this study identifies persistent fibroblast activation in patients with longstanding heart disease, which might be detected by circulating AEBP1 and therapeutically modulated by its targeted silencing in human cardiac fibroblasts.

RNF13 protects against pathological cardiac hypertrophy through p62-NRF2 pathway

Heart failure (HF) severely impairs human health because of its high incidence and mortality. Cardiac hypertrophy is the main cause of HF, while its underlying mechanism is not fully clear. As an E3 ubiquitin ligase, Ring finger protein 13 (RNF13) plays a crucial role in many disorders, such as liver immune, neurological disease and tumorigenesis, whereas the function of RNF13 in cardiac hypertrophy remains largely unknown. In the present study, we found that the protein expression of RNF13 is up-regulated in the transverse aortic constriction (TAC)-induced murine hypertrophic hearts and phenylephrine (PE)-induced cardiomyocyte hypertrophy. Functional investigations indicated that RNF13 global knockout mice accelerates the degree of TAC-induced cardiac hypertrophy, including cardiomyocyte enlargement, cardiac fibrosis and heart dysfunction. On the contrary, adeno-associated virus 9 (AAV9) mediated-RNF13 overexpression mice alleviated cardiac hypertrophy. Furthermore, we demonstrated that adenoviral RNF13 attenuates the PE-induced cardiomyocyte hypertrophy and down-regulates the expression of cardiac hypertrophic markers, while the opposite results were observed in the RNF13 knockdown group. The RNA-sequence of RNF13 knockout and wild type mice showed that RNF13 deficiency activates oxidative stress after TAC surgery. In terms of the mechanism, we found that RNF13 directly interacted with p62 and promoted the activation of downstream NRF2/HO-1 signaling. Finally, we proved that p62 knockdown can reverse the effect of RNF13 in cardiac hypertrophy. In conclusion, RNF13 protects against the cardiac hypertrophy via p62-NRF2 axis.

Exosomes derived from cardiac fibroblasts with angiotensin II stimulation provoke hypertrophy and autophagy inhibition in cardiomyocytes

Although accumulating evidence has revealed that autophagy inhibition contributes to the development of pathological cardiac hypertrophy, the mechanisms leading to declined autophagy activity in the hypertrophic heart remain to be elucidated. Exosomes are known to be important mediators of intercellular communication, and the involvement of exosomes in cardiovascular abnormities has attracted increasing attentions. Cardiac fibroblasts (CFs) are the most abundant cell type in the heart. Here, we investigated the potential role of CFs-derived exosomes in regulating cardiomyocyte hypertrophy and autophagy. Exosomes from rat CFs treated with angiotensin II (Ang II-CFs-exosomes) were collected and characterized. Our experiments showed that these exosomes could induce hypertrophic responses and impair autophagy activity in primary neonatal rat cardiomyocytes (NRCMs). Ang II-CFs-exosomes blocked the autophagic flux of NRCMs via inhibiting the formation of autolysosomes. Moreover, the pro-hypertrophic effects and autophagy inhibition induced by Ang II-CFs-exosomes was validated in mice receiving injection of the exosomes. These findings highlight a novel role of Ang II-CFs-exosomes in suppressing cardiomyocyte autophagy, which may help to better understand the pathogenesis of cardiac hypertrophy.

Lutein suppresses ferroptosis of cardiac microvascular endothelial cells via positive regulation of IRF in cardiac hypertrophy

Cardiac microvascular dysfunction contributes to cardiac hypertrophy (CH) and can progress to heart failure. Lutein is a carotenoid with various pharmacological properties, such as anti-apoptotic, anti-inflammatory, and antioxidant effects. Limited research has been conducted on the effects of lutein on pressure overload-induced CH. Studies have shown that CH is accompanied by ferroptosis in the cardiac microvascular endothelial cells (CMECs). This study aimed to investigate the effect of lutein on ferroptosis of CMECs in CH. The transcription factor interferon regulatory factor (IRF) is associated with immune system function, tumor suppression, and apoptosis. The results of this study suggested that pressure overload primarily inhibits IRF expression, resulting in endothelial ferroptosis. Administration of lutein increased the expression of IRF, providing protection to endothelial cells during pressure overload. IRF silencing downregulated solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) expression, leading to the induction of ferroptosis in CMECs. Lutein supplementation suppressed endothelial ferroptosis by upregulating IRF. These data suggest that IRF may function as a transcription factor for SLC7A11 and that lutein represses ferroptosis in CMECs by upregulating IRF expression. Therefore, targeting IRF may be a promising therapeutic strategy for effective cardioprotection in patients with CH and heart failure.

DNA Damage and Nuclear Morphological Changes in Cardiac Hypertrophy Are Mediated by SNRK Through Actin Depolymerization

BACKGROUND

Proper nuclear organization is critical for cardiomyocyte function, because global structural remodeling of nuclear morphology and chromatin structure underpins the development and progression of cardiovascular disease. Previous reports have implicated a role for DNA damage in cardiac hypertrophy; however, the mechanism for this process is not well delineated. AMPK (AMP-activated protein kinase) family of proteins regulates metabolism and DNA damage response (DDR). Here, we examine whether a member of this family, SNRK (SNF1-related kinase), which plays a role in cardiac metabolism, is also involved in hypertrophic remodeling through changes in DDR and structural properties of the nucleus.

METHODS

We subjected cardiac-specific Snrk-/- mice to transaortic banding to assess the effect on cardiac function and DDR. In parallel, we modulated SNRK in vitro and assessed its effects on DDR and nuclear parameters. We also used phosphoproteomics to identify novel proteins that are phosphorylated by SNRK. Last, coimmunoprecipitation was used to verify Destrin (DSTN) as the binding partner of SNRK that modulates its effects on the nucleus and DDR.

RESULTS

Cardiac-specific Snrk-/- mice display worse cardiac function and cardiac hypertrophy in response to transaortic banding, and an increase in DDR marker pH2AX (phospho-histone 2AX) in their hearts. In addition, in vitro Snrk knockdown results in increased DNA damage and chromatin compaction, along with alterations in nuclear flatness and 3-dimensional volume. Phosphoproteomic studies identified a novel SNRK target, DSTN, a member of F-actin depolymerizing factor proteins that directly bind to and depolymerize F-actin. SNRK binds to DSTN, and DSTN downregulation reverses excess DNA damage and changes in nuclear parameters, in addition to cellular hypertrophy, with SNRK knockdown. We also demonstrate that SNRK knockdown promotes excessive actin depolymerization, measured by the increased ratio of G-actin to F-actin. Last, jasplakinolide, a pharmacological stabilizer of F-actin, rescues the increased DNA damage and aberrant nuclear morphology in SNRK-downregulated cells.

CONCLUSIONS

These results indicate that SNRK is a key player in cardiac hypertrophy and DNA damage through its interaction with DSTN. This interaction fine-tunes actin polymerization to reduce DDR and maintain proper cardiomyocyte nuclear shape and morphology.

miR-455-5p promotes pathological cardiac remodeling via suppression of PRMT1-mediated Notch signaling pathway

Pathological cardiac remodeling plays an essential role in the progression of cardiovascular diseases, and numerous microRNAs have been reported to participate in pathological cardiac remodeling. However, the potential role of microRNA-455-5p (miR-455-5p) in this process remains to be elucidated. In the present study, we focused on clarifying the function and searching the direct target of miR-455-5p, as well as exploring its underlying mechanisms in pathological cardiac remodeling. We found that overexpression of miR-455-5p by transfection of miR-455-5p mimic in vitro or tail vain injection of miR-455-5p agomir in vivo provoked cardiac remodeling, whereas genetic knockdown of miR-455-5p attenuated the isoprenaline-induced cardiac remodeling. Besides, miR-455-5p directly targeted to 3'-untranslated region of protein arginine methyltransferase 1 (PRMT1) and subsequently downregulated PRMT1 level. Furthermore, we found that PRMT1 protected against cardiac hypertrophy and fibrosis in vitro. Mechanistically, miR-455-5p induced cardiac remodeling by downregulating PRMT1-induced asymmetric di-methylation on R1748, R1750, R1751 and R1752 of Notch1, resulting in suppression of recruitment of Presenilin, Notch1 cleavage, NICD releasing and Notch signaling pathway. Finally, circulating miR-455-5p was positively correlated with parameters of left ventricular wall thickening. Taken together, miR-455-5p plays a provocative role in cardiac remodeling via inactivation of the PRMT1-mediated Notch signaling pathway, suggesting miR-455-5p/PRMT1/Notch1 signaling axis as potential therapeutic targets for pathological cardiac remodeling.

SOX4 as a potential therapeutic target for pathological cardiac hypertrophy

Pathological cardiac hypertrophy can lead to heart failure, making its prevention crucial. SOX4, a SOX transcription factor, regulates tissue growth and development, although its role in pathological cardiac hypertrophy is unclear. We found that the SOX4 expression was elevated in hypertrophic hearts and angiotensin II (Ang II)-treated neonatal rat cardiomyocytes (NRCMs), and knocking down the SOX4 expression in NRCMs and mouse hearts significantly reduced the hypertrophic response. Mechanistically, SOX4 can bind to the SIRT3 promoter, inhibit SIRT3 transcription and expression, and thus affect downstream MnSOD acetylation levels, leading to abnormal increases in ROS and oxidative stress levels and promoting the occurrence of cardiac hypertrophy. In conclusion, this study identified a new role for SOX4 in regulating cardiac hypertrophy, and decreasing SOX4 expression may be a potential treatment for pathological cardiac hypertrophy.

Deciphering transcriptional dynamics of cardiac hypertrophy and failure in a chamber-specific manner

Pressure overload-induced pathological cardiac hypertrophy (CH) is a complexed and adaptive remodeling of the heart, predominantly involving an increase in cardiomyocyte size and thickening of ventricular walls. Over time, these changes can lead to heart failure (HF). However, the individual and shared biological mechanisms of both processes remain poorly understood. This study aimed to identify key genes and signaling pathways associated with CH and HF following aortic arch constriction (TAC) at four weeks and six weeks, respectively, and to investigate potential underlying molecular mechanisms in this dynamic transition from CH to HF at the whole cardiac transcriptome level. Initially, a total of 363, 482, and 264 differentially expressed genes (DEGs) for CH, and 317, 305, and 416 DEGs for HF were identified in the left atrium (LA), left ventricle (LV), and right ventricle (RV), respectively. These identified DEGs could serve as biomarkers for the two conditions in different heart chambers. Additionaly, two communal DEGs, elastin (ELN) and hemoglobin beta chain-beta S variant (HBB-BS), were found in all chambers, with 35 communal DEGs in the LA and LV and 15 communal DEGs in the LV and RV in both CH and HF. Functional enrichment analysis of these genes emphasized the crucial roles of the extracellular matrix and sarcolemma in CH and HF. Lastly, three groups of hub genes, including the lysyl oxidase (LOX) family, fibroblast growth factors (FGF) family, and NADH-ubiquinone oxidoreductase (NDUF) family, were determined to be essential genes of dynamic changes from CH to HF.

The lncRNA Sweetheart regulates compensatory cardiac hypertrophy after myocardial injury in murine males

After myocardial infarction in the adult heart the remaining, non-infarcted tissue adapts to compensate the loss of functional tissue. This adaptation requires changes in gene expression networks, which are mostly controlled by transcription regulating proteins. Long non-coding transcripts (lncRNAs) are taking part in fine-tuning such gene programs. We describe and characterize the cardiomyocyte specific lncRNA Sweetheart RNA (Swhtr), an approximately 10 kb long transcript divergently expressed from the cardiac core transcription factor coding gene Nkx2-5. We show that Swhtr is dispensable for normal heart development and function but becomes essential for the tissue adaptation process after myocardial infarction in murine males. Re-expressing Swhtr from an exogenous locus rescues the Swhtr null phenotype. Genes that depend on Swhtr after cardiac stress are significantly occupied and therefore most likely regulated by NKX2-5. The Swhtr transcript interacts with NKX2-5 and disperses upon hypoxic stress in cardiomyocytes, indicating an auxiliary role of Swhtr for NKX2-5 function in tissue adaptation after myocardial injury.

Virtual drug screen reveals context-dependent inhibition of cardiomyocyte hypertrophy

BACKGROUND AND PURPOSE

Pathological cardiomyocyte hypertrophy is a response to cardiac stress that typically leads to heart failure. Despite being a primary contributor to pathological cardiac remodelling, the therapeutic space that targets hypertrophy is limited. Here, we apply a network model to virtually screen for FDA-approved drugs that induce or suppress cardiomyocyte hypertrophy.

EXPERIMENTAL APPROACH

A logic-based differential equation model of cardiomyocyte signalling was used to predict drugs that modulate hypertrophy. These predictions were validated against curated experiments from the prior literature. The actions of midostaurin were validated in new experiments using TGFβ- and noradrenaline (NE)-induced hypertrophy in neonatal rat cardiomyocytes.

KEY RESULTS

Model predictions were validated in 60 out of 70 independent experiments from the literature and identify 38 inhibitors of hypertrophy. We additionally predict that the efficacy of drugs that inhibit cardiomyocyte hypertrophy is often context dependent. We predicted that midostaurin inhibits cardiomyocyte hypertrophy induced by TGFβ, but not noradrenaline, exhibiting context dependence. We further validated this prediction by cellular experiments. Network analysis predicted critical roles for the PI3K and RAS pathways in the activity of celecoxib and midostaurin, respectively. We further investigated the polypharmacology and combinatorial pharmacology of drugs. Brigatinib and irbesartan in combination were predicted to synergistically inhibit cardiomyocyte hypertrophy.

CONCLUSION AND IMPLICATIONS

This study provides a well-validated platform for investigating the efficacy of drugs on cardiomyocyte hypertrophy and identifies midostaurin for consideration as an antihypertrophic drug.

The Effects of 16-HETE Enantiomers on Hypertrophic Markers in Human Fetal Ventricular Cardiomyocytes, RL-14 Cells

BACKGROUND

Cytochrome P450 (CYP) metabolizes arachidonic acid to produce bioactive metabolites such as EETs and HETEs: mid-chain, subterminal, and terminal HETEs. Recent studies have revealed the role of CYP1B1 and its associated cardiotoxic mid-chain HETE metabolites in developing cardiac hypertrophy and heart failure. Subterminal HETEs have also been involved in various physiological and pathophysiological processes; however, their role in cardiac hypertrophy has not been fully defined.

OBJECTIVE

The objective of the current study is to determine the possible effect of subterminal HETEs, R and S enantiomers of 16-HETE, on CYP1B1 expression in vitro using human cardiomyocytes RL-14 cells.

METHODS

In the study, RL14 cell line was treated with vehicle and either of the 16-HETE enantiomers for 24 h. Subsequently, the following markers were assessed: cell viability, cellular size, hypertrophic markers, CYP1B1 gene expression (at mRNA, protein, and activity levels), luciferase activity, and CYP1B1 mRNA and protein half-lives.

RESULTS

The results of the study showed that 16-HETE enantiomers significantly increased hypertrophic markers and upregulated CYP1B1 mRNA and protein expressions in RL-14 cell line. The upregulation of CYP1B1 by 16-HETE enantiomers occurs via a transcriptional mechanism as evidenced by transcriptional induction and luciferase reporter assay. Furthermore, neither post-transcriptional nor post-translational modification was involved in such modulation since there was no change in CYP1B1 mRNA and protein stabilities upon treatment with 16-HETE enantiomers.

CONCLUSION

The current study provides the first evidence that 16R-HETE and 16S-HETE increase CYP1B1 gene expression through a transcriptional mechanism.

New insights into the effect of VMP1 on the treatment of pressure overload-induced pathological cardiac hypertrophy: Involving SERCA-regulated autophagic flux

Pathological cardiac hypertrophy is an adaptive reaction in response to pressure or volume overload. Autophagy is critical for damage caused by pathological cardiac hypertrophy. Vacuole membrane protein 1 (VMP1) is an endoplasmic reticulum (ER) transmembrane protein that is effective in activating autophagy. However, the role of VMP1 in pathological cardiac hypertrophy and its underlying mechanisms remain elusive. This study was designed to explore the potential mechanisms of VMP1 on pressure overload-induced pathological cardiac hypertrophy. In this work, abdominal aorta constriction (AAC) surgery was used to induce pathological cardiac hypertrophy in male C57BL/6 mice. H9C2 cardiomyocytes were treated with phenylephrine stimulation (PE) to induce the hypertrophic response. The in vivo results revealed that mice with AAC surgery caused pathological cardiac hypertrophy as evidenced by improved cardiac function according to multiple echocardiographic parameters. Moreover, elevated VMP1 expression was also observed in mice after AAC surgery. VMP1 knockdown aggravated changes in cardiac structure, cardiac dysfunction, and fibrosis. Meanwhile, VMP1 knockdown suppressed autophagy and endoplasmic reticulum calcium ATPase (SERCA) activity in heart tissues. H9C2 cardiomyocytes with VMP1 overexpression were used to investigate the specific mechanism of VMP1 in pathological cardiac hypertrophy, and VMP1 overexpression increased autophagic flux by upregulating SERCA activity. In conclusion, these findings revealed that VMP1 protected against pressure overload-induced pathological cardiac hypertrophy by inducing SERCA-regulated autophagic flux. Our results provide valuable insights regarding the pathophysiology of pathological cardiac hypertrophy and clues to a novel target for the treatment of pathological cardiac hypertrophy.

Alpha-lipoic Acid Protects Against Chronic Alcohol Consumption-induced Cardiac Damage by the Aldehyde Dehydrogenase 2-associated PINK/Parkin Pathway

ABSTRACT

Chronic alcohol intake contributes to high mortality rates due to ethanol-induced cardiac hypertrophy and contractile dysfunction, which are accompanied by increased oxidative stress and disrupted mitophagy. Alpha-lipoic acid (α-LA), a well-known antioxidant, has been shown to protect against cardiac hypertrophy and inflammation. However, little is known about its role and mechanism in the treatment of alcoholic cardiomyopathy. Here, we evaluated the role of α-LA in alcohol-induced cardiac damage by feeding mice a 4.8% (v/v) alcohol diet with or without α-LA for 6 w. Our results suggested that chronic alcohol consumption increased mortality, blood alcohol concentrations, and serum aldehyde levels, but a-LA attenuated the elevations in mortality and aldehydes. Chronic alcohol intake also induced cardiac dysfunction, including enlarged left ventricles, reduced left ventricular ejection fraction, enhanced cardiomyocyte size, and increased serum levels of brain natriuretic peptide, lactate dehydrogenase, and creatine kinase myocardial isoenzyme. Moreover, alcohol intake led to the accumulation of collagen fiber and mitochondrial dysfunction, the effects of which were alleviated by α-LA. In addition, α-LA intake also prevented the increase in reactive oxygen species production and the decrease in mitochondrial number that were observed after alcohol consumption. Chronic alcohol exposure activated PINK1/Parkin-mediated mitophagy. These effects were diminished by α-LA intake by the activation of aldehyde dehydrogenase 2. Our data indicated that α-LA helps protect cardiac cells against the effects of chronic alcohol intake, likely by inhibiting PINK1/Parkin-related mitophagy through the activation of aldehyde dehydrogenase 2.

Cyclovirobuxine D alleviates aldosterone-induced myocardial hypertrophy by protecting mitochondrial function depending on the mutual regulation of Nrf2-SIRT3

BACKGROUND

Cyclovirobuxine D (CVB-D) is a natural alkaloid that exhibits multiple pharmacological activities, such as anti-inflammatory, anti-oxidative stress, and anti-cancer properties. However, its specific protective mechanism of action for myocardial hypertrophy remains unresolved.

PURPOSE

This work was to investigate the ameliorative impact of CVB-D in myocardial hypertrophy, and to elucidate aldosterone (ALD)-induced myocardial hypertrophy by inhibiting the SIRT3 mediated Nrf2 activation.

METHODS

The myocardial hypertrophy model was reproduced by ALD both in vitro and in vivo, and the protective effect of CVB-D on myocardium and mitochondria was evaluated by TEM, H&E, qPCR, Western blot and ChIP. An immunoprecipitation experiment was adopted to evaluate the acetylation level of Nrf2 and the binding between SIRT3 and Nrf2. Additionally, bardoxolone-methyl (BAR, an Nrf2 agonist), ML385 (an Nrf2 inhibitor), resveratrol (RES, a SIRT3 agonist), and 3-TYP (a SIRT3 inhibitor) were used to confirm the molecular mechanism of CVB-D. Lastly, a molecular docking technique was employed to predict the binding site of SIRT3 and Nrf2 proteins.

RESULTS

Our findings suggested that CVB-D improved mitochondrial function, leading to a reduction in ALD-induced cardiomyocyte hypertrophy. By CVB-D treatment, there was an activation of mutual regulation between Nrf2 and SIRT3. Specifically, CVB-D resulted in the increase of Nrf2 protein in the nucleus and activated Nrf2 signaling pathway, thus up-regulating SIRT3. The activation of SIRT3 and the protective action of mitochondrion disappeared because of the intervention of ML385. After CVB-D activated SIRT3, the acetylation level of Nrf2 decreased, followed by activating the Nrf2 pathway. The activation of Nrf2 and mitochondrial protection by CVB-D were reversed by 3-TYP. Our results are also supported by Co-IP and molecular docking analysis, revealing that CVB-D promotes SIRT3-mediated Nrf2 activation.

CONCLUSION

Thus, CVB-D ameliorates ALD-induced myocardial hypertrophy by recovering mitochondrial function by activating the mutual regulation of Nrf2 and SIRT3. Thus, CVB-D could be a beneficial drug for myocardial hypertrophy.

Astragaloside IV derivative HHQ16 ameliorates infarction-induced hypertrophy and heart failure through degradation of lncRNA4012/9456

Reversing ventricular remodeling represents a promising treatment for the post-myocardial infarction (MI) heart failure (HF). Here, we report a novel small molecule HHQ16, an optimized derivative of astragaloside IV, which effectively reversed infarction-induced myocardial remodeling and improved cardiac function by directly acting on the cardiomyocyte to reverse hypertrophy. The effect of HHQ16 was associated with a strong inhibition of a newly discovered Egr2-affiliated transcript lnc9456 in the heart. While minimally expressed in normal mouse heart, lnc9456 was dramatically upregulated in the heart subjected to left anterior descending coronary artery ligation (LADL) and in cardiomyocytes subjected to hypertrophic stimulation. The critical role of lnc9456 in cardiomyocyte hypertrophy was confirmed by specific overexpression and knockout in vitro. A physical interaction between lnc9456 and G3BP2 increased NF-κB nuclear translocation, triggering hypertrophy-related cascades. HHQ16 physically bound to lnc9456 with a high-affinity and induced its degradation. Cardiomyocyte-specific lnc9456 overexpression induced, but knockout prevented LADL-induced, cardiac hypertrophy and dysfunction. HHQ16 reversed the effect of lnc9456 overexpression while lost its protective role when lnc9456 was deleted, further confirming lnc9456 as the bona fide target of HHQ16. We further identified the human ortholog of lnc9456, also an Egr2-affiliated transcript, lnc4012. Similarly, lnc4012 was significantly upregulated in hypertrophied failing hearts of patients with dilated cardiomyopathy. HHQ16 also specifically bound to lnc4012 and caused its degradation and antagonized its hypertrophic effects. Targeted degradation of pathological increased lnc4012/lnc9456 by small molecules might serve as a novel promising strategy to regress infarction-induced cardiac hypertrophy and HF.

The novel peptide athycaltide-1 attenuates Ang II-induced pathological myocardial hypertrophy by reducing ROS and inhibiting the activation of CaMKII and ERK1/2

Pathological myocardial hypertrophy initially develops as an adaptive response to cardiac stress, which can be induced by many diseases. It is accompanied by adverse cardiovascular events, including heart failure, arrhythmias, and death. The purpose of this research was to explore the molecular mechanism of a novel peptide Athycaltide-1 (ATH-1) in the treatment of Ang II-induced pathological myocardial hypertrophy. In this study, the mRNA of Control group, Ang II group, ATH-1 group and Losartan group mice were sequenced by high-throughput sequencing technology. The results showed that the differentially expressed genes (DEGs) were significantly enriched in cell response to oxidative stress, regulation of reactive oxygen species metabolism and calmodulin binding. Then, the oxidation level of mouse hearts and H9c2 cardiomyocytes in each group and the expression of key proteins of CaMKII/HDAC/MEF2C and ERK1/2 signaling pathways were detected to preliminarily verify the positive effect of ATH-1. At the same time, the effect of ATH-1 was further determined by adding reactive oxygen species (ROS) inhibitor N-acetylcysteine (NAC) and CaMKII inhibitor AIP in vitro. The results showed that ATH-1 could significantly reduce the level of oxidative stress in hypertrophic cardiomyocytes and inhibiting the activation of CaMKII and ERK1/2.

The Anti-Inflammatory Mediator 17(R)-Resolvin D1 Attenuates Pressure Overload-Induced Cardiac Hypertrophy and Fibrosis

Background

Increased inflammation contributes to pressure overload-induced myocardial remodeling. 17(R)-Resolvin D1 (17(R)-RvD1), a potent lipid mediator derived from docosahexaenoic acid, possesses anti-inflammatory and pro-resolving properties. However, the association between 17(R)-RvD1 and pressure overload-induced cardiac hypertrophy remains unclear.

Methods

Transverse aortic constriction (TAC) surgery was performed to establish a cardiac hypertrophy model. C57BL/6J mice were randomly assigned to the Sham, TAC and TAC+17(R)-RvD1 groups. 17(R)-RvD1 was injected (2 μg/kg, i.p.) before TAC surgery and once every other day after surgery for 4 weeks. The same volume of saline was injected into the mice in both Sham group and TAC group. Then, cardiac function was evaluated and heart tissues were collected for biological analysis.

Results

17(R)-RvD1 treatment attenuated TAC-induced increase in left ventricular diameter and decrease in left ventricular contractility, mitigated increased cardiomyocyte cross-sectional area, and downregulated the expression of hypertrophic genes. Besides, 17(R)-RvD1 attenuated myocardial fibrosis, as indicated by the decreased LV collagen volume and expression of fibrotic genes. In addition, 17(R)-RvD1 ameliorated the inflammatory response in cardiac tissue, as illustrated by the decreased infiltration of CD68+ macrophages and reduced production of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6. 17(R)-RvD1 treatment significantly suppressed the activation of NLRP3 inflammasome after TAC surgery, which might be responsible for the attenuation of inflammation in cardiac tissue.

Conclusion

17(R)-RvD1 attenuated pressure overload-induced cardiac hypertrophy and fibrosis, and the possible mechanism may be associated with the inhibition of NLRP3 inflammasome. 17(R)-RvD1 may serve as a potential drug for the treatment of cardiac hypertrophy.

Sustained Increases in Cardiomyocyte Protein O-Linked β-N-Acetylglucosamine Levels Lead to Cardiac Hypertrophy and Reduced Mitochondrial Function Without Systolic Contractile Impairment

Background Lifestyle and metabolic diseases influence the severity and pathogenesis of cardiovascular disease through numerous mechanisms, including regulation via posttranslational modifications. A specific posttranslational modification, the addition of O-linked β-N acetylglucosamine (O-GlcNAcylation), has been implicated in molecular mechanisms of both physiological and pathologic adaptations. The current study aimed to test the hypothesis that in cardiomyocytes, sustained protein O-GlcNAcylation contributes to cardiac adaptations, and its progression to pathophysiology. Methods and Results Using a naturally occurring dominant-negative O-GlcNAcase (dnOGA) inducible cardiomyocyte-specific overexpression transgenic mouse model, we induced dnOGA in 8- to 10-week-old mouse hearts. We examined the effects of 2-week and 24-week dnOGA overexpression, which progressed to a 1.8-fold increase in protein O-GlcNAcylation. Two-week increases in protein O-GlcNAc levels did not alter heart weight or function; however, 24-week increases in protein O-GlcNAcylation led to cardiac hypertrophy, mitochondrial dysfunction, fibrosis, and diastolic dysfunction. Interestingly, systolic function was maintained in 24-week dnOGA overexpression, despite several changes in gene expression associated with cardiovascular disease. Specifically, mRNA-sequencing analysis revealed several gene signatures, including reduction of mitochondrial oxidative phosphorylation, fatty acid, and glucose metabolism pathways, and antioxidant response pathways after 24-week dnOGA overexpression. Conclusions This study indicates that moderate increases in cardiomyocyte protein O-GlcNAcylation leads to a differential response with an initial reduction of metabolic pathways (2-week), which leads to cardiac remodeling (24-week). Moreover, the mouse model showed evidence of diastolic dysfunction consistent with a heart failure with preserved ejection fraction. These findings provide insight into the adaptive versus maladaptive responses to increased O-GlcNAcylation in heart.

Effects of maternal hypothyroidism on postnatal cardiomyocyte proliferation and cardiac disease responses of the progeny

Maternal hypothyroidism (MH) could adversely affect the cardiac disease responses of the progeny. This study tested the hypothesis that MH reduces early postnatal cardiomyocyte (CM) proliferation so that the adult heart of MH progeny has a smaller number of larger cardiac myocytes, which imparts adverse cardiac disease responses following injury. Thyroidectomy (TX) was used to establish MH. The progeny from mice that underwent sham or TX surgery were termed Ctrl (control) or MH (maternal hypothyroidism) progeny, respectively. MH progeny had similar heart weight (HW) to body weight (BW) ratios and larger CM size consistent with fewer CMs at postnatal day 60 (P60) compared with Ctrl (control) progeny. MH progeny had lower numbers of EdU+, Ki67+, and phosphorylated histone H3 (PH3)+ CMs, which suggests they had a decreased CM proliferation in the postnatal timeframe. RNA-seq data showed that genes related to DNA replication were downregulated in P5 MH hearts, including bone morphogenetic protein 10 (Bmp10). Both in vivo and in vitro studies showed Bmp10 treatment increased CM proliferation. After transverse aortic constriction (TAC), the MH progeny had more severe cardiac pathological remodeling compared with the Ctrl progeny. Thyroid hormone (T4) treatment for MH mothers preserved their progeny's postnatal CM proliferation capacity and prevented excessive pathological remodeling after TAC. Our results suggest that CM proliferation during early postnatal development was significantly reduced in MH progeny, resulting in fewer CMs with hypertrophy in adulthood. These changes were associated with more severe cardiac disease responses after pressure overload.NEW & NOTEWORTHY Our study shows that compared with Ctrl (control) progeny, the adult progeny of mothers who have MH (MH progeny) had fewer CMs. This reduction of CM numbers was associated with decreased postnatal CM proliferation. Gene expression studies showed a reduced expression of Bmp10 in MH progeny. Bmp10 has been linked to myocyte proliferation. In vivo and in vitro studies showed that Bmp10 treatment of MH progeny and their myocytes could increase CM proliferation. Differences in CM number and size in adult hearts of MH progeny were linked to more severe cardiac structural and functional remodeling after pressure overload. T4 (synthetic thyroxine) treatment of MH mothers during their pregnancy, prevented the reduction in CM number in their progeny and the adverse response to disease stress.

17-(R/S)-hydroxyeicosatetraenoic acid (HETE) induces cardiac hypertrophy through the CYP1B1 in enantioselective manners

Cardiac cellular hypertrophy is the increase in the size of individual cardiac cells. Cytochrome P450 1B1 (CYP1B1) is an extrahepatic inducible enzyme that is associated with toxicity, including cardiotoxicity. We previously reported that 19-hydroxyeicosatetraenoic acid (19-HETE) inhibited CYP1B1 and prevented cardiac hypertrophy in enantioselective manner. Therefore, our aim is to investigate the effect of 17-HETE enantiomers on cardiac hypertrophy and CYP1B1. Human adult cardiomyocyte (AC16) cells were treated with 17-HETE enantiomers (20 µM); cellular hypertrophy was evaluated by cell surface area and cardiac hypertrophy markers. In addition, CYP1B1 gene, protein and activity were assessed. Human recombinant CYP1B1 and heart microsomes of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-treated rats were incubated with 17-HETE enantiomers (10-80 nM). Our results demonstrated that 17-HETE induced cellular hypertrophy, which is manifested by increase in cell surface area and cardiac hypertrophy markers. 17-HETE enantiomers allosterically activated CYP1B1 and selectively upregulated CYP1B1 gene and protein expression in AC16 cells at uM range. In addition, CYP1B1 was allosterically activated by 17-HETE enantiomers at nM range in recombinant CYP1B1 and heart microsomes. In conclusion, 17-HETE acts as an autocrine mediator, leading to the cardiac hypertrophy through induction of CYP1B1 activity in the heart.

ATGL deficiency aggravates pressure overload-triggered myocardial hypertrophic remodeling associated with the proteasome-PTEN-mTOR-autophagy pathway

Persistent myocardial hypertrophy frequently leads to heart failure (HF). Intramyocardial triacylglycerol (TAG) accumulation is closely related with cardiac remodeling and abnormal contractile function. Adipose triglyceride lipase (ATGL), a key enzyme in TAG metabolism, regulates cardiac function. However, its associated molecular pathways have not been fully defined. Here, cardiac hypertrophy and HF were induced in wild-type (WT) or ATGL knockout (KO) mice through transverse aortic constriction (TAC) for up to 4 weeks. TAC in WT mice significantly reduced cardiac function and autophagy while enhancing left ventricular hypertrophy, interstitial fibrosis, inflammatory response, superoxide generation, and cardiomyocyte apoptosis, accompanied with upregulation of the proteasome activity, reduction of PTEN level and activation of AKT-mTOR signaling, and these effects were further aggravated in ATGL KO mice. Interestingly, ATGL KO-mediated cardiac dysfunction and remodeling were markedly reversed by proteasome inhibitor (epoxomicin) or autophagic activator (rapamycin), but accelerated by PTEN inhibitor (VO-OHpic) or autophagy inhibitor 3-MA. Mechanistically, ATGL KO upregulated proteasome expression and activity, which in turn mediates PTEN degradation leading to activation of AKT-mTOR signaling and inhibition of autophagy, thereby enhancing hypertrophic remodeling and HF. In conclusion, ATGL KO contributes to TAC-induced cardiac dysfunction and adverse remodeling probably associated with the proteasome-PTEN-mTOR-autophagy pathway. Therefore, modulation of this pathway may have a therapeutic effect potential for hypertrophic heart disease. TAC-induced downregulation of ATGL results in increased proteasome (β1i/β2i/β5i) activity, which in turn promotes degradation of PTEN and activation of AKT-mTOR signaling and then inhibits autophagy and ATP production, thereby leading to cardiac hypertrophic remodeling and dysfunction. Conversely, blocking proteasome activity or activating autophagy attenuates these effects.

Effect of SH2B1 on glucose metabolism during pressure overload-induced cardiac hypertrophy and cardiac dysfunction

This study mainly explored the effect and mechanism of Src homology 2 (SH2) B adaptor protein 1 (SH2B1) on cardiac glucose metabolism during pressure overload-induced cardiac hypertrophy and dysfunction. A pressure-overloaded cardiac hypertrophy model was constructed, and SH2B1-siRNA was injected through the tail vein. Haematoxylin and eosin (H&E) staining was used to detect myocardial morphology. ANP, BNP, β-MHC and the diameter of myocardial fibres were quantitatively measured to evaluate the degree of cardiac hypertrophy, respectively. GLUT1, GLUT4, and IR were detected to assess cardiac glucose metabolism. Cardiac function was determined by echocardiography. Then, glucose oxidation and uptake, glycolysis and fatty acid metabolism were assessed in Langendorff perfusion of hearts. Finally, PI3K/AKT activator was used to further explore the relevant mechanism. The results showed that during cardiac pressure overload, with the aggravation of cardiac hypertrophy and dysfunction, cardiac glucose metabolism and glycolysis increased, and fatty acid metabolism decreased. After SH2B1-siRNA transfection, cardiac SH2B1 expression was knocked down, and the degree of cardiac hypertrophy and dysfunction was alleviated compared with the Control-siRNA transfected group. Simultaneously, cardiac glucose metabolism and glycolysis were reduced, and fatty acid metabolism was enhanced. The SH2B1 expression knockdown mitigated the cardiac hypertrophy and dysfunction by reducing cardiac glucose metabolism. After using PI3K/AKT activator, the effect of SH2B1 expression knockdown on cardiac glucose metabolism was reversed during cardiac hypertrophy and dysfunction. Collectively, SH2B1 regulated cardiac glucose metabolism by activating the PI3K/AKT pathway during pressure overload-induced cardiac hypertrophy and cardiac dysfunction.

Visfatin aggravates transverse aortic constriction-induced cardiac remodelling by enhancing macrophage-mediated oxidative stress in mice

Previous studies have reported that visfatin can regulate macrophage polarisation, which has been demonstrated to participate in cardiac remodelling. The aims of this study were to investigate whether visfatin participates in transverse aortic constriction (TAC)-induced cardiac remodelling by regulating macrophage polarisation. First, TAC surgery and angiotensin II (Ang II) infusion were used to establish a mouse cardiac remodelling model, visfatin expression was measured, and the results showed that TAC surgery or Ang II infusion increased visfatin expression in the serum and heart in mice, and phenylephrine or hydrogen peroxide promoted the release of visfatin from macrophages in vitro. All these effects were dose-dependently reduced by superoxide dismutase. Second, visfatin was administered to TAC mice to observe the effects of visfatin on cardiac remodelling. We found that visfatin increased the cross-sectional area of cardiomyocytes, aggravated cardiac fibrosis, exacerbated cardiac dysfunction, further regulated macrophage polarisation and aggravated oxidative stress in TAC mice. Finally, macrophages were depleted in TAC mice to investigate whether macrophages mediate the regulatory effect of visfatin on cardiac remodelling, and the results showed that the aggravating effects of visfatin on oxidative stress and cardiac remodelling were abrogated. Our study suggests that visfatin enhances cardiac remodelling by promoting macrophage polarisation and enhancing oxidative stress. Visfatin may be a potential target for the prevention and treatment of clinical cardiac remodelling.

mAKAPβ signalosome: A potential target for cardiac hypertrophy

Pathological cardiac hypertrophy is the result of a prolonged increase in the workload of the heart that activates various signaling pathways such as MAPK pathway, PKA-dependent cAMP signaling, and CaN-NFAT signaling pathway which further activates genes for cardiac remodeling. Various signalosomes are present in the heart that regulates the signaling of physiological and pathological cardiac hypertrophy. mAKAPβ is one such scaffold protein that regulates signaling pathways involved in promoting cardiac hypertrophy. It is present in the outer nuclear envelope of the cardiomyocytes, which provides specificity of the target toward the heart. In addition, nuclear translocation of signaling components and transcription factors such as MEF2D, NFATc, and HIF-1α is facilitated due to the localization of mAKAPβ near the nuclear envelope. These factors are required for activation of genes promoting cardiac remodeling. Downregulation of mAKAPβ improves cardiac function and attenuates cardiac hypertrophy which in turn prevents the development of heart failure. Unlike earlier therapies for heart failure, knockout or silencing of mAKAPβ is not associated with side effects because of its high specificity in the striated myocytes. Downregulating expression of mAKAPβ is a favorable therapeutic approach toward attenuating cardiac hypertrophy and hence preventing heart failure. This review discusses mAKAPβ signalosome as a potential target for cardiac hypertrophy intervention.

Resveratrol prevents Ang II-induced cardiac hypertrophy by inhibition of NF-κB signaling

BACKGROUND

Pathological cardiac hypertrophy is a hallmark of various cardiovascular diseases (CVD) including chronic heart failure (HF) and an important target for the treatment of these diseases. Aberrant activation of Angiotensin II (Ang II)/AT1R signaling pathway is one of the main triggers of cardiac hypertrophy, which further gives rise to excessive inflammation that is mediated by the key transcription factor NF-κB. Resveratrol (REV) is a natural polyphenol with multiple anti-inflammatory and anti-oxidative effects, however the ability of REV in preventing Ang II-induced cardiac hypertrophy in combination with NF-κB signaling activation remains unclear.

METHODS

Murine models of cardiac hypertrophy was conducted via implantation of Ang II osmotic pumps. Primary neonatal rat cardiomyocyte and heart tissues were examined to determine the effect and underlying mechanism of REV in preventing Ang II-induced cardiac hypertrophy.

RESULTS

Administrations of REV significantly prevented Ang II-induced cardiac hypertrophy, as well as robustly attenuated Ang II-induced cardiac fibrosis, and cardiac dysfunction. Furthermore, REV not only directly prevented Ang II/AT1R signal transductions, but also prevented Ang II-induced expressions of pro-inflammatory cytokines and activation of NF-κB signaling pathway.

CONCLUSIONS

Our study provides important new mechanistic insight into the cardioprotective effects of REV in preventing Ang II-induced cardiac hypertrophy via inhibiting adverse NF-κB signaling activation. Our findings further suggest the therapeutic potential of REV as a promising drug for the treatment of cardiac hypertrophy and heart failure.

Tripartite motif‑containing 14 may aggravate cardiac hypertrophy via the AKT signalling pathway in neonatal rat cardiomyocytes and transgenic mice

Tripartite motif‑containing 14 (TRIM14) is an E3 ubiquitin ligase that primarily participates in the natural immune response and in tumour development via ubiquitination. However, the role of TRIM14 in cardiac hypertrophy is not currently clear. The present study examined the role of TRIM14 in cardiac hypertrophy and its potential molecular mechanism. TRIM14 was overexpressed in neonatal rat cardiomyocytes using adenovirus and cardiomyocyte hypertrophy was induced using phenylephrine (PE). Cardiomyocyte hypertrophy was assessed by measuring cardiomyocyte surface area and markers of hypertrophy. In addition, TRIM14‑transgenic (TRIM14‑TG) mice were created and cardiac hypertrophy was induced using transverse aortic constriction (TAC). Cardiac function, heart weight‑to‑body weight ratio (HW/BW), cardiomyocyte cross‑sectional area, cardiac fibrosis and hypertrophic markers were further examined. The expression of AKT signalling pathway‑related proteins was detected. TRIM14 overexpression in cardiomyocytes promoted PE‑induced increases in cardiomyocyte surface area and hypertrophic markers. TRIM14‑TG mice developed worse cardiac function, greater HW/BW, cross‑sectional area and cardiac fibrosis, and higher levels of hypertrophic markers in response to TAC. TRIM14 overexpression also increased the phosphorylation levels of AKT, GSK‑3β, mTOR and p70S6K in vivo and in vitro. To the best our knowledge, the present study was the first to reveal that overexpression of TRIM14 aggravated cardiac hypertrophy in vivo and in vitro, which may be related to activation of the AKT signalling pathway.

Paeoniflorin alleviates AngII-induced cardiac hypertrophy in H9c2 cells by regulating oxidative stress and Nrf2 signaling pathway

Cardiac hypertrophy is frequently associated with ventricular dysfunction and heart failure. Paeoniflorin, has been widely used to treat cardiovascular dysfunction-related diseases. However, the underlying mechanism has been unclear. Here, we investigated the potential inhibitory effects and mechanism of paeoniflorin on oxidative stress of cardiac hypertrophy induced by angiotensin II (AngII) in vitro. Using MTS assay, qRT-PCR, WGA staining assay, and western blot, different dosages (50-400 μM) of paeoniflorin were utilized to examine the antihypertrophy effects on H9c2 cells. Western blot examination revealed the presence of apoptosis-related proteins Bax, Bcl2, and Cytc, antioxidative stress-related proteins Nrf2, HO-1, SOD, and CAT, and mitophagy-related proteins PINK1 and Parkin. qRT-PCR was used to detect the mRNA expression of Bax, Bcl2, Nrf2, and HO-1. TUNEL, caspase3/9 enzyme viability, and MDA, T-AOC, and superoxide levels were all evaluated using commercial kits.The fluorescent probes DCFH-DA and JC-1 were employed to measure cellular ROS and MMP levels. Nrf2 siRNA was utilized to investigate Nrf2's role in paeoniflorin-treated cardiac hypertrophy. Paeoniflorin dramatically reduced cell section area (CSA) and hypertrophic marker (ANP, BNP) expression while inhibiting oxidative stress by modulating ROS and MDA, CAT, SOD, and T-AOC levels. Furthermore, in AngII-induced cardiomyocyte hypertrophy, paeoniflorin restores H9c2 apoptosis by restoring Bax, Bcl-2 Cyt-C, Caspase 3, and Caspase 9 levels. Paeoniflorin also restored Nrf2/HO-1 and PINK1/Parkin expression, and its anti-AngII activities were mediated by Nrf2, which was regulated by Nrf2 knockdown. In conclusion, Our data confirm that paeoniflorin alleviates cardiac hypertrophy through modulating oxidative stress and Nrf2 signaling pathway in vitro.

Metabolic Drivers and Rescuers of Heart Failure

Cardiac hypertrophy and heart failure involve a number of metabolic alterations. Human genetic mutations and murine genetic deficiency models of metabolic enzymes or transporters largely suggest that these alterations in metabolism are maladaptive and contribute to the cardiac remodeling and dysfunction. Here, we discuss insights into metabolic alterations identified in cardiac hypertrophy and failure, as well as dietary and pharmacologic therapies that counteract these metabolic alterations and have been shown to significantly improve heart failure.

Reduced expression of transmembrane protein 43 during cardiac hypertrophy leads to worsening heart failure in mice

Transmembrane protein 43 (TMEM43), a member of the transmembrane protein subfamily, was found to be associated with arrhythmogenic right ventricular cardiomyopathy. However, its role in cardiac hypertrophy has not been elucidated. Here, we used a pressure overload-induced cardiac hypertrophy model to explore the role of TMEM43 in heart failure. Mice were subjected to aortic banding (AB) to induce cardiac hypertrophy. The mice were also randomly selected to receive injection of adeno-associated virus 9 (AAV9)-shTMEM43 to knockdown TMEM43 in cardiomyocytes or control AAV9 (ScRNA). Four weeks after AB, the mice were subjected to echocardiography to evaluate cardiac function. Neonatal rat cardiomyocytes (NRCMs) were stimulated with angiotensin II (AngII, 1 μM) and transfected with an adenovirus to over-express TMEM43. We found that TMEM43 was downregulated in mouse hearts and cardiomyocytes poststimulation. Mice with TMEM43 knockdown showed worsening heart failure accompanied by deteriorating cardiac function and exacerbated cardiac hypertrophy and fibrosis at 4 weeks post-AB. NRCMs over-expressing TMEM43 exhibited an ameliorated hypertrophic response. Moreover, we found that TMEM43 deficiency increased nuclear factor kappa B (NF-κB) activation in mouse hearts post-AB, while TMEM43 over-expression reduced NF-κB activation in cardiomyocytes upon AngII stimulation. Thus, we conclude that reduced expression of TMEM43 during cardiac hypertrophy leads to worsening heart failure in mice.

The CREG1-FBXO27-LAMP2 axis alleviates diabetic cardiomyopathy by promoting autophagy in cardiomyocytes

Autophagy plays an important role in the development of diabetic cardiomyopathy. Cellular repressor of E1A-stimulated genes 1 (CREG1) is an important myocardial protective factor. The aim of this study was to investigate the effects and mechanisms of CREG1 in diabetic cardiomyopathy. Male C57BL/6 J mice, Creg1 transgenic mice and cardiac-specific knockout mice were used to establish a type 2 diabetes model. Small animal ultrasound, Masson's staining and western blotting were used to evaluate cardiac function, myocardial fibrosis and autophagy. Neonatal mouse cardiomyocytes (NMCMs) were stimulated with palmitate, and the effects of CREG1 on NMCMs autophagy were examined. CREG1 deficiency exacerbated cardiac dysfunction, cardiac hypertrophy and fibrosis in mice with diabetic cardiomyopathy, which was accompanied by exacerbated autophagy dysfunction. CREG1 overexpression improved cardiac function and ameliorated cardiac hypertrophy and fibrosis in diabetic cardiomyopathy by improving autophagy. CREG1 protein expression was decreased in palmitate-induced NMCMs. CREG1 knockdown exacerbated cardiomyocyte hypertrophy and inhibited autophagy. CREG1 overexpression inhibited cardiomyocyte hypertrophy and improved autophagy. LAMP2 overexpression reversed the effect of CREG1 knockdown on palmitate-induced inhibition of cardiomyocyte autophagy. CREG1 inhibited LAMP2 protein degradation by inhibiting the protein expression of F-box protein 27 (FBXO27). Our findings indicate new roles of CREG1 in the development of diabetic cardiomyopathy.