The role of post-translational modifications in cardiac hypertrophy

Xinyang tablet alleviated cardiac dysfunction in a cardiac pressure overload model by regulating the receptor-interacting serum/three-protein kinase 3/FUN14 domain containing 1-mediated mitochondrial unfolded protein response and mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Xinyang tablet (XYT) has been used for heart failure (HF) for over twenty years in clinical practice, but the underlying molecular mechanism remains poorly understood.

AIMS OF THE STUDY

In the present study, we aimed to explore the protective effects of XYT in HF in vivo and in vitro.

MATERIALS AND METHODS

Transverse aortic constriction was performed in vivo to establish a mouse model of cardiac pressure overload. Echocardiography, tissue staining, and real-time quantitative PCR (qPCR) were examined to evaluate the protective effects of XYT on cardiac function and structure. Adenosine 5'-triphosphate production, reactive oxygen species staining, and measurement of malondialdehyde and superoxide dismutase was used to detect mitochondrial damage. Mitochondrial ultrastructure was observed by transmission electron microscope. Immunofluorescence staining, qPCR, and Western blotting were performed to evaluate the effect of XYT on the mitochondrial unfolded protein response and mitophagy, and to identify its potential pharmacological mechanism. In vitro, HL-1 cells and neonatal mouse cardiomyocytes were stimulated with Angiotensin II to establish the cell model. Western blotting, qPCR, immunofluorescence staining, and flow cytometry were utilized to determine the effects of XYT on cardiomyocytes. HL-1 cells overexpressing receptor-interacting serum/three-protein kinase 3 (RIPK3) were generated by transfection of RIPK3-overexpressing lentiviral vectors. Cells were then co-treated with XYT to determine the molecular mechanisms.

RESULTS

In the present study, XYT was found to exerta protective effect on cardiac function and structure in the pressure overload mice. And it was also found XYT reduced mitochondrial damage by enhancing mitochondrial unfolded protein response and restoring mitophagy. Further studies showed that XYT achieved its cardioprotective role through regulating the RIPK3/FUN14 domain containing 1 (FUNDC1) signaling. Moreover, the overexpression of RIPK3 successfully reversed the XYT-induced protective effects and significantly attenuated the positive effects on the mitochondrial unfolded protein response and mitophagy.

CONCLUSIONS

Our findings indicated that XYT prevented pressure overload-induced HF through regulating the RIPK3/FUNDC1-mediated mitochondrial unfolded protein response and mitophagy. The information gained from this study provides a potential strategy for attenuating mitochondrial damage in the context of pressure overload-induced heart failure using XYT.

Multifaceted role of dynamin-related protein 1 in cardiovascular disease: From mitochondrial fission to therapeutic interventions

Mitochondria are central to cellular energy production and metabolic regulation, particularly in cardiomyocytes. These organelles constantly undergo cycles of fusion and fission, orchestrated by key proteins like Dynamin-related Protein 1 (Drp-1). This review focuses on the intricate roles of Drp-1 in regulating mitochondrial dynamics, its implications in cardiovascular health, and particularly in myocardial infarction. Drp-1 is not merely a mediator of mitochondrial fission; it also plays pivotal roles in autophagy, mitophagy, apoptosis, and necrosis in cardiac cells. This multifaceted functionality is often modulated through various post-translational alterations, and Drp-1's interaction with intracellular calcium (Ca2 + ) adds another layer of complexity. We also explore the pathological consequences of Drp-1 dysregulation, including increased reactive oxygen species (ROS) production and endothelial dysfunction. Furthermore, this review delves into the potential therapeutic interventions targeting Drp-1 to modulate mitochondrial dynamics and improve cardiovascular outcomes. We highlight recent findings on the interaction between Drp-1 and sirtuin-3 and suggest that understanding this interaction may open new avenues for therapeutically modulating endothelial cells, fibroblasts, and cardiomyocytes. As the cardiovascular system increasingly becomes the focal point of aging and chronic disease research, understanding the nuances of Drp-1's functionality can lead to innovative therapeutic approaches.

Post-translational modifications of vertebrate striated muscle myosin heavy chains

Post-translational modifications (PTMs) play a crucial role in regulating the function of many sarcomeric proteins, including myosin. Myosins comprise a family of motor proteins that play fundamental roles in cell motility in general and muscle contraction in particular. A myosin molecule consists of two myosin heavy chains (MyHCs) and two pairs of myosin light chains (MLCs); two MLCs are associated with the neck region of each MyHC's N-terminal head domain, while the two MyHC C-terminal tails form a coiled-coil that polymerizes with other MyHCs to form the thick filament backbone. Myosin undergoes extensive PTMs, and dysregulation of these PTMs may lead to abnormal muscle function and contribute to the development of myopathies and cardiovascular disorders. Recent studies have uncovered the significance of PTMs in regulating MyHC function and showed how these PTMs may provide additional modulation of contractile processes. Here, we discuss MyHC PTMs that have been biochemically and/or functionally studied in mammals' and rodents' striated muscle. We have identified hotspots or specific regions in three isoforms of myosin (MYH2, MYH6, and MYH7) where the prevalence of PTMs is more frequent and could potentially play a significant role in fine-tuning the activity of these proteins.

Melanoma differentiation-associated protein 5 prevents cardiac hypertrophy via apoptosis signal-regulating kinase 1-c-Jun N-terminal kinase/p38 signaling

Pathological cardiac hypertrophy (CH) is driven by maladaptive changes in myocardial cells in response to pressure overload or other stimuli. CH has been identified as a significant risk factor for the development of various cardiovascular diseases, ultimately resulting in heart failure. Melanoma differentiation-associated protein 5 (MDA5), encoded by interferon-induced with helicase C domain 1 (IFIH1), is a cytoplasmic sensor that primarily functions as a detector of double-stranded ribonucleic acid (dsRNA) viruses in innate immune responses; however, its role in CH pathogenesis remains unclear. Thus, the aim of this study was to examine the relationship between MDA5 and CH using cellular and animal models generated by stimulating neonatal rat cardiomyocytes with phenylephrine and by performing transverse aortic constriction on mice, respectively. MDA5 expression was upregulated in all models. MDA5 deficiency exacerbated myocardial pachynsis, fibrosis, and inflammation in vivo, whereas its overexpression hindered CH development in vitro. In terms of the underlying molecular mechanism, MDA5 inhibited CH development by promoting apoptosis signal-regulating kinase 1 (ASK1) phosphorylation, thereby suppressing c-Jun N-terminal kinase/p38 signaling pathway activation. Rescue experiments using an ASK1 activation inhibitor confirmed that ASK1 phosphorylation was essential for MDA5-mediated cell death. Thus, MDA5 protects against CH and is a potential therapeutic target.

Reduced mitochondrial pyruvate carrier expression in hearts with heart failure and reduced ejection fraction patients: ischemic vs. non-ischemic origin

Introduction and objectives

Mitochondrial pyruvate carrier (MPC) mediates the entry of pyruvate into mitochondria, determining whether pyruvate is incorporated into the Krebs cycle or metabolized in the cytosol. In heart failure (HF), a large amount of pyruvate is metabolized to lactate in the cytosol rather than being oxidized inside the mitochondria. Thus, MPC activity or expression might play a key role in the fate of pyruvate during HF. The purpose of this work was to study the levels of the two subunits of this carrier, named MPC1 and MPC2, in human hearts with HF of different etiologies.

Methods

Protein and mRNA expression analyses were conducted in cardiac tissues from three donor groups: patients with HF with reduced ejection fraction (HFrEF) with ischemic cardiomyopathy (ICM) or idiopathic dilated cardiomyopathy (IDC), and donors without cardiac pathology (Control). MPC2 plasma levels were determined by ELISA.

Results

Significant reductions in the levels of MPC1, MPC2, and Sirtuin 3 (SIRT3) were observed in ICM patients compared with the levels in the Control group. However, no statistically significant differences were revealed in the analysis of MPC1 and MPC2 gene expression among the groups. Interestingly, Pyruvate dehydrogenase complex (PDH) subunits expression were increased in the ICM patients. In the case of IDC patients, a significant decrease in MPC1 was observed only when compared with the Control group. Notably, plasma MPC2 levels were found to be elevated in both disease groups compared with that in the Control group.

Conclusion

Decreases in MPC1 and/or MPC2 levels were detected in the cardiac tissues of HFrEF patients, with ischemic or idiopatic origen, indicating a potential reduction in mitochondrial pyruvate uptake in the heart, which could be linked to unfavorable clinical features.

Hypertrophic cardiomyopathy in MYBPC3 carriers in aging

Hypertrophic cardiomyopathy (HCM) is characterized by abnormal thickening of the myocardium, leading to arrhythmias, heart failure, and elevated risk of sudden cardiac death, particularly among the young. This inherited disease is predominantly caused by mutations in sarcomeric genes, among which those in the cardiac myosin binding protein-C3 (MYBPC3) gene are major contributors. HCM associated with MYBPC3 mutations usually presents in the elderly and ranges from asymptomatic to symptomatic forms, affecting numerous cardiac functions and presenting significant health risks with a spectrum of clinical manifestations. Regulation of MYBPC3 expression involves various transcriptional and translational mechanisms, yet the destiny of mutant MYBPC3 mRNA and protein in late-onset HCM remains unclear. Pathogenesis related to MYBPC3 mutations includes nonsense-mediated decay, alternative splicing, and ubiquitin-proteasome system events, leading to allelic imbalance and haploinsufficiency. Aging further exacerbates the severity of HCM in carriers of MYBPC3 mutations. Advancements in high-throughput omics techniques have identified crucial molecular events and regulatory disruptions in cardiomyocytes expressing MYBPC3 variants. This review assesses the pathogenic mechanisms that promote late-onset HCM through the lens of transcriptional, post-transcriptional, and post-translational modulation of MYBPC3, underscoring its significance in HCM across carriers. The review also evaluates the influence of aging on these processes and MYBPC3 levels during HCM pathogenesis in the elderly. While pinpointing targets for novel medical interventions to conserve cardiac function remains challenging, the emergence of personalized omics offers promising avenues for future HCM treatments, particularly for late-onset cases.

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.

AAAKB: A manually curated database for tracking and predicting genes of Abdominal aortic aneurysm (AAA)

Abdominal aortic aneurysm (AAA), an extremely dangerous vascular disease with high mortality, causes massive internal bleeding due to aneurysm rupture. To boost the research on AAA, efforts should be taken to organize and link the information about AAA-related genes and their functions. Currently, most researchers screen through genetic databases manually, which is cumbersome and time-consuming. Here, we developed "AAAKB" a manually curated knowledgebase containing genes, SNPs and pathways associated with AAA. In order to facilitate researchers to further explore the mechanism network of AAA, AAAKB provides predicted genes that are potentially associated with AAA. The prediction is based on the protein interaction information of genes collected in the database, and the random forest algorithm (RF) is used to build the prediction model. Some of these predicted genes are differentially expressed in patients with AAA, and some have been reported to play a role in other cardiovascular diseases, illustrating the utility of the knowledgebase in predicting novel genes. Also, AAAKB integrates a protein interaction visualization tool to quickly determine the shortest paths between target proteins. As the first knowledgebase to provide a comprehensive catalog of AAA-related genes, AAAKB will be an ideal research platform for AAA. Database URL: http://www.lqlgroup.cn:3838/AAAKB/.

Mettl13 protects against cardiac contractile dysfunction by negatively regulating C-Cbl-mediated ubiquitination of SERCA2a in ischemic heart failure

Ischemic heart failure (HF) remains a leading cause of morbidity and mortality. Maintaining homeostasis of cardiac function and preventing cardiac remodeling deterioration are critical to halting HF progression. Methyltransferase-like protein 13 (Mettl13) has been shown to regulate protein translation efficiency by acting as a protein lysine methyltransferase, but its role in cardiac pathology remains unexplored. This study aims to characterize the roles and mechanisms of Mettl13 in cardiac contractile function and HF. We found that Mettl13 was downregulated in the failing hearts of mice post-myocardial infarction (MI) and in a cellular model of oxidative stress. Cardiomyocyte-specific overexpression of Mettl13 mediated by AAV9-Mettl13 attenuated cardiac contractile dysfunction and fibrosis in response to MI, while silencing of Mettl13 impaired cardiac function in normal mice. Moreover, Mettl13 overexpression abrogated the reduction in cell shortening, Ca2+ transient amplitude and SERCA2a protein levels in the cardiomyocytes of adult mice with MI. Conversely, knockdown of Mettl13 impaired the contractility of cardiomyocytes, and decreased Ca2+ transient amplitude and SERCA2a protein expression in vivo and in vitro. Mechanistically, Mettl13 impaired the stability of c-Cbl by inducing lysine methylation of c-Cbl, which in turn inhibited ubiquitination-dependent degradation of SERCA2a. Furthermore, the inhibitory effects of knocking down Mettl13 on SERCA2a protein expression and Ca2+ transients were partially rescued by silencing c-Cbl in H2O2-treated cardiomyocytes. In conclusion, our study uncovers a novel mechanism that involves the Mettl13/c-Cbl/SERCA2a axis in regulating cardiac contractile function and remodeling, and identifies Mettl13 as a novel therapeutic target for ischemic HF.

Treatment of human cardiac fibroblasts with the protein arginine deiminase inhibitor BB-Cl-amidine activates the Nrf2/HO-1 signaling pathway

BACKGROUND

Cardiac fibrosis contributes to end-stage extracellular matrix remodeling and heart failure (HF). Cardiac fibroblasts (CFs) differentiate into myofibroblasts (myoFbs) to preserve the structural integrity of the heart; however, the molecular mechanisms regulating CF transdifferentiation remain poorly understood. Protein arginine deiminase (PAD), which converts arginine to citrulline, has been shown to play a role in myocardial infarction, fibrosis, and HF. This study aimed to investigate the role of PAD in CF differentiation to myoFbs and identify the citrullinated proteins that were associated with phenotypic changes in CFs.

RESULTS

Gene expression analysis showed that PAD1 and PAD2 isoforms, but not PAD4 isoforms, were abundant in both CFs and myoFbs, and PAD1 was significantly upregulated in myoFbs. The pan-PAD inhibitor BB-Cl-amidine (BB-Cl) downregulated the mRNA expression of PAD1 and PAD2 as well as the protein expression of the fibrosis marker COL1A1 in CFs and myoFbs. Interestingly, a proteomic approach pointed to the activation of the Nrf2/HO-1 signaling pathway upon BB-Cl treatment in CFs and myoFbs. BB-Cl administration resulted in the upregulation of HO-1 at both the gene and protein levels in CFs and myoFbs. Importantly, the protein citrullination landscape of CFs consisting of 86 novel citrullination sites associated with focal adhesion (FN1(R1054)), inflammation (TAGLN(R12)) and DNA replication (EEF2(R767)) pathways was identified.

CONCLUSIONS

In summary, we revealed that BB-Cl treatment resulted in increased HO-1 expression via the Nrf2 pathway, which could prevent excessive tissue damage, thereby leading to substantial clinical benefits for the treatment of cardiac fibrosis.

Orchestration of Mitochondrial Function and Remodeling by Post-Translational Modifications Provide Insight into Mechanisms of Viral Infection

The regulation of mitochondria structure and function is at the core of numerous viral infections. Acting in support of the host or of virus replication, mitochondria regulation facilitates control of energy metabolism, apoptosis, and immune signaling. Accumulating studies have pointed to post-translational modification (PTM) of mitochondrial proteins as a critical component of such regulatory mechanisms. Mitochondrial PTMs have been implicated in the pathology of several diseases and emerging evidence is starting to highlight essential roles in the context of viral infections. Here, we provide an overview of the growing arsenal of PTMs decorating mitochondrial proteins and their possible contribution to the infection-induced modulation of bioenergetics, apoptosis, and immune responses. We further consider links between PTM changes and mitochondrial structure remodeling, as well as the enzymatic and non-enzymatic mechanisms underlying mitochondrial PTM regulation. Finally, we highlight some of the methods, including mass spectrometry-based analyses, available for the identification, prioritization, and mechanistic interrogation of PTMs.

Angiotensin II-induced calcium overload affects mitochondrial functions in cardiac hypertrophy by targeting the USP2/MFN2 axis

Ubiquitination, a common type of post-translational modification, is known to affect various diseases, including cardiac hypertrophy. Ubiquitin-specific peptidase 2 (USP2) plays a crucial role in regulating cell functions, but its role in cardiac functions remains elusive. The present study aims to investigate the mechanism of USP2 in cardiac hypertrophy. Animal and cell models of cardiac hypertrophy were established using Angiotensin II (Ang II) induction. Our experiments revealed that Ang II induced USP2 downregulation in the in vitro and in vivo models. USP2 overexpression suppressed the degree of cardiac hypertrophy (decreased ANP, BNP, and β-MHC mRNA levels, cell surface area, and ratio of protein/DNA), calcium overload (decreased Ca²⁺ concentration and t-CaMKⅡ and p-CaMKⅡ, and increased SERCA2), and mitochondrial dysfunction (decreased MDA and ROS and increased MFN1, ATP, MMP, and complex Ⅰ and II) both in vitro and in vivo. Mechanically, USP2 interacted with MFN2 and improved the protein level of MFN2 through deubiquitination. Rescue experiments confirmed that MFN2 downregulation neutralized the protective role of USP2 overexpression in cardiac hypertrophy. Overall, our findings suggested that USP2 overexpression mediated deubiquitination to upregulate MFN2, thus alleviating calcium overload-induced mitochondrial dysfunction and cardiac hypertrophy.

Roles of histone acetylation sites in cardiac hypertrophy and heart failure

Heart failure results from various physiological and pathological stimuli that lead to cardiac hypertrophy. This pathological process is common in several cardiovascular diseases and ultimately leads to heart failure. The development of cardiac hypertrophy and heart failure involves reprogramming of gene expression, a process that is highly dependent on epigenetic regulation. Histone acetylation is dynamically regulated by cardiac stress. Histone acetyltransferases play an important role in epigenetic remodeling in cardiac hypertrophy and heart failure. The regulation of histone acetyltransferases serves as a bridge between signal transduction and downstream gene reprogramming. Investigating the changes in histone acetyltransferases and histone modification sites in cardiac hypertrophy and heart failure will provide new therapeutic strategies to treat these diseases. This review summarizes the association of histone acetylation sites and histone acetylases with cardiac hypertrophy and heart failure, with emphasis on histone acetylation sites.

ABRO1 arrests cardiomyocyte proliferation and myocardial repair by suppressing PSPH

The role of Abraxas 2 (ABRO1 or KIAA0157), a component of the lysine63-linked deubiquitinating system, in the cardiomyocyte proliferation and myocardial regeneration is unknown. Here, we found that ABRO1 regulates cardiomyocyte proliferation and cardiac regeneration in the postnatal heart by targeting METTL3-mediated m6A methylation of Psph mRNA. The deletion of ABRO1 increased cardiomyocyte proliferation in hearts and restored the heart function after myocardial injury. On the contrary, ABRO1 overexpression significantly inhibited the neonatal cardiomyocyte proliferation and cardiac regeneration in mouse hearts. The mechanism by which ABRO1 regulates cardiomyocyte proliferation mainly involved METTL3-mediated Psph mRNA methylation and CDK2 phosphorylation. In the early postnatal period, METTL3-dependent m6A methylation promotes cardiomyocyte proliferation by hypermethylation of Psph mRNA and upregulating PSPH expression. PSPH dephosphorylates cyclin-dependent kinase 2 (CDK2), a positive regulator of cell cycle, at Thr14/Tyr15 and increases its activity. Upregulation of ABRO1 restricts METTL3 activity and halts the cardiomyocyte proliferation in the postnatal hearts. Thus, our study reveals that ABRO1 is an essential contributor in the cell cycle withdrawal and attenuation of proliferative response in the postnatal cardiomyocytes and could act as a potential target to accelerate cardiomyocyte proliferation and cardiac repair in the adult heart.

Targeting mitochondrial impairment for the treatment of cardiovascular diseases: From hypertension to ischemia-reperfusion injury, searching for new pharmacological targets

Mitochondria and mitochondrial proteins represent a group of promising pharmacological target candidates in the search of new molecular targets and drugs to counteract the onset of hypertension and more in general cardiovascular diseases (CVDs). Indeed, several mitochondrial pathways result impaired in CVDs, showing ATP depletion and ROS production as common traits of cardiac tissue degeneration. Thus, targeting mitochondrial dysfunction in cardiomyocytes can represent a successful strategy to prevent heart failure. In this context, the identification of new pharmacological targets among mitochondrial proteins paves the way for the design of new selective drugs. Thanks to the advances in omics approaches, to a greater availability of mitochondrial crystallized protein structures and to the development of new computational approaches for protein 3D-modelling and drug design, it is now possible to investigate in detail impaired mitochondrial pathways in CVDs. Furthermore, it is possible to design new powerful drugs able to hit the selected pharmacological targets in a highly selective way to rescue mitochondrial dysfunction and prevent cardiac tissue degeneration. The role of mitochondrial dysfunction in the onset of CVDs appears increasingly evident, as reflected by the impairment of proteins involved in lipid peroxidation, mitochondrial dynamics, respiratory chain complexes, and membrane polarization maintenance in CVD patients. Conversely, little is known about proteins responsible for the cross-talk between mitochondria and cytoplasm in cardiomyocytes. Mitochondrial transporters of the SLC25A family, in particular, are responsible for the translocation of nucleotides (e.g., ATP), amino acids (e.g., aspartate, glutamate, ornithine), organic acids (e.g. malate and 2-oxoglutarate), and other cofactors (e.g., inorganic phosphate, NAD⁺, FAD, carnitine, CoA derivatives) between the mitochondrial and cytosolic compartments. Thus, mitochondrial transporters play a key role in the mitochondria-cytosol cross-talk by leading metabolic pathways such as the malate/aspartate shuttle, the carnitine shuttle, the ATP export from mitochondria, and the regulation of permeability transition pore opening. Since all these pathways are crucial for maintaining healthy cardiomyocytes, mitochondrial carriers emerge as an interesting class of new possible pharmacological targets for CVD treatments.

Upregulation of key genes Eln and Tgfb3 were associated with the severity of cardiac hypertrophy

Background

Hypertension-induced cardiac hypertrophy is one of the most common pre-conditions that accompanies heart failure. This study aimed to identify the key pathogenic genes in the disease process.

Methods

GSE18224 was re-analyzed and differentially expressed genes (DEGs) were obtained. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were carried out. Networks of transcription factor (TF)-mRNA, microRNA (miRNA)-mRNA and Protein-Protein interaction (PPI) were constructed, and a key module was further screened out from PPI network. GSE36074 dataset and our transverse aortic constriction (TAC) mouse model were used to validate gene expression in the module. Finally, the correlation between the genes and biomarkers of cardiac hypertrophy were evaluated.

Results

Totally, there were 348 DEGs in GSE18224, which were mainly enriched in biological processes including collagen fibril organization, cellular response to transforming growth factor-beta stimulus and were involved in ECM-receptor interaction and Oxytocin signaling pathway. There were 387 miRNAs targeted by 257 DEGs, while 177 TFs targeted 71 DEGs. The PPI network contained 222 nodes and 770 edges, with 18 genes screened out into the module. After validation, 8 genes, which were also significantly upregulated in the GSE36074 dataset, were selected from the 18 DEGs. 2 of the 8 DEGs, including Eln and Tgfb3 were significantly upregulated in our mouse model of myocardial hypertrophy. Finally, the expression of Eln and Tgfb3 were found to be positively correlated with the level of the disease biomarkers.

Conclusions

Upregulated key genes Eln and Tgfb3 were positively correlated with the severity of cardiac hypertrophy, which may provide potential therapeutic targets for the disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08778-0.

Upregulation of Phospholipase C Gene Expression Due to Norepinephrine-Induced Hypertrophic Response

The activation of phospholipase C (PLC) is thought to have a key role in the cardiomyocyte response to several different hypertrophic agents such as norepinephrine, angiotensin II and endothelin-1. PLC activity results in the generation of diacylglycerol and inositol trisphosphate, which are downstream signal transducers for the expression of fetal genes, increased protein synthesis, and subsequent cardiomyocyte growth. In this article, we describe the signal transduction elements that regulate PLC gene expression. The discussion is focused on the norepinephrine- α₁-adrenoceptor signaling pathway and downstream signaling processes that mediate an upregulation of PLC isozyme gene expression. Evidence is also indicated to demonstrate that PLC activities self-regulate the expression of PLC isozymes with the suggestion that PLC activities may be part of a coordinated signaling process for the perpetuation of cardiac hypertrophy. Accordingly, from the information provided, it is plausible that specific PLC isozymes could be targeted for the mitigation of cardiac hypertrophy.

Global profiling of protein lysine malonylation in mouse cardiac hypertrophy

Lysine malonylation, a novel identified protein posttranslational modification (PTM), is conservative and present in both eukaryotic and prokaryotic cells. Previous studies have reported that malonylation plays an important role in inflammation, angiogenesis, and diabetes. However, its potential role in cardiac remodeling remains unknown. Here, we observed a reduced lysine malonylation in hypertrophic mice hearts created by transverse aortic constriction (TAC) for 8 weeks. We also detected a decreased lysine malonylation in hypertrophic H9C2 cardiomyocytes induced by angiotensin II for 48 h. Using a proteomic method based on affinity purification and LC-MS/MS, we identified total 679 malonylated sites in 330 proteins in the hearts of sham mice and TAC mice. Bioinformatic analysis of the proteomic data revealed enrichment of malonylated proteins involved in cardiac structure and contraction, cGMP-PKG pathway, and metabolism. Specifically, we detected a decreased lysine malonylation in myocardial isocitrate dehydrogenase 2 (IDH2) by immunoprecipitation coupled with Western blotting both in vivo and in vitro. Together, our work suggests an important role and implication of protein lysine malonylation in cardiac hypertrophy, especially the IDH2. SIGNIFICANCE: Heart failure is the terminal stage of cardiac hypertrophy, which imposes an enormous clinical and economic burden worldwide. Despite our knowledge on the pathophysiology of the disease, current therapeutic approaches are still largely limited. Cardiac hypertrophy can be regulated at post-translational modifications (PTMs), and several PTMs have been reported in cardiac hypertrrophy and heart failure. In our study, we first reported a novel PTMs, lysine malonylation, in cardiac hypertophy. we found a reduced lysine malonylation in hypertrophic mice hearts in vivo and H9C2 cardiomyocytes after stimulating with angiotensinII for 48 h in vitro. Using affinity purification and LC-MS/MS, we identified 679 malonylated sites in 330 proteins in the hearts of sham and TAC mice. Compared to the sham group, 5 sites in 2 proteins were quantified as downregulated targets using a 2-fold threshold (downregulation <0.5-fold, P < 0.05). Functional analysis showed a significant enrichment in cardiac structure and contraction, cGMP-PKG pathway and metabolism. Notably, we identified a decreased Kmal level in isocitrate dehydrogenase 2 (IDH2), but the protein level of IDH2 has no changed in cardiac hypertrophy, These results highlight that lysine malonylation is associated with cardiac hypertrophy, and may be a new therapeutic target of the disease.

Role of Phospholipase C in Catecholamine-induced Increase in Myocardial Protein Synthesis

The activation of the α1-adrenoceptor-(α1-AR) by norepinephrine results in the G-protein (Gqα) mediated increase in the phosphoinositide-specific phospholipase C (PLC) activity. The byproducts of PLC hydrolytic activity, namely, 1,2-diacylglycerol and inositol-1,4,5-trisphosphate, are important downstream signal transducers for increased protein synthesis in the cardiomyocyte and the subsequent hypertrophic response. In this article, evidence is outlined to demonstrate the role of cardiomyocyte PLC isozymes in the catecholamine-induced increase in protein synthesis by using a blocker of α1-AR and an inhibitor of PLC. The discussion will be focused on the α1-AR-Gqα-PLC-mediated hypertrophic signaling pathway from the viewpoint that it may compliment the other β1-AR-Gs protein-adenylyl cyclase signal transduction mechanisms in the early stages of cardiac hypertrophy development, but may become more relevant at the late stage of cardiac hypertrophy. From the information provided here, it is suggested that some specific PLC isozymes may potentially serve as important targets for the attenuation of cardiac hypertrophy in the vulnerable patient population at-risk for heart failure.

Sbk2, a Newly Discovered Atrium-Enriched Regulator of Sarcomere Integrity

BACKGROUND

Heart development relies on tight spatiotemporal control of cardiac gene expression. Genes involved in this intricate process have been identified using animals and pluripotent stem cell-based models of cardio(myo)genesis. Recently, the repertoire of cardiomyocyte differentiation models has been expanded with iAM-1, a monoclonal line of conditionally immortalized neonatal rat atrial myocytes (NRAMs), which allows toggling between proliferative and differentiated (ie, excitable and contractile) phenotypes in a synchronized and homogenous manner.

METHODS

In this study, the unique properties of conditionally immortalized NRAMs (iAMs) were exploited to identify and characterize (lowly expressed) genes with an as-of-yet uncharacterized role in cardiomyocyte differentiation.

RESULTS

Transcriptome analysis of iAM-1 cells at different stages during one cycle of differentiation and subsequent dedifferentiation identified ≈13 000 transcripts, of which the dynamic changes in expression upon cardiomyogenic differentiation mostly opposed those during dedifferentiation. Among the genes whose expression increased during differentiation and decreased during dedifferentiation were many with known (lineage-specific) functions in cardiac muscle formation. Filtering for cardiac-enriched low-abundance transcripts, identified multiple genes with an uncharacterized role during cardio(myo)genesis including Sbk2 (SH3 domain binding kinase family member 2). Sbk2 encodes an evolutionarily conserved putative serine/threonine protein kinase, whose expression is strongly up- and downregulated during iAM-1 cell differentiation and dedifferentiation, respectively. In neonatal and adult rats, the protein is muscle-specific, highly atrium-enriched, and localized around the A-band of cardiac sarcomeres. Knockdown of Sbk2 expression caused loss of sarcomeric organization in NRAMs, iAMs and their human counterparts, consistent with a decrease in sarcomeric gene expression as evinced by transcriptome and proteome analyses. Interestingly, co-immunoprecipitation using Sbk2 as bait identified possible interaction partners with diverse cellular functions (translation, intracellular trafficking, cytoskeletal organization, chromatin modification, sarcomere formation).

CONCLUSIONS

iAM-1 cells are a relevant and suitable model to identify (lowly expressed) genes with a hitherto unidentified role in cardiomyocyte differentiation as exemplified by Sbk2: a regulator of atrial sarcomerogenesis.

Loss of talin in cardiac fibroblasts results in augmented ventricular cardiomyocyte hypertrophy in response to pressure overload

Pressure overload of the heart is characterized by concentric hypertrophy and interstitial fibrosis. Cardiac fibroblasts (CFs) in the ventricular wall become activated during injury and synthesize and compact the extracellular matrix, which causes interstitial fibrosis and stiffening of the ventricular heart walls. Talin1 (Tln1) and Talin2 (Tln2) are mechanosensitive proteins that participate in focal adhesion transmission of signals from the extracellular environment to the actin cytoskeleton of CFs. The aim of the present study was to determine whether the removal of Tln1 and Tln2 from CFs would reduce interstitial fibrosis and cardiac hypertrophy. Twelve-week-old male and female Tln2-null (Tln2-/-) and Tln2-null, CF-specific Tln1 knockout (Tln2-/-;Tln1CF-/-) mice were given angiotensin-II (ANG II) (1.5 mg/kg/day) or saline through osmotic pumps for 8 wk. Cardiomyocyte area and measures of heart thickness were increased in the male ANG II-infused Tln2-/-;Tln1CF-/- mice, whereas there was no increase in interstitial fibrosis. Systolic blood pressure was increased in the female Tln2-/-;Tln1CF-/- mice after ANG II infusion compared with the Tln2-/- mice. However, there was no increase in cardiac hypertrophy in the Tln2-/-;Tln1CF-/- mice, which was seen in the Tln2-/- mice. Collectively, these data indicate that in male mice, the absence of Tln1 and Tln2 in CFs leads to cardiomyocyte hypertrophy in response to ANG II, whereas it results in a hypertrophy-resistant phenotype in female mice. These findings have important implications for the role of mechanosensitive proteins in CFs and their impact on cardiomyocyte function in the pathogenesis of hypertension and cardiac hypertrophy.NEW & NOTEWORTHY The role of talins has been previously studied in cardiomyocytes; however, these mechanotransductive proteins that are members of the focal adhesion complex have not been examined in cardiac fibroblasts previously. We hypothesized that loss of talins in cardiac fibroblasts would reduce interstitial fibrosis in the heart with a pressure overload model. However, we found that although loss of talins did not alter fibrosis, it did result in cardiomyocyte and ventricular hypertrophy.

Lingguizhugan decoction dynamically regulates MAPKs and AKT signaling pathways to retrogress the pathological progression of cardiac hypertrophy to heart failure

BACKGROUND

Heart failure (HF) is a grave health concern, with high morbidity and mortality, calling for the urgent need for new and alternative pharmacotherapies. Lingguizhugan decoction (LD) is a classic Chinese formula clinically used to treat HF. However, the underlying mechanisms involved are not fully elucidated.

PURPOSE

Based on that, this study aims to investigate the effects and underlying mechanisms of LD on HF.

METHODS

After confirming the therapeutic benefits of LD in transverse aortic constriction (TAC)-induced HF mice, network pharmacology and transcriptomic analyzes were utilized to predict the potential molecular targets and pathways of LD treatment in failing hearts, which were evaluated at 3 and 9 w after TAC. UHPLC-QE-MS analysis was utilized to detect bioactive ingredients from LD and plasma of LD-treated rats.

RESULTS

Our results showed that LD markedly alleviated cardiac dysfunction via down-regulating CH-related genes and proteins expression in TAC mice. Significantly, cardiac hypertrophy signaling, including AKT and MAPKs signaling pathways, were identified, suggesting the pathways as likely regulatory targets for LD treatment. LD inhibited p38 and ERK phosphorylated expression levels, with the latter effect likely dependent on regulation of AMPK. Interestingly, LD exerted a dual modulatory role in the AKT-GSK3β/mTOR/P70S6K signaling pathway's regulation, which was characterized by stimulatory activity at 3 w and inhibitory effects at 9 w. Finally, 15 bioactive compounds detected from plasma were predicted as the potential regulators of the AKT-GSK3β/mTOR and MAPKs signaling pathways.

CONCLUSION

Our study shows LD's therapeutic efficacy in failing hearts, signifies LD as HF medication that acts dynamically by balancing AKT-GSK3β/mTOR/P70S6K and MAPKs pathways, and reveals possible bioactive compounds responsible for LD effects on HF.

O-Linked β-N-Acetylglucosamine Modification: Linking Hypertension and the Immune System

The O-linked β-N-acetylglucosamine modification (O-GlcNAcylation) of proteins dynamically regulates protein function, localization, stability, and interactions. This post-translational modification is intimately linked to cardiovascular disease, including hypertension. An increasing number of studies suggest that components of innate and adaptive immunity, active players in the pathophysiology of hypertension, are targets for O-GlcNAcylation. In this review, we highlight the potential roles of O-GlcNAcylation in the immune system and discuss how those immune targets of O-GlcNAcylation may contribute to arterial hypertension.

Friend or foe? Unraveling the complex roles of protein tyrosine phosphatases in cardiac disease and development

Regulation of protein tyrosine phosphorylation is critical for most, if not all, fundamental cellular processes. However, we still do not fully understand the complex and tissue-specific roles of protein tyrosine phosphatases in the normal heart or in cardiac pathology. This review compares and contrasts the various roles of protein tyrosine phosphatases known to date in the context of cardiac disease and development. In particular, it will be considered how specific protein tyrosine phosphatases control cardiac hypertrophy and cardiomyocyte contractility, how protein tyrosine phosphatases contribute to or ameliorate injury induced by ischaemia / reperfusion or hypoxia / reoxygenation, and how protein tyrosine phosphatases are involved in normal heart development and congenital heart disease. This review delves into the newest developments and current challenges in the field, and highlights knowledge gaps and emerging opportunities for future research.

Zerumbone prevents pressure overload-induced left ventricular systolic dysfunction by inhibiting cardiac hypertrophy and fibrosis

BACKGROUND

Cardiac hypertrophy and fibrosis are hallmarks of cardiac remodeling and are involved functionally in the development of heart failure (HF). However, it is unknown whether Zerumbone (Zer) prevents left ventricular (LV) systolic dysfunction by inhibiting cardiac hypertrophy and fibrosis.

PURPOSE

This study investigated the effect of Zer on cardiac hypertrophy and fibrosis in vitro and in vivo.

STUDY DESIGN/METHODS

In primary cultured cardiac cells from neonatal rats, the effect of Zer on phenylephrine (PE)-induced hypertrophic responses and transforming growth factor beta (TGF-β)-induced fibrotic responses was observed. To determine whether Zer prevents the development of pressure overload-induced HF in vivo, a transverse aortic constriction (TAC) mouse model was utilized. Cardiac function was evaluated by echocardiography. The changes of cardiomyocyte surface area were observed using immunofluorescence staining and histological analysis (HE and WGA staining). Collagen synthesis and fibrosis formation were measured by scintillation counter and picrosirius staining, respectively. The total mRNA levels of genes associated with hypertrophy (ANF and BNP) and fibrosis (Postn and α-SMA) were measured by qRT-PCR. The protein expressions (Akt and α-SMA) were assessed by western blotting.

RESULTS

Zer significantly suppressed PE-induced increase in cell size, mRNA levels of ANF and BNP, and Akt phosphorylation in cardiomyocytes. The TGF-β-induced increase in proline incorporation, mRNA levels of Postn and α-SMA, and protein expression of α-SMA were decreased by Zer in cultured cardiac fibroblasts. In the TAC male C57BL/6 mice, echocardiography results demonstrated that Zer improved cardiac function by increasing LV fractional shortening and reducing LV wall thickness compared with the vehicle group. ZER significantly reduced the level of phosphorylated Akt both in cultured cardiomyocytes treated with PE and in the hearts of TAC. Finally, Zer inhibited the pressure overload-induced cardiac hypertrophy and cardiac fibrosis.

CONCLUSION

Zer ameliorates pressure overload-induced LV dysfunction, at least in part by suppressing both cardiac hypertrophy and fibrosis.

The triumvirate of NF-κB, inflammation and cytokine storm in COVID-19

The coronavirus disease (COVID-19) has once again reminded us of the significance of host immune response and consequential havocs of the immune dysregulation. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) inflicts severe complications to the infected host, including cough, dyspnoea, fever, septic shock, acute respiratory distress syndrome (ARDs), and multiple organ failure. These manifestations are the consequence of the dysregulated immune system, which gives rise to excessive and unattended production of pro-inflammatory mediators. Elevated circulatory cytokine and chemokine levels are accompanied by spontaneous haemorrhage, thrombocytopenia and systemic inflammation, which are the cardinal features of life-threatening cytokine storm syndrome in advanced COVID-19 diseases. Coronavirus hijacked NF-kappa B (NF-κB) is responsible for upregulating the expressions of inflammatory cytokine, chemokine, alarmins and inducible enzymes, which paves the pathway for cytokine storm. Given the scenario, the systemic approach of simultaneous inhibition of NF-κB offers an attractive therapeutic intervention. Targeted therapies with proteasome inhibitor (VL-01, bortezomib, carfilzomib and ixazomib), bruton tyrosine kinase inhibitor (acalabrutinib), nucleotide analogue (remdesivir), TNF-α monoclonal antibodies (infliximab and adalimumab), N-acetylcysteine and corticosteroids (dexamethasone), focusing the NF-κB inhibition have demonstrated effectiveness in terms of the significant decrease in morbidity and mortality in severe COVID-19 patients. Hence, this review highlights the activation, signal transduction and cross-talk of NF-κB with regard to cytokine storm in COVID-19. Moreover, the development of therapeutic strategies based on NF-κB inhibition are also discussed herein.

Alpha Mangostin Derived from Garcinia magostana Linn Ameliorates Cardiomyocyte Hypertrophy and Fibroblast Phenotypes in Vitro

Cardiac hypertrophy and fibrosis are significant risk factors for chronic heart failure (HF). Since pharmacotherapy agents targeting these processes have not been established, we investigated the effect of alpha-magostin (α-man) on cardiomyocyte hypertrophy and fibrosis in vitro. Primary cultured cardiomyocytes and cardiac fibroblasts were prepared from neonatal rats. After α-man treatment, phenylephrine (PE) and transforming growth factor-beta (TGF-β) were added to the cardiomyocytes and cardiac fibroblasts to induce hypertrophic and fibrotic responses, respectively. Hypertrophic responses were assessed by measuring the cardiomyocyte surface area and hypertrophic gene expression levels. PE-induced phosphorylation of Akt, extracellular signal-regulated kinase (ERK)1/2, and p38 was examined by Western blotting. Fibrotic responses were assessed by measuring collagen synthesis, fibrotic gene expression levels, and myofibroblast differentiation. In addition, TGF-β-induced reactive oxygen species (ROS) production was investigated. In cultured cardiomyocytes, α-man significantly suppressed PE-induced increases in the cardiomyocyte surface area, and the mRNA levels (atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP)). Treatment with α-man significantly suppressed PE-induced Akt phosphorylation, but not ERK and p38 phosphorylation. In cultured cardiac fibroblasts, α-man significantly suppressed TGF-β-induced increases in L-proline incorporation, mRNA levels (POSTN and alpha-smooth muscle actin (α-SMA)), and myofibroblast differentiation. Additionally, it significantly inhibited TGF-β-induced reduced nicotinamide adenine dinucleotide phosphate oxidase4 (NOX4) expression and ROS production in cardiac fibroblasts. Treatment with α-man significantly ameliorates hypertrophy by inhibiting Akt phosphorylation in cardiomyocytes and fibrosis by inhibiting NOX4-generating ROS in fibroblasts. These findings suggest that α-man is a possible natural product for the prevention of cardiac hypertrophy and fibrosis.

Therapeutic potential and recent advances on targeting mitochondrial dynamics in cardiac hypertrophy: A concise review

Pathological cardiac hypertrophy begins as an adaptive response to increased workload; however, sustained hemodynamic stress will lead it to maladaptation and eventually cardiac failure. Mitochondria, being the powerhouse of the cells, can regulate cardiac hypertrophy in both adaptive and maladaptive phases; they are dynamic organelles that can adjust their number, size, and shape through a process called mitochondrial dynamics. Recently, several studies indicate that promoting mitochondrial fusion along with preventing mitochondrial fission could improve cardiac function during cardiac hypertrophy and avert its progression toward heart failure. However, some studies also indicate that either hyperfusion or hypo-fission could induce apoptosis and cardiac dysfunction. In this review, we summarize the recent knowledge regarding the effects of mitochondrial dynamics on the development and progression of cardiac hypertrophy with particular emphasis on the regulatory role of mitochondrial dynamics proteins through the genetic, epigenetic, and post-translational mechanisms, followed by discussing the novel therapeutic strategies targeting mitochondrial dynamic pathways.

Post-translational Acetylation Control of Cardiac Energy Metabolism

Perturbations in myocardial energy substrate metabolism are key contributors to the pathogenesis of heart diseases. However, the underlying causes of these metabolic alterations remain poorly understood. Recently, post-translational acetylation-mediated modification of metabolic enzymes has emerged as one of the important regulatory mechanisms for these metabolic changes. Nevertheless, despite the growing reports of a large number of acetylated cardiac mitochondrial proteins involved in energy metabolism, the functional consequences of these acetylation changes and how they correlate to metabolic alterations and myocardial dysfunction are not clearly defined. This review summarizes the evidence for a role of cardiac mitochondrial protein acetylation in altering the function of major metabolic enzymes and myocardial energy metabolism in various cardiovascular disease conditions.

SUMOylation as a Therapeutic Target for Myocardial Infarction

Myocardial infarction is a prevalent and life-threatening cardiovascular disease. The main goal of existing interventional therapies is to restore coronary reperfusion while few are designed to ameliorate the pathology of heart diseases via targeting the post-translational modifications of those critical proteins. Small ubiquitin-like modifier (SUMO) proteins are recently discovered to form a new type of protein post-translational modifications (PTM), known as SUMOylation. SUMOylation and deSUMOylation are dynamically balanced in the maintenance of various biological processes including cell division, DNA repair, epigenetic transcriptional regulation, and cellular metabolism. Importantly, SUMOylation plays a critical role in the regulation of cardiac functions and the pathology of cardiovascular diseases, especially in heart failure and myocardial infarction. This review summarizes the current understanding on the effects of SUMOylation and SUMOylated proteins in the pathophysiology of myocardial infarction and identifies the potential treatments against myocardial injury via targeting SUMO. Ultimately, this review recommends SUMOylation as a key therapeutic target for treating cardiovascular diseases.

Detection of single peptide with only one amino acid modification via electronic fingerprinting using reengineered durable channel of Phi29 DNA packaging motor

Protein post-translational modification (PTM) is crucial to modulate protein interactions and activity in various biological processes. Emerging evidence has revealed PTM patterns participate in the pathology onset and progression of various diseases. Current PTM identification relies mainly on mass spectrometry-based approaches that limit the assessment to the entire protein population in question. Here we report a label-free method for the detection of the single peptide with only one amino acid modification via electronic fingerprinting using reengineered durable channel of phi29 DNA packaging motor, which bears the deletion of 25-amino acids (AA) at the C-terminus or 17-AA at the internal loop of the channel. The mutant channels were used to detect propionylation modification via single-molecule fingerprinting in either the traditional patch-clamp or the portable MinION™ platform of Oxford Nanopore Technologies. Up to 2000 channels are available in the MinION™ Flow Cells. The current signatures and dwell time of individual channels were identified. Peptides with only one propionylation were differentiated. Excitingly, identification of single or multiple modifications on the MinION™ system was achieved. The successful application of PTM differentiation on the MinION™ system represents a significant advance towards developing a label-free and high-throughput detection platform utilizing nanopores for clinical diagnosis based on PTM.

PEX5 prevents cardiomyocyte hypertrophy via suppressing the redox-sensitive signaling pathways MAPKs and STAT3

Peroxisomal biogenesis factor 5 (PEX5) is a member of peroxisome biogenesis protein family which serves as a shuttle receptor for the import of peroxisome matrix protein. The function of PEX5 on cardiomyocyte hypertrophy remained to be elucidated. Our study demonstrated that the protein expression level of PEX5 was declined in primary neonatal rat cardiomyocytes treated with phenylephrine (PE) and hearts from cardiac hypertrophic rats induced by abdominal aortic constriction (AAC). Overexpression of PEX5 alleviated cardiomyocyte hypertrophy induced by PE, while silencing of PEX5 exacerbated cardiomyocyte hypertrophy. PEX5 improved redox imbalance by decreasing cellular reactive oxygen species level and preserving peroxisomal catalase. Moreover, PEX5 knockdown aggravated PE-induced activation of redox-sensitive signaling pathways, including mitogen-activated protein kinase (MAPK) pathway and signal transducer and activator of transcription 3 (STAT3); whereas PEX5 overexpression suppressed activation of MAPK and STAT3. But PEX5 did not affect PE-induced phosphorylation of mammalian target of rapamycin (mTOR). In conclusion, the present study suggests that PEX5 protects cardiomyocyte against hypertrophy via regulating redox homeostasis and inhibiting redox-sensitive signaling pathways MAPK and STAT3.

Heritability and Pedigree Analyses of Hypertrophic Cardiomyopathy in Rhesus Macaques (Macaca Mulatta)

In a colony of rhesus macaques at California National Primate Research Center (CNPRC), naturally occurring hypertrophic cardiomyopathy (HCM) classified by left ventricular hypertrophy without obvious underlying diseases has been identified during necropsy over the last two decades. A preliminary pedigree analysis suggested a strong genetic predisposition of this disease with a founder effect. However, the mode of inheritance was undetermined due to insufficient pedigree data. Since 2015, antemortem examination using echocardiographic examination as well as other cardiovascular analyses have been performed on large numbers of rhesus macaques at the colony. Based on antemortem examination, HCM was diagnosed in additional 65 rhesus macaques. Using HCM cases diagnosed based on antemortem and postmortem examinations, the heritability (h²) was estimated to determine the degree of genetic and environmental contributions to the development of HCM in rhesus macaques at the CNPRC. The calculated mean and median heritability (h²) of HCM in this colony of rhesus macaques were 0.5 and 0.51 (95% confidence interval; 0.14-0.82), respectively. This suggests genetics influence development of HCM in the colony of rhesus macaques. However, post-translational modifications and environmental factors are also likely to contribute the variability of phenotypic expression. Based on the pedigree analysis, an autosomal recessive trait was suspected, but an autosomal dominant mode of inheritance with incomplete penetrance was also possible. Further investigation with more data from siblings, offspring, and parents of HCM-affected rhesus macaques are warranted. Importantly, the findings of the present study support conducting genetic investigations such as whole genome sequencing to identify the causative variants of inherited HCM in rhesus macaques.

Dual-specificity Phosphatase 9 protects against Cardiac Hypertrophy by targeting ASK1

The functions of dual-specificity phosphatase 9 (DUSP9) in hepatic steatosis and metabolic disturbance during nonalcoholic fatty liver disease were discussed in our prior study. However, its roles in the pathophysiology of pressure overload-induced cardiac hypertrophy remain to be illustrated. This study attempted to uncover the potential contributions and underpinning mechanisms of DUSP9 in cardiac hypertrophy. Utilizing the gain-and-loss-of-functional approaches of DUSP9 the cardiac phenotypes arising from the pathological, echocardiographic, and molecular analysis were quantified. The results showed increased levels of DUSP9 in hypertrophic mice heart and angiotensin II treated cardiomyocytes. In accordance with the results of cellular hypertrophy in response to angiotensin II, cardiac hypertrophy exaggeration, fibrosis, and malfunction triggered by pressure overload was evident in the case of cardiac-specific conditional knockout of DUSP9. In contrast, transgenic mice hearts with DUSP9 overexpression portrayed restoration of the hypertrophic phenotypes. Further explorations of molecular mechanisms indicated the direct interaction of DUSP9 with ASK1, which further repressed p38 and JNK signaling pathways. Moreover, blocking ASK1 with ASK1-specific inhibitor compensated the pro-hypertrophic effects induced by DUSP9 deficiency in cardiomyocytes. The main findings of this study suggest the potential of DUSP9 in alleviating cardiac hypertrophy at least partially by repressing ASK1, thereby looks promising as a prospective target against cardiac hypertrophy.

The poly(ADP-ribosyl)ation of BRD4 mediated by PARP1 promoted pathological cardiac hypertrophy

The bromodomain and extraterminal (BET) family member BRD4 is pivotal in the pathogenesis of cardiac hypertrophy. BRD4 induces hypertrophic gene expression by binding to the acetylated chromatin, facilitating the phosphorylation of RNA polymerases II (Pol II) and leading to transcription elongation. The present study identified a novel post-translational modification of BRD4: poly(ADP-ribosyl)ation (PARylation), that was mediated by poly(ADP-ribose)polymerase-1 (PARP1) in cardiac hypertrophy. BRD4 silencing or BET inhibitors JQ1 and MS417 prevented cardiac hypertrophic responses induced by isoproterenol (ISO), whereas overexpression of BRD4 promoted cardiac hypertrophy, confirming the critical role of BRD4 in pathological cardiac hypertrophy. PARP1 was activated in ISO-induced cardiac hypertrophy and facilitated the development of cardiac hypertrophy. BRD4 was involved in the prohypertrophic effect of PARP1, as implied by the observations that BRD4 inhibition or silencing reversed PARP1-induced hypertrophic responses, and that BRD4 overexpression suppressed the anti-hypertrophic effect of PARP1 inhibitors. Interactions of BRD4 and PARP1 were observed by co-immunoprecipitation and immunofluorescence. PARylation of BRD4 induced by PARP1 was investigated by PARylation assays. In response to hypertrophic stimuli like ISO, PARylation level of BRD4 was elevated, along with enhanced interactions between BRD4 and PARP1. By investigating the PARylation of truncation mutants of BRD4, the C-terminal domain (CTD) was identified as the PARylation modification sites of BRD4. PARylation of BRD4 facilitated its binding to the transcription start sites (TSS) of hypertrophic genes, resulting in enhanced phosphorylation of RNA Pol II and transcription activation of hypertrophic genes. The present findings suggest that strategies targeting inhibition of PARP1-BRD4 might have therapeutic potential for pathological cardiac hypertrophy.

Comprehensive bioinformatics analysis reveals kinase activity profiling associated with heart failure

Heart failure is a complex clinical syndrome originating from cardiac injury, which leads to considerable morbidity and mortality. Among the dynamic molecular adaptations occurring in heart failure development, aggravation of the disease is often attributed to global or local abnormality of the kinase. Therefore, the overall monitoring of kinase activity is indispensable. In this study, a bioinformatics analysis method was developed to conduct deep mining of transcriptome and phosphoproteome in failing heart tissue. A total of 982 differentially expressed genes and 9781 phosphorylation sites on 3252 proteins were identified. Via upstream regulator relations and kinase-substrate relations, a dendrogram of kinases can be constructed to monitor its abnormality. The results show that, on the dendrogram, the distribution of kinases demonstrated complex kinase activity changes and certain rules that occur during heart failure. Finally, we also identified the hub kinases in heart failure and verified the expression of these kinases by reverse-transcription polymerase chain reaction and Western blot analysis. In conclusion, for the first time, we have systematically analyzed the differences in kinases during heart failure and provided an unprecedented breadth of multi-omics data. These results can bring about a sufficient data foundation and novel research perspectives.

Heart failure-emerging roles for the mitochondrial pyruvate carrier

The mitochondrial pyruvate carrier (MPC) is the entry point for the glycolytic end-product pyruvate to the mitochondria. MPC activity, which is controlled by its abundance and post-translational regulation, determines whether pyruvate is oxidised in the mitochondria or metabolised in the cytosol. MPC serves as a crucial metabolic branch point that determines the fate of pyruvate in the cell, enabling metabolic adaptations during health, such as exercise, or as a result of disease. Decreased MPC expression in several cancers limits the mitochondrial oxidation of pyruvate and contributes to lactate accumulation in the cytosol, highlighting its role as a contributing, causal mediator of the Warburg effect. Pyruvate is handled similarly in the failing heart where a large proportion of it is reduced to lactate in the cytosol instead of being fully oxidised in the mitochondria. Several recent studies have found that the MPC abundance was also reduced in failing human and mouse hearts that were characterised by maladaptive hypertrophic growth, emulating the anabolic scenario observed in some cancer cells. In this review we discuss the evidence implicating the MPC as an important, perhaps causal, mediator of heart failure progression.

Inhibition of SENP2-mediated Akt deSUMOylation promotes cardiac regeneration via activating Akt pathway

Post-translational modification (PTM) by small ubiquitin-like modifier (SUMO) is a key regulator of cell proliferation and can be readily reversed by a family of SUMO-specific proteases (SENPs), making SUMOylation an ideal regulatory mechanism for developing novel therapeutic strategies for promoting a cardiac regenerative response. However, the role of SUMOylation in cardiac regeneration remains unknown. In the present study, we assessed whether targeting protein kinase B (Akt) SUMOylation can promote cardiac regeneration. Quantitative PCR and Western blotting results showed that small ubiquitin-like modifier-specific protease 2 (SENP2) is up-regulated during postnatal heart development. SENP2 deficiency promoted P7 and adult cardiomyocyte (CM) dedifferentiation and proliferation both in vitro and in vivo. Mice with SENP2 deficiency exhibited improved cardiac function after MI due to CM proliferation and angiogenesis. Mechanistically, the loss of SENP2 up-regulated Akt SUMOylation levels and increased Akt kinase activity, leading to a decrease in GSK3β levels and subsequently promoting CM proliferation and angiogenesis. In summary, inhibition of SENP2-mediated Akt deSUMOylation promotes CM differentiation and proliferation by activating the Akt pathway. Our results provide new insights into the role of SUMOylation in cardiac regeneration.

High glucose induces Drp1-mediated mitochondrial fission via the Orai1 calcium channel to participate in diabetic cardiomyocyte hypertrophy

Mitochondrial dysfunction and impaired Ca2+ handling are involved in the development of diabetic cardiomyopathy (DCM). Dynamic relative protein 1 (Drp1) regulates mitochondrial fission by changing its level of phosphorylation, and the Orai1 (Ca2+ release-activated calcium channel protein 1) calcium channel is important for the increase in Ca2+ entry into cardiomyocytes. We aimed to explore the mechanism of Drp1 and Orai1 in cardiomyocyte hypertrophy caused by high glucose (HG). We found that Zucker diabetic fat rats induced by administration of a high-fat diet develop cardiac hypertrophy and impaired cardiac function, accompanied by the activation of mitochondrial dynamics and calcium handling pathway-related proteins. Moreover, HG induces cardiomyocyte hypertrophy, accompanied by abnormal mitochondrial morphology and function, and increased Orai1-mediated Ca2+ influx. Mechanistically, the Drp1 inhibitor mitochondrial division inhibitor 1 (Mdivi-1) prevents cardiomyocyte hypertrophy induced by HG by reducing phosphorylation of Drp1 at serine 616 (S616) and increasing phosphorylation at S637. Inhibition of Orai1 with single guide RNA (sgOrai1) or an inhibitor (BTP2) not only suppressed Drp1 activity and calmodulin-binding catalytic subunit A (CnA) and phosphorylated-extracellular signal-regulated kinase (p-ERK1/2) expression but also alleviated mitochondrial dysfunction and cardiomyocyte hypertrophy caused by HG. In addition, the CnA inhibitor cyclosporin A and p-ERK1/2 inhibitor U0126 improved HG-induced cardiomyocyte hypertrophy by promoting and inhibiting phosphorylation of Drp1 at S637 and S616, respectively. In summary, we identified Drp1 as a downstream target of Orai1-mediated Ca2+ entry, via activation by p-ERK1/2-mediated phosphorylation at S616 or CnA-mediated dephosphorylation at S637 in DCM. Thus, the Orai1-Drp1 axis is a novel target for treating DCM.

Potential regulatory role of epigenetic RNA methylation in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide, especially in developing countries. To date, several approaches have been proposed for the prevention and treatment of CVDs. However, the increased risk of developing cardiovascular events that result in hospitalization has become a growing public health concern. The pathogenesis of CVDs has been analyzed from various perspectives. Recent data suggest that regulatory RNAs play a multidimensional role in the development of CVDs. Studies have identified several mRNA modifications that have contributed to the functional characterization of various cardiac diseases. RNA methylation, such as N6-methyladenosine, N1-methyladenosine, 5-methylcytosine, N7-methylguanosine, N4-acetylcytidine, and 2'-O-methylation are novel epigenetic modifications that affect the regulation of cell growth, immunity, DNA damage, calcium signaling, apoptosis, and aging in cardiomyocytes. In this review, we summarize the role of RNA methylation in the pathophysiology of CVDs and the potential of using epigenetics to treat such disorders.

Emerging roles of protein O-GlcNAcylation in cardiovascular diseases: Insights and novel therapeutic targets

Cardiovascular diseases (CVDs) are the leading cause of death globally. While the major focus of pharmacological and non-pharmacological interventions has been on targeting disease pathophysiology and limiting predisposing factors, our understanding of the cellular and molecular mechanisms underlying the pathogenesis of CVDs remains incomplete. One mechanism that has recently emerged is protein O-GlcNAcylation. This is a dynamic, site-specific reversible post-translational modification of serine and threonine residues on target proteins and is controlled by two enzymes: O-linked β-N-acetylglucosamine transferase (OGT) and O-linked β-N-acetylglucosaminidase (OGA). Protein O-GlcNAcylation alters the cellular functions of these target proteins which play vital roles in pathways that modulate vascular homeostasis and cardiac function. Through this review, we aim to give insights on the role of protein O-GlcNAcylation in cardiovascular diseases and identify potential therapeutic targets in this pathway for development of more effective medicines to improve patient outcomes.

Sirt6 Deacetylase: A Potential Key Regulator in the Prevention of Obesity, Diabetes and Neurodegenerative Disease

Sirtuins, NAD + dependent proteins belonging to class III histone deacetylases, are involved in regulating numerous cellular processes including cellular stress, insulin resistance, inflammation, mitochondrial biogenesis, chromatin silencing, cell cycle regulation, transcription, and apoptosis. Of the seven mammalian sirtuins present in humans, Sirt6 is an essential nuclear sirtuin. Until recently, Sirt6 was thought to regulate chromatin silencing, but new research indicates its role in aging, diabetes, cardiovascular disease, lipid metabolism, neurodegenerative diseases, and cancer. Various murine models demonstrate that Sirt6 activation is beneficial in alleviating many disease conditions and increasing lifespan, showing that Sirt6 is a critical therapeutic target in the treatment of various disease conditions in humans. Sirt6 also regulates the pathogenesis of multiple diseases by acting on histone proteins and non-histone proteins. Endogenous and non-endogenous modulators regulate both activation and inhibition of Sirt6. Few Sirt6 specific non-endogenous modulators have been identified. Hence the identification of Sirt6 specific modulators may have potential therapeutic roles in the diseases described above. In this review, we describe the development of Sirt6, the role it plays in the human condition, the functional role and therapeutic importance in disease processes, and specific modulators and molecular mechanism of Sirt6 in the regulation of metabolic homeostasis, cardiovascular disease, aging, and neurodegenerative disease.

The challenge of detecting modifications on proteins

Post-translational modifications (PTMs) are integral to the regulation of protein function, characterising their role in this process is vital to understanding how cells work in both healthy and diseased states. Mass spectrometry (MS) facilitates the mass determination and sequencing of peptides, and thereby also the detection of site-specific PTMs. However, numerous challenges in this field continue to persist. The diverse chemical properties, low abundance, labile nature and instability of many PTMs, in combination with the more practical issues of compatibility with MS and bioinformatics challenges, contribute to the arduous nature of their analysis. In this review, we present an overview of the established MS-based approaches for analysing PTMs and the common complications associated with their investigation, including examples of specific challenges focusing on phosphorylation, lysine acetylation and redox modifications.

SENP3 regulates high glucose-induced endothelial dysfunction via ROS dependent signaling

BACKGROUND

The current study aimed to explore the role of SENP3 in endothelial cell dysfunction in a high-glucose setting.

METHODS

The gene and protein expressions of SENP3 in high-glucose cultured HAECs were examined using quantitative PCR and western blotting. The effects of SENP3 on HAEC viability, apoptosis, migration, and endothelial-monocyte adhesion were evaluated in vitro by knockdown. Moreover, a mouse streptozotocin-induced type I diabetes model was established for SENP3 expression assessment. In addition, the effects of SENP3 on ROS-related signaling pathways were investigated in high-glucose cultured HAECs.

RESULTS

Significantly increased levels of SENP3 mRNA and protein were found in high-glucose cultured HAECs in a time-dependent manner. SENP3 knockdown reversed high glucose-induced HAEC viability, apoptosis, and migration reduction. SENP3 knockdown attenuated the high glucose-induced intercellular adhesion of THP-1 monocytic cells and HAECs via downregulation of ICAM-1 and VCAM-1 expression. Increased levels of SENP3, ICAM-1, and VCAM-1 expression were observed in the aorta tissue of mice with type I diabetes. Downregulation of SENP3 expression was observed in HAECs cultured with high glucose levels using the free radical scavenger N-acetyl-L-cysteine or NOX4 siRNA.

CONCLUSIONS

SENP3 was involved in high glucose-induced endothelial dysfunction, and ROS-dependent signaling served as the mechanism.

A systematic review of post-translational modifications in the mitochondrial permeability transition pore complex associated with cardiac diseases

The mitochondrial permeability transition pore (mPTP) opening is involved in the pathophysiology of multiple cardiac diseases, such as ischemia/reperfusion injury and heart failure. A growing number of evidence provided by proteomic screening techniques has demonstrated the role of post-translational modifications (PTMs) in several key components of the pore in response to changes in the extra/intracellular environment and bioenergetic demand. This could lead to a fine, complex regulatory mechanism that, under pathological conditions, can shift the state of mitochondrial functions and, thus, the cell's fate. Understanding the complex relationship between these PTMs is still under investigation and can provide new, promising therapeutic targets and treatment approaches. This review, using a systematic review of the literature, presents the current knowledge on PTMs of the mPTP and their role in health and cardiac disease.

Drug Development and the Use of Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Disease Modeling and Drug Toxicity Screening

: Over the years, numerous groups have employed human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) as a superb human-compatible model for investigating the function and dysfunction of cardiomyocytes, drug screening and toxicity, disease modeling and for the development of novel drugs for heart diseases. In this review, we discuss the broad use of iPSC-CMs for drug development and disease modeling, in two related themes. In the first theme-drug development, adverse drug reactions, mechanisms of cardiotoxicity and the need for efficient drug screening protocols-we discuss the critical need to screen old and new drugs, the process of drug development, marketing and Adverse Drug reactions (ADRs), drug-induced cardiotoxicity, safety screening during drug development, drug development and patient-specific effect and different mechanisms of ADRs. In the second theme-using iPSC-CMs for disease modeling and developing novel drugs for heart diseases-we discuss the rationale for using iPSC-CMs and modeling acquired and inherited heart diseases with iPSC-CMs.

Glutaredoxin-2 and Sirtuin-3 deficiencies impair cardiac mitochondrial energetics but their effects are not additive

Altered redox biology and oxidative stress have been implicated in the progression of heart failure. Glutaredoxin-2 (GRX2) is a glutathione-dependent oxidoreductase and catalyzes the reversible deglutathionylation of mitochondrial proteins. Sirtuin-3 (SIRT3) is a class III histone deacetylase and regulates lysine acetylation in mitochondria. Both GRX2 and SIRT3 are considered as key in the protection against oxidative damage in the myocardium. Knockout of either contributes to adverse heart pathologies including hypertrophy, hypertension, and cardiac dysfunction. Here, we created and characterized a GRX2 and SIRT3 double-knockout mouse model, hypothesizing that their deletions would have an additive effect on oxidative stress, and exacerbate mitochondrial function and myocardial structural remodeling. Wildtype, single-gene knockout (Sirt3^-/-, Grx2^-/-), and double-knockout mice (Grx2^-/-/Sirt3^-/-) were compared in heart weight, histology, mitochondrial respiration and H₂O₂ production. Overall, the hearts from Grx2^-/-/Sirt3^-/- mice displayed increased fibrosis and hypertrophy versus wildtype. In the Grx2^-/- and the Sirt3^-/- we observed changes in mitochondrial oxidative capacity, however this was associated with elevated H₂O₂ emission only in the Sirt3^-/-. Similar changes were observed but not worsened in hearts from Grx2^-/-/Sirt3^-/- mice, suggesting that these changes were not additive. In human myocardium, using genetic and histopathological data from the human Genotype-Tissue Expression consortium, we confirmed that SIRT3 expression correlates inversely with heart pathology. Altogether, GRX2 and SIRT3 are important in the control of cardiac mitochondrial redox and oxidative processes, but their combined absence does not exacerbate effects, consistent with the overall conclusion that they function together in the complex redox and antioxidant systems in the heart.

Myotubularin-related protein 14 suppresses cardiac hypertrophy by inhibiting Akt

Cardiac hypertrophy (CH) is an independent risk factor for many cardiovascular diseases, and is one of the primary causes of morbidity and mortality in elderly people. Pathological CH involves excessive protein synthesis, increased cardiomyocyte size, and ultimately the development of heart failure. Myotubularin-related protein 14 (MTMR14) is a member of the myotubularin (MTM)-related protein family, which is involved in apoptosis, aging, inflammation, and autophagy. However, its exact function in CH is still unclear. Herein, we investigated the roles of MTMR14 in CH. We show that MTMR14 expression was increased in hypertrophic mouse hearts. Mice deficient in heart MTMR14 exhibited an aggravated aortic-banding (AB)-induced CH phenotype. In contrast, MTMR14 overexpression prevented pressure overload-induced hypertrophy. At the molecular level, prevention of CH in the absence of MTMR14 involved elevations in Akt pathway components, which are key elements that regulate apoptosis and cell proliferation. These results demonstrate that MTMR14 is a new molecular target for the treatment of CH.