G Protein-Coupled Estrogen Receptor 1 Inhibits Angiotensin II-Induced Cardiomyocyte Hypertrophy via the Regulation of PI3K-Akt-mTOR Signalling and Autophagy

Sex-related differences in hypertrophy response and cardiac expression of G protein-coupled estrogen receptor in rats with pressure overload

There is increasing evidence that gender impacts the onset and progression of cardiovascular pathology. However, it is vastly unclear how this variable determines the ultimate outcomes, particularly in the setting of pressure overload-induced left ventricular hypertrophy (LVH). This study was carried out to fill this gap, at least in part, by assessing myocardial expression of G protein-coupled estrogen receptor (GPER) in female and male rats afflicted with LVH. Both female and male rats underwent abdominal aorta banding to induce LVH or were kept intact as control groups. At the end of the experiment, carotid artery catheterization was performed to measure systolic (SBP) and diastolic (DBP) blood pressure. Fibrosis and cardiomyocyte cross-sectional area were assessed by conventional histological analyses. Protein and mRNA expression were evaluated by Western blot/immunofluorescence staining and real-time RT-PCR technique, respectively. In LVH groups, male rats exhibited higher SBP and DBP, heart weight to body weight ratio, and fibrosis compared with female rats. However, both sexes showed a similar increase in cardiomyocyte size after LVH induction. In female, but not in male rats, LVH instigated the GPER mRNA and protein expression in the heart. These results, confirm a significant interaction between gender and myocardial remodeling in terms of GPER expression. Thus, it can be argued that sex differences in the cardiac GPER expression may be responsible for sex differences in the pressure overload-induced LVH. In other words, the female heart seems to unleash stronger protection against pressure overload than that of males in light of a higher GPER expression.

S100A9 as a Key Myocardial Injury Factor Interacting with ATP5 Exacerbates Mitochondrial Dysfunction and Oxidative Stress in Sepsis-Induced Cardiomyopathy

Purpose

Sepsis-induced cardiomyopathy (SICM) is a prevalent cardiac dysfunction caused by sepsis. Mitochondrial dysfunction is a crucial pathogenic factor associated with adverse cardiovascular adverse events; however, research on SICM remains insufficient.

Methods

To investigate the factors contributing to the pathological progression of SICM, we performed a comprehensive analysis of transcriptomic data from the GEO database using bioinformatics and machine learning techniques. CRISPR-Cas9 S100A9 knockout mice and primary cardiomyocytes were exposed to lipopolysaccharide to simulate SICM. Transcriptome analysis and mass spectrometry of primary cardiomyocytes were used to determine the potential pathogenic mechanisms of S100A9. The mitochondrial ultrastructure and mitochondrial membrane potential (MMP) were detected using transmission electron microscopy and flow cytometry, respectively. Pink1/Parkin and Drp1 proteins were detected using Western blotting to evaluate mitochondrial autophagy and division. The mtDNA and mRNA levels of mitochondrial transcription factors and synthases were evaluated using real-time polymerase chain reaction.

Results

Bioinformatics analysis identified 12 common differentially expressed genes, including SERPINA3N, LCN2, MS4A6D, LRG1, OSMR, SOCS3, FCGR2b, S100A9, S100A8, CASP4, ABCA8A, and NFKBIZ. Significant S100A9 upregulation was closely associated with myocardial injury exacerbation and cardiac function deterioration. GSEA revealed that myocardial contractile function, oxidative stress, and mitochondrial function were significantly affected by S100A9. Knocking out S100A9 alleviates the inflammatory response and mitochondrial dysfunction. The interaction of S100A9 with ATP5 enhanced mitochondrial division and autophagy, inhibited MMP and ATP synthesis, and induced oxidative stress, which are related to the Nlrp3-Nfkb-Caspase1 and Drp1-Pink1-Parkin signaling pathways. The expression of mitochondrial transcription factors (TFAM and TFBM) and ATP synthetases (ATP6 and ATP8, as well as COX1, COX2, and COX3) was further suppressed by S100A9 in SICM. Targeted S100A9 inhibition by paquinimod partially reversed myocardial mitochondrial dysfunction and oxidative stress.

Conclusion

The interaction of S100A9 with ATP5 exacerbates myocardial damage in sepsis by inducing mitochondrial dysfunction and oxidative stress.

Advances in Research on the Effectiveness and Mechanism of Active Ingredients from Traditional Chinese Medicine in Regulating Hepatic Stellate Cells Autophagy Against Hepatic Fibrosis

Hepatic fibrosis (HF) is a pathological process of structural and functional impairment of the liver and is a key component in the progression of chronic liver disease. There are no specific anti-hepatic fibrosis (anti-HF) drugs, and HF can only be improved or prevented by alleviating the cause. Autophagy of hepatic stellate cells (HSCs) is closely related to the development of HF. In recent years, traditional Chinese medicine (TCM) has achieved good therapeutic effects in the prevention and treatment of HF. Several active ingredients from TCM (AITCM) can regulate autophagy in HSCs to exert anti-HF effects through different pathways, but relevant reviews are lacking. This paper reviewed the research progress of AITCM regulating HSCs autophagy against HF, and also discussed the relationship between HSCs autophagy and HF, pointing out the problems and limitations of the current study, in order to provide references for the development of anti-HF drugs targeting HSCs autophagy in TCM. By reviewing the literature in PubMed, Web of Science, Embase, CNKI and other databases, we found that the relationship between autophagy of HSCs and HF is currently controversial. HSCs autophagy may promote HF by consuming lipid droplets (LDs) to provide energy for their activation. However, in contrast, inducing autophagy in HSCs can exert the anti-HF effect by stimulating their apoptosis or senescence, reducing type I collagen accumulation, inhibiting the extracellular vesicles release, degrading pro-fibrotic factors and other mechanisms. Some AITCM inhibit HSCs autophagy to resist HF, with the most promising direction being to target LDs. While, others induce HSCs autophagy to resist HF, with the most promising direction being to target HSCs apoptosis. Future research needs to focus on cell targeting research, autophagy targeting research and in vivo verification research, and to explore the reasons for the contradictory effects of HSCs autophagy on HF.

Diosmetin as a promising natural therapeutic agent: In vivo, in vitro mechanisms, and clinical studies

Diosmetin, a natural occurring flavonoid, is primarily found in citrus fruits, beans, and other plants. Diosmetin demonstrates a variety of pharmacological activities, including anticancer, antioxidant, anti-inflammatory, antibacterial, metabolic regulation, cardiovascular function improvement, estrogenic effects, and others. The process of literature search was done using PubMed, Web of Science and ClinicalTrials databases with search terms containing Diosmetin, content, anticancer, anti-inflammatory, antioxidant, pharmacological activity, pharmacokinetics, in vivo, and in vitro. The aim of this review is to summarize the in vivo, in vitro and clinical studies of Diosmetin over the last decade, focusing on studies related to its anticancer, anti-inflammatory, and antioxidant activities. It is found that DIO has significant therapeutic effects on skin and cardiovascular system diseases, and its research in pharmacokinetics and toxicology is summarized. It provides the latest information for researchers and points out the limitations of current research and areas that should be strengthened in future research, so as to facilitate the relevant scientific research and clinical application of DIO.

Spatial omics reveals molecular changes in focal cortical dysplasia type II

Focal cortical dysplasia (FCD) represents a group of diverse localized cortical lesions that are highly epileptogenic and occur due to abnormal brain development caused by genetic mutations, involving the mammalian target of rapamycin (mTOR). These somatic mutations lead to mosaicism in the affected brain, posing challenges to unravel the direct and indirect functional consequences of these mutations. To comprehensively characterize the impact of mTOR mutations on the brain, we employed here a multimodal approach in a preclinical mouse model of FCD type II (Rheb), focusing on spatial omics techniques to define the proteomic and lipidomic changes. Mass Spectrometry Imaging (MSI) combined with fluorescence imaging and label free proteomics, revealed insight into the brain's lipidome and proteome within the FCD type II affected region in the mouse model. MSI visualized disrupted neuronal migration and differential lipid distribution including a reduction in sulfatides in the FCD type II-affected region, which play a role in brain myelination. MSI-guided laser capture microdissection (LMD) was conducted on FCD type II and control regions, followed by label free proteomics, revealing changes in myelination pathways by oligodendrocytes. Surgical resections of FCD type IIb and postmortem human cortex were analyzed by bulk transcriptomics to unravel the interplay between genetic mutations and molecular changes in FCD type II. Our comparative analysis of protein pathways and enriched Gene Ontology pathways related to myelination in the FCD type II-affected mouse model and human FCD type IIb transcriptomics highlights the animal model's translational value. This dual approach, including mouse model proteomics and human transcriptomics strengthens our understanding of the functional consequences arising from somatic mutations in FCD type II, as well as the identification of pathways that may be used as therapeutic strategies in the future.

S100A9 exacerbates sepsis-induced acute lung injury via the IL17-NFκB-caspase-3 signaling pathway

BACKGROUND

Sepsis-induced acute lung injury (ALI) is associated with considerable morbidity and mortality in critically ill patients. S100A9, a key endothelial injury factor, is markedly upregulated in sepsis-induced ALI; however, its specific mechanism of action has not been fully elucidated.

METHODS

The Gene Expression Omnibus database transcriptome data for sepsis-induced ALI were used to screen for key differentially expressed genes (DEGs). Using bioinformatics analysis methods such as Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction network analyses, the pathogenesis of sepsis-induced ALI was revealed. Intratracheal infusion of lipopolysaccharide (LPS, 10 mg/kg) induced ALI in wild-type (WT) and S100A9 knockout mice. Multiomics analyses (transcriptomics and proteomics) were performed to investigate the potential mechanisms by which S100A9 exacerbates acute lung damage. Hematoxylin-eosin, Giemsa, and TUNEL staining were used to evaluate lung injury and cell apoptosis. LPS (10 μg/mL)-induced murine lung epithelial MLE-12 cells were utilized to mimic ALI and were modulated by S100A9 lentiviral transfection. The impact of S100A9 on cell apoptosis and inflammatory responses were identified using flow cytometry and PCR. The expression of interleukin (IL)-17-nuclear factor kappa B (NFκB)-caspase-3 signaling components was identified using western blotting.

RESULTS

Six common DEGs (S100A9, S100A8, IFITM6, SAA3, CD177, and MMP9) were identified in the six datasets related to ALI in sepsis. Compared to WT sepsis mice, S100A9 knockout significantly alleviated LPS-induced ALI in mice, with reduced lung structural damage and inflammatory exudation, decreased exfoliated cell and protein content in the lung lavage fluid, and reduced apoptosis and necrosis of pulmonary epithelial cells. Transcriptomic analysis revealed that knocking out S100A9 significantly affected 123 DEGs, which were enriched in immune responses, defense responses against bacteria or lipopolysaccharides, cytokine-cytokine receptor interactions, and the IL-17 signaling pathway. Proteomic analysis revealed that S100A9 knockout alleviated muscle contraction dysfunction and structural remodeling in sepsis-induced ALI. Multiomics analysis revealed that S100A9 may be closely related to interferon-induced proteins with tetratricopeptide repeats and oligoadenylate synthase-like proteins. LPS decreased MLE12 cell activity, accompanied by high expression of S100A9. The expression of IL-17RA, pNFκB, and cleaved-caspase-3 were increased by S100A9 overexpression and reduced by S100A9 knockdown in LPS-stimulated MLE12 cells. S100A9 knockdown decreases transcription of apoptosis-related markers Bax, Bcl and caspase-3, alleviating LPS-induced apoptosis.

CONCLUSIONS

S100A9 as a key biomarker of sepsis-induced acute lung injury, and exacerbates lung damage and epithelial cell apoptosis induced by LPS via the IL-17-NFκB-caspase-3 signaling pathway.

Rap1GAP exacerbates myocardial infarction by regulating the AMPK/SIRT1/NF-κB signaling pathway

Rap1 GTPase-activating protein (Rap1GAP) is an important tumor suppressor. The purpose of this study was to investigate the role of Rap1GAP in myocardial infarction (MI) and its potential mechanism. Left anterior descending coronary artery ligation was performed on cardiac-specific Rap1GAP conditional knockout (Rap1GAP-CKO) mice and control mice with MI. Seven days after MI, Rap1GAP expression in the hearts of control mice peaked, the expression of proapoptotic markers (Bax and cleaved caspase-3) increased, the expression of antiapoptotic factors (Bcl-2) decreased, and the expression of the inflammatory factors IL-6 and TNF-α increased; thus, apoptosis occurred, inflammation, infarct size, and left ventricular dysfunction increased, while the heart changes caused by MI were alleviated in Rap1GAP-CKO mice. Mouse heart tissue was obtained for transcriptome sequencing, and gene set enrichment analysis (GSEA) was used to analyze Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. We found that Rap1GAP was associated with the AMPK and NF-κB signaling pathways and that Rap1GAP inhibited AMPK/SIRT1 and activated the NF-κB signaling pathway in model animals. Similar results were observed in primary rat myocardial cells subjected to oxygen-glucose deprivation (OGD) to induce ischemia and hypoxia. Activating AMPK with the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) reversed the damage caused by Rap1GAP overexpression in cardiomyocytes. In addition, the coimmunoprecipitation results showed that exogenous Rap1GAP interacted with AMPK. Rap1GAP was verified to regulate the AMPK SIRT1/NF-κB signaling pathway and exacerbate the damage to myocardial cells caused by ischemia and hypoxia. In conclusion, our results suggest that Rap1GAP promotes MI by modulating the AMPK/SIRT1/NF-κB signaling pathway and that Rap1GAP may be a therapeutic target for MI treatment in the future.

Targeting estrogen receptor signaling for treating heart failure

Heart failure (HF) is a significant public health problem worldwide. It has long been noted that premenopausal women, compared to postmenopausal women and men, have lower rates for developing this disease, as well as subsequent morbidity and mortality. This difference has been attributed to estrogen playing a cardioprotective role in these women, though exactly how it does so remains unclear. In this review, we examine the presence of estrogen receptors within the cardiovascular system, as well as the role they play behind the cardioprotective effect attributed to estrogen. Furthermore, we highlight the underlying mechanisms behind their alleviation of HF, as well as possible treatment approaches, such as hormone replacement therapy and exercise regimens, to manipulate these mechanisms in treating and preventing HF.

Transforming growth factor-β and bone morphogenetic protein signaling pathways in pathological cardiac hypertrophy

Pathological cardiac hypertrophy (referred to as cardiac hypertrophy) is a maladaptive response of the heart to a variety of pathological stimuli, and cardiac hypertrophy is an independent risk factor for heart failure and sudden death. Currently, the treatments for cardiac hypertrophy are limited to improving symptoms and have little effect. Elucidation of the developmental process of cardiac hypertrophy at the molecular level and the identification of new targets for the treatment of cardiac hypertrophy are crucial. In this review, we summarize the research on multiple active substances related to the pathogenesis of cardiac hypertrophy and the signaling pathways involved and focus on the role of transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signaling in the development of cardiac hypertrophy and the identification of potential targets for molecular intervention. We aim to identify important signaling molecules with clinical value and hope to help promote the precise treatment of cardiac hypertrophy and thus improve patient outcomes.

Cardiac-specific Trim44 knockout in rat attenuates isoproterenol-induced cardiac remodeling via inhibition of AKT/mTOR pathway

When pathological hypertrophy progresses to heart failure (HF), the prognosis is often very poor. Therefore, it is crucial to find new and effective intervention targets. Here, myocardium-specific Trim44 knockout rats were generated using CRISPR-Cas9 technology. Cardiac phenotypic observations revealed that Trim44 knockout affected cardiac morphology at baseline. Rats with Trim44 deficiency exhibited resistance to cardiac pathological changes in response to stimulation via isoproterenol (ISO) treatment, including improvement of cardiac remodeling and dysfunction by morphological and functional observations, reduced myocardial fibrosis and reduced expression of molecular markers of cardiac stress. Furthermore, signal transduction validation associated with growth and hypertrophy development in vivo and in vitro demonstrated that Trim44 deficiency inhibited the activation of signaling pathways involved in myocardial hypertrophy, especially response to pathological stress. In conclusion, the present study indicates that Trim44 knockout attenuates ISO-induced pathological cardiac remodeling through blocking the AKT/mTOR/GSK3β/P70S6K signaling pathway. This is the first study to demonstrate the function and importance of Trim44 in the heart at baseline and under pathological stress. Trim44 could be a novel therapeutic target for prevention of cardiac hypertrophy and HF.

Summary: This is the first study to demonstrate the function of Trim44 in the heart at baseline and under pathological stress. Trim44 could be a novel therapeutic target for prevention of cardiac hypertrophy.

Gender differences in GRK2 in cardiovascular diseases and its interactions with estrogen

G protein-coupled receptor kinase 2 (GRK2) is a multifunctional protein involved in regulating G protein-coupled receptor (GPCR) and non-GPCR signaling in the body. In the cardiovascular system, increased expression of GRK2 has been implicated in the occurrence and development of several cardiovascular diseases (CVDs). Recent studies have found gender differences in GRK2 in the cardiovascular system under physiological and pathological conditions, where GRK2's expression and activity are increased in males than in females. The incidence of CVDs in premenopausal women is lower than in men of the same age, which is related to estrogen levels. Given the shared location of GRK2 and estrogen receptors, estrogen may interact with GRK2 by modulating vital molecules such as calmodulin (CaM), caveolin, RhoA, nitrate oxide (NO), and mouse double minute 2 homolog (Mdm2), via signaling pathways mediated by estrogen's genomic (ERα and ERβ), and non-genomic (GPER) receptors, conferring cardiovascular protection in females. Highlighting the gender differences in GRK2 and understanding its interaction with estrogen in the cardiovascular system is pertinent in treating gender-related CVDs. As a result, this article explores the gender differences of GRK2 in the cardiovascular system and its relationship with estrogen during disease conditions. Estrogen's protective and therapeutic effects and its mechanism on GRK2-related cardiovascular diseases have also been discussed.

The protective effect of Apelin-13 against cardiac hypertrophy through activating the PI3K-AKT-mTOR signaling pathway

Objectives

To determine the protective effect of Apelin-13 on cardiac hypertrophy through activating the PI3K-AKT-mTOR signaling pathway.

Materials and Methods

The phenylephrine-induced cardiomyocyte hypertrophy model was established in H9C2 cells in vitro. Electroporation transfection technology was utilized to prepare and screen the H9C2 cells inducing low expression of the angiotensin type one receptor-related protein (Si-APJ). H9C2 and Si-APJ cells were divided independently into five groups: the control group, the PE group, the PE+Apelin group, the PE+Rapa group, and the PE+Apelin+Rapa group. RT-PCR was performed to analyze the mRNA expression levels of myosin heavy chain 7 (MYH7). Expression of the PI3K/AKT/mTOR pathway proteins and MYH7 was investigated by western blot.

Results

The expression of PI3K/AKT/mTOR phosphorylated proteins was significantly higher in the PE group compared with the PE+Apelin group in H9C2 cells (P<0.05). Conversely, in Si-APJ H9C2 cells, the expression of PI3K/AKT/mTOR phosphorylated proteins was decreased (P<0.05). In H9C2 cells, the expression of MYH7 protein was increased in the PE group compared with the control group (P<0.05). In the same cell line, the expression of MYH7 in the PE+Apelin group was decreased significantly compared with the PE group (P<0.05). In Si-APJ H9C2 cells, compared with the control group, the expression of MYH7 in the PE group still increased significantly (P<0.05). In contrast, in the same cell line, there was no statistically significant difference in MYH7 expression between the PE+Apelin, PE+Rapa, and PE+Apelin+Rapa groups compared to the PE group (P>0.05).

Conclusion

Apelin-13 reduces PE-induced cardiac hypertrophy by activating the PI3K/AKT/mTOR signaling pathway.

The emerging role of estrogen's non-nuclear signaling in the cardiovascular disease

Sexual dimorphism exists in the epidemiology of cardiovascular disease (CVD), which indicates the involvement of sexual hormones in the pathophysiology of CVD. In particular, ample evidence has demonstrated estrogen's protective effect on the cardiovascular system. While estrogen receptors, bound to estrogen, act as a transcription factor which regulates gene expressions by binding to the specific DNA sequence, a subpopulation of estrogen receptors localized at the plasma membrane induces activation of intracellular signaling, called "non-nuclear signaling" or "membrane-initiated steroid signaling of estrogen". Although the precise molecular mechanism of non-nuclear signaling as well as its physiological impact was unclear for a long time, recent development of genetically modified animal models and pathway-selective estrogen receptor stimulant bring new insights into this pathway. We review the published experimental studies on non-nuclear signaling of estrogen, and summarize its role in cardiovascular system, especially focusing on: (1) the molecular mechanism of non-nuclear signaling; (2) the design of genetically modified animals and pathway-selective stimulant of estrogen receptor.

Myotubularin‐Related Protein14 Prevents Neointima Formation and Vascular Smooth Muscle Cell Proliferation by Inhibiting Polo‐Like Kinase1

Background

Restenosis is one of the main bottlenecks in restricting the further development of cardiovascular interventional therapy. New signaling molecules involved in the progress have continuously been discovered; however, the specific molecular mechanisms remain unclear. MTMR14 (myotubularin‐related protein 14) is a novel phosphoinositide phosphatase that has a variety of biological functions and is involved in diverse biological processes. However, the role of MTMR14 in vascular biology remains unclear. Herein, we addressed the role of MTMR14 in neointima formation and vascular smooth muscle cell (VSMC) proliferation after vessel injury.

Methods and Results

Vessel injury models were established using SMC‐specific conditional MTMR14‐knockout and ‐transgenic mice. Neointima formation was assessed by histopathological methods, and VSMC proliferation and migration were assessed using fluorescence ubiquitination‐based cell cycle indicator, transwell, and scratch wound assay. Neointima formation and the expression of MTMR14 was increased after injury. MTMR14 deficiency accelerated neointima formation and promoted VSMC proliferation after injury, whereas MTMR14 overexpression remarkably attenuated this process. Mechanistically, we demonstrated that MTMR14 suppressed the activation of PLK1 (polo‐like kinase 1) by interacting with it, which further leads to the inhibition of the activation of MEK/ERK/AKT (mitogen‐activated protein kinase kinase/extracellular‐signal‐regulated kinase/protein kinase B), thereby inhibiting the proliferation of VSMC from the medial to the intima and thus preventing neointima formation.

Conclusions

MTMR14 prevents neointima formation and VSMC proliferation by inhibiting PLK1. Our findings reveal that MTMR14 serves as an inhibitor of VSMC proliferation and establish a link between MTMR14 and PLK1 in regulating VSMC proliferation. MTMR14 may become a novel potential therapeutic target in the treatment of restenosis.

Quantitative Proteomic Analysis of Zearalenone Exposure on Uterine Development in Weaned Gilts

The aim of this study was to explore the effect of zearalenone (ZEA) exposure on uterine development in weaned gilts by quantitative proteome analysis with tandem mass spectrometry tags (TMT). A total of 16 healthy weaned gilts were randomly divided into control (basal diet) and ZEA3.0 treatments groups (basal diet supplemented with 3.0 mg/kg ZEA). Results showed that vulva size and uterine development index were increased (p < 0.05), whereas serum follicle stimulation hormone, luteinizing hormone and gonadotropin-releasing hormone were decreased in gilts fed the ZEA diet (p < 0.05). ZEA, α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL) were detected in the uteri of gilts fed a 3.0 mg/kg ZEA diet (p < 0.05). The relative protein expression levels of creatine kinase M-type (CKM), atriopeptidase (MME) and myeloperoxidase (MPO) were up-regulated (p < 0.05), whereas aldehyde dehydrogenase 1 family member (ALDH1A2), secretogranin-1 (CHGB) and SURP and G-patch domain containing 1 (SUGP1) were down-regulated (p < 0.05) in the ZEA3.0 group by western blot, which indicated that the proteomics data were dependable. In addition, the functions of differentially expressed proteins (DEPs) mainly involved the cellular process, biological regulation and metabolic process in the biological process category. Some important signaling pathways were changed in the ZEA3.0 group, such as extracellular matrix (ECM)-receptor interaction, focal adhesion and the phosphoinositide 3-kinase−protein kinase B (PI3K-AKT) signaling pathway (p < 0.01). This study sheds new light on the molecular mechanism of ZEA in the uterine development of gilts.

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.

Insulin activates LC-PUFA biosynthesis of hepatocytes by regulating the PI3K/Akt/mTOR/Srebp1 pathway in teleost Siganus canaliculatus

Insulin is well known an important metabolic regulator in glucose and lipid metabolism. It has been proved to activate long-chain (≥ C₂₀) polyunsaturated fatty acids (LC-PUFA) biosynthesis in mammals, but little is known about such a role in fish. To explore the effects and molecular mechanisms of insulin in fish LC-PUFA biosynthesis, we treated the rabbitfish S. canaliculatus hepatocyte line (SCHL) cells with 65 nM insulin for 12 h, and the results showed that the mRNA levels of genes encoding the key enzymes and transcription factor involved in rabbitfish LC-PUFA biosynthesis such as Δ6Δ5 fads2, elovl5 and srebp1, as well as those of PI3K pathway genes including pdk1, akt2 and mtor increased significantly. Moreover, SCHL cells treated with different PI3K/Akt pathway inhibitors (LY294002, Wortmannin, AKTi-1/2) alone or combined with insulin decreased the mRNA levels of PI3K/Akt/mTOR downstream signaling genes, including Δ6Δ5 fads2, Δ4 fads2, elovl5, elovl4 and srebp1. While PI3K/Akt agonists (740 Y-P, IGF-1, SC-79) had the opposite results. The results of fatty acid composition analysis of hepatocytes showed that insulin stimulation increased the Δ6Δ5 Fads2-dependent PUFA desaturation indexes, while Elovl5-dependent PUFA elongation indexes had upward trends, and consequently LC-PUFA contents increased. Taken together, these results indicated that insulin activated LC-PUFA biosynthesis probably through PI3K/Akt/mTOR/Srebp1 pathway in S. canaliculatus hepatocytes.

Diosmetin Protects against Cardiac Hypertrophy via p62/Keap1/Nrf2 Signaling Pathway

An important pathophysiological consequence of pressure overload-induced cardiac hypertrophy is adverse cardiac remodeling, including structural changes in cardiomyocytes and extracellular matrix. Diosmetin (DIO), a monomethoxyflavone isolated from citrus fruits, had antioxidative stress effects in multiple organs. The purpose of this study was to examine the biological effect of diosmetin on pathological cardiac hypertrophy. In mice, diosmetin treatment reduced cardiac hypertrophy and dysfunction in an aortic banding- (AB-) induced pressure overload model and reducing myocardial oxidative stress by increasing antioxidant gene expression. In vitro, diosmetin (10 or 50 μm, 12 h or 24 h) protected PE-induced cardiomyocyte hypertrophy in neonatal rat cardiomyocytes. Mechanistically, diosmetin inhibited autophagy by activating the PI3K/Akt pathway. In particular, diosmetin induced the accumulation of p62 and its interaction with Keap1, promoted the nuclear translocation of Nrf2, and increased the expression of antioxidant stress genes in the process of cardiac hypertrophy. Furthermore, knockdown of p62 in rat primary cardiomyocytes abrogate the protective effect of diosmetin on cardiomyocyte hypertrophy. Similarly, the Nrf2 inhibitor ML385 obviously abolished the above effects by diosmetin treatment. In conclusion, our results suggest that diosmetin protects cardiac hypertrophy under pressure overload through the p62/Keap1/Nrf2 signaling pathway, suggesting the potential of diosmetin as a novel therapy for pathological cardiac hypertrophy.

Sexual dimorphism in cardiac remodeling: the molecular mechanisms ruled by sex hormones in the heart

Heart failure (HF) is growing in prevalence, due to an increase in aging and comorbidities. Heart failure with reduced ejection fraction (HFrEF) is more common in men, whereas heart failure with preserved ejection fraction (HFpEF) has a higher prevalence in women. However, the reasons for these epidemiological trends are not clear yet. Since HFpEF affects mostly postmenopausal women, sex hormones should play a pivotal role in HFpEF development. Furthermore, for HFpEF, contrary to HFrEF, effective therapeutic approaches are missing. Interestingly, studies evidenced that some therapies can have better results in women than in HFpEF men, emphasizing the necessity of understanding these observations at a molecular level. Thus, herein, we review the molecular mechanisms of estrogen and androgen actions in the heart in physiological conditions and explain how its dysregulation can lead to disease development. This clarification is essential in the road for an effective personalized management of HF, particularly HFpEF, towards the development of sex-specific therapeutic approaches.

Chronic GPR30 agonist therapy causes restoration of normal cardiac functional performance in a male mouse model of progressive heart failure: Insights into cellular mechanisms

AIMS

G protein-coupled estrogen receptor 30 (GPR30) activation by its agonist, G1, exhibits beneficial actions in female with heart failure (HF). Recent evidence indicates its cardiovascular benefits may also include male as well. However, whether and how GPR30 activation may limit HF progression and have a salutary role in males is unknown. We hypothesized that chronic G1 treatment improves LV and cardiomyocyte function, [Ca²⁺]_i regulation and β-adrenergic reserve, thus limiting HF progression in male.

MAIN METHODS

We compared left ventricle (LV) and myocyte function, [Ca²⁺]_i transient ([Ca²⁺]_iT) and β-AR modulation in control male mice (12/group) and isoproterenol-induced HF (150 mg/kg s.c. for 2 days). Two weeks after isoproterenol injection, HF mice received placebo, or G1 (150 μg/kg/day s.c. mini-pump) for 2 weeks.

KEY FINDINGS

Isoproterenol-treated mice exhibited HF with preserved ejection fraction (HFpEF) at 2-weeks and progressed to HF with reduced EF (HFrEF) at 4-weeks, manifested by significantly increased LV time constant of relaxation (τ), decreased EF and mitral flow (dV/dt_max), which were accompanied by reduced myocyte contraction (dL/dt_max), relaxation (dR/dt_max) and [Ca²⁺]_iT. Acute isoproterenol-superfusion caused significantly smaller increases in dL/dt_max, dR/dt_max and [Ca²⁺]_iT. G1 treatment in HF increased basal and isoproterenol-stimulated increases in EF and LV contractility of E_ES. Importantly, G1 improved basal and isoproterenol-stimulated dL/dt_max, dR/dt_max and [Ca²⁺]_iT to control levels and restored normal cardiac β-AR subtypes modulation.

SIGNIFICANCE

Chronic G1 treatment restores normal myocyte basal and β-AR-stimulated contraction, relaxation, and [Ca²⁺]_iT, thereby reversing LV dysfunction and playing a rescue role in a male mouse model of HF.

Saikosaponin-d alleviates hepatic fibrosis through regulating GPER1/autophagy signaling

BACKGROUND

Hepatic fibrosis is the final pathway of chronic liver disease characterized by excessive accumulation of extracellular matrix (ECM), which eventually develop into cirrhosis and liver cancer. Emerging studies demonstrated that Saikosaponin-d (SSd) exhibits a protective role in liver fibrosis. However, the mechanism underlying anti-liver fibrosis of SSd in vivo and in vitro remains unclear.

METHODS AND RESULTS

Transforming growth factor (TGF)-β and carbon tetrachloride (CCl₄) were used for creating liver fibrosis model in vitro and in vivo, respectively. The role of SSd in regulating liver fibrosis was assessed through Sirius red and Masson staining, and IHC assay. We found that SSd attenuated remarkably CCl₄-induced liver fibrosis as evidenced by decreased collagen level, and decreased expression of fibrotic markers Col 1 and α-SMA. Meanwhile, SSd repressed autophagy activation as suggested by decreased BECN1 expression and increased p62 expression. Compared with HSCs from CCl₄-treated group, the primary HSCs from SSd-treated mice exhibited a marked inactivation of autophagy. Mechanistically, SSd treatment enhanced the expression of GPER1 in primary HSCs and in TGF-β-treated LX-2 cells. GPER1 agonist G1 repressed autophagy activation, whereas GPER1 antagonist G15 activated autophagy and G15 also damaged the function of SSd on suppressing autophagy, leading to subsequent increased levels of fibrotic marker level in LX-2 cells.

CONCLUSIONS

Our findings highlight that SSd alleviates hepatic fibrosis by regulating GPER1/autophagy pathway.

The protective effects of 17-β estradiol and SIRT1 against cardiac hypertrophy: a review

One of the major causes of morbidity and mortality worldwide is cardiac hypertrophy (CH), which leads to heart failure. Sex differences in CH can be caused by sex hormones or their receptors. The incidence of CH increases in postmenopausal women due to the decrease in female sex hormone 17-β estradiol (E2) during menopause. E2 and its receptors inhibit CH in humans and animal models. Silent information regulator 1 (SIRT1) is a NAD⁺-dependent HDAC (histone deacetylase) and plays a major role in biological processes, such as inflammation, apoptosis, and oxidative stress responses. Probably SIRT1 because of these effects, is one of the main suppressors of CH and has a cardioprotective effect. On the other hand, estrogen and its agonists are highly efficient in modulating SIRT1 expression. In the present study, we review the protective effects of E2 and SIRT1 against CH.

The Diabetic Cardiomyopathy: The Contributing Pathophysiological Mechanisms

Individuals with diabetes mellitus (DM) disclose a higher incidence and a poorer prognosis of heart failure (HF) than non-diabetic people, even in the absence of other HF risk factors. The adverse impact of diabetes on HF likely reflects an underlying “diabetic cardiomyopathy” (DM–CMP), which may by exacerbated by left ventricular hypertrophy and coronary artery disease (CAD). The pathogenesis of DM-CMP has been a hot topic of research since its first description and is still under active investigation, as a complex interplay among multiple mechanisms may play a role at systemic, myocardial, and cellular/molecular levels. Among these, metabolic abnormalities such as lipotoxicity and glucotoxicity, mitochondrial damage and dysfunction, oxidative stress, abnormal calcium signaling, inflammation, epigenetic factors, and others. These disturbances predispose the diabetic heart to extracellular remodeling and hypertrophy, thus leading to left ventricular diastolic and systolic dysfunction. This Review aims to outline the major pathophysiological changes and the underlying mechanisms leading to myocardial remodeling and cardiac functional derangement in DM-CMP.

G protein-coupled estrogen receptor 1: a novel target to treat cardiovascular disease in a sex-specific manner?

As an agonist of the classical nuclear receptors, estrogen receptor-α and -β (NR3A1/2), estrogen has been assumed to inhibit the development of cardiovascular disease in premenopausal women. Indeed, reduced levels of estrogen after menopause are believed to contribute to accelerated morbidity and mortality rates in women. However, estrogen replacement therapy has variable effects on cardiovascular risk in postmenopausal women, including increased serious adverse events. Interestingly, preclinical studies have shown that selective activation of the novel membrane-associated G protein-coupled estrogen receptor, GPER, can promote cardiovascular protection. These benefits are more evident in ovariectomised than intact females or in males. It is therefore possible that selective targeting of the GPER in postmenopausal women could provide cardiovascular protection with fewer adverse effects that are caused by conventional 'receptor non-specific' estrogen replacement therapy. This review describes new data regarding the merits of targeting GPER to treat cardiovascular disease with a focus on sex differences.

Breast cancer and the renin-angiotensin system (RAS): Therapeutic approaches and related metabolic diseases

The Renin-Angiotensin System (RAS) is classically recognized for regulating blood pressure and fluid balance. Recently, this role has extended to other areas including inflammation, obesity, diabetes, as well as breast cancer. RAS components are expressed in normal and cancerous breast tissues, and downregulation of RAS inhibits metastasis, proliferation, angiogenesis, and desmoplasia in the tumor microenvironment. Therefore, RAS inhibitors (Angiotensin receptor blockers, ARBs, or angiotensin converting enzyme inhibitors, ACE-I) may be beneficial as preventive adjuvant therapies to thwart breast cancer development and improve outcomes, respectively. Given the beneficial effects of RAS inhibitors in metabolic diseases, which often co-exist in breast cancer patients, combining RAS inhibitors with other breast cancer therapies may enhance the effectiveness of current treatments. This review scrutinizes above associations, to advance our understanding of the role of RAS in breast cancer and its potential for repurposing of RAS inhibitors to improve the therapeutic approach for breast cancer patients.

Stress-induced differential gene expression in cardiac tissue

The stress response is adaptive and aims to guarantee survival. However, the persistence of a stressor can culminate in pathology. Catecholamines released as part of the stress response over activate beta adrenoceptors (β-AR) in the heart. Whether and how stress affects the expression of components of the intracellular environment in the heart is still, however, unknown. This paper used microarray to analyze the gene expression in the left ventricle wall of rats submitted to foot shock stress, treated or not treated with the selective β₂-AR antagonist ICI118,551 (ICI), compared to those of non-stressed rats also treated or not with ICI, respectively. The main findings were that stress induces changes in gene expression in the heart and that β₂-AR plays a role in this process. The vast majority of genes disregulated by stress were exclusive for only one of the comparisons, indicating that, in the same stressful situation, the profile of gene expression in the heart is substantially different when the β₂-AR is active or when it is blocked. Stress induced alterations in the expression of such a large number of genes seems to be part of stress-induced adaptive mechanism.

Rap1GAP Mediates Angiotensin II-Induced Cardiomyocyte Hypertrophy by Inhibiting Autophagy and Increasing Oxidative Stress

Abnormal autophagy and oxidative stress contribute to angiotensin II- (Ang II-) induced cardiac hypertrophy and heart failure. We previously showed that Ang II increased Rap1GAP gene expression in cardiomyocytes associated with hypertrophy and autophagy disorders. Using real-time PCR and Western blot, we found that Rap1GAP expression was increased in the heart of Sprague Dawley (SD) rats infused by Ang II compared with saline infusion and in Ang II vs. vehicle-treated rat neonatal cardiomyocytes. Overexpression of Rap1GAP in cultured cardiomyocytes exacerbated Ang II-induced cardiomyocyte hypertrophy, reactive oxygen species (ROS) generation, and cell apoptosis and inhibited autophagy. The increased oxidative stress caused by Rap1GAP overexpression was inhibited by the treatment of autophagy agonists. Knockdown of Rap1GAP by siRNA markedly attenuated Ang II-induced cardiomyocyte hypertrophy and oxidative stress and enhanced autophagy. The AMPK/AKT/mTOR signaling pathway was inhibited by overexpression of Rap1GAP and activated by the knockdown of Rap1GAP. These results show that Rap1GAP-mediated pathway might be a new mechanism of Ang II-induced cardiomyocyte hypertrophy, which could be a potential target for the future treatment of cardiac hypertrophy and heart failure.

Mibefradil Alleviates High-Glucose-induced Cardiac Hypertrophy by Inhibiting PI3K/Akt/mTOR-mediated Autophagy

Cardiac hypertrophy causes heart failure and is associated with hyperglycemia in patients with diabetes mellitus. Mibefradil, which acts as a T-type calcium channel blocker, exerts beneficial effects in patients with heart failure. In this study, we explored the effects and mechanism of mibefradil on high-glucose-induced cardiac hypertrophy in H9c2 cells. H9c2 cells were incubated in a high-glucose medium and then treated with different concentrations of mibefradil in the presence or absence of the Akt inhibitor MK2206 or mTOR inhibitor rapamycin. Cell size was evaluated through immunofluorescence, and mRNA expression of cardiac hypertrophy markers (atrial natriuretic peptide, brain natriuretic peptide, and β-myosin heavy chain) was assessed by using quantitative real-time polymerase chain reaction. Changes in the expression of p-PI3K, p-Akt, and p-mTOR were evaluated using Western blotting, and autophagosome formation was detected using transmission electron microscopy. Our results indicate that mibefradil reduced the size of H9c2 cells, decreased mRNA expression of atrial natriuretic peptide, brain natriuretic peptide, and β-myosin heavy chain, and decreased the level of autophagic flux. However, MK2206 and rapamycin induced autophagy and reversed the effects of mibefradil on high-glucose-induced H9c2 cells. In conclusion, mibefradil ameliorated high-glucose-induced cardiac hypertrophy by activating the PI3K/Akt/mTOR pathway and inhibiting excessive autophagy. Our study shows that mibefradil can be used therapeutically to ameliorate cardiac hypertrophy in patients with diabetes mellitus.

Inhibition of lncRNA Gm15834 Attenuates Autophagy-Mediated Myocardial Hypertrophy via the miR-30b-3p/ULK1 Axis in Mice

Emerging evidence reveals that autophagy plays crucial roles in cardiac hypertrophy. Long noncoding RNAs (lncRNAs) are novel transcripts that function as gene regulators. However, it is unclear whether lncRNAs regulate autophagy in cardiac hypertrophy. Here, we identified a novel transcript named lncRNA Gm15834, which was upregulated in the transverse aortic constriction (TAC) model in vivo and the angiotensin-II (Ang-II)-induced cardiac hypertrophy model in vitro and was regulated by nuclear factor kappa B (NF-κB). Importantly, forced expression of lncRNA Gm15834 enhanced autophagic activity of cardiomyocytes and promoted myocardial hypertrophy, whereas silencing of lncRNA Gm15834 attenuated autophagy-induced myocardial hypertrophy. Mechanistically, we found that lncRNA Gm15834 could function as an endogenous sponge RNA of microRNA (miR)-30b-3p, which was downregulated in cardiac hypertrophy. Inhibition of miR-30b-3p enhanced cardiomyocyte autophagic activity and aggravated myocardial hypertrophy, whereas overexpression of miR-30b-3p suppressed autophagy-induced myocardial hypertrophy by targeting the downstream autophagy factor of unc-51-like kinase 1 (ULK1). Moreover, inhibition of lncRNA Gm15834 by adeno-associated virus carrying short hairpin RNA (shRNA) suppressed cardiomyocyte autophagic activity, improved cardiac function, and mitigated cardiac hypertrophy. Taken together, our study identified a novel regulatory axis encompassing lncRNA Gm15834/miR-30b-3p/ULK1/autophagy in cardiac hypertrophy, which may provide a potential therapy target for cardiac hypertrophy.

G Protein-Coupled Estrogen Receptor 1 (GPER1) Mediates Aldosterone-Induced Endothelial Inflammation in a Mineralocorticoid Receptor-Independent Manner

OBJECTIVE

It has been increasingly appreciated that G protein-coupled estrogen receptor 1 (GPER1) mediates both proinflammatory and anti-inflammatory response of estrogen. It is also involved in some rapid vascular effects of aldosterone in a mineralocorticoid receptor (MR) independent manner. However, whether GPER1 mediates aldosterone-induced inflammation response in endothelial cells and its relationship with MR are yet undetermined and therefore require further explanation.

METHOD

Based on the hypothesis that GPER1 plays a role in the aldosterone-related vascular inflammation, the present study utilized a model of human umbilical vein endothelial cells transfected with MR siRNA and induced for inflammatory response with increasing concentration of aldosterone.

RESULTS

It was discovered that induction of aldosterone had no effect on the expression of GPER1 but promoted the expression of MR. Suppression of MR did not influence GPER1 expression, and GPER1 was capable of mediating part of aldosterone-induced endothelial inflammatory response. This effect may involve phosphoinositide 3-kinases (PI3K) pathway signaling.

CONCLUSION

These findings not only demonstrated the role of GPER1 in aldosterone-induced vascular inflammation but also suggested an alternative for pharmaceutical treatment of hyperaldosteronism considering the unsatisfying effect on cardiovascular risks with MR antagonists.

The endocrinological component and signaling pathways associated to cardiac hypertrophy

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

G-Protein-Coupled Estrogen Receptor 1 Promotes Gender Disparities in Hepatocellular Carcinoma via Modulation of SIN1 and mTOR Complex 2 Activity

Due to its intricate heterogeneity and limited treatment, hepatocellular carcinoma (HCC) has been considered a major cause of cancer-related mortality worldwide. Increasing evidence indicates that G-protein-coupled estrogen receptor 1 (GPER1) can promote estrogen-dependent hepatocellular proliferation by activating AKT signaling. The mTOR complex 2 (mTORC2), whose integrity and activity are modulated by its subunit Sin1, controls the activation of AKT by phosphorylation at position S473. In this study, we investigate the modulation of Sin1 and how estrogen signaling may influence the mTORC2-AKT cascade in HCC cells and a DEN-induced mouse model. We have found that estradiol-dependent Sin1 expression is transcriptionally modulated by GPER1 as well as ERα. GPER1 is able to regulate Sin1 stability via nuclear translocation, therefore increasing Sin1-mTORC2-AKT activation. Moreover, Sin1 interacts with ERα and further enhances its transcriptional activity. Sin1 is highly expressed in acute liver injury and in cases of HCC harboring high expression of GPER1 and constitutive activation of mTORC2-AKT signaling. GPER1 inhibition using the antagonist G-15 reverses DEN-induced acute liver injury by suppressing Sin1 expression and mTORC2-AKT activation. Notably, SIN1 expression varies between male and female mice in the context of both liver injury and liver cancer. In addition, high SIN1 expression is predictive of good prognosis in both male and female patients with HCC who are free from hepatitis virus infection and who report low alcohol consumption. Hence, here we demonstrate that Sin1 can be regulated by GPER1 both through nongenomic and indirect genomic signaling. IMPLICATIONS: This study suggests that Sin1 may be a novel HCC biomarker which is gender-dependent and sensitive to particular risk factor.

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.

Chronic GPER1 Activation Protects Against Oxidative Stress-Induced Cardiomyoblast Death via Preservation of Mitochondrial Integrity and Deactivation of Mammalian Sterile-20-Like Kinase/Yes-Associated Protein Pathway

Introduction: Estrogen (17β-estradiol, E2) is well-known to induce cardioprotective effects against ischemia/reperfusion (I/R) injury. We recently reported that acute application of E2 at the onset of reperfusion in vivo induces cardioprotective effects against I/R injury via activation of its non-steroidal receptor, G protein-coupled estrogen receptor 1 (GPER1). Here, we investigated the impact and mechanism underlying chronic GPER1 activation in cultured H9c2 rat cardiomyoblasts. Methods: H9c2 rat cardiomyoblasts were cultured and pretreated with the cytotoxic agent H₂O₂ for 24 h and incubated in the presence of vehicle (control), GPER1 agonists E2 and G1, or GPER1 agonists supplemented with G15 (GPER1 antagonist) for 48 or 96 h. After treatment, cells were collected to measure the rate of cell death and viability using flow cytometry and Calcein AM assay or MTT assay, respectively. The resistance to opening of the mitochondrial permeability transition pore (mPTP), the mitochondrial membrane potential, and ATP production was assessed using fluorescence microscopy, and the mitochondrial structural integrity was observed with electron microscopy. The levels of the phosphorylation of mammalian sterile-20-like kinase (MST1) and yes-associated protein (YAP) were assessed by Western blot analysis in whole-cell lysate, while the expression levels of mitochondrial biogenesis genes, YAP target genes, and proapoptotic genes were measured by qRT-PCR. Results: We found that after H₂O₂ treatment, chronic E2/G1 treatment decreased cell death effect was associated with the prevention of the S phase of the cell cycle arrest compared to control. In the mitochondria, chronic E2/G1 activation treatment preserved the cristae morphology, and increased resistance to opening of mPTP, but with little change to mitochondrial fusion/fission. Additionally, chronic E2/G1 treatment predominantly reduced phosphorylation of MST1 and YAP, as well as increased MST1 and YAP protein levels. E2 treatment also upregulated the expression levels of TGF-β and PGC-1α mRNAs and downregulated PUMA and Bim mRNAs. Except for ATP production, all the E2 or G1 effects were prevented by the cotreatment with the GPER1 antagonist, G15. Conclusion: Together, these results indicate that chronic GPER1 activation with its agonists E2 or G1 treatment protects H9c2 cardiomyoblasts against oxidative stress-induced cell death and increases cell viability by preserving mitochondrial structure and function as well as delaying the opening of mPTP. These chronic GPER1 effects are associated with the deactivation of the non-canonical MST1/YAP mechanism that leads to genetic upregulation of cell growth genes (CTGF, CYR61, PGC-1α, and ANKRD1), and downregulation of proapoptotic genes (PUMA and Bim).

The role of post-translational modifications in cardiac hypertrophy

Pathological cardiac hypertrophy involves excessive protein synthesis, increased cardiac myocyte size and ultimately the development of heart failure. Thus, pathological cardiac hypertrophy is a major risk factor for many cardiovascular diseases and death in humans. Extensive research in the last decade has revealed that post‐translational modifications (PTMs), including phosphorylation, ubiquitination, SUMOylation, O‐GlcNAcylation, methylation and acetylation, play important roles in pathological cardiac hypertrophy pathways. These PTMs potently mediate myocardial hypertrophy responses via the interaction, stability, degradation, cellular translocation and activation of receptors, adaptors and signal transduction events. These changes occur in response to pathological hypertrophy stimuli. In this review, we summarize the roles of PTMs in regulating the development of pathological cardiac hypertrophy. Furthermore, PTMs are discussed as potential targets for treating or preventing cardiac hypertrophy.

Non-genomic Effects of Estrogen on Cell Homeostasis and Remodeling With Special Focus on Cardiac Ischemia/Reperfusion Injury

This review takes into consideration the main mechanisms involved in cellular remodeling following an ischemic injury, with special focus on the possible role played by non-genomic estrogen effects. Sex differences have also been considered. In fact, cardiac ischemic events induce damage to different cellular components of the heart, such as cardiomyocytes, vascular cells, endothelial cells, and cardiac fibroblasts. The ability of the cardiovascular system to counteract an ischemic insult is orchestrated by these cell types and is carried out thanks to a number of complex molecular pathways, including genomic (slow) or non-genomic (fast) effects of estrogen. These pathways are probably responsible for differences observed between the two sexes. Literature suggests that male and female hearts, and, more in general, cardiovascular system cells, show significant differences in many parameters under both physiological and pathological conditions. In particular, many experimental studies dealing with sex differences in the cardiovascular system suggest a higher ability of females to respond to environmental insults in comparison with males. For instance, as cells from females are more effective in counteracting the ischemia/reperfusion injury if compared with males, a role for estrogen in this sex disparity has been hypothesized. However, the possible involvement of estrogen-dependent non-genomic effects on the cardiovascular system is still under debate. Further experimental studies, including sex-specific studies, are needed in order to shed further light on this matter.

Female Heart Health: Is GPER the Missing Link?

The G Protein-Coupled Estrogen Receptor (GPER) is a novel membrane-bound receptor that mediates non-genomic actions of the primary female sex hormone 17β-estradiol. Studies over the past two decades have elucidated the beneficial actions of this receptor in a number of cardiometabolic diseases. This review will focus specifically on the cardiac actions of GPER, since this receptor is expressed in cardiomyocytes as well as other cells within the heart and most likely contributes to estrogen-induced cardioprotection. Studies outlining the impact of GPER on diastolic function, mitochondrial function, left ventricular stiffness, calcium dynamics, cardiac inflammation, and aortic distensibility are discussed. In addition, recent data using genetic mouse models with global or cardiomyocyte-specific GPER gene deletion are highlighted. Since estrogen loss due to menopause in combination with chronological aging contributes to unique aspects of cardiac dysfunction in women, this receptor may provide novel therapeutic effects. While clinical studies are still required to fully understand the potential for pharmacological targeting of this receptor in postmenopausal women, this review will summarize the evidence gathered thus far on its likely beneficial effects.