Neuregulin-1 suppresses cardiomyocyte apoptosis by activating PI3K/Akt and inhibiting mitochondrial permeability transition pore

Comparative Serum Proteome Profiling of Canine Benign Prostatic Hyperplasia before and after Castration

BPH is the most prevalent prostatic condition in aging dogs. Nevertheless, clinical diagnosis and management remain inconsistent. This study employed in-solution digestion coupled with nano-liquid chromatography tandem mass spectrometry to assess serum proteome profiling of dogs with BPH and those dogs after castration. Male dogs were divided into two groups; control and BPH groups. In the BPH group, each dog was evaluated at two time points: Day 0 (BF subgroup) and Day 30 after castration (AT subgroup). In the BF subgroup, three proteins were significantly upregulated and associated with dihydrotestosterone: solute carrier family 5 member 5, tyrosine-protein kinase, and FRAT regulator of WNT signaling pathway 1. Additionally, the overexpression of polymeric immunoglobulin receptors in the BF subgroup hints at its potential as a novel protein linked to the BPH development process. Conversely, alpha-1-B glycoprotein (A1BG) displayed significant downregulation in the BF subgroup, suggesting A1BG's potential as a predictive protein for canine BPH. Finasteride was associated with increased proteins in the AT subgroup, including apolipoprotein C-I, apolipoprotein E, apolipoprotein A-II, TAO kinase 1, DnaJ homolog subfamily C member 16, PH domain and leucine-rich repeat protein phosphatase 1, neuregulin 1, and pseudopodium enriched atypical kinase 1. In conclusion, this pilot study highlighted alterations in various serum proteins in canine BPH, reflecting different pathological changes occurring in this condition. These proteins could be a source of potential non-invasive biomarkers for diagnosing this disease.

STAT5b is a key effector of NRG-1/ERBB4-mediated myocardial growth

The growth factor Neuregulin-1 (NRG-1) regulates myocardial growth and is currently under clinical investigation as a treatment for heart failure. Here, we demonstrate in several in vitro and in vivo models that STAT5b mediates NRG-1/EBBB4-stimulated cardiomyocyte growth. Genetic and chemical disruption of the NRG-1/ERBB4 pathway reduces STAT5b activation and transcription of STAT5b target genes Igf1, Myc, and Cdkn1a in murine cardiomyocytes. Loss of Stat5b also ablates NRG-1-induced cardiomyocyte hypertrophy. Dynamin-2 is shown to control the cell surface localization of ERBB4 and chemical inhibition of Dynamin-2 downregulates STAT5b activation and cardiomyocyte hypertrophy. In zebrafish embryos, Stat5 is activated during NRG-1-induced hyperplastic myocardial growth, and chemical inhibition of the Nrg-1/Erbb4 pathway or Dynamin-2 leads to loss of myocardial growth and Stat5 activation. Moreover, CRISPR/Cas9-mediated knockdown of stat5b results in reduced myocardial growth and cardiac function. Finally, the NRG-1/ERBB4/STAT5b signaling pathway is differentially regulated at mRNA and protein levels in the myocardium of patients with pathological cardiac hypertrophy as compared to control human subjects, consistent with a role of the NRG-1/ERBB4/STAT5b pathway in myocardial growth.

The mechanism and treatment of targeted anti-tumour drugs induced cardiotoxicity

As the intensive anti-tumour therapy and combination of multiple anti-tumour drugs, cardiotoxicity events caused by anti-tumour drugs have also increased significantly, and the incidence of cardiotoxicity also increased with survival time. Different types of anti-tumour drugs could cause all kinds of cardiotoxicity which increase the difficulties in treatment and even live threatening. In this review, we concentrated in the targeted anti-tumour drugs such as human epidermal growth factor receptor-2 (HER2) inhibitors, tyrosine kinase inhibitors (TKIs), immune checkpoint inhibitors (ICIs), and proteasome inhibitors (Pls). The molecular mechanism of how these drugs induce cardiotoxicity is introduced which includes several signal pathways. These drugs induced cardiotoxicity involved heart failure, hypertension, atherosis and thrombosis, QT interval prolongation, and myocarditis. Some of the cardiotoxicity could be moderate and reversible but others could have happened severely.The aim of this review is to summarise the targeted anti-tumour drugs induced cardiotoxicity and treatment strategies.

Apatinib enhances the anti-tumor effect of paclitaxel via the PI3K/p65/Bcl-xl pathway in triple-negative breast cancer

Background

Apatinib is a new generation of small molecule tyrosine kinase inhibitor, which can highly selectively inhibit phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR-2). This study aimed to investigate the synergistic effects of apatinib and paclitaxel (PTX) on triple-negative breast cancer (TNBC) in vivo and in vitro, and to explore the molecular mechanism of the PI3K/p65/Bcl-xl pathway.

Methods

In vitro, 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (MTT) method, flow cytometry (FCM), wound healing assay, and transwell matrix assay were conducted to measure the effects of apatinib and PTX on cell viability, apoptosis, migration, and invasion in TNBC cell line MDA-MB-468. Western blot (WB) was conducted to detect protein expression levels of PI3K, p65, and Bcl-xl after the application of apatinib and PTX. In vivo, MDA-MB-468 tumor-bearing nude mice were treated with apatinib and PTX, and tumor growth was observed.

Results

In vitro, apatinib and PTX could synergistically suppress the cell viability, the combined group had the most obvious effect. Apatinib and PTX could promote apoptosis and suppress migration and invasion of TNBC cells. Apatinib could reduce the expression of p-PI3K, p65, and Bcl-xl proteins (P<0.05). In vivo, apatinib and PTX could inhibit tumor size and weight of model mice, and the combined agents had a more significant effect.

Conclusions

Apatinib could enhance the anti-tumor effect of PTX on TNBC cells through the PI3K/p65/Bcl-xl molecular pathway, and apatinib combined with PTX might be a promising option for TNBC treatment.

The Molecular Mechanisms of Cardiotoxicity Induced by HER2, VEGF, and Tyrosine Kinase Inhibitors: an Updated Review

AIM

In recent decades, there has been a revolutionary decrease in cancer-related mortality and an increase in survival due to the introduction of novel targeted drugs. Nevertheless, drugs targeting human epidermal growth factor receptor 2 (HER-2), angiogenesis, and other tyrosine kinases also come with unexpected cardiac side effects, including heart failure, hypertension, arterial thrombosis, and arrhythmias, and have mechanisms that are unlike those of classic chemotherapeutic agents. In addition, it is challenging to address some problems, as the existing guidelines need to be more specific, and further large-scale clinical trials and experimental studies are required to confirm the benefit of administering cardioprotective agents to patients treated with targeted therapies. Therefore, an improved understanding of cardiotoxicity becomes increasingly important to minimize the pernicious effects and maximize the beneficial effects of targeted agents.

METHODS

"Cardiotoxicity", "targeted drugs", "HER2", "trastuzumab", "angiogenesis inhibitor", "VEGF inhibitor" and "tyrosine kinase inhibitors" are used as keywords for article searches.

RESULTS

In this article, we report several targeted therapies that induce cardiotoxicity and update knowledge of the clinical evidence, molecular mechanisms, and management measures.

Nrg1/ErbB2 regulates differentiation and apoptosis of neural stem cells in the cochlear nucleus through PI3K/Akt pathway

Sensorineural hearing loss (SNHL) is a common causes of disability. Neural stem cells (NSCs) from the cochlear nuclei have been considered to be a potential direction for the treatment of SNHL. Neuregulin 1 (NRG1)/ErbB2 signaling displays an essential role in nervous system development. In this study, we aimed to explore the roles of NRG1/ErbB2 in differentiation and apoptosis of cochlear nuclei NSCs. The data showed that the expression of NGR1 and ErbB2 in cochlear nuclei NSCs isolated from rats were increased with the age of rats. NRG1 treatment reduced the nestin-positive cells number, increased the MAP2-positive and GFAP-positive cells number, decreased the expression of cleaved-caspase-3, and increased the activation of PI3K/AKT. ErbB2 knockdown by lentiviral-mediated ErbB2 shRNA infection reversed the effect of NRG1 on cochlear nuclei NSCs. LY294002 administration further enhanced the effect of ErbB2 silencing on the expression of nestin, MAP2, GFAP and cleaved-caspase-3. Taken together, NRG1/ErbB2 regulates differentiation and apoptosis of cochlear nucleus NSCs through PI3K/Akt pathway.

Ischaemic preconditioning-induced serum exosomes protect against myocardial ischaemia/reperfusion injury in rats by activating the PI3K/AKT signalling pathway

Ischaemia/reperfusion (I/R) injury can lead to severe arrhythmia and aggravate myocardial damage. Exosomes are small-membrane vesicles that play a protective role in myocardial I/R injury. This study aimed to explore the protective effects of ischaemic preconditioning (IPC)-induced serum exosomes (IPC-Exo) on myocardial I/R injury in rats and its underlying mechanism. Serum exosomes were extracted from IPC rats and quantified using a bicinchoninic acid assay kit. IPC-Exo (50 μg) was injected into the infarcted myocardium immediately after ligation. Rats were randomly divided into Sham, I/R, IPC-Exo + I/R, I/R + LY294002, and I/R + IPC-Exo + LY294002 groups. Haemodynamic parameters were measured by physiological recording. Transthoracic echocardiography was used to detect cardiac function. The serum levels of creatine kinase isomer-MB, lactate dehydrogenase, aspartate transaminase, tumour necrosis factor-alpha, interleukin (IL)-1β, and IL-10 were detected by enzyme-linked immunosorbent assay. Triphenyl tetrazolium chloride staining was used to measure the myocardial infarct size. Apoptosis in myocardial tissues was detected by TUNEL staining. Western blotting was used to detect the levels of PI3K/AKT and apoptosis-related proteins. Our results showed that treatment with IPC-Exo ameliorated cardiac function and reduced inflammatory factor production, cardiomyocyte apoptosis, and myocardial infarct size. Moreover, IPC-Exo treatment promoted the protein expression of Bcl-2, p-PI3K, and p-AKT but inhibited that of caspase-3 and Bax. However, treatment with LY294002 significantly reversed that IPC-Exo-induced increase in p-PI3K and p-AKT levels, improvement of haemodynamics, and decrease of inflammatory factor production and apoptosis in the I/R + IPC-Exo group. Taken together, our results suggest that IPC-Exo may alleviate I/R injury via activating the PI3K/AKT signalling pathway.

Curcumin protects cardiomyopathy damage through inhibiting the production of reactive oxygen species in type 2 diabetic mice

Type 2 diabetes mellitus (DM)-induced cardiomyopathy is a multifactorial and complex disease involving oxidative stress, lipids, and fibrosis. It is based on metabolic disorders and microvascular disease and causes extensive focal necrosis of the heart muscle. Curcumin (CUR) is a natural polyphenol isolated from turmeric rhizomes and plays an important role in the antioxidant, anti-apoptotic and anti-inflammatory effects of diabetes. Therefore, we established a mouse model of diabetic cardiomyopathy (DCM) in type 2 diabetic db/db mice in our study. We divided the experiment into three groups: the control group, DM group and DM + CUR group.We performed cardiac dissection on mice treated in different conditions and conducted special pathological staining on isolated cardiac tissue. We were surprised to find that a high glucose environment can promote cardiomyocyte apoptosis by TUNEL assay. In addition, after detecting dihydroethiidine (DHE), hematoxylin-eosin (H&E) and Oil Red O staining, we unexpectedly found that CUR can inhibit the production of reactive oxygen species (ROS), reduce myocardial apoptosis, and myocardial lipid accumulation. CUR upregulated the expression of Bcl-2, and downstream the expression of Bax and Caspase-3 proteins by immunohistochemical determination and western blotting. Therefore, these results suggest that CUR has a certain protective effect on diabetic cardiomyopathy by inhibiting the production of ROS.

Phosphorylated GSK‑3β protects stress‑induced apoptosis of myoblasts via the PI3K/Akt signaling pathway

Facial jaw muscle is involved in the occurrence, development, treatment and maintenance of maxillofacial deformities. The structure and function of this tissue can be altered by changes in external stimuli, and orthodontists can regulate its reconstruction using orthopedic forces. The PI3K/Akt signaling pathway is most well‑known for its biological functions in cell proliferation, survival and apoptosis. In the present study, the effects of the PI3K/Akt signaling pathway in cyclic stretch‑induced myoblast apoptosis were investigated. For this purpose, L6 rat myoblasts were cultured under mechanical stimulation and treated with the PI3K kinase inhibitor, LY294002, to elucidate the role of the PI3K/Akt signaling pathway. Cells were stained with Hoechst 33258 to visualize morphological changes and apoptosis of myoblasts, and western blotting was performed to detect expression of Akt, phosphorylated (p)‑Akt (Ser473), glycogen synthase kinase 3β (GSK‑3β) and p‑GSK‑3β (Ser9). After addition of PI3K inhibitor, the expression of total Akt and GSK‑3β did not significantly differ among groups; however, the levels of p‑Akt and p‑GSK‑3β were lower in inhibitor‑treated groups than in those treated with loading stress alone. In addition, the rate of apoptosis in myoblasts subjected to cyclic stretch increased in a time‑dependent manner, peaking at 24 h. Collectively, it was also demonstrated that the PI3K/Akt/GSK‑3β pathway plays an important role in stretch‑induced myoblast apoptosis.

Neuregulin-1 promotes mitochondrial biogenesis, attenuates mitochondrial dysfunction, and prevents hypoxia/reoxygenation injury in neonatal cardiomyocytes

Neuregulin-1 (NRG-1)/erythroblastic leukaemia viral oncogene homologues (ErbB) pathway activation plays a crucial role in regulating the adaptation of the adult heart to physiological and pathological stress. In the present study, we investigate the effect of recombined human NRG-1 (rhNRG-1) on mitochondrial biogenesis, mitochondrial function, and cell survival in neonatal rat cardiac myocytes (NRCMs) exposed to hypoxia/reoxygenation (H/R). The results of this study showed that, in the H/R-exposed NRCMs, mitochondrial biogenesis was impaired, as manifested by the decrease of the expression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) and mitochondrial membrane proteins, the inner membrane (Tim23), mitofusin 1 (Mfn1), and mitofusin 2 (Mfn2). RhNRG-1 pretreatment effectively restored the expression of PGC-1α and these membrane proteins, upregulated the expression of the anti-apoptosis proteins Bcl-2 and Bcl-xL, preserved the mitochondrial membrane potential, and attenuated H/R-induced cell apoptosis. Blocking PGC-1 expression with siRNA abolished the beneficial role of rhNRG-1 on mitochondrial function and cell survival. The results of the present study strongly suggest that NRG-1/ErbB activation enhances the adaption of cardiomyocytes to H/R injury via promoted mitochondrial biogenesis and improved mitochondrial homeostasis. SIGNIFICANCE OF THE STUDY: The results of this research revealed for the first time the relationship between neuregulin-1 (NRG-1)/erythroblastic leukaemia viral oncogene homologues (ErbB) activation and mitochondrial biogenesis in neonatal cardiomyocytes and verified the significance of this promoted mitochondrial biogenesis in attenuating hypoxia/reoxygenation injury. This finding may open a new field to further understand the biological role of NRG-1/ErbB signalling pathway in cardiomyocyte.

Mechanisms of the Multitasking Endothelial Protein NRG-1 as a Compensatory Factor During Chronic Heart Failure

Heart failure is a complex syndrome whose phenotypic presentation and disease progression depends on a complex network of adaptive and maladaptive responses. One of these responses is the endothelial release of NRG (neuregulin)-1—a paracrine growth factor activating ErbB2 (erythroblastic leukemia viral oncogene homolog B2), ErbB3, and ErbB4 receptor tyrosine kinases on various targets cells. NRG-1 features a multitasking profile tuning regenerative, inflammatory, fibrotic, and metabolic processes. Here, we review the activities of NRG-1 on different cell types and organs and their implication for heart failure progression and its comorbidities. Although, in general, effects of NRG-1 in heart failure are compensatory and beneficial, translation into therapies remains unaccomplished both because of the complexity of the underlying pathways and because of the challenges in the development of therapeutics (proteins, peptides, small molecules, and RNA-based therapies) for tyrosine kinase receptors. Here, we give an overview of the complexity to be faced and how it may be tackled.

Cancer therapy-induced cardiomyopathy: can human induced pluripotent stem cell modelling help prevent it?

Cardiotoxic effects from cancer therapy are a major cause of morbidity during cancer treatment. Unexpected toxicity can occur during treatment and/or after completion of therapy, into the time of cancer survivorship. While older drugs such as anthracyclines have well-known cardiotoxic effects, newer drugs such as tyrosine kinase inhibitors, proteasome inhibitors, and immunotherapies also can cause diverse cardiovascular and metabolic complications. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are increasingly being used as instruments for disease modelling, drug discovery, and mechanistic toxicity studies. Promising results with hiPSC-CM chemotherapy studies are raising hopes for improving cancer therapies through personalized medicine and safer drug development. Here, we review the cardiotoxicity profiles of common chemotherapeutic agents as well as efforts to model them in vitro using hiPSC-CMs.

Neuregulin-1β attenuates sepsis-induced diaphragm atrophy by activating the PI3K/Akt signaling pathway

The aim of this study was to investigate the protective effects of neuregulin-1β (NRG-1β) on sepsis-induced diaphragm atrophy and the possible underlying mechanisms. Sprague-Dawley rats were randomly divided into sham, sepsis and NRG groups. Sepsis was induced by cecal ligation and puncture (CLP). In the NRG group, rats received tail vein injections of NRG-1β (10 μg/kg) every 12 h for 72 h after CLP. At 3 days after surgery, diaphragm contractile forces were measured by determining the force-frequency curve and muscle fiber areas by hematoxylin-eosin staining. Moreover, the NRG-1 expression level in the diaphragm was detected by Western blotting. Furthermore, the proteins in the PI3K/Akt signaling pathway and its downstream Akt-mTOR and Akt-FOXO axes were detected by Western blotting analysis. In L6 myotubes treated with lipopolysaccharide (LPS) and NRG-1β, PI3K/Akt signaling pathway-related protein expression was further determined using the PI3K inhibitor LY294002. Exogenous NRG-1β could compensate for sepsis-induced diminished NRG-1 in the diaphragm and attenuate the reduction in diaphragm contractile forces and muscle fiber areas during sepsis. Moreover, NRG-1β treatment could activate the PI3K/Akt signaling pathway in the diaphragm during sepsis. The inhibition of p70S6K and 4E-BP1 on the Akt-mTOR axis and the increased expression of Murf1 on the Akt-FOXO axis were reversed after NRG-1 treatment. In addition, NRG-1β could activate the PI3K/Akt signaling pathway in L6 myotubes treated with LPS, while the PI3K inhibitor LY294002 blocked the effects of NRG-1β. NRG-1 expression in the diaphragm was reduced during sepsis, and exogenously administered recombinant human NRG-1β could attenuate sepsis-induced diaphragm atrophy by activating the PI3K/Akt signaling pathway.

Personalized medicine in cardio-oncology: the role of induced pluripotent stem cell

Treatment of cancer has evolved in the last decade with the introduction of new therapies. Despite these successes, the lingering cardiotoxic side-effects from chemotherapy remain a major cause of morbidity and mortality in cancer survivors. These effects can develop acutely during treatment, or even years later. Although many risk factors can be identified prior to beginning therapy, unexpected toxicity still occurs, often with lasting consequences. Specifically, cardiotoxicity results in cardiac cell death, eventually leading to cardiomyopathy and heart failure. Certain risk factors may predispose an individual to experiencing adverse cardiovascular effects, and when unexpected cardiotoxicity occurs, it is generally managed with supportive care. Animal models of chemotherapy-induced cardiotoxicity have provided some mechanistic insights, but the precise mechanisms by which these drugs affect the heart remains unknown. Moreover, the genetic rationale as to why some patients are more susceptible to developing cardiotoxicity has yet to be determined. Many genome-wide association studies have identified genomic variants that could be associated with chemotherapy-induced cardiotoxicity, but the lack of validation has made these studies more speculative rather than definitive. With the advent of human induced pluripotent stem cell (iPSC) technology, researchers not only have the opportunity to model human diseases, but also to screen drugs for their efficacy and toxicity using human cell models. Furthermore, it allows us to conduct validation studies to confirm the role of genomic variants in human diseases. In this review, we discuss the role of iPSCs in modelling chemotherapy-induced cardiotoxicity.

Circulating neuregulin-1 levels in polycystic ovary syndrome

Neuregulin-1 (NRG1) has been shown to be associated with the regulation of inflammation and ovulation. The aim of this study was to investigate the relationship between serum NRG1 levels and various clinical and metabolic parameters in women with polycystic ovary syndrome (PCOS). This case-controlled study included 38 women with PCOS and 46 age and body mass index (BMI)-matched controls without PCOS. The serum NRG1 levels of the women with PCOS were found to be significantly lower compared to the control group. The high sensitivity C-reactive protein (hs-CRP) levels of the PCOS subjects were significantly higher than in the control group. The circulating NRG1 levels were negatively correlated with a homeostasis model assessment of insulin resistance (HOMA-IR) and the hs-CRP in the PCOS group. There is no significant correlation between the circulating NRG1 levels and the serum insulin in the PCOS group. There was a trend toward high NRG1 levels in the PCOS subjects with high BMI, but the difference failed to reach a statistical significance. Decreased NRG1 levels in PCOS subjects may be associated with insulin resistance and a low-grade chronic inflammation. Impact statement What is already known on this subject? Although there have been many studies related to NRG1, we could not find any study explaining the relationship between NRG1 and PCOS. This study provides first and novel insights into the relationship between serum NRG1 levels and the insulin resistance in women with PCOS. What do the results of this study add? A decline in the NRG1 levels in PCOS may be associated with insulin resistance and a low-grade chronic inflammation. What are the implications of these findings for clinical practice and/or further research? Decreased NRG1 levels may play an important role in the reproductive and endocrine properties of PCOS. We think that NRG1 research may be contribute to the clarification of PCOS pathophysiology. Future research investigating NRG1 levels in obese and non-obese cases, as well as in ovulatory and anovulatory PCOS patients, will make a significant contribution to the resolution of the mystery under PCOS aetiology.

Exercise and Cardioprotection: A Natural Defense Against Lethal Myocardial Ischemia-Reperfusion Injury and Potential Guide to Cardiovascular Prophylaxis

Similar to ischemic preconditioning, high-intensity exercise has been shown to decrease infarct size following myocardial infarction. In this article, we review the literature on beneficial effects of exercise, exercise requirements for cardioprotection, common methods utilized in laboratories to study this phenomenon, and discuss possible mechanisms for exercise-mediated cardioprotection.

Developmental Exposure to Di-(2-ethylhexyl) Phthalate Induces Cerebellar Granule Cell Apoptosis via the PI3K/AKT Signaling Pathway

Di-(2-ethylhexyl) phthalate (DEHP) is an ubiquitous environmental contaminant because of its extensive use in plastics and its persistence. As an environmental endocrine disruptor, it is suspected to interfere with neurodevelopment in people. However, evidence of the effects of maternal DEHP exposure on cerebellar development in offspring is scarce. The objective of this study was to investigate maternal exposure to DEHP and its effect on apoptosis of cerebellar granule cells (CGCs) and related mechanisms. Pregnant Wistar rats were administrated DEHP (0, 30, 300 and 750 mg/kg/d) by gavage from gestational day (GD) 0 to postnatal day (PN) 21. Primary CGCs were also exposed to mono-(2-ethylhexyl) phthalate (MEHP), the main metabolite of DEHP, for 24 h with concentrations of 0, 25, 100 and 250 µM. The CGCs of male offspring from 300 and 750 mg/kg/d DEHP exposure groups showed significantly increased apoptosis. In addition, the PI3K/AKT signaling pathway was inhibited in the male offspring of the 300 and 750 mg/kg/d DEHP exposure groups. However, effects on female pups were not obvious. Apoptosis was also elevated and the PI3K/AKT signaling pathway was inhibited after primary CGCs were exposed to MEHP. Furthermore, apoptosis was reduced after treatment with the PI3K/AKT signaling pathway activator, insulin-like growth factor (IGF) 1, and increased after treatment with LY294002, an inhibitor of the PI3K/AKT signaling pathway. These results suggested that maternal DEHP exposure induced apoptosis in the CGCs of male pups via the PI3K/AKT signaling pathway, and the apoptosis could be rescued by IGF1 and aggravated by LY294002.

MicroRNA-503 regulates hypoxia-induced cardiomyocytes apoptosis through PI3K/Akt pathway by targeting IGF-1R

Coronary heart disease is the second highest specific cause of death. H9c2 cardiomyocytes were subjected to hypoxia (1% O₂) for 0, 6, 12, 24 and 48 h. Cell apoptosis and the activity of caspase3/7 was detected using ELISA; western blot was applied to determine the cleaved-caspase3 (c-caspase3), cleaved-PARP (c-PARP) and cytochrome C (Cyto C) expression after the inhibitor negative control (in-NC), miR-503 inhibitor, mimic negative control (mi-NC) and miR-503 mimic were transfected into cells for 48 h. Moreover, flow cytometry was applied to evaluate mitochondrial membrane potential. In addition, luciferase reporter gene assay was used for detection the relationship between miR-503 and insulin-like growth-factor-1 receptor (IGF-1R). Real-time PCR showed microRNA-503 (miR-503) was elevated in a time-dependent manner under hypoxia. MiR-503 inhibition prevented cell apoptosis and reduced caspase3/7 activity and the expression of c-caspase3 and c-PARP, prevented mitochondrial membrane potential collapse and reduced the cyto C level in cytosol. While, miR-503 overexpression showed a pro-apoptotic role and resulted in mitochondrial membrane potential loss. MiR-503 directly targets IGF-1R in H9c2 cardiomyocytes. The depletion of IGF-1R using a specific IGF-1R siRNA (siIGF-1R) abolished anti-apoptotic function of miR-503 inhibitor, and LY294002 showed a similar trend. In summary, miR-503 promoted cell apoptosis, caused mitochondrial membrane potential collapse and the emancipation of cyto C from mitochondrial through PI3K/Akt pathway via targeting IGF-1R in H9c2 cardiomyocytes.

Pharmacological postconditioning with Neuregulin-1 mimics the cardioprotective effects of ischaemic postconditioning via ErbB4-dependent activation of reperfusion injury salvage kinase pathway

Background

The protective effect of Neuregulin-1 (NRG-1) on heart failure is well established. In this study, we assessed whether NRG-1 could protect the heart by mimicking the cardioprotective effects of ischaemic postconditioning (IP).

Methods

We used a myocardial reperfusion injury rat model in vivo to compare the cardioprotective effects of NRG-1(3 μg/kg, iv. at the onset of reperfusion) and IP. In Langendorff isolated heart perfusion experiments, we used the erythroblastic leukaemia viral oncogene homolog 4 (ErbB4) inhibitor AG1478, a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and a mitogen-activated protein/extracellular signal regulated kinase (MEK) inhibitor PD98059 to clarify whether the protective effects of NRG-1and IP depend on the NRG-1/ErbB4 signals and the reperfusion injury salvage kinase (RISK) pathway. Infarct size was detected by Evans blue and TTC. Apoptosis was detected by TUNEL assays. The expression of NRG-1/ErbB4 and downstream ERK1/2, AKT, AMPK and p70s6K were detected by western blotting. Hematoxylin/eosin (H&E) staining was used for histological analysis.

Results

We found that NRG-1 and IP had similar effects on reducing myocardial infarct size and apoptosis in vivo. NRG-1 heart protein levels were upregulated in the IP group. Phosphorylation of AKT, ERK1/2 and ErbB4 were also increased in both the IP and NRG-1 groups. Furthermore, in Langendorff analyses, the ErbB4 inhibitor AG1478 suppressed the phosphorylation of ErbB4 and the RISK pathway and aggravated myocardial edema and fiber fracture, thereby inhibited the cardioprotective effects in both the IP and NRG-1 groups. For assessment of downstream signals, the PI3K inhibitor LY294002 and the MEK inhibitor PD98059 suppressed the phosphorylation of AKT and ERK1/2 respectively and abolished the cardioprotective effects induced by IP and NRG-1.

Conclusion

In conclusion, both IP and NRG-1 could reduce infarct size and apoptosis through ErbB4-dependent activation of the RISK pathway in the same model; these results indicated the therapeutic potential of NRG-1 as a pharmacological postconditioning agent against myocardial reperfusion injury.

Mesenchymal stromal cells protect human cardiomyocytes from amyloid fibril damage

BACKGROUND AIMS

Light chain (AL) amyloidosis is a protein misfolding disease characterized by extracellular deposition of immunoglobulin light chains (LC) as amyloid fibrils. Patients with LC amyloid involvement of the heart have the worst morbidity and mortality. Current treatments target the plasma cells to reduce further production of amyloid proteins. There is dire need to understand the mechanisms of cardiac tissue damage from amyloid to develop novel therapies. We recently reported that LC soluble and fibrillar species cause apoptosis and inhibit cell growth in human cardiomyocytes. Mesenchymal stromal cells (MSCs) can promote wound healing and tissue remodeling. The objective of this study was to evaluate MSCs to protect cardiomyocytes affected by AL amyloid fibrils.

METHODS

We used live cell imaging and proteomics to analyze the effect of MSCs in the growth arrest caused by AL amyloid fibrils.

RESULTS

We evaluated the growth of human cardiomyocytes (RFP-AC16 cells) in the presence of cytotoxic LC amyloid fibrils. MSCs reversed the cell growth arrest caused by LC fibrils. We also demonstrated that this effect requires cell contact and may be mediated through paracrine factors modulating cell adhesion and extracellular matrix remodeling. To our knowledge, this is the first report of MSC protection of human cardiomyocytes in amyloid disease.

CONCLUSIONS

This important proof of concept study will inform future rational development of MSC therapy in cardiac LC amyloid.

Repair Injured Heart by Regulating Cardiac Regenerative Signals

Cardiac regeneration is a homeostatic cardiogenic process by which the sections of malfunctioning adult cardiovascular tissues are repaired and renewed employing a combination of both cardiomyogenesis and angiogenesis. Unfortunately, while high-quality regeneration can be performed in amphibians and zebrafish hearts, mammalian hearts do not respond in kind. Indeed, a long-term loss of proliferative capacity in mammalian adult cardiomyocytes in combination with dysregulated induction of tissue fibrosis impairs mammalian endogenous heart regenerative capacity, leading to deleterious cardiac remodeling at the end stage of heart failure. Interestingly, several studies have demonstrated that cardiomyocyte proliferation capacity is retained in mammals very soon after birth, and cardiac regeneration potential is correspondingly preserved in some preadolescent vertebrates after myocardial infarction. There is therefore great interest in uncovering the molecular mechanisms that may allow heart regeneration during adult stages. This review will summarize recent findings on cardiac regenerative regulatory mechanisms, especially with respect to extracellular signals and intracellular pathways that may provide novel therapeutics for heart diseases. Particularly, both in vitro and in vivo experimental evidences will be presented to highlight the functional role of these signaling cascades in regulating cardiomyocyte proliferation, cardiomyocyte growth, and maturation, with special emphasis on their responses to heart tissue injury.

TGF-β improves myocardial function and prevents apoptosis induced by anoxia-reoxygenation, through the reduction of endoplasmic reticulum stress

BACKGROUND

Transforming growth factor-β (TGF-β) is known for its role in ventricular remodeling, inflammatory response, cell survival, and apoptosis. However, its role in improving myocardial function in rat hearts subjected to ischemia-reperfusion (I/R) and protecting against apoptosis induced in cardiomyocytes by anoxia-reoxygenation (A/R) has not been elucidated. This study investigated the protective effects and molecular mechanisms of TGF-β on myocardial function and cardiomyocyte apoptosis.

METHODS AND RESULTS

We used TUNEL staining, we tested cell viability, and we measured mitochondrial membrane potential and levels of mitochondrial ROS after 6 h of simulated anoxia together with various durations of simulated reoxygenation in H9c2 cells. We further observed the contractile function in rat hearts after they were subjected to 30 min global ischemia and 180 min reperfusion. Pretreatment with TGF-β markedly inhibited apoptosis in H9c2 cells, as evidenced by increased cell viability and decreased numbers of TUNEL-positive cells, maintained mitochondrial membrane potential, and diminished mitochondrial production of reactive oxygen species (ROS). These changes were associated with the inhibition of endoplasmic reticulum (ER) stress-dependent markers of apoptosis (GRP78, CHOP, caspase-12, and JNK), and the modulation of the expression of Bcl2/Bax. Furthermore, TGF-β improved I/R-induced myocardial contractile dysfunction. All of these protective effects were concentration-dependent.

CONCLUSION

Our results show that TGF-β prevents A/R-induced apoptosis of cardiomyocytes and improves myocardial function in rat hearts injured by I/R.

Neuregulin as a heart failure therapy and mediator of reverse remodeling

The beta isoform of Neuregulin-1 (NRG-1β), along with its receptors (ErbB2-4), is required for cardiac development. NRG-1β, as well as the ErbB2 and ErbB4 receptors, is also essential for maintenance of adult heart function. These observations have led to its evaluation as a therapeutic for heart failure. Animal studies and ongoing clinical trials have demonstrated beneficial effects of two forms of recombinant NRG-1β on cardiac function. In addition to the possible role for recombinant NRG-1βs as heart failure therapies, endogenous NRG-1β/ErbB signaling appears to play a role in restoring cardiac function after injury. The potential mechanisms by which NRG-1β may act as both a therapy and a mediator of reverse remodeling remain incompletely understood. In addition to direct effects on cardiac myocytes NRG-1β acts on the vasculature, interstitium, cardiac fibroblasts, and hematopoietic and immune cells, which, collectively, may contribute to NRG-1β's role in maintaining cardiac structure and function, as well as mediating reverse remodeling.

Neuregulin-1 protects myocardial cells against H2 O2 -induced apoptosis by regulating endoplasmic reticulum stress

Neuregulin-1 (NRG-1) is a stress-mediated growth factor secreted by cardiovascular endothelial cells and provides the protection to myocardial cells, but the underlying mechanisms are not fully understood. This study aimed to demonstrate that NRG-1 protects myocardial cells exposed to oxidative damage by regulating endoplasmic reticulum (ER) stress. Neonatal rat cardiac myocytes (NRCMs) were isolated and treated with H2 O2 as a cellular model of ER stress. NRCMs were pretreated with different concentrations of NRG-1. We found that NRG-1 increased the viability and reduced the apoptosis of NRCMs treated by H2 O2 . Moreover, NRG-1 reduced lactate dehydrogenase level, increased superoxide dismutase activity and decreased malondialdehyde content in NRCMs treated by H2 O2 . Finally, we demonstrated that NRG-1 alleviated ER stress and decreased CHOP and GRP78 protein levels in NRCMs treated by H2 O2 . Taken together, these data indicate that NRG-1 relieves oxidative and ER stress in NRCMs and suggest that NRG-1 is a promising agent for cardioprotection.

Flos Puerariae extract prevents myocardial apoptosis via attenuation oxidative stress in streptozotocin-induced diabetic mice

Background

Diabetic cardiomyopathy (DCM) suggests a direct cellular insult to myocardium. Apoptosis is considered as one of the hallmarks of DCM. Oxidative stress plays a key role in the pathogenesis of DCM. In this study, we explored the prevention of myocardial apoptosis by crude extract from Flos Puerariae (FPE) in experimental diabetic mice.

Methods

Experimental diabetic model was induced by intraperitoneally injection of streptozotocin (STZ, 50 mg/kg/day) for five consecutive days in C57BL/6J mice. FPE (100, 200 mg/kg) was orally administrated once a day for ten weeks. Cardiac structure changes, apoptosis, superoxide production, NADPH oxidase subunits expression (gp91^phox, p47^phox, and p67^phox), and related regulatory factors were assessed in the heart of mice.

Results

Diabetic mice were characterized by high blood glucose (≥11.1 mmol/L) and reduced body weight. In the end of the experiment, aberrant myofilament structure, as well as TUNEL positive cardiac cells coupled with increased Bax/Bcl-2 ratio and Caspase-3 expression was found in diabetic mice. Moreover, ROS formation, the ratio of NADP⁺/NADPH and NADPH oxidase subunits expression of gp91^phox and p47^phox, lipid peroxidation level was significantly increased, while antioxidant enzyme SOD and GSH-Px activity were reduced in the myocardial tissue of diabetic mice. In contrast, treatment with FPE resulted in a normalized glucose and weight profile. FPE administration also preserved myocardial structure and reduced apoptotic cardiac cell death in diabetic mice. The elevated markers of oxidative stress were significantly reversed by FPE supplementation. Further, FPE treatment markedly inhibited the increased Bax/Bcl-2 ratio and Caspase-3 expression, as well as suppressed JNK and P38 MAPK activation in the heart of diabetic mice.

Conclusions

Our data demonstrate for the first time that FPE may have therapeutic potential for STZ-induced diabetic cardiomyopathy through preventing myocardial apoptosis via attenuation oxidative stress. And this effect is probably mediated by JNK and P38 MAPK signaling pathway.

Magnesium lithospermate B improves myocardial function and prevents simulated ischemia/reperfusion injury-induced H9c2 cardiomyocytes apoptosis through Akt-dependent pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Magnesium lithospermate B (MLB), an active polyphenol acid of Radix Salviae Miltiorrhizae (Danshen), showed a wide range of pharmacological activities in cardiovascular diseases. However, its role in protection against ischemia/reperfusion injury in H9c2 cardiomyocytes has not been elucidated. This study was aimed to investigate the protective effect and potential molecular mechanisms of MLB on apoptosis in H9c2 cardiomyocytes in vitro.

MATERIALS AND METHODS

We tested cell viability, shortening amplitude, necrosis, apoptosis, and the expression levels of Akt, phosphorylated Akt, Bcl-2 and Bax after 2-h simulated ischemia and 24-h simulated reperfusion in H9c2 cardiomyocytes. We further observed the contractile function in hearts after they were subjected to global 30-min ischemia and 180-min reperfusion.

RESULTS

Pretreatment with MLB markedly increased cell viability and while reducing evidence of necrosis and apoptosis in H9c2 cardiomyocytes. In addition, the expression of Bcl-2 and Bax protein was modulated. The results also showed that MLB significantly increased phosphorylation of Akt and that this phosphorylation can be partially inhibited by phosphoinositide 3-kinase/Akt inhibitor. Furthermore, MLB improved MI/R-induced myocardial contractile function.

CONCLUSION

Our results showed that MLB prevents I/R-induced myocardial damage by reducing necrosis and apoptosis in H9c2 cardiomyocytes and improving myocardial function in rat hearts.

Protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling pathway plays a major role in reactive oxygen species (ROS)-mediated endoplasmic reticulum stress-induced apoptosis in diabetic cardiomyopathy

Background

Endoplasmic reticulum (ER) stress is considered one of the mechanisms contributing to reactive oxygen species (ROS)- mediated cell apoptosis. In diabetic cardiomyopathy (DCM), cell apoptosis is generally accepted as the etiological factor and closely related to cardiac ROS generation. ER stress is proposed the link between ROS and cell apoptosis; however, the signaling pathways and their roles in participating ER stress- induced apoptosis in DCM are still unclear.

Methods

In this study, we investigated the signaling transductions in ROS- dependent ER stress- induced cardiomocyte apoptosis in animal model of DCM. Moreover, in order to clarify the roles of IRE1 (inositol - requiring enzyme-1), PERK (protein kinase RNA (PKR)- like ER kinase) and ATF6 (activating transcription factor-6) in conducting apoptotic signal in ROS- dependent ER stress- induced cardiomocyte apoptosis, we further investigated apoptosis in high- glucose incubated cardiomyocytes with IRE1, ATF6 and PERK- knocked down respectively.

Results

we demonstrated that the ER stress sensors, referred as PERK, IRE1 and ATF6, were activated in ROS- mediated ER stress- induced cell apoptosis in rat model of DCM which was characterized by cardiac pump and electrical dysfunctions. The deletion of PERK in myocytes exhibited stronger protective effect against apoptosis induced by high- glucose incubation than deletion of ATF6 or IRE in the same myocytes. By subcellular fractionation, rather than ATF6 and IRE1, in primary cardiomyocytes, PERK was found a component of MAMs (mitochondria-associated endoplasmic reticulum membranes) which was the functional and physical contact site between ER and mitochondria.

Conclusions

ROS- stimulated activation of PERK signaling pathway takes the major responsibility rather than IRE1 or ATF6 signaling pathways in ROS- medicated ER stress- induced myocyte apoptosis in DCM.

New molecular markers for the evaluation of gamete quality

PURPOSE

Only 30 % of IVF cycles result in a pregnancy, so that multiple embryos need to be replaced, per treatment cycle, to increase pregnancy rates, resulting in a multiple gestation rate of 25 %. The use of new markers in the gamete selection, could reduce the number of the oocytes to be fertilized and embryos to be produced, but the tools to evidence the gamete competence remain unavailable and more studies are needed to identify bio-markers to select the best oocyte and sperm to produce embryos with higher implantation potentiality.

METHODS

To define oocyte competence, the apoptosis of the surrounding cumulus cells and the oxygen consumption rates for individual oocytes before fertilization seems to provide a non-invasive marker of oocyte competence and hence a quantitative assessment of the reproductive potential for the oocyte. The chromatin integrity seems to be used also as biological marker of sperm competence, together with the morphological evaluation of large vacuoles in the head.

RESULTS

The apoptosis rate of cumulus cells lower than 25 % and an higher oxygen consumption could be an evidence of an overall metabolic activity, related to a better fertilization ability and embryo cleavage quality. The apoptosis rate of the sperm chromatin, evaluated by direct Tunel in situ analysis, seems to be, also for the male gamete, a marker of competence and implantation potentiality, in particular when it is lower than 20 %. The evaluation of the presence of large vacuoles in the sperm head prior to perform ICSI seems to increase the implantation rate, but it is not associated to chromatin integrity.

CONCLUSIONS

The biological concept of competence appears unrelated to any morphological parameters, so that it is necessary to investigate new molecular markers in the gamete selection. Apoptosis of cumulus cells in the oocytes and spermatozoa, revealing the presence of large vacuoles, could help to determine the competence of the gamete to be fertilize.

Neuregulin-1 protects against doxorubicin-induced apoptosis in cardiomyocytes through an Akt-dependent pathway

In previous studies, it has been shown that recombinant human neuregulin-1(rhNRG-1) is capable of improving the survival rate in animal models of doxorubicin (DOX)-induced cardiomyopathy; however, the underlying mechanism of this phenomenon remains unknown. In this study, the role of rhNRG-1 in attenuating doxorubicin-induce apoptosis is confirmed. Neonatal rat ventricular myocytes (NRVMs) were subjected to various treatments, in order to both induce apoptosis and determine the effects of rhNRG-1 on the process. Activation of apoptosis was determined by observing increases in the protein levels of classic apoptosis markers (including cleaved caspase-3, cytochrome c, Bcl-2, BAX and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining). The activation of Akt was detected by means of western blot analysis. The study results showed that doxorubicin increased the number of TUNEL positive cells, as well as the protein levels of cleaved caspase-3 and cytochrome c, and reduced the ratio of Bcl-2/Bax. However, all of these effects were markedly antagonized by pretreament with rhNRG-1. It was then further demonstrated that the effects of rhNRG-1 could be blocked by the phosphoinositole-3-kinase inhibitor LY294002, indicating the involvement of the Akt process in mediating the process. RhNRG-1 is a potent inhibitor of doxorubicin-induced apoptosis, which acts through the PI3K-Akt pathway. RhNRG-1 is a novel therapeutic drug which may be effective in preventing further damage from occurring in DOX-induced damaged myocardium.