Human Myocardial Cells Research Articles

MicroRNA-520d-3p alleviates hypoxia/reoxygenation-induced damage in human cardiomyocytes by targeting ATG-12.

Hypoxia/reoxygenation (H/R) induced injury results in extensive damages to myocardial tissue in patients with coronary heart disease, which leads to heart failure. MicroRNA (miRNA) is thought to be associated with myocardial H/R injury. The purpose of this study was to investigate the in vitro role of microRNA-520d-3p in human myocardial cell (HCM) myocardial H/R injury. MTT method and Annexin V-FITC flow cytometry were employed to measure the viability and apoptosis of H/R treated HCM. RT-qPCR was employed to determine miRNA and mRNA expression. MicroRNA-520d-3p mimic and microRNA-520d-3p inhibitor were used to overexpression and inhibit the expression of microRNA-520d-3p. In addition, pcDNA3.1-ATG12 was used to upregulate ATG12 expression. The protein levels of ATG12, Bcl-2 and autophagy related-genes were determined by western blotting. Hypoxia/reoxygenation (H/R) injury could inhibit cell viability, apoptosis and inhibited microRNA-520d-3p expression in HCM. The down-regulation of microRNA-520d-3p inhibited cell viability and induced apoptosis in HCM. The overexpression of microRNA-520d-3p attenuated the effects of H/R treatment on the viability and apoptosis of HCM cells. In addition, microRNA-520d-3p inhibited the expression of autophagy-associated 12 (ATG12). More importantly, H/R treatment could promote autophagy in HCM, and microRNA-520d-3p mimic transfection could significantly reverse this effect. Our result indicated that overexpression of microRNA-520d-3p attenuated the effect of H/R treatments on cell viability, apoptosis and autophagy, through partly regulating ATG12 expression in HCM.

Clinical Significance of Serum PGC-1 Alpha Levels in Diabetes Mellitus with Myocardial Infarction Patients and Reduced ROS-Oxidative Stress in Diabetes Mellitus with Myocardial Infarction Model.

BackgroundIn this study, we explored the clinical significance of serum peroxisome proliferator-activated receptor gamma co-activator 1 (PGC-1) alpha levels in diabetes mellitus with myocardial infarction (DMMI) patients and investigated the possible mechanism.Materials and MethodsSerum samples were obtained from patients with DMMI or normal volunteer in Baoding First Center Hospital. C57BL/6 mice were induced by a single intraperitoneal (i.p.) injection of 100 mg/kg STZ (streptozocin) for in vivo model. Human myocardial cell lines H9C2 cells were induced with high glucose medium (33 mmol/L glucose) for in vitro model. Western blot was used to analyze the protein expressions in this study.ResultsSerum PGC-1 alpha levels were down-regulated in patients with DMMI. There was negative correlation between serum PGC-1 alpha levels and glycated hemoglobin, blood glucose or glucagon in DMMI patients. Recombination of PGC-1 alpha protein decreased the levels of glycated hemoglobin, blood glucose and glucagon, and inhibited oxidative stress and myocardial damage in mice of DMMI. Over-expression of PGC-1 alpha reduced reactive oxygen species (ROS)-oxidative stress, while down-regulation of PGC-1 alpha promoted ROS-oxidative stress via regulation of hemeoxygenase−1 (HO-1) expression in in vitro model of DMMI. The inhibition of HO-1 expression attenuated the anti-oxidation effects of PGC-1 alpha in vitro.ConclusionPGC-1 alpha attenuated ROS-oxidative stress in diabetic cardiomyopathy model, and PGC-1 alpha served as a potential intervention to alleviate DMMI in clinical applications.

RETRACTED: Structural diversity and anticancer activity on human myocardial aneurysm cells of two Cu(II)-coordination polymers

This article has been retracted, and the online PDF has been watermarked “RETRACTION”. The retraction notice is available at http://doi.org/10.3233/MGC-220954.

Zero-/two-dimensional coordination complexes based on the substituted imidazo[1,2-a]pyridine ligands: structural diversity and antitumor activity on human myocardial aneurysm cells

In the current study, two similar substituted imidazo[1,2-α]pyridine ligands with different coordination groups were facilely synthesized, and were further used for construction of two novel Cu(II)-based coordination complexes with the chemical formulae of Cu(L1)2(H2O)4 (1, HL1 = (E)−4-(3-(2-chloroimidazo[1,2-a]pyridin-3-yl)acryloyl)benzoic acid) and [Cu(L2)2]n (2, HL2 = (E)−4-(2-chloroimidazo[1,2-α]pyridin-3-yl)−2-oxobut-3-enoic acid) via a one pot solvothermal reaction. In addition, their inhibitory effect on human myocardial aneurysm cells were evaluated. Firstly, to explore the inhibitory effect of complexes on cancer cell viability and proliferation, the Cell Counting Kit-8 (CCK-8) assay was performed. Next, to evaluate the influence of the compounds on the cell migration and invasion ability, the transwell assay was conducted. In addition to this, for the cancer cell apoptosis evaluation after compounds treatment, the flow cytometry was carried out in this research.

Atorvastatin lipid nanocapsules and gold nanoparticles embedded in injectable thermo-gelling hydrogel scaffold containing adipose tissue extracellular matrix for myocardial tissue regeneration.

This study aimed to prepare, optimise, and characterise the novel hybrid hydrogel scaffold containing atorvastatin lipid nanocapsules (LNCs) and gold nanoparticles (NPs) to improve cardiomyoblasts proliferation and regeneration of myocardium. A thermo-responsive aminated guaran (AGG) hydrogel was prepared to encompass extracellular matrix (ECM) fetched from human adipose tissue. Emulsion phase-inversion technique was used to obtain LNCs. Biocompatibility, tensile strength, conductivity, and proliferation of human myocardial cells of the optimised formulation were studied. The LNCs have a spherical shape, and the optimised formulation showed a mean particle size of 18.79 nm, the zeta potential of - 11.4 mV, drug loading of 99.99%, and release efficiency percent over 72 h was 18.73%. The injectable thermo-sensitive hydrogel prepared using 1 w/v% of AGG, 35 w/w% of ECM, ∼0.5 mg/ml of gold NPs and atorvastatin loaded LNCs showed the best physical characteristics. The hybrid scaffold loaded with atorvastatin and gold NPs improved the proliferation of cardiomyoblasts more than sevenfold with enhanced cell attachment to the scaffold. The tensile strength and the conductivity of the scaffold were 300 kPa and 0.14 S/m, respectively. Injectable hybrid adipose tissue prepared by ECM and AGG hydrogel loaded with atorvastatin and gold NPs showed promising physical characteristics for myocardial tissue engineering.

GSK621 attenuates oxygen glucose deprivation/re-oxygenation-induced myocardial cell injury via AMPK-dependent signaling

Recent studies have implied that activation of AMP-dependent protein kinase (AMPK) could protect myocardial cells from oxygen glucose deprivation-re-oxygenation (OGD/R). The aim of the present study is to test whether GSK621, a novel and direct AMPK activator, could exert myocardial cell protection against OGD/R. We show that in AC16 human myocardial cells and primary murine myocardiocytes GSK621 dose-dependently activated AMPK signaling. GSK621 pretreatment potently inhibited OGD/R-induced viability reduction, cell death and apoptosis in AC16 cells and primary myocardiocytes. Furthermore, GSK621 attenuated OGD/R-induced reactive oxygen species production and oxidative injury in the myocardial cells. AMPKα1 knockdown (via targeted shRNA), knockout (via a CRISPR/Cas9 construct) or dominant negative mutation (T172A) not only blocked GSK621-induced AMPK activation, but also nullified GSK621-mediated myocardial cell protection against OGD/R. Further studies demonstrated that GSK621 activated AMPK downstream Nrf2 signaling. Contrarily, Nrf2 silencing by targeted shRNAs almost abolished GSK621-induced anti-OGD/R myocardial cell protection. We conclude that GSK621 protects myocardial cells from OGD/R through activation of AMPK-dependent signaling.

Assessing cardiac irisin activities and their associations on coronary and endothelial activities to compare their recoveries from oxidative stress-induced cardiac cell injury by Chunglijagam-tang, a Korean herbal medicine for “Heart Governs Vessels”

Involuntary cardiac pumping supplies oxygen and nutrients into coronary and peripheral arteries, which has been recognized as main dynamics of body. Among the molecules regarding cardiac dynamics, we aimed to investigate whether oxidative stress would induce the production of the exercise hormone and its levels could be regulated by herbal medicine, which represents “Heart Governs Vessels.” We searched MEDLINE for exercise hormone and screened titles and abstracts. The primary human myocardial, coronary arterial and peripheral cell lines were treated with hydrogen peroxide to mimic oxidative stress condition. Activity of irisin, an exercise hormone, was measured by ELISA assay. Expression of NADPH oxidase 2, an irisin’s putative target, was determined by immunoblot assay. Among the cardiovascular effects, we found that left ventricular systolic functions could be affected by several molecules, including irisin. In primary myocardial, coronary arterial and peripheral cell lines, irisin secretion and NADPH oxidase 2 expression was increased by 75 µM hydrogen peroxide. Interestingly, ChungliJagam-tang inhibited NOX2 activities by 31.45%, 42.62%, and 47.22% in an oxidative stress-induced primary myocardial, coronary arterial and peripheral cell lines, respectively. In conclusion, the changes in NOX2 level under an oxidative stress condition which mimicked left ventricular functions are associated with cardiac irisin activities and they were controlled by the herbal prescription on “Heart Governs Vessels”.

Hybrids of arenobufagin and benzoisoselenazol reducing the cardiotoxicity of arenobufagin

Arenobufagin is a naturally occurring bufadienolide showing promising antitumor activity accompanied however with apparent cardiac toxicity. Following the recent discovery that oxidative damage possibly be an important cause of the cardiac toxicity of cardenolides, a strategy fusing the antitumor agent arenobufagin with a benzoisoselenazol fragment, a reactive oxygen species (ROS) scavenger, has been developed. Six novel hybrids were synthesized and their ROS scavenging activities as well as their in vitro cytotoxicity against the human hepatocellular carcinoma cell line HepG2, an adriamycin-resistant subline HepG2/ADM, and the human myocardial cell line AC16 were evaluated. The results indicate that the hybrids exhibit various degrees of in vitro ROS scavenging activities, and weaker cytotoxicity than that of arenobufagin against the myocardial cell line AC16. These findings suggest the feasibility of a strategy in which the cardiotoxicity of the potential antitumor agent arenobufagin is reduced.

The impact of in vitro cell culture duration on the maturation of human cardiomyocytes derived from induced pluripotent stem cells of myogenic origin

Ischemic heart disease, also known as coronary artery disease (CAD), poses a challenge for regenerative medicine. iPSC technology might lead to a breakthrough due to the possibility of directed cell differentiation delivering a new powerful source of human autologous cardiomyocytes. One of the factors supporting proper cell maturation is in vitro culture duration. In this study, primary human skeletal muscle myoblasts were selected as a myogenic cell type reservoir for genetic iPSC reprogramming. Skeletal muscle myoblasts have similar ontogeny embryogenetic pathways (myoblasts vs. cardiomyocytes), and thus, a greater chance of myocardial development might be expected, with maintenance of acquired myogenic cardiac cell characteristics, from the differentiation process when iPSCs of myoblastoid origin are obtained. Analyses of cell morphological and structural changes, gene expression (cardiac markers), and functional tests (intracellular calcium transients) performed at two in vitro culture time points spanning the early stages of cardiac development (day 20 versus 40 of cell in vitro culture) confirmed the ability of the obtained myogenic cells to acquire adult features of differentiated cardiomyocytes. Prolonged 40-day iPSC-derived cardiomyocytes (iPSC-CMs) revealed progressive cellular hypertrophy; a better-developed contractile apparatus; expression of marker genes similar to human myocardial ventricular cells, including a statistically significant CX43 increase, an MHC isoform switch, and a troponin I isoform transition; more efficient intercellular calcium handling; and a stronger response to β-adrenergic stimulation.

Endothelial Barrier Restoration after Inflammation‐Induced Hyperpermeability

Inflammation is characterized by an increase in endothelial barrier permeability (hyperpermeability) to macromolecules. Major efforts have focused on understanding the mechanisms involved in the hyperpermeability response of endothelial cells; however, less attention has been given to the restoration of vascular barrier integrity following hyperpermeability. Because many negative effects of hyperpermeability are due to its persistence beyond what is required for preserving organ function, we are investigating mechanisms that terminate hyperpermeability and thereby restore microvascular barrier properties. Understanding the mechanisms involved in the restoration of endothelial barrier integrity will have direct clinical impact because sustained inflammation is a hallmark in clinical disorders such as trauma and ischemia‐reperfusion. We demonstrated that eNOS translocation from plasma membrane to cytosol is required for the onset of hyperpermeability. We also demonstrated that stimulation of Epac1 (exchange protein activated by cAMP) contributes to restoration of basal permeability after ischemia‐reperfusion. In this study, we tested the hypothesis that 1) hyperpermeability induces delayed increase in cAMP concentration; and 2) cAMP stimulates Epac1 and VASP (vasodilator‐stimulated phosphoprotein) to promote translocation of eNOS back to the plasma membrane, and restores endothelial barrier properties. We use human microvascular (HMVEC) and mouse myocardial endothelial cells (Myend) to study the restoration of endothelial barrier after hyperpermeability induced by platelet‐activating factor (PAF). Myend VASP knockout (KO) endothelial cells (EC) have significantly greater baseline permeability to macromolecules as well as hyperpermeability response to PAF compared to wild type Myend cells. Stimulation of Epac1 in HMVEC inactivates their hyperpermeability response to PAF. However, Epac1 stimulation fails to inactivate PAF‐induced hyperpermeability in VASP KO Myend EC. PAF activates VASP by phosphorylation at Serine 157 and Serine 239. This phosphorylation is sensitive to eNOS inhibition indicating that PAF stimulates production of eNOS‐derived NO and VASP phosphorylation in a sequential manner. In addition, stimulation of Epac1 after the onset of PAF‐induced hyperpermeability translocates eNOS back from the cytosol to the plasma membrane in HMVEC and in control Myend. eNOS is preferentially located in the cytosol in Myend VASP KO cells. Lack of VASP prevents movement of eNOS associated with stimulation of Epac1. We conclude that VASP is a required protein for movement of eNOS and restoration of EC barrier.Support or Funding InformationRutgers School of Gradute StudiesThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Quercetin enhances chemotherapeutic effect of doxorubicin against human breast cancer cells while reducing toxic side effects of it

Doxorubicin (Dox) is an efficient drug for breast cancer chemotherapy, however, its toxic side effects on non-tumor tissues, especially on myocardial cells, sometimes limit its clinical application. Therefore, it is necessary to develop a new drug, which can be combined with Dox to potentiate the anti-tumor effect of Dox at a lower concentration and attenuate the toxic side effects of it. Quercetin (Que) has anti-tumor activity in addition to its protective effects on various cells. By preparing human non-tumoral MCF-10A mammary cells, human breast cancer MCF-7 and MDA-MB-231 cells and human myocardial AC16 cells, here, we wanted to evaluate whether Que might represent such an agent and investigate its possible mechanisms of potentiating the anti-tumor effect of Dox at a lower concentration. The results showed that Que could increase intracellular accumulation of Dox in breast cancer cells through down-regulating the expression of efflux ABC transporters including P-gp, BCRP and MRP1, which can effectively eliminate cancerous cells including breast cancer stem cells (BCSCs), thereby potentiating the anti-tumor effect of Dox. Furthermore, Que attenuated the cytotoxicity of Dox to non-tumoral MCF-10A mammary cells and myocardial AC16 cells. Therefore, Que could be used as a novel agent combined with Dox in breast cancer therapy, which could potentiate the anti-tumor effect of Dox at a lower concentration and attenuate the toxic side effects of it.

Asiatic acid enhances survival of human AC16 cardiomyocytes under hypoxia by upregulating miR-1290.

Asiatic acid (AA) could attenuate ischemia/reperfusion induced myocardial apoptosis through upregulating the Akt/GSK-3β/HIF-1α pathway. HIF-3α is a negative regulator of HIF-1α, whose mRNA is a potential target of miR-1290. AA could upregulate miR-1290 in non-small-cell lung cancer A549 cells. This work aimed to investigate whether AA could inhibit hypoxia induced cardiomyocyte apoptosis through regulating the miR-1290/HIF3A/HIF-1α axis. The AC16 human myocardial cell line cultured under normoxic or hypoxic conditions was treated with various doses of AA for 24 h. Afterwards cell viability, apoptosis and the expression of miR-1290, HIF3A, and HIF1A were evaluated. Cells transfected with miR-1290 mimic or inhibitor were used to determine the role of miR-1290 in the anti-apoptosis effect of AA and the expression of HIF3A and HIF1A. Dual luciferase assay was performed to confirm miR-1290 targeting of HIF3A. HIF3A overexpression was achieved by transfection of HIF3A1 overexpressing lentivirus, and its effect on miR-1290 and AA-regulated survival of cardiomyocytes was evaluated. AA treatment protected cardiomyocytes from hypoxia-induced apoptosis and upregulated miR-1290 and HIF1A, but downregulated HIF3A under hypoxia. The protective effect of AA was abolished by miR-1290 knockdown, whereas enhanced by miR-1290 overexpression. In addition, miR-1290 knockdown increased HIF1A expression, but reduced HIF3A expression in cardiomyocytes. Dual luciferase assay confirmed miR-1290 direct targeting the 3' UTR of HIF3A. HIF3A overexpression counteracted the anti-apoptosis effect of AA or miR-1290. In conclusion, AA can protect cardiomyocytes against hypoxia-induced apoptosis through regulating the miR-1290/HIF3A/HIF-1α axis, and miR-1290 may be a potential target in the prevention of myocardial ischemia-reperfusion injury. © 2017 IUBMB Life, 69(9):660-667, 2017.

Age-dependent electrical and morphological remodeling of the Drosophila heart caused by hERG/seizure mutations.

Understanding the cellular-molecular substrates of heart disease is key to the development of cardiac specific therapies and to the prevention of off-target effects by non-cardiac targeted drugs. One of the primary targets for therapeutic intervention has been the human ether a go-go (hERG) K+ channel that, together with the KCNQ channel, controls the rate and efficiency of repolarization in human myocardial cells. Neither of these channels plays a major role in adult mouse heart function; however, we show here that the hERG homolog seizure (sei), along with KCNQ, both contribute significantly to adult heart function as they do in humans. In Drosophila, mutations in or cardiac knockdown of sei channels cause arrhythmias that become progressively more severe with age. Intracellular recordings of semi-intact heart preparations revealed that these perturbations also cause electrical remodeling that is reminiscent of the early afterdepolarizations seen in human myocardial cells defective in these channels. In contrast to KCNQ, however, mutations in sei also cause extensive structural remodeling of the myofibrillar organization, which suggests that hERG channel function has a novel link to sarcomeric and myofibrillar integrity. We conclude that deficiency of ion channels with similar electrical functions in cardiomyocytes can lead to different types or extents of electrical and/or structural remodeling impacting cardiac output.

Depletion of ubiA prenyltransferase domain containing 1 expression promotes angiotensin II‑induced hypertrophic response in AC16 human myocardial cells via modulating the expression levels of coenzyme Q10 and endothelial nitric oxide synthase.

UbiA prenyltransferase domain containing1 (UBIAD1) is closely associated with cardiovascular diseases. However, at the cellular level, little is known about how UBIAD1 is expressed and functions in cardiomyocyte hypertrophy. The aim of the present study was to investigate the expression and role of UBIAD1 in angiotensin II (Ang II)‑induced hypertrophy in AC16 cardiomyoblast cells. The loss‑of‑function approach was used to knock down UBIAD1 in vehicle‑ and Ang II‑stimulated AC16 cells. The levels of atrial natriuretic factor (ANF) and caspase-3 were measured and compared between vehicle‑ and Ang II‑treated AC16 cells pretreated with control siRNA or siRNA against UBIAD1. In addition, the levels of coenzyme Q10 (CoQ10) and endothelial nitric oxide synthase (eNOS) were evaluated and compared between these groups. Ang II induced hypertrophy and apoptosis in AC16 cells, accompanied by increased expression of ANF and caspase-3, and decreased expression of UBIAD1. These effects were potentiated by UBIAD1 knockdown. In addition, Ang II treatment suppressed the expression of CoQ10 and eNOS, as well as the production of NO, and these inhibitory effects were also enhanced by UBIAD1 knockdown. Thus, silencing of UBIAD1 expression promotes a myocardial hypertrophic response to Ang II stimulation, in part, by suppressing the expression of CoQ10 and eNOS.

Genome-wide transcriptional analysis of cardiovascular-related genes and pathways induced by PM2.5 in human myocardial cells.

Air pollution has been a major environment-related health threat. Most of the studies on PM2.5 toxicity have verified on the cardiovascular system and endothelial cells. However, researches on PM2.5-induced myocardial-related toxicity are limited. This study aims to fully understand the toxic effects of PM2.5 on human myocardial cell (AC16) and explore its molecular mechanism based on microarray analysis and bioinformatics analysis. Microarray data analysis manifested that PM2.5-induced toxicity affected expression of 472 genes compared with the control group, including 166 upregulated genes and 306 downregulated genes in human myocardial (AC16) cells. GO analysis showed that cellular processes such as immune response, cell maturation, embryonic heart tube morphogenesis, cellular response to electrical stimulus, skeletal muscle tissue regeneration, and negative regulation of signal transduction were upregulated, while regulation of transcription (DNA-dependent), rhythmic process, protein destabilization apoptotic process, and innate immune response were downregulated. The pathway analysis indicates that cell signaling pathways such as cytokine-cytokine receptor interaction, NF-κB signaling pathway, chemokine signaling pathway, endocrine and other factor-regulated calcium reabsorption, HTLV-I infection, and cell adhesion molecules (CAMs) were upregulated, while the TGF-β signaling pathway was downregulated. In addition, Signal-net showed that the TUBA4A, ADRBK2, BRIX1, SMC4, EIF5B, PRMT1, ATG4B, and NDC80 genes were significantly decreased, while the expression of the KRT6B gene was markedly increased compared with the control group. All the genes were verified by qRT-PCR. This study had provided new bioinformatics evidences in PM2.5-induced myocardial tissue toxicity which is necessary for further cardiovascular system toxicity studies.

Downregulation of microRNA‑199a‑5p protects cardiomyocytes in cyanotic congenital heart disease by attenuating endoplasmic reticulum stress.

Chronic hypoxia is a key pathological change in patients with cyanotic congenital heart defect (CCHD). It has been demonstrated that enhanced myocardial unfolded protein response (UPR) increases the capacity to buffer endoplasmic reticulum (ER) stress and to avoid subsequent apoptosis caused by the hypoxia that underlies CCHD. The present study was performed to determine the regulatory role of microRNAs (miRNAs) in this cytoprotective UPR process. The results revealed that miR‑199a‑5p was markedly downregulated in the cardiac tissue of patients with CCHD and in human myocardial cells cultured in hypoxic conditions. The two major UPR modulators, 78 kDa glucose‑regulated protein (GRP78) and activating transcription factor 6 (ATF6), were potential target genes of miR‑199a‑5p in CCHD myocardial specimens. In addition, the miR‑199a‑5p mimic and inhibitor were evidently able to change GRP78 and ATF6 gene expression and ER stress‑associated apoptosis in hypoxia‑treated cardiomyocytes. The interaction between miR‑199a‑5p and the ATF6 and GRP78 3'‑UTR binding sites in myocardial cells was also confirmed by luciferase assay. Thus, it is concluded that myocardial downregulation of miR‑199a‑5p favors the UPR against hypoxia‑induced ER stress in CCHD, which contributes to myocardial protection.

Downregulated endogenous sulfur dioxide/aspartate aminotransferase pathway is involved in angiotensin II-stimulated cardiomyocyte autophagy and myocardial hypertrophy in mice

BackgroundThe study was designed to investigate if endogenous sulfur dioxide (SO2) was involved in cardiomyocyte autophagy and myocardial hypertrophy stimulated by angiotensin II (Ang II). MethodsThirty-two C57 mice were randomly divided into control, SO2, Ang II and Ang II+SO2 groups. Human myocardial cell line H9c2 was divided into four groups including control, SO2, Ang II and Ang II+SO2 groups. Blood pressure and myocardial hypertrophy of the mice were measured two weeks after Ang II administration. LC3 II/I ratio, and Beclin1, Atg4B and p62 expressions were determined both in vivo and in vitro. Autophagosome was observed in H9c2 cells with confocal microscope. Endogenous SO2 generation and aspartate aminotransferase (AAT) expression were measured. ResultsIn animal studies, hypertension and myocardial hypertrophy developed two weeks after Ang II administration. LC3 II/I ratio and Beclin1 and Atg4B expressions were markedly elevated (P all <0.05), but p62 expression was lowered (P<0.05) both in vivo and in vitro. Compared with control group, endogenous SO2 levels, AAT activity and AAT2 expression were obviously down-regulated (P all <0.05). However, SO2 donor significantly reduced Ang II-induced myocardial hypertrophy in mice. LC3 II/I ratio and Beclin1 and Atg4B expressions were down-regulated (P all <0.05) but p62 expression was significantly increased (P<0.05) in the presence of SO2 both in vivo and in vitro. ConclusionDown-regulated endogenous SO2/AAT2 pathway might be involved in the pathogenesis of myocardial hypertrophy. SO2 prevented Ang II -induced myocardial hypertrophy accompanied by down-regulating cardiomyocyte autophagy.

MicroRNA-208a in an early stage myocardial infarction rat model and the effect on cAMP-PKA signaling pathway.

The expression level of microRNA-208a (miR-208a) in a rat model with myocardial infarction and the effect of cAMP-PKA signaling pathway in early stage of myocardial infarction in rats were investigated. The early myocardial infarction model was established in 12 male Sprague-Dawley rats by ligation of the anterior descending coronary artery, and 12 rats were selected as the control group (sham operation group). Reverse-transcription quantitative PCR was conducted to detect the expression levels of miR-208a in the myocardium of and the expression levels of miR-208a in the serum of rats in the two groups. Western blot analysis was used to evaluate the expression levels of cAMP-PKA protein in the rat tissues in the two groups. After stimulating high levels of miR-208a expression in human myocardial cells (HCM), western blot analysis was used to detect the cAMP-PKA protein levels. The expression levels of miR-208a in myocardial tissues in rats with myocardial infarction were significantly higher than those in the control group, and the difference was statistically significant (P<0.05). The expression levels of miR-208a in the early stage of myocardial infarction rats were also significantly higher than those in the control group, and the difference was statistically significant (P<0.05). The level of cAMP-PKA protein in myocardial tissue in rats with chronic myocardial infarction was also significantly higher. Transfection of human myocardial cells with miR-208a analogue significantly increased the cAMP-PKA protein levels in human myocardial cells. In conclusion, the over expression of miR-208a in myocardial infarction tissue and the high levels of this miRNA in the serum, may be involved in the process of myocardial infarction by influencing the cAMP-PKA signaling pathway in myocardial cells.

3,3′,5-triiodothyroxine inhibits apoptosis and oxidative stress by the PKM2/PKM1 ratio during oxygen-glucose deprivation/reperfusion AC16 and HCM-a cells: T3 inhibits apoptosis and oxidative stress by PKM2/PKM1 ratio

Oxidative stress (OS) plays a crucial role in the development of myocardial disease, which can induce the dysfunction of cardiac muscle cells. 3,3′,5-triiodothyroxine (T3) is a hormone secreted from the thyroid gland that has been shown to protect cells by improving the redox state and to regulate the expression of pyruvate kinase muscle isozyme (PKM, including two isoforms PKM1 and PKM2). The present study aimed to reveal the key effects of T3 on protecting human myocardial cell lines from oxidative stress and the downstream molecular mechanism. An oxygen-glucose deprivation/reperfusion model (OGDR) and three subtypes of the deiodinase family (DIO1, DIO2, and DIO3), which convert thyroxine (T4) to T3, were tested in this model. Our results show that the expression of DIO1, DIO2 and T3 was downregulated, but DIO3 was upregulated in OGDR-treated AC16 and HCM-a cells. Then, OGDR-treated cells were treated with T3 and T4. The results show that T3 inhibited the expression of reactive oxygen species (ROS) and malonic dialdehyde (MDA), but upregulated glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). The effects of T4 were not notable. T3 also protected OGDR cells from apoptosis and upregulated the PKM2/PKM1 ratio. Further mechanistic studies found that PKM2 inhibition by small interfering RNA (siRNA) could attenuate the anti-OS and anti-apoptotic effects of T3. These findings suggest that T3 can inhibit apoptosis and oxidative stress in OGDR-treated AC16 and HCM-a cells by regulating the PKM2/PKM1 ratio.

Progress in research on defective protein trafficking and functional restoration in HERG-associated long QT syndrome

The human ether-a-go-go related gene (HERG) encodes the α -subunit of the rapid component of the delayed rectifier K(+) channel, which is essential for the third repolarization of the action potential of human myocardial cells. Mutations of the HERG gene can cause type II hereditary long QT syndrome (LQT2), characterized by prolongation of the QT interval, abnormal T wave, torsade de pointes, syncope and sudden cardiac death. So far more than 300 HERG mutations have been identified, the majority of which can cause LQT2 due to HERG protein trafficking defect. It has been reported that certain drugs can induce acquired long QT syndrome through directly blocking the pore and/or affecting the HERG trafficking. The trafficking defects and K(+) currents can be restored with low temperature and certain drugs. However, the mechanisms underlying defective trafficking caused by HERG mutations and the inhibition/restoration of HERG trafficking by drugs are still unknown. This review summarizes the current understanding of the molecular mechanisms including HERG trafficking under physiological and pathological conditions, and the effects of drugs on the HERG trafficking, in order to provide theoretical evidence for the diagnosis and treatment of long QT syndrome.