MAP4K4 exacerbates cardiac microvascular injury in diabetes by facilitating S-nitrosylation modification of Drp1.

Dynamin-related protein 1 (Drp1) is a crucial regulator of mitochondrial dynamics, the overactivation of which can lead to cardiovascular disease. Multiple distinct posttranscriptional modifications of Drp1 have been reported, among which S-nitrosylation was recently introduced. However, the detailed regulatory mechanism of S-nitrosylation of Drp1 (SNO-Drp1) in cardiac microvascular dysfunction in diabetes remains elusive. The present study revealed that mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) was consistently upregulated in diabetic cardiomyopathy (DCM) and promoted SNO-Drp1 in cardiac microvascular endothelial cells (CMECs), which in turn led to mitochondrial dysfunction and cardiac microvascular disorder. Further studies confirmed that MAP4K4 promoted SNO-Drp1 at human C644 (mouse C650) by inhibiting glutathione peroxidase 4 (GPX4) expression, through which MAP4K4 stimulated endothelial ferroptosis in diabetes. In contrast, inhibition of MAP4K4 via DMX-5804 significantly reduced endothelial ferroptosis, alleviated cardiac microvascular dysfunction and improved cardiac dysfunction in db/db mice by reducing SNO-Drp1. In parallel, the C650A mutation in mice abolished SNO-Drp1 and the role of Drp1 in promoting cardiac microvascular disorder and cardiac dysfunction. In conclusion, our findings demonstrate that MAP4K4 plays an important role in endothelial dysfunction in DCM and reveal that SNO-Drp1 and ferroptosis activation may act as downstream targets, representing potential therapeutic targets for DCM.

P16INK4a deletion alleviates contrast-induced acute kidney injury by ameliorating renal cell apoptosis and suppressing inflammation and oxidative stress.

Contrast-induced acute kidney injury (CI-AKI) is the third leading cause of hospital-acquired acute kidney injury. Cellular senescence is associated with CI-AKI. P16INK4a (p16) is a cell cycle regulator and link to aging and senescence. We found that the expression of p16 was elevated in CI-AKI renal tissues, however its role in CI-AKI remains insufficiently understood. In this study, we used p16 knockout (p16KO) mice and wild-type (WT) littermates to establish CI-AKI mice model to elucidate the impact of p16 on CI-AKI. The results showed that serum creatinine (SCr), blood urea nitrogen (BUN), and serum neutrophil gelatinase-associated lipocalin (NGAL) levels were markedly reduced in p16KO CI-AKI mice. Both immunohistochemistry and western blot analyses confirmed that p16 knockout alleviated renal cell apoptosis. Furthermore, interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α (TNF-α) were attenuated by downregulating NLRP3 and NF-κB inflammasomes. Additionally, ROS levels were diminished via activating Nrf2/Keap-1 pathway in p16KO CI-AKI mice. Collectively, our findings suggest that p16 deletion exerts protective effects against apoptosis, inflammation, and oxidative stress in CI-AKI mice model, p16 deletion might be a potential therapeutic strategy for ameliorating CI-AKI.

Rosmarinic acid attenuates TNF-α induced cardiomyocyte injury via regulating miR-344a-3p.

To investigate whether rosmarinic acid protects cardiomyocytes from inflammatory damage through miRNAs, high-throughput sequencing and bioinformatics analysis were performed to identify TNF-α-induced inflammatory damage in cardiomyocytes and miRNAs differentially expressed in TNF-α-induced inflammatory injury in cardiomyocytes, and the bioinformatics analysis shown that the expression levels of 10 miRNAs were significantly up-regulated, and the expression levels of 6 miRNAs were significantly down-regulated. Among them, the expression level of miR-344a-3p was significantly up-regulated in the experimental group, while the expression level of miR-449c-5p was significantly down-regulated in experimental group of cells. The target genes of miR-344a-3p and miR-449c-5p were CCR1 and ATP2B4 respectively. The luciferase reporter system showed that luciferase activity in the WT-CCR1+miR-344a-3p mimic group was significantly decreased, and the expression of CCR1 was significantly decreased at mRNA and protein level after miR-344a-3p was transfected into H9C2 cells, indicating that TNF-α-induced inflammatory injury in cardiomyocytes, rosmarinic acid may up-regulate the expression of miR-344a-3p, thereby inhibiting the expression of CCR1 and ultimately protecting the cardiomyocytes from inflammatory damage. Thus, we thought that CCR1 might be a new therapeutic target for cardiomyocyte injury.

1,25(OH)2D3 ameliorates doxorubicin­induced cardiomyopathy by inhibiting the NLRP3 inflammasome and oxidative stress.

Doxorubicin (DOX), as a chemotherapy agent with marked therapeutic effect, can be used to treat certain types of cancer such as leukemia, lymphoma and breast cancer. However, the toxic effects of DOX on cardiomyocytes limit its clinical application. Oxidative stress has been documented to serve a pivotal role in DOX-induced cardiomyopathy. Previous studies have reported that 1,25(OH)2D3 has antioxidant and anti-inflammatory effects and can inhibit the renin-angiotensin system. However, the effects of 1,25(OH)2D3 on the pathophysiological processes of DOX-induced cardiomyopathy and its mechanisms remain poorly understood. To investigate these potential effects, C57BL/6J mice were used to construct a DOX-induced cardiomyopathy model and treated with 1,25(OH)2D3. At 4 weeks after the first injection of DOX, cardiac function and myocardial injury were evaluated by echocardiograph and ELISA. Masson's trichrome staining and RT-qPCR were used to assess myocardial fibrosis, and immunohistochemistry and western blotting were performed to analyze expression levels of inflammation and oxidative stress, and the NLRP3 inflammasome pathway. ChIP assay was used to assess the effects of 1,25(OH)2D3 on histone modification in the NLRP3 and Nrf2 promoters. The results showed that 1,25(OH)2D3 treatment increased LVEF and LVFS, reduced serum levels of BNP and cTnT, inhibited the collagen deposition and profibrotic molecular expression, and downregulated the levels of inflammatory cytokines in DOX-induced cardiomyopathy. ROS and antioxidant indices were also ameliorated after 1,25(OH)2D3 treatment. In addition, 1,25(OH)2D3 was found to inhibit the NLRP3 inflammasome and KEAP-Nrf2 pathways through regulation of the levels of H3K4me3, H3K27me3 and H2AK119Ub in the NLRP3 and Nrf2 promoters. In conclusion, the present study demonstrated that 1,25(OH)2D3 regulated histone modification in the NLRP3 and Nrf2 promoters, which in turn inhibits the activation of NLRP3 inflammasome and oxidative stress in cardiomyocytes, alleviating DOX-induced cardiomyopathy. Therefore, 1,25(OH)2D3 may be a potential drug candidate for the treatment of DOX-induced cardiomyopathy.

Inflammasome activation and metabolic remodelling in p16-positive aging cells aggravates high-fat diet-induced lung fibrosis by inhibiting NEDD4L-mediated K48-polyubiquitin-dependent degradation of SGK1.

BACKGROUND: Chronic changes caused by a high-fat diet (HFD) may be associated with weakened lung function in obese patients. However, few studies have focused on the role of senescent cells in HFD-induced pulmonary fibrosis. This study aimed to determine whether (i) obesity causes the accumulation of aging cells in the lungs, (ii) p16 accumulation in aging epithelial cells or fibroblasts exacerbates long-term HFD-induced senescence-associated pulmonary fibrosis (SAPF) and (iii) p16 deletion or clearance of aging cells ameliorates HFD-induced SAPF through inactivation of the inflammasome and metabolic remodelling. METHODS: Twelve-month old male mice of p16INK4a (hereafter p16) knockout (p16-- ) and wild-type (WT), ApoE knockout (ApoE-- ) and ApoE-- p16-- were fed a HFD to induce obesity, and the effects of treatment with the senolytic drug ABT263 or the SGK1 specific inhibitor EMD638683 on fibrosis, inflammaging, gene expression, integrin-inflammasome signalling and metabolism were examined. A549 and IMR-90 cells were transduced with p16-overexpressing adenovirus, and treated with palmitic and oleic acids (P&O) to induce steatosis in vitro. RESULTS: We found that long-term HFD promoted the expression of p16 and the increase of senescent cells in the lung. P16 knockout or ABT263 treatment alleviated pulmonary fibrosis, the increase of senescent cells and senescence-associated secretory phenotype (SASP) in HFD-fed mice, as well as in P&O-treated A549 and IMR-90 cells. RNA sequencing and bioinformatics analyses revealed that p16 knockout inhibited activation of the integrin-inflammasome pathway and cellular glycolysis. Mass spectrometry, co-immunoprecipitation and GST pull-down assays demonstrated that p16 bound to the N-terminal of SGK1, thereby interfering with the interaction between the E3 ubiquitin ligase NEDD4L and SGK1, and subsequently inhibiting K48-polyubiquitin-dependent degradation of SGK1 mediated by the NEDD4L-Ubch5 complex. EMD638683 was found to alleviate HFD-induced pulmonary fibrosis and activation of the integrin-inflammasome pathway. CONCLUSION: P16 accumulation promoted activation of integrin- inflammasome pathway and cell glycolysis by binding to the N- terminal of SGK1, intefering with the interaction between the E3 ubiquitin ligase NEDD4L and SGK1, thereby inhibiting K48- polyubiquitin- dependent degradation of SGK1 mediated by the NEDD4L-Ubch5 complex. ABT263 or EMD638683 could be used as potential drugs to treat pulmonary fibrosis in obese patients.

The crystallin alpha B (HSPB5)-tripartite motif containing 33 (TRIM33) axis mediates myocardial fibrosis induced by angiotensinogen II through transforming growth factor-ß (TGF-ß1)-Smad3/4 signaling.

Myocardial fibrosis, a common pathological manifestation of cardiac remodeling (CR), often leads to heart failure (HF) and even death. The underlying molecular mechanism of the role of TRIM33 in Ang II-induced myocardial fibrosis is not fully understood. We found that TRIM33 was specifically upregulated in CFs and myocardial tissue after Ang II stimulation. Adult mice induced by Ang II were used as in vivo models, and Ang II-induced neonatal mouse primary cardiac fibroblasts (CFs) were used as in vitro models. The level of CF fibrosis in vitro was assessed by CF proliferation, migration, activation and extracellular matrix (ECM) synthesis. In addition, Masson staining, the heart weight/body weight (HW/BW) ratio and echocardiography were used to evaluate the in vivo effect of TRIM33. TRIM33 expression was specifically upregulated in CFs and myocardial tissue after Ang II stimulation. In in vitro experiments, we found that TRIM33 knockdown promoted Ang II-induced CF proliferation, while TRIM33 overexpression weakened Ang II-induced CF proliferation, migration, activation and collagen synthesis. Mechanistically, we showed that TRIM33, negatively regulated by HSPB5, mediated its antifibrotic effect by inhibiting the activation of TGF-ß1 and its downstream genes, Smad3 and Smad4. Finally, TRIM33 overexpression suppressed fibrosis and promoted cardiac repair and functional recovery in Ang II-induced mice. Our results clearly establish that TRIM33 limits cardiac fibrosis by hindering CF proliferation, migration, activation and collagen synthesis. Enhancing these beneficial functions of TRIM33 by a targeting vector might be a novel therapeutic strategy for CR.

Roflumilast Attenuates Doxorubicin-Induced Cardiotoxicity by Targeting Inflammation and Cellular Senescence in Cardiomyocytes Mediated by SIRT1.

BACKGROUND AND PURPOSE: Cardiotoxicity is an important side effect of the treatment of a malignant tumor with Doxorubicin. Currently, decreasing the dosage of Doxorubicin to alleviate the side effects on cardiac function is the common method to deal with the cardiotoxicity induced by Doxorubicin. The present study aims to investigate the therapeutic effects of Roflumilast on Doxorubicin-induced inflammation and cellular senescence, as well as the potential mechanism in H9c2 myocardial cells. METHODS: The injured cardiac cell model was established by incubation with 5 µmol/L Doxorubicin. MTT was used to evaluate the cell viability of treated H9c2 cardiac cells. The expression of 4-HNE was determined using an immunofluorescence assay. The gene expression levels of IL-17, IL-6, TNF-α, IL-4, PAI-1, p21, and SIRT1 were evaluated using qRT-PCR and the protein levels of Gpx4, PAI-1, p21, and SIRT1 were determined using Western blot analysis. Secretions of IL-17, IL-6, TNF-α, IL-4, CK-MB, and cTnI were measured using ELISA. Cellular senescence was assessed using SA-ß-Gal staining. Si-RNA technology was used to knockdown the expression of SIRT1 in H9c2 cardiac cells. RESULTS: Cell viability of H9c2 cardiac cells was significantly inhibited by Doxorubicin but rescued by Roflumilast. The upregulated 4-HNE and downregulated Gpx4 were reversed by Roflumilast. The secretions of IL-6 and IL-17 were promoted by Doxorubicin and suppressed by Roflumilast. The increased SA-ß-Gal staining induced by Doxorubicin was inhibited by Roflumilast. P21 and PAI-1 were significantly upregulated and SIRT1 was greatly downregulated by Doxorubicin, all of which were reversed by Roflumilast. The anti-senescent effect of Roflumilast was abolished by knocking down SIRT1. CONCLUSION: Roflumilast might attenuate Doxorubicin-induced inflammation and cellular senescence in cardiomyocytes by upregulating SIRT1.

Resveratrol improves cardiac function by promoting M2-like polarization of macrophages in mice with myocardial infarction.

Macrophage polarization determines the transition from the inflammation phase to the inflammation resolution phase after myocardial infarction (MI). The aim of the present study was to investigate whether resveratrol (RSV) could inhibit the inflammatory mediators associated with the regulation of macrophage phenotypes and functions in MI mice. We initially discovered that RSV significantly improved cardiac function and suppressed the expression of fibrosis markers, such as collagen-I, collagen-III, and fibronectin, and pro-inflammatory cytokines, including interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α). RSV inhibited the expression of M1-like macrophage-related biomarkers (e.g., TNF-α and MCP-1) when bone marrow-derived macrophages (BMDMs) were stimulated with lipopolysaccharide (LPS) and interferon-γ (INF-γ). In contrast, it upregulated M2-like macrophage-related biomarkers (e.g., CD163 and Arg-1) when BMDMs were stimulated with interleukin-4 (IL-4) and interleukin-10 (IL-10). In addition, we found that RSV promoted M2-like macrophage polarization under anoxic conditions, which could be related to JAK2-SATA3 phosphorylation. In summary, RSV might promote anti-inflammatory M2-like polarization of macrophages after MI to improve cardiac function via the regulation of JAK2-SATA3 phosphorylation.

P16INK4a played a critical role in exacerbating acute tubular necrosis in acute kidney injury.

Acute kidney injury (AKI) is a common clinical syndrome with high morbidity and mortality, which is mostly caused by acute tubular necrosis (ATN). AKI is associated with many factors, including cell senescence, inflammatory infiltration, apoptosis and excessive accumulation of reactive oxygen species (ROS). P16INK4a (hereafter termed p16) inhibits cell cycle, and the absence of p16 can significantly slow the progression of cell senescence. We found that the expression of p16 was significantly increased after ATN. To determine whether p16 could exacerbate ATN degree and whether p16 deletion had protective effects against the ATN and renal dysfunction in AKI progression, glycerol-rhabdomyolysis-induced ATN was performed in eight-week-old p16 knockout and wild-type (WT) littermates. Their ATN phenotypes were analyzed; the levels of serum creatinine and serum urea nitrogen were detected; inflammation, cell apoptosis, ROS level and ROS signaling pathway molecules were examined using histopathological and molecular techniques. We found that compared to WT mice, p16 deletion has protective effects against the ATN phenotype and renal dysfunction in AKI progression through ameliorating inflammatory infiltration and proinflammatory factor expression by inhibiting NF-κB proinflammatory pathway, decreasing cell apoptosis by balancing the expressions between pro-apoptotic and anti-apoptotic molecules, and reducing ROS levels and downregulating ROS signaling pathway molecules including AIF, PGAM5 and KEAP1. Thus, p16 deletion or inhibition and p16 positive cell clearance would be a novel strategy for preventing ATN in AKI progression.

Protective effects of sodium tanshinone IIA sulfonate on cardiac function after myocardial infarction in mice.

Sodium tanshinone IIA sulfonate (STS), a water-soluble derivative of tanshinone IIA, has been used in traditional Chinese medicine for many years. Many experiments have demonstrated that STS has anti-inflammatory, anti-apoptosis and angiogenesis effects. However, it is unclear whether STS has the same beneficial effects on myocardial infarction in vivo. The aim of our experiments was to investigate whether STS could improve cardiac function and prevent myocardial remodeling after myocardial infarction (MI) in mice. The MI model was established by surgical ligation of the left anterior descending (LAD) coronary artery. Then the mice were randomly divided into STS and untreated groups. The results of treatment for 3 weeks showed that STS could increase the survival rate, reduce the release of some inflammatory cytokines, inhibit cell apoptosis and promote angiogenesis. The study presents a new potential treatment method for ischemic heart disease.

Hypoxia-Inducible Factor 1 alpha (HIF-1α)/Vascular Endothelial Growth Factor (VEGF) Pathway Participates in Angiogenesis of Myocardial Infarction in Muscone-Treated Mice: Preliminary Study.

BACKGROUND Angiogenesis plays a crucial role in myocardial infarction (MI) treatment by ameliorating myocardial remodeling, thus improving cardiac function and preventing heart failure. Muscone has been reported to have beneficial effects on cardiac remodeling in MI mice. However, the effects of muscone on angiogenesis in MI mice and its underlying mechanisms remain unknown. MATERIAL AND METHODS Mice were randomly divided into sham, MI, and MI+muscone groups. The MI mouse model was established by ligating the left anterior descending coronary artery. Mice in the sham group received the same procedure except for ligation. Mice were administered muscone or an equivalent volume of saline for 4 consecutive weeks. Cardiac function was evaluated by echocardiograph after MI for 2 and 4 weeks. Four weeks later, all mice were sacrificed and Masson's trichrome staining was used to assess myocardial fibrosis. Isolectin B4 staining was applied to evaluate the angiogenesis in mouse hearts. Immunohistochemistry, Western blot analysis, and quantitative real-time polymerase chain reaction (qPCR) were performed to analyze expression levels of HIF-1a and its downstream genes. RESULTS Compared with the MI group, muscone treatment significantly improved cardiac function and reduced myocardial fibrosis. Moreover, muscone enhanced angiogenesis in the peri-infarct region and p-VEGFR2 expression in the vascular endothelial cells. Western blot analysis and qPCR showed that muscone upregulated expression levels of HIF-1a and VEGFA. CONCLUSIONS Muscone improved cardiac function in MI mice through augmented angiogenesis. The potential mechanism of muscone treatment in regulating angiogenesis of MI mice was upregulating expression levels of HIF-1α and VEGFA.

Muscone improves cardiac function in mice after myocardial infarction by alleviating cardiac macrophage-mediated chronic inflammation through inhibition of NF-κB and NLRP3 inflammasome.

Muscone is the main active monomer of traditional Chinese medicine musk. Previous studies have reported a variety of beneficial effects of muscone. However, the effects of muscone on chronic inflammation after myocardial infarction (MI) are rarely reported. This study evaluated the anti-inflammatory effects of muscone on myocardial infarction by establishing a MI model in mice. We found that muscone remarkably decreased the levels of inflammatory cytokines (IL-1ß, TNF-α and IL-6), and ultimately improved cardiac function and survival rate. Furthermore, the main anti-inflammatory effect of muscone was alleviating cardiac macrophage-mediated inflammatory response in heart tissues after MI. Bone marrow-derived macrophages (BMDMs) induced with lipopolysaccharide (LPS) were used as an in vitro inflammation model to further clarify anti-inflammatory mechanisms of muscone. Muscone significantly downregulated the levels of LPS-induced inflammatory cytokines and inhibited NF-κB and NLRP3 inflammasome activation in BMDMs. Moreover, ROS and antioxidant indices in LPS-induced BMDMs were also ameliorated after muscone treatment. To sum up, our study found that muscone alleviated cardiac macrophage-mediated chronic inflammation by inhibiting NF-κB and NLRP3 inflammasome activation, thereby improving cardiac function in MI mice. Besides, the inhibitory effect of muscone on inflammation may be related to the scavenging of ROS. It is suggested that muscone may serve as a promising and effective drug for post-MI treatment.

Ad-HGF improves the cardiac remodeling of rat following myocardial infarction by upregulating autophagy and necroptosis and inhibiting apoptosis.

Cell death in MI is the most critical determinant of subsequent left ventricular remodeling and heart failure. Besides apoptosis, autophagy and necroptosis have been recently found to be another two regulated cell death styles. HGF has been reported to have a protective role in MI, but its impact on the three death styles remains unclear. Thus, our study was performed to investigate the distribution of autophagy, apoptosis and necroptosis in cardiac tissues after MI and explore the role and mechanism of Ad-HGF on cardiac remodeling by regulating the three death styles. We firstly showed the distribution of autophagy, apoptosis and necroptosis differs in temporal and spatial context after MI using immunofluorescence. Notably, Ad-HGF treatment improves the cardiac remodeling of SD rats following MI by preserving the heart function, reducing the scar size and aggresomes. Further mechanism study reveals Ad-HGF promotes autophagy and necroptosis and inhibits apoptosis in vivo and in vitro. Co-immunoprecipitation assays showed Ad-HGF treatment significantly decreased the binding of Bcl-2 to Beclin1 but enhanced Bcl-2 binding to Bax in H9c2 cells under hypoxia. Moreover, HGF-induced sequestration of Bax by Bcl-2 allows Bax to become inactive, thereby inhibiting apoptosis. In addition, Ad-HGF markedly increased the formation of Beclin1-Vps34-Atg14L complex, which accounted for promoting autophagy. Both the western blot and activity assay showed Ad-HGF significantly decreased the caspase 8 protein and activity levels, which obligated the cell to undergo necroptosis under hypoxia and block apoptosis. Thus, our findings offer new evidence and strategies for the treatment of MI and post-MI cardiac remodeling.

Necroptosis Induced by Ad-HGF Activates Endogenous C-Kit+ Cardiac Stem Cells and Promotes Cardiomyocyte Proliferation and Angiogenesis in the Infarcted Aged Heart.

BACKGROUND/AIMS: The discovery of c-kit+ cardiac stem cells (CSCs) provided us with new therapeutic targets to repair the damaged heart. However, the precise mechanisms regulating CSC proliferation and differentiation in the aged heart remained elusive. Necroptosis, a type of regulated cell death, has recently been shown to occur following myocardial infarction (MI); however, its effect on c-kit+ CSCs remains unknown. We investigated the effects of hepatocyte growth factor (HGF) and necroptosis on the proliferation and differentiation of endogenous c-kit+ CSCs in aged rat hearts following MI. METHODS: The c-kit+ CSCs and HGF/p-Met expression levels in neonatal, adult and aged rats were compared using immunofluorescence and Western blotting. Immediately after MI, adenovirus carrying the HGF gene (Ad-HGF) was injected into the left ventricular wall surrounding the infarct areas of the aged rat heart. The proliferation and differentiation of the endogenous c-kit+ CSCs were studied using immunofluorescence. The signalling pathways were analysed via Western blotting and ELISA. RESULTS: HGF/p-Met expression levels and c-kit+ CSC abundance gradually decreased with age. Ad-HGF promoted c-kit+ CSC differentiation into precursor cells of cardiomyocyte, endothelial and smooth muscle cell lineages and enhanced cardiomyocyte proliferation and angiogenesis in aged rats; these effects were reversed by the inhibition of necroptosis. Ad-HGF administration induced necroptosis by increasing the expression of receptor interacting protein kinase (RIP) 1 and receptor interacting protein kinase (RIP) 3 proteins in the infarcted heart. Moreover, Ad-HGF-induced necroptosis increased high-mobility group box 1 protein (HMGB1) levels and enhanced the abundance of c-kit+ cells in the bone marrow, which may partly account for the beneficial effect of necroptosis on the c-kit+ CSCs. CONCLUSION: Ad-HGF-induced necroptosis facilitated aged heart repair after MI by promoting c-kit+ CSC proliferation and differentiation. These findings may lead to the development of new methods for the treatment of ischaemic heart disease in aged populations.

Exogenous HGF Prevents Cardiomyocytes from Apoptosis after Hypoxia via Up-Regulating Cell Autophagy.

BACKGROUND: Hepatocyte growth factor (HGF) is widely known as a protective factor in ischemic myocardium, however HGF sensitive cellular mechanism remained ill-defined. Autophagy at early stage of hypoxia has been demonstrated to play a role in protecting myocardium both in vivo and vitro. We performed this study to investigate the association between the protective effect of HGF and autophagy. METHODS: Ventricular myocytes were isolated from neonatal rat heart (NRVMs). We evaluated cardiomyocytes apoptosis by Hoechst staining and flow cytometry. Autophagy was assessed by transmission electron microscope and mRFP-GFP-LC3 adenovirus infection. Mitochondrial membrane potential was estimated by JC-1 staining. Western blotting and ELISA assay were used to quantify protein concentrations. RESULTS: We found that autophagy in NRVMs increased at early stage after hypoxia and HGF release was consistent with the change of autophagy. Exogenous HGF enhanced autophagy and decreased apoptosis, while neutralizing HGF yielded opposite effects. Besides, inhibition of autophagy increased apoptosis of myocytes. Furthermore, exogenous HGF induced Parkin, the marker of mitochondrial autophagy, indicating increased clearance of injured mitochondria. CONCLUSIONS: Our results revealed a potential mechanism in which exogenous HGF prevented NRVMs from apoptosis after hypoxia. Upregulation of Parkin through administration of exogenous HGF may be a potential therapeutic strategy ptotecting myocytes during ischemia.

Puerarin improves cardiac function through regulation of energy metabolism in Streptozotocin-Nicotinamide induced diabetic mice after myocardial infarction.

It is well recognized that the incidence of heart failure and the risk of death is high in diabetic patients after myocardial infarction (MI). Accumulating evidence showed that puerarin (PUE) has protecting function on both cardiovascular disease and diabetes. The aim of this study is to explore whether puerarin could improve cardiac function in diabetic mice after MI and the underlying mechanism. The left anterior of Streptozotocin (STZ)-Nicotinamide (NA) induced diabetic mice were ligated permanently except for the Shame group. Then the operated mice were randomly treated with PUE or saline. Cardiac function was evaluated by echocardiograph before and at 1, 2, 4 weeks after MI. GLUT4/CD36/p-Akt/PPAR α of the heart was examined after treatment for 4 weeks. The results indicated that PUE significantly increased survival rate, improved cardiac function compared with MI group. Moreover, PUE increased expression and translocation of GLUT4 while attenuated expression and translocation of CD36. Western blot analysis showed that PUE enhanced phosphorylation of Akt and decreased PPAR α. This study demonstrated that PUE improved cardiac function after MI in diabetic mice through regulation of energy metabolism, the possible mechanism responsible for the effect of PUE was increasing the expression and translocation of GLUT4 while attenuating the expression and translocation of CD36.