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Abstract Objectives To explore the role and possible mechanisms of action of apolipoprotein O (APOO) in autophagy in Myocardial Infarction (MI) in vivo and in vitro. Methods Differential gene expression and single Gene Set Enrichment Analysis (GSEA) were used to evaluate MI-related candidate genes. Animal and cell MI models were established. Sh-APOO, si-APOO, and SB203580 were used to inhibit the expression of APOO or p38MAPK. Western blot and qRT-PCR were used to analyze the expression levels of the target protein or mRNA. Apoptosis was observed using the TUNEL assay. The plasma concentrations of CK-MB and cTn-I in humans and mice were determined. Results In the GSE23294 dataset, APOO mRNA was highly expressed in the left ventricle of mice with MI; GSEA revealed that APOO was positively correlated with p38MAPK, autophagy, and apoptosis. The plasma concentration of APOO in patients with MI was significantly higher than that in healthy subjects. The expression of APOO, Beclin-1, LC3, and Bax in mouse and AC16 cell MI models increased, while the level of Bcl-2 decreased. After silencing the APOO gene, the expression of APOO was downregulated; meanwhile, changes in autophagy, apoptosis and myocardial cell injury were reversed in vivo and in vitro. Furthermore, autophagy was alleviated after AC16 cells were treated with SB203580. Conclusions The increased APOO expression in mouse and cell MI models may activate autophagy and apoptosis by regulating the p38MAPK signaling pathway, thus aggravating the myocardial injury. HIGHLIGHTS APOO was highly expressed in the left ventricle of mice with myocardial infarction. Increasing of APOO may activate autophagy and apoptosis in myocardial infarction. The regulation of APOO in autophagy and apoptosis was regulated by p38MAPK signaling pathway.
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Abstract Background: Pioglitazone has been widely used as an insulin-sensitizing agent for improving glycemic control in patients with type 2 diabetes mellitus. However, cardiovascular risk and protective effects of pioglitazone remain controversial. Objectives: In this study, we investigated whether pioglitazone affects cardiomyocyte apoptosis and hypertrophy by regulating the VEGFR-2 signaling pathway. Methods: Cardiomyocytes were enzymatically isolated from 1- to 3-day-old Sprague-Dawley rat ventricles. Effects of pioglitazone and the VEGFR-2-selective inhibitor apatinib on cardiomyocyte apoptotic rate was determined using flow cytometry, and hypertrophy was evaluated using [3H]-leucine incorporation. The protein expressions of unphosphorylated and phosphorylated VEGFR-2, Akt, P53, and mTOR were determined by Western-Blotting. Analysis of variance (ANOVA) was used to assess the differences between groups. Results: Pioglitazone and VEGFR-2-selective inhibitor apatinib reduced rat cardiomyocyte viability and cardiomyocyte hypertrophy induced by angiotensin II in vitro. Furthermore, in the same in vitro model, pioglitazone and apatinib significantly increased the expression of Bax and phosphorylated P53 and decreased the expression of phosphorylated VEGFR-2, Akt, and mTOR, which promote cardiomyocyte hypertrophy. Conclusions: These findings indicate that pioglitazone induces cardiomyocyte apoptosis and inhibits cardiomyocyte hypertrophy by modulating the VEGFR-2 signaling pathway.
Resumo Fundamento: A pioglitazona tem sido amplamente utilizada como droga sensibilizadora da insulina para melhorar o controle glicêmico em pacientes com diabetes mellitus tipo 2. No entanto, o risco cardiovascular bem como os efeitos protetores da pioglitazona ainda são controversos. Objetivos: Neste estudo, investigamos se os efeitos da pioglitazona sobre a apoptose e a hipertrofia de cardiomiócitos ocorrem via regulação da via de sinalização do VEGFR-2. Métodos: os cardiomiócitos foram isolados enzimaticamente dos ventrículos de ratos Sprague-Dawley de 1-3 anos de vida. Os efeitos da pioglitazona e do inibidor seletivo de VEGFR-2 apatinib sobre a taxa de apoptose dos cardiomiócitos foram avaliados por citometria de fluxo, e a hipertrofia avaliada por incorporação de leucina-[3H]. As expressões de VEGFR-2, Akt, P53, e mTOR fosforiladas e não fosforiladas foram determinadas por Western Blotting. Análise de variância (ANOVA) foi usada para avaliar diferenças entre os grupos. Resultados: a pioglitazona e o apatinib reduziram a viabilidade e a hipertrofia de cardiomiócitos induzida por angiotensina II in vitro. Além disso, no mesmo modelo in vitro, a pioglitazona e o apatinib aumentaram significativamente a expressão de Bax e P53 fosforilada, e diminuiu a expressão de VEGFR-2, Akt, e mTOR, que promove hipertrofia de cardiomiócitos. Conclusões: Esses resultados indicam que a pioglitazona induz a apoptose e inibe a hipertrofia de cardiomiócitos pela modulação da via de sinalização de VEGFR-2.