Heat shock protein 22 reduces phenylephrine-induced cardiomyocytes hypertrophy

Abstract

Objective \nTo investigate the effect of Hsp22 on phenylephrine-induced cardiomyocytes hypertrophy. \n \n \nMethods \nPrimary rat myocardial cells were isolated and cultured in Department of Cardiology, the First Affiliated Hospital of Zhengzhou University. Cells were divided into four groups randomly: Control group, model group, treatment group with 1 μg/mL Hsp22, and treatment group with 10 μg/mL Hsp22. Phenylephrine stimuli was used to induce cardiomyocytes hypertrophy model. Cell viability was measured by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cardiomyocytes surface area was evaluated by α-actin immunofluorescence staining. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the transcription level of hypertrophic markers. Reactive oxygen species level was detected by 2 ,7 -Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescent probe. Apoptosis was detected by TUNEL staining. Signal pathway protein expression was detected by Western blot. SPSS 13.0 was used for statistical analysis. Data were expressed as mean ± standard deviation. All data were analyzed by one-way ANOVA between groups. Comparisons between two groups were performed using LSD-t test. A P<0.05 was considered statistically significant. \n \n \nResults \nDifferent concentrations of Hsp22 had no effect on cardiomyocytes viability (F=6.622; P>0.05). Phenylephrine stimulation significantly increased cardiomyocytes area (t=10.80; P<0.05), increased the transcription level of hypertrophy markers atrial natriuretic peptide (t=37.72; P<0.05), type B natriuretic peptide (t=16.85; P<0.05), and myosin heavy chain beta (t=41.53; P<0.05). Different concentrations of Hsp22 significantly reduced cardiomyocytes area (PE+1 μg/mL Hsp22 t=4.018; P<0.05; PE+10 μg/mL Hsp22 t=10.80; P<0.05), reduced the transcription level of hypertrophic markers atrial natriuretic peptide (PE+1 μg/mL Hsp22 t=27.12, P<0.05; PE+10 μg/mL Hsp22 t=37.72, P<0.05), type B natriuretic peptide (PE+1 μg/mL Hsp22 t=4.82, P<0.05; PE+10 μg/mL Hsp22 t=12.74, P<0.05), and myosin heavy chain beta ( PE+1 μg/mL Hsp22 t=23.68, P<0.05; PE+10 μg/mL Hsp22 t=30.54, P<0.05). Western blot showed that Hsp22 increased the activation of AMP-activated protein kinase α (PE+1 μg/mL Hsp22 t=5.89, P<0.05; PE+10 μg/mL Hsp22 t=5.88, P<0.05), reduced mTOR phosphorylation level (PE+1 μg/mL Hsp22 t=16.80, P<0.05; PE+10 μg/mL Hsp22 t=20.46, P<0.05). \n \n \nConclusions \nHsp22 inhibits cardiomyocytes hypertrophy by activating AMP-activated protein kinase α. Hsp22 may become a potential anti-hypertrophic drug. \n \n \nKey words: \nHeat shock protein 22;\xa0Phenylephrine;\xa0Cardiomyocytes hypertrophy;\xa0Oxidative stress;\xa0AMP-activated protein kinase α