Abstract.Resistin has been previously demonstrated to induce cardiac hypertrophy, however, the underlying molecular mechanisms of resistin-induced cardiac hypertrophy remain unclear. Using H9c2 cells, the present study investigated the liver kinase B1 (LKB1)/adenosine monophosphate-activated protein kinase (AMPK) signaling pathway for a potential role in mediating resistin-induced cardiomyocyte hypertrophy. Treatment of H9c2 cells with resistin increased cell surface area, protein synthesis, and expression of hypertrophic marker brain natriuretic peptide and β-myosin heavy chain. Treatment with metformine attenuated these effects of resistin. Furthermore, treatment with resistin decreased phosphorylation of LKB1 and AMPK, whereas pretreatment with metformin increased phosphorylation of LKB1 and AMPK that is reduced by resistin. These results suggest that resistin induces cardiac hypertrophy through the inactivation of the LKB1/AMPK cell signaling pathway.

Abstract. It has been reported that resistin induces, whereas apelin inhibits cardiac hypertrophy. However, the underlying molecular mechanisms of apelin inhibiting resistin-induced cardiac hypertrophy remain unclear. The aim of the current study is to investigate the effects of apelin on resistin-induced cardiomyocyte hypertrophy and elucidate the underlying molecular mechanism. H9c2 cells were used in the present study, and cell surface area and protein synthesis were evaluated. Reverse transcription-quantitative polymerase chain reaction was performed to analyze the expression levels of hypertrophic markers, brain natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC). In addition, western blotting was conducted to examine phosphorylation of extracellular signal-regulated kinase (ERK)1/2. Following treatment of H9c2 cells with resistin, cell surface area, protein synthesis, and BNP and β-MHC mRNA expression levels were increased. Subsequent to co-treatment of H9c2 cells with apelin and resistin, lead to the inhibition of resistin-induced hypertrophic effects by apelin. In addition, treatment with resistin increased phosphorylation of ERK1/2, whereas pretreatment with apelin decreased phosphorylation of ERK1/2, which was increased by resistin. These results indicate that resistin-induced cardiac hypertrophy is inhibited by apelin via inactivation of ERK1/2 cell signaling.

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Bone morphogenetic protein-4 (BMP4) is a member of the bone morphogenetic protein family which plays an important role in bone formation, inflammation and cardiac hypertrophy. The aim of this study was to investigate the underlying molecular mechanism that BMP4-induced cardiomyocyte hypertrophy. H9c2 cells were used to measure cell surface area and protein synthesis. Western blot was used to examine hypertrophic marker brain natriuretic peptide (BNP) protein expression and phosphorylation of ERK1/2. The results exhibited that cell surface area, protein synthesis and BNP protein expression were increased with BMP4 treatment. While PD98059 inhibited these effects of BMP4. In addition, BMP4 treatment increased phosphorylation of ERK1/2 in a time-and dose-dependent manner. PD98059 treatment decreased phosphorylation of ERK1/2 that was increased by BMP4. These results suggest that BMP4 induces cardiomyocyte hypertrophy through the activation of ERK1/2 cell signaling pathway.

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