Department of Cardiology, The First Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China.
Department of Cardiology, Linfen People's Hospital, Linfen, Shanxi 041000, P.R. China.
Int J Mol Med. 2017 Aug;40(2):499-504. doi: 10.3892/ijmm.2017.3038. Epub 2017 Jun 22.
The model of urotensin II (UII)-induced cardiomyocyte hypertrophy has been widely used in studies on hypertrophy. However, the molecular mechanisms responsible for UII-induced cardiomyocyte hypertrophy have not yet been fully elucidated. It has been demonstrated that cardiomyocyte hypertrophy induced by UII is associated with changes in the intracellular Ca2+ concentration. In the present study, we investigated whether the cAMP-dependent protein kinase A (PKA)‑mediated upregulation of the phosphorylation levels of phospholamban (PLN) at Ser16 contributes to UII-induced cardiomyocyte hypertrophy. After primary cultures of neonatal rat cardiomyocytes were exposed to UII for 48 h, cell size, protein/DNA contents and intracellular Ca2+ levels were detected. Western blot analysis was used to quantify the phosphorylated and total forms of PKA, PLN and the total amount of sarco/endoplasmic reticulum Ca2+-ATPase (SERCA)2a. UII increased the cell size, the protein/DNA ratio and the intracellular Ca2+ levels, consistent with the characteristics of hypertrophic response. In addition, exposure to UII upregulated the phosphorylation levels of PKA, and the expression levels of its downstream proteins, PLN and SERCA2a. However, treatment with PKA inhibitor (KT-5720) reversed all these effects of UII. On the whole, our results suggest that UII induces cardiomyocyte hypertrophy through the PKA-mediated upregulation of PLN phosphorylation at Ser16, which provides a new experimental foundation for the prevention and/or treatment of cardiac hypertrophy.
尾加压素 II（UII）诱导的心肌细胞肥大模型已广泛应用于肥大研究。然而，导致 UII 诱导的心肌细胞肥大的分子机制尚未完全阐明。已经证明，UII 诱导的心肌细胞肥大与细胞内 Ca2+浓度的变化有关。在本研究中，我们研究了 cAMP 依赖性蛋白激酶 A（PKA）介导的磷酸化水平是否上调磷蛋白（PLN）在 Ser16 处的磷酸化水平对 UII 诱导的心肌细胞肥大的作用。在原代培养的新生大鼠心肌细胞暴露于 UII 48 h 后，检测细胞大小、蛋白/DNA 含量和细胞内 Ca2+水平。Western blot 分析用于定量 PKA、PLN 和肌浆/内质网 Ca2+-ATP 酶（SERCA）2a 的总蛋白和磷酸化形式。UII 增加了细胞大小、蛋白/DNA 比值和细胞内 Ca2+水平，符合肥大反应的特征。此外，暴露于 UII 可上调 PKA 的磷酸化水平，以及其下游蛋白 PLN 和 SERCA2a 的表达水平。然而，PKA 抑制剂（KT-5720）处理逆转了 UII 的所有这些作用。总的来说，我们的结果表明，UII 通过 PKA 介导的 PLN 在 Ser16 处的磷酸化水平上调诱导心肌细胞肥大，这为预防和/或治疗心肌肥大提供了新的实验基础。
