神经肽Y1受体亚型经CaMKⅡ-MEF2途径诱导心肌细胞肥大

Neuropeptide Y1 receptor subtype induces cardiomyocyte hypertrophy via CaMK Ⅱ-MEF2 pathway

目的探讨神经肽Y（NPY）Y1受体亚型在心肌肥大中的作用，并探讨can^2＋／CaM-CaMKⅡ-MEF2信号途径在其中的作用。方法用不同浓度的NPY或Y1受体激动剂Leu31，Pr034NPY刺激原代培养的SD乳鼠心肌细胞；氚-亮氨酸（^3H-Leu）掺入量法测定心肌细胞蛋白质合成速率；荧光定量PCR法测肥大相关基因ANF以及β-MHC mRNA的表达；免疫荧光染色法检测心肌细胞表面积及心肌细胞MEF2表达。结果Leu31，Pr034NPY与NPY的作用相似：两者均使心肌细胞。H-Leu掺人量显著增加（P〈0．05），心肌细胞ANF以及13-MHC mRNA表达明显上调（P〈0．05），心肌细胞表面积显著增加[（2270．93±80．09）μm^2比（3340．64±101．06）μm^2；（2256．57±57．0）／am0比（2915．48±43．39）／μm^2；均为P〈0．05]。 CaMK Ⅱ抑制剂KN-93可有效阻断Leu31，Pro34 NPY对心肌细胞蛋白合成速率和肥大基因表达的刺激作用。Leu31，Pr034 NPY刺激24h，心肌细胞MEF2表达量显著增加（P〈0．05）。结论神经肽Y。受体亚型经Ca^2＋／CaM-CaMKⅡ-MEF2信号途径诱导心肌肥大。

Objective To investigate the effect of neuropeptide Y （NPY） Y1 receptor subtype on cardiac hypertrophy, and to determine the role of Ca^2＋/CaM-CaMK Ⅱ-MEF： signaling pathway in this process. Methods The primary cultured SD rat cardiomyocytes were stimulated with different concentrations of NPY or YI receptor agonists, Leu31 and Pro34 NPY. The ^3Tritium-leueine （^3H-Leu） incorporation assay was used to assess the rate of protein synthesis in cardiomyocytes. The mRNA expressions of the hypertrophy-related genes ANF and β-MHC were measured by fluorescence quantitative PCR. The immunofluorescence staining was used to determine the surface area of cardiomyocytes and expression of cardiomyocyte MEF2. Results The effects of Leu31, Pro34 NPY and NPY were similar. Both of them significantly increased the incorporation of eardiomyocytes ^3H-Leu （P〈0.05）. The mRNA expressions of cardiomyocytes ANF and 13- MHC were significantly up-regulated （P〈0.05）. The surface area of cardiomyocytes significantly increased [ （2 270.93±80.09）pm2 vs （3 340.64±101.06）μm^2; （2 256.57±57.0）μm^2 vs （2 915.48±43.39）μm^2; all P〈 0.05]. The CaMK Ⅱ inhibitor KN-93 could effectively block the stimulatory effects of Leu31 and Pro34 NPY on protein synthesis rate and hypertrophy gene expression in cardiomyocytes. The expression of MEF2 in cardiomyocytes remarkably increased after stimulation of Leu31 and Pro34 NPY for 24 h （P〈0.05）. Conclusion The neuropeptide Y1 receptor subtype induces cardiac hypertrophy via Ca^2＋/CaM-CaMK Ⅱ-MEF2signalingpathway.