Table_11_PERM1 regulates energy metabolism in the heart via ERRα/PGC−1α axis.docx

AimsPERM1 is a striated muscle-specific regulator of mitochondrial bioenergetics. We previously demonstrated that PERM1 is downregulated in the failing heart and that PERM1 positively regulates metabolic genes known as targets of the transcription factor ERRα and its coactivator PGC-1α in cultured cardiomyocytes. The aims of this study were to determine the effect of loss of PERM1 on cardiac function and energetics using newly generated Perm1-knockout (Perm1–/–) mice and to investigate the molecular mechanisms of its transcriptional control.Methods and resultsEchocardiography showed that ejection fraction and fractional shortening were lower in Perm1–/– mice than in wild-type mice (both p < 0.05), and the phosphocreatine-to-ATP ratio was decreased in Perm1–/– hearts (p < 0.05), indicating reduced contractile function and energy reserves of the heart. Integrated proteomic and metabolomic analyses revealed downregulation of oxidative phosphorylation and upregulation of glycolysis and polyol pathways in Perm1–/– hearts. To examine whether PERM1 regulates energy metabolism through ERRα, we performed co-immunoprecipitation assays, which showed that PERM1 bound to ERRα in cardiomyocytes and the mouse heart. DNA binding and reporter gene assays showed that PERM1 was localized to and activated the ERR target promoters partially through ERRα. Mass spectrometry-based screening in cardiomyocytes identified BAG6 and KANK2 as potential PERM1’s binding partners in transcriptional regulation. Mammalian one-hybrid assay, in which PERM1 was fused to Gal4 DNA binding domain, showed that the recruitment of PERM1 to a gene promoter was sufficient to activate transcription, which was blunted by silencing of either PGC-1α, BAG6, or KANK2.ConclusionThis study demonstrates that PERM1 is an essential regulator of cardiac energetics and function and that PERM1 is a novel transcriptional coactivator in the ERRα/PGC-1α axis that functionally interacts with BAG6 and KANK2.

AimsPERM1为一种特异性调节线粒体生物能的横纹肌调节因子。我们先前证实，在心功能不全的心脏中PERM1表达下调，并且PERM1在培养的心肌细胞中正向调节被称为转录因子ERRα及其共激活因子PGC-1α靶点的代谢基因。本研究旨在利用新近构建的Perm1敲除（Perm1–/–）小鼠模型，确定PERM1缺失对心脏功能与能量代谢的影响，并探究其转录调控的分子机制。研究方法与结果：超声心动图显示，与野生型小鼠相比，Perm1–/–小鼠的射血分数和缩短分数显著降低（均p < 0.05），而Perm1–/–心脏中的磷酸肌酸与ATP比值下降（p < 0.05），提示心脏收缩功能和能量储备减弱。整合蛋白质组学和代谢组学分析揭示了Perm1–/–心脏中氧化磷酸化下调及糖酵解和多元醇途径上调。为考察PERM1是否通过ERRα调节能量代谢，我们进行了共免疫沉淀实验，结果显示PERM1在心肌细胞和小鼠心脏中与ERRα结合。DNA结合和报告基因实验表明，PERM1通过ERRα部分定位于并激活ERR靶基因启动子。基于质谱技术的筛选在心肌细胞中鉴定了BAG6和KANK2为PERM1转录调控中的潜在结合伙伴。哺乳动物单杂交实验中，将PERM1与Gal4 DNA结合域融合，表明PERM1招募至基因启动子足以激活转录，而PGC-1α、BAG6或KANK2的沉默则削弱了这一转录激活作用。结论：本研究证实了PERM1是心脏能量和功能的重要调节因子，并且PERM1是ERRα/PGC-1α轴中的一种新型转录共激活因子，在功能上与BAG6和KANK2相互作用。