Department of Pathology and Laboratory Medicine (H.M., S.Y., Y.Z., T.F., Z.L., C.Y., J.M.T., L.Q., J.L.), University of North Carolina at Chapel Hill.
McAllister Heart Institute (H.M., S.Y., Y.Z., T.F., Z.L., C.Y., J.M.T., L.Q., J.L.), University of North Carolina at Chapel Hill.
Circulation. 2019 Apr 2;139(14):1725-1740. doi: 10.1161/CIRCULATIONAHA.118.037803.
Hypertrophic response to pathological stimuli is a complex biological process that involves transcriptional and epigenetic regulation of the cardiac transcriptome. Although previous studies have implicated transcriptional factors and signaling molecules in pathological hypertrophy, the role of RNA-binding protein in this process has received little attention.
Here we used transverse aortic constriction and in vitro cardiac hypertrophy models to characterize the role of an evolutionary conserved RNA-binding protein Lin28a in pathological cardiac hypertrophy. Next-generation sequencing, RNA immunoprecipitation, and gene expression analyses were applied to identify the downstream targets of Lin28a. Epistatic analysis, metabolic assays, and flux analysis were further used to characterize the effects of Lin28a and its downstream mediator in cardiomyocyte hypertrophic growth and metabolic remodeling.
Cardiac-specific deletion of Lin28a attenuated pressure overload-induced hypertrophic growth, cardiac dysfunction, and alterations in cardiac transcriptome. Mechanistically, Lin28a directly bound to mitochondrial phosphoenolpyruvate carboxykinase 2 ( Pck2) mRNA and increased its transcript level. Increasing Pck2 was sufficient to promote hypertrophic growth similar to that caused by increasing Lin28a, whereas knocking down Pck2 attenuated norepinephrine-induced cardiac hypertrophy. Epistatic analysis demonstrated that Pck2 mediated, at least in part, the role of Lin28a in cardiac hypertrophic growth. Furthermore, metabolomic analyses highlighted the role for Lin28a and Pck2 in promoting cardiac biosynthesis required for cell growth.
Our study demonstrates that Lin28a promotes pathological cardiac hypertrophy and glycolytic reprograming, at least in part, by binding to and stabilizing Pck2 mRNA.
病理性刺激引起的肥厚反应是一个复杂的生物学过程，涉及心脏转录组的转录和表观遗传调控。尽管先前的研究已经表明转录因子和信号分子在病理性肥厚中起作用，但 RNA 结合蛋白在这一过程中的作用却很少受到关注。
在这里，我们使用横主动脉缩窄和体外心肌肥厚模型来描述进化保守的 RNA 结合蛋白 Lin28a 在病理性心肌肥厚中的作用。应用下一代测序、RNA 免疫沉淀和基因表达分析来鉴定 Lin28a 的下游靶标。上位性分析、代谢测定和通量分析进一步用于描述 Lin28a 及其下游介体在心肌细胞肥厚生长和代谢重塑中的作用。
心脏特异性敲除 Lin28a 可减轻压力超负荷诱导的肥厚生长、心脏功能障碍和心脏转录组改变。在机制上，Lin28a 直接与线粒体磷酸烯醇丙酮酸羧激酶 2（Pck2）mRNA 结合并增加其转录水平。增加 Pck2 足以促进类似于增加 Lin28a 引起的肥厚生长，而敲低 Pck2 则减弱去甲肾上腺素诱导的心肌肥厚。上位性分析表明，Pck2 介导了 Lin28a 在心脏肥厚生长中的作用，至少部分是这样。此外，代谢组学分析强调了 Lin28a 和 Pck2 在促进心脏生物合成以满足细胞生长所需的作用。
我们的研究表明，Lin28a 通过与 Pck2 mRNA 结合并稳定其水平，促进病理性心肌肥厚和糖酵解重编程，至少部分是这样。
