Abstract：
Physiological and pathological cardiovascular processes are tightly regulated by several cellular mechanisms. Non-coding RNAs, including long non-coding RNAs (lncRNAs), represent one important class of molecules involved in regulatory processes within the cell. The lncRNA non-coding repressor of NFAT (NRON) was described as a repressor of the nuclear factor of activated T cells (NFAT) in different in vitro studies. Although the calcineurin/NFAT-signaling pathway is one of the most important pathways in pathological cardiac hypertrophy, a potential regulation of hypertrophy by NRON in vivo has remained unclear. Applying subcellular fractionation and RNA fluorescence in situ hybridization (RNA-FISH), we found that, unlike what is known from T cells, in cardiomyocytes, NRON predominantly localizes to the nucleus. Hypertrophic stimulation in neonatal mouse cardiomyocytes led to a downregulation of NRON, while NRON overexpression led to an increase in expression of hypertrophic markers. To functionally investigate NRON in vivo, we used a mouse model of transverse aortic constriction (TAC)-induced hypertrophy and performed NRON gain- and loss-of-function experiments. Cardiomyocyte-specific NRON overexpression in vivo exacerbated TAC-induced hypertrophy, whereas cardiomyocyte-specific NRON deletion attenuated cardiac hypertrophy in mice. Heart weight, cardiomyocyte cell size, hypertrophic marker gene expression, and left ventricular mass showed a NRON-dependent regulation upon TAC-induced hypertrophy. In line with this, transcriptome profiling revealed an enrichment of anti-hypertrophic signaling pathways upon NRON-knockout during TAC-induced hypertrophy. This set of data refutes the hypothesized anti-hypertrophic role of NRON derived from in vitro studies in non-cardiac cells and suggests a novel regulatory function of NRON in the heart in vivo.
摘要：
生理和病理心血管过程受到几种细胞机制的严格调节。非编码RNA,包括长链非编码RNA（lncRNAs），代表参与细胞内调节过程的一类重要分子。在不同的体外研究中，NFAT（NRON）的lncRNA非编码阻遏物被描述为活化T细胞核因子（NFAT）的阻遏物。尽管钙调磷酸酶/NFAT信号通路是病理性心肌肥大中最重要的通路之一,目前尚不清楚NRON在体内对肥大的潜在调节作用.应用亚细胞分级分离和RNA荧光原位杂交（RNA-FISH），我们发现,与已知的T细胞不同，在心肌细胞中，NRON主要定位于细胞核。新生小鼠心肌细胞的肥大刺激导致NRON的下调，而NRON过表达导致肥大性标志物表达增加。为了在体内功能研究NRON，我们使用了横主动脉缩窄(TAC)诱导的肥大小鼠模型,并进行了NRON功能增益和功能丧失实验.体内心肌细胞特异性NRON过表达加剧了TAC诱导的肥大，而心肌细胞特异性NRON缺失可减弱小鼠的心肌肥大。心脏重量，心肌细胞大小，肥大标记基因表达，在TAC诱导的肥大后，左心室质量显示出NRON依赖性调节。与此相符,转录组分析显示，在TAC诱导的肥大期间，NRON敲除后，抗肥大信号通路的富集。这组数据反驳了源自非心脏细胞中的体外研究的NRON的假设的抗肥大作用,并且暗示了NRON在体内心脏中的新的调节功能。
