Translational Control of Cardiac Fibrosis

项目总结： 心血管疾病(CVD)是世界范围内发病率和死亡率的主要原因。心力衰竭 心力衰竭(HF)是心血管疾病的一种主要形式，由心肌细胞(CM)肥大和凋亡引起，与 心脏成纤维细胞(CF)的激活和增殖。尽管转化生长因子-β-IL-11轴诱导蛋白质合成 已观察到促纤维化基因，促进促纤维化基因翻译的机制 在CF中还没有被发现。因此，填补这一空白并从药理上鉴定 心脏纤维化的靶向翻译控制决定因素是至关重要的。 氨基酰-tRNA合成酶(ARSS)催化氨基酸与同源tRNA的连接。在……里面 在哺乳动物中，谷氨酰-脯氨基-tRNA合成酶(Eprs)催化谷氨酸(E)和 与它们的同源tRNAs结合，以合成蛋白质。通过筛选转化生长因子-β-1诱导的ARSS 激活的人CFs、CHD中含有SNPs的人ARSS、与ISO诱导相关的小鼠ARSS GWAS引起的心肌病，以及ISO诱导的小鼠心力衰竭的ARSS，我们已经确定Eprs是 关键的ARS参与了各种心脏病理。在本项目中，我们发现EPRS是一种 多个促肝纤维化刺激的下游整合结节。我们发现激活转录因子 5作为Eprs的上游转录调节因子。中草药常青酮(Halo) 药物衍生化合物，是一种Prolyl-tRNA合成酶特异性抑制物。低剂量光晕，砷 以及小鼠基因组中Eprs一个等位基因的基因敲除，可以减少心肌肥厚和 多种心力衰竭小鼠模型中的纤维化。我们在Halo-Seq中使用了RNA-Seq和多聚体谱-Seq。 经处理的成纤维细胞在转录和翻译水平上的基因表达变化 EPRS抑制。除了胶原蛋白，我们还发现了新的富含脯氨酸密码子(PRR)的基因，这些基因是 Eprs在转录后水平上调，可能在心肌纤维化中起关键作用。 Eprs失活促进PRR mRNA的翻译抑制与增强的mRNA结合 腐烂。这种效应需要eIF5A的失活，eIF5A是解码富含Pro密码子的延伸因子。 我们的中心假设是：心肌梗死应激诱导的EPR通过增加ProtRNAPro促进心肌纤维化 并且增强了促纤维化的PRR mRNAs在CFs中的稳定和翻译激活。我们会 通过追求3个目标来检验这一假设。目标1.确定是否在全球范围内和在CFS中下调监管，以及 Eprs的药理作用抑制可预防或逆转心衰模型的心肌纤维化。目标2.确定 Eprs新的下游PRR促肝纤维化基因靶点及其上游调控 EPRS的路径。目的3.确定eIF5A介导的翻译调控和mRNA的机制 PRR基因的衰变。该项目将通过以下方式促进新治疗方法的发展 抑制翻译因子，并确定新的药理靶点。

Project Summary: Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Heart failure (HF), a major form of CVD, results from cardiomyocyte (CM) hypertrophy and apoptosis, combined with cardiac fibroblast (CF) activation and proliferation. Although TGF-b-IL-11 axis induced protein synthesis of pro-fibrotic genes have been observed, the mechanisms that promote pro-fibrotic mRNA translation in CF have not been identified. Therefore, filling this gap and identifying the pharmacologically targetable translational control determinants of cardiac fibrosis is of paramount importance. Aminoacyl-tRNA synthetases (ARSs) catalyze the ligation of amino acids to cognate tRNAs. In mammals, glutamyl-prolyl-tRNA synthetase (EPRS) catalyzes the attachment of glutamic acid (E) and proline (P), to their cognate tRNAs for protein synthesis. By screening of ARSs induced in TGF-b- activated human CFs, human ARSs with SNPs in CHD, mouse ARSs associated with ISO-induced cardiomyopathy by GWAS, and ISO-induced ARSs in mouse failing hearts, we have identified EPRS as the key ARS involved in various cardiac pathologies. In this project, we uncovered EPRS as an integrated node downstream of multiple pro-fibrotic stimuli. We found that activating transcription factor 5 acts as an upstream transcriptional regulator of EPRS. Halofuginone (Halo), a Chinese herbal medicine-derived chemical compound, is a prolyl-tRNA synthetase-specific inhibitor. Low-dose Halo, as well as genetic knockout of one allele of EPRS in the mouse genome, reduces cardiac hypertrophy and fibrosis in multiple HF mouse models. We employed RNA-Seq and polysome profiling-Seq in Halo- treated fibroblasts to define gene expression changes at the transcriptomic and translatomic level upon EPRS inhibition. We identified novel proline codon rich (PRR) genes in addition to collagens, which are upregulated by EPRS at the posttranscriptional level and may play critical roles in cardiac fibrosis. Inactivation of EPRS promotes translational repression of PRR mRNA coupled with enhanced mRNA decay. This effect requires inactivation of eIF5A, an elongation factor for decoding Pro-rich codons. Our central hypothesis is: MI stress-induced EPRS promote cardiac fibrosis via increased Pro-tRNAPro pool, and enhanced stabilization and translational activation of pro-fibrotic PRR mRNAs in CFs. We will test this hypothesis by pursuing 3 aims. Aim 1. Determine if downregulation, globally and in CFs, and pharmacological inhibition of EPRS prevent or reverse cardiac fibrosis in HF models. Aim 2. Determine novel preferential downstream PRR pro-fibrotic mRNA targets of EPRS and upstream regulatory pathway of EPRS. Aim 3. Determine mechanisms of eIF5A-mediated translational control and mRNA decay of PRR genes. This project will promote the development of novel therapeutic approaches by inhibiting translation factors, and identification of novel pharmacological targets.