Control of Cardiogenesis by microRNA Editing

描述（由申请人提供）： 该申请涉及广泛的挑战领域（15）：转化科学和特定挑战主题15-HL-102：基于microRNA技术开发心脏、肺和血液疾病的治疗策略。一种类型的RNA编辑涉及通过阿达尔（作用于RNA的腺苷脱氨酶）的作用将双链RNA中的腺苷残基转化为肌苷。A？IRNA编辑重新编码并多样化重要哺乳动物基因的功能，如谷氨酸受体亚基和5-羟色胺受体2C。然而，最常见的目标为A？I编辑是非编码RNA，其含有位于内含子和3 'UTR内的重复元件如Alu和LINE的反向重复序列。非编码重复RNA编辑的生物学意义在很大程度上是未知的。最近，我们发现某些miRNA基因的初级转录物（pri-miRNAs）被编辑。pri-miRNA的编辑导致抑制其加工或编辑的成熟miRNA的表达，所述成熟miRNA沉默与未编辑的miRNA靶向的基因不同的基因。我们的研究结果揭示了一个以前未知的作用A？miRNA介导的基因沉默中的IRNA编辑。心脏是在E10阶段首次检测到ADAR 1的胚胎组织。在E10.5的主动脉囊和E14.5的包括主动脉瓣的胚胎心脏的选定区域中检测到ADAR 2表达。ADAR 1无效突变小鼠具有胚胎致死表型，包括心脏畸形，可能是由于心肌细胞增殖不足或凋亡增加。ADAR 1和ADAR 2对未知靶dsRNA的编辑可能在胚胎心脏发育的调控中起关键作用。最近出现的miRNA介导的RNA干扰作为一个以前未被怀疑的机制，以调节心脏发育过程中。一组选择的miRNA已经显示出在胚胎心脏发育期间抑制调节心肌细胞增殖/分化的基因。此外，这些miRNAs的异常表达与先天性室间隔缺损或成人心脏的病理状况如心室肥大、增生和心律失常有关。我们的初步研究表明，miRNA-1，miRNA-133 a和miR-208基因的初级转录物经历A？我在编辑。在这项挑战资助申请中，我们将研究这些miRNA的初级转录本的RNA编辑是否在心肌细胞增殖/分化和胚胎心脏发育的调节中发挥作用。RNA编辑的作用将在体外通过miRNA加工测定和在体外诱导P19 CL 6小鼠胚胎干细胞分化为心肌细胞期间进行研究。本提案中获得的信息对于未来开发基于miRNA的各种心血管疾病治疗至关重要。 公共卫生相关性：我们的研究建议，基于以前未探索的范式，将揭示关键信息，以更好地了解心脏的正常和有缺陷的发展，功能和成人心脏疾病的机制。通过这项研究计划获得的信息对于未来开发一种新的基于miRNA的干预措施来预防先天性心脏病和病理性心脏病（如心脏肥大和心律失常）至关重要。

DESCRIPTION (provided by applicant): This application addresses broad Challenge Areas (15): Translational Science and Specific Challenge Topic 15-HL-102: Develop therapeutic strategies for heart, lung, and blood diseases based on microRNA technology. One type of RNA editing involves the conversion of adenosine residues into inosine in double-stranded RNA by the action of ADAR (adenosine deaminase acting on RNA). The A?I RNA editing recodes and diversifies the function of important mammalian genes such as glutamate receptor subunits and serotonin receptor 2C. However, the most common targets for A?I editing are non-coding RNAs that contain inverted repeats of repetitive elements such as Alu and LINE located within introns and 3'UTRs. The biological significance of non-coding, repetitive RNA editing is largely unknown. Recently, we found that primary transcripts of certain miRNA genes (pri-miRNAs) are edited. Editing of pri-miRNAs results in inhibition of their processing or expression of edited mature miRNAs that silence genes different from those targeted by unedited miRNAs. Our findings revealed a previously unknown role for A?I RNA editing in miRNA-mediated gene silencing. The heart is the embryonic tissue where ADAR1 is first detected, at stage E10. ADAR2 expression is detected in the aortic sac at E10.5 and selected regions of embryonic heart including aortic valve at E14.5. ADAR1 null mutant mice have embryonic lethal phenotypes including heart malformation possibly due to hypoproliferation or increased apoptosis of cardiomyocytes. Editing of an unknown target dsRNA(s) by ADAR1 and ADAR2 may play a critical role in the regulation of embryonic heart development. The miRNA-mediated RNA interference recently emerged as a previously unsuspected mechanism to regulate cardiogenesis during development. A select set of miRNAs have been shown to repress genes that regulate proliferation/differentiation of cardiomyocytes during development of embryonic heart. Furthermore, aberrant expression of these miRNAs is associated with congenital ventricular septal defects or pathological conditions of adult heart such as ventricular hypertrophy, hyperplasia and arrhythmias. Our preliminary studies indicate that primary transcripts of miRNA-1, miRNA-133a and miR-208 genes undergo A?I editing. In this Challenge Grant application, we will investigate whether RNA editing of primary transcripts of these miRNAs play a role in the regulation of cardiomyocyte proliferation/differentiation and embryonic heart development. The effects of the RNA editing will be investigated in vitro by a miRNA processing assay and during in vitro induced differentiation of P19CL6 mouse embryonic stem cells to cardiomyocytes. Information obtained in this proposal will be essential for the future development of miRNA-based therapy of various cardiovascular diseases. Public Health Relevance: Our research proposal, based on previously unexplored paradigms, will reveal critical information for better understanding of the mechanisms underlying normal and defective development of heart, and function and disease of adult heart. Information obtained through this research proposal is essential for the future development of a new miRNA-based intervention for prevention of congenital heart defects and pathological cardiac conditions such as cardiac hypertrophy and arrhythmias.