Maturation of let-7 miRNAs

let-7 miRNA 的成熟

• 批准号: RGPIN-2020-05258
• 负责人: Legault, Pascale
• 金额: $ 3.64万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739771
• 关键词: Maturation; let; miRNAs

MicroRNAs (miRNAs) play important roles in the regulation of gene expression by recognizing messenger RNAs (mRNA) through sequence complementarity as part of the RNA-induced silencing complex (RISC). Typically, targeting an mRNA by formation of the miRNA-guided RISC leads to translational arrest and degradation of the mRNA. In humans, the genome encodes around 2,000 miRNAs, which have the potential to regulate over 60% of all mRNAs. Misregulation of miRNA levels can change gene expression patterns, and these changes have been directly linked to developmental defects and several human diseases. The miRNAs of the let-7 family are highly conserved across animal species and play several important roles in many biological processes. Given the key role of let-7 miRNAs as development regulators and tumor suppressors, their biogenesis is tightly regulated. This starts with transcription by RNA polymerase II of a primary miRNA (pri-miRNA), which undergoes two cleavage steps, first by the Drosha/DGCR8 (Microprocessor) complex to yield the precursor miRNA (pre-miRNA) and then by Dicer to yield a miRNA duplex. A number of recent studies have led to the general view that numerous post-transcriptional mechanisms regulate miRNA maturation and that this allows for specific temporal and spatial expression of miRNAs. Moreover, several proteins have been identified that target immature forms of let-7 miRNAs (pri-let-7 and pre-let-7) to control their maturation, including TRBP, Lin28 (Lin28A and Lin28B), Musashi1, TUT4, hnRNPA1 and KHSRP proteins. However, much remains to be known about the mechanistic details of these interactions and how they regulate miRNA maturation. The long-term objective of our research program is to gain a detailed understanding of specific mechanisms that regulate let-7 miRNA maturation. Our working hypothesis is that miRNA maturation requires a complex interplay of protein/protein and protein/RNA interactions that target the pri- and pre-miRNAs to either stimulate or repress the activity of the two main miRNA processing enzymes, Drosha and Dicer. Our current focus is on a subset of proteins known to play critical functions in the regulation of let-7 miRNA levels. In the next five years, we will characterize the mechanistic details by which these proteins regulate the maturation of the let-7 miRNAs at both the molecular and atomic levels. Our work will involve biochemical, biophysical and structural characterization of select protein/protein and protein/RNA complexes that regulate the Dicer and/or Drosha cleavage steps of miRNA maturation. Our studies will provide critical and timely insights into our understanding of miRNA maturation and how miRNA levels are controlled. In addition, given that miRNAs have enormous potential for medical and agricultural applications, our basic research will provide crucial information needed to help evaluate and exploit these new cutting-edge applications.

microRNA（miRNAs）作为RNA诱导沉默复合物（RISC）的一部分，通过序列互补性识别信使RNA（mRNA），在基因表达调控中发挥重要作用。通常，通过形成miRNA引导的RISC靶向mRNA导致mRNA的翻译停滞和降解。在人类中，基因组编码约2，000种miRNA，其具有调节超过60%的所有mRNA的潜力。miRNA水平的失调可以改变基因表达模式，这些变化与发育缺陷和几种人类疾病直接相关。 let-7家族的miRNAs在动物物种中高度保守，并在许多生物学过程中发挥重要作用。由于let-7 miRNA作为发育调节因子和肿瘤抑制因子的关键作用，它们的生物发生受到严格调控。这开始于通过RNA聚合酶II转录初级miRNA（pri-miRNA），其经历两个切割步骤，首先通过Drosha/DGCR 8（微处理器）复合物产生前体miRNA（pre-miRNA），然后通过Dicer产生miRNA双链体。最近的一些研究已经导致了一种普遍的观点，即许多转录后机制调节miRNA的成熟，并且这允许miRNA的特定时间和空间表达。此外，已经鉴定了几种靶向let-7 miRNA的未成熟形式（pri-let-7和pre-let-7）以控制其成熟的蛋白质，包括TRBP、Lin 28（Lin 28 A和Lin 28 B）、Musashi 1、TUT 4、hnRNPA 1和KHSRP蛋白。然而，关于这些相互作用的机制细节以及它们如何调节miRNA成熟，还有很多东西有待了解。 我们研究计划的长期目标是详细了解调节let-7 miRNA成熟的特定机制。我们的工作假设是，miRNA成熟需要蛋白质/蛋白质和蛋白质/RNA相互作用的复杂相互作用，这些相互作用靶向pri-miRNA和pre-miRNA，以刺激或抑制两种主要miRNA加工酶Drosha和Dicer的活性。我们目前的重点是已知在let-7 miRNA水平调节中发挥关键功能的蛋白质子集。在接下来的五年里，我们将在分子和原子水平上描述这些蛋白质调节let-7 miRNAs成熟的机制细节。我们的工作将涉及选择的蛋白质/蛋白质和蛋白质/RNA复合物的生物化学，生物物理和结构表征，调节miRNA成熟的Dicer和/或Drosha切割步骤。我们的研究将为我们理解miRNA成熟以及miRNA水平如何控制提供关键和及时的见解。此外，鉴于miRNAs在医学和农业应用方面具有巨大的潜力，我们的基础研究将提供帮助评估和利用这些新的前沿应用所需的关键信息。