Non-canonical miRNA biogenesis mechanisms in Drosophila and mammals

项目摘要 microRNA（miRNAs）是一类丰富的小调控RNA， 通常来源于Drosha和Dicer对发夹转录物的逐步切割 RNase III酶。由此产生的成熟miRNAs介导广泛的后- 转录调控，并且涉及多种疾病，包括癌症。 这一建议扩展了我们长期以来对了解非典型 microRNA生物合成的策略，以及它们在正常和 不正常的环境例如，我们过去的努力发现了各种各样的非规范 这些底物绕过Drosha和/或Dicer以产生活性microRNA。在目前的努力中， 我们报告了Drosha和Dicer对选择性加工的意想不到的见解。一是 从一个非典型的miRNA中获得见解，提出一个新的核生物学通用模型。 Drosha及其辅因子DGCR 8在操纵子上的microRNA生物合成，涉及 新的辅因子。其次，我们建立在观察到的催化失活的切丁酶是 在癌症中选择，以揭示选择性生物发生效应和意想不到的分子 和表型的后果。 我们将剖析潜在的生物发生机制的模型，并评估 利用基因组策略的这些监管策略的更广泛影响。总体而言， 更好地了解microRNA是如何产生的，我们将提高我们的能力， 实验性地利用它们，并帮助解释与 核心microRNA生物发生因子的突变。

PROJECT ABSTRACT microRNAs (miRNAs) are an abundant class of small regulatory RNAs that typically derive from stepwise cleavages of hairpin transcripts by the Drosha and Dicer RNase III enzymes. The resulting mature miRNAs mediate extensive networks of post- transcriptional regulation, and are implicated in a variety of diseases including cancer. This proposal extends our long-standing commitment to understanding atypical strategies for microRNA biogenesis, and their implications during normal and dysfunctional settings. For example, our past efforts uncovered diverse non-canonical substrates that bypass Drosha and/or Dicer to yield active microRNAs. In current efforts, we report unexpected insights into selective processing by Drosha and Dicer. First, we gain insights from a non-canonical miRNA to propose a new general model for nuclear microRNA biogenesis by Drosha and its cofactor DGCR8 at operons, which involves novel cofactors. Second, we build on the observation that catalytic inactivation of Dicer is selected in cancer to uncover selective biogenesis effects and unexpected molecular and phenotypic consequences. We will dissect the models of underlying biogenesis mechanisms, and evaluate the broader impacts of these regulatory strategies using genomic strategies. Overall, by better understanding how microRNAs are generated, we will improve our capacity to harness them experimentally, as well as help interpret recurrent diseases linked to mutation of core microRNA biogenesis factors.