Regulation of Mammalian mRNA Decapping

描述（由申请人提供）：mRNA稳定性的控制是真核基因表达转录后调控的关键决定因素。即使是mRNA稳定性的微小改变也可能产生深远的影响，并可能表现为临床表型，如异常表达原癌基因的能力所示，可导致恶性肿瘤。尽管mRNA稳定性在控制基因表达中的重要性，但直到最近才在控制mRNA转换及其最终生理后果的成分的鉴定和表征方面取得进展。我们的研究重点是参与mRNA衰变的核酸酶，特别是mRNA 5'端脱帽和脱帽的细胞生物学意义。我们现在已经确定了多种确认和假定的脱帽酶，它们似乎调节了mrna和途径的一个选择子集。在本提案中，我们将扩展mRNA脱帽酶的细胞生物学和功能作用。我们已经证明Dcp2脱扣酶选择性地调节与先天免疫有关的mrna的脱扣，并将在Aim1的先天免疫应答中继续发挥其作用。我们已经鉴定了一类以哺乳动物DXO蛋白为代表的新型脱帽蛋白，它具有不寻常的内在双重脱帽和外切酶活性。我们已经证明DXO在核前mrna 5'端质量控制机制中优先作用于不完全覆盖的前mrna，现在有证据表明它还作为一种“典型”脱帽酶，不成比例地调节参与细胞骨架结构和细胞迁移的mrna子集。我们将探讨DXO在Aim2中mRNA脱壳和细胞迁移中的作用。在Aim3中，我们将继续努力鉴定额外的mRNA脱帽酶，并破译我们最近在体外证明具有脱帽活性的六个新的Nudix家族蛋白的功能作用，Nudt2, Nudt3, Nudt12, Nudt15， Nudt17和Nudt19。我们将首先关注进化上保守的Nudt3蛋白，初步数据表明它是细胞中真正的脱帽酶。总的来说，这项工作将为涉及基因表达的基本转录后调控机制提供新的见解，并为病理条件下治疗干预的创新方法提供框架。

DESCRIPTION (provided by applicant): The control of mRNA stability is a critical determinant in the post-transcriptional regulation of eukaryotic gene expression. Even minor alterations in mRNA stability can have profound consequences and may manifest as clinical phenotypes as illustrated by the ability of aberrantly expressed proto-oncogenes that can give rise to malignancies. Despite the importance of mRNA stability in the control of gene expression, progress has only recently been made in the identification and characterization of the components that control mRNA turnover and their ultimate physiological consequence. We have focused our efforts on the study of nucleases involved in mRNA decay, in particular, mRNA 5'end decapping and the cell biological significance of decapping. We have now identified multiple confirmed and putative decapping enzymes, which appear to modulate a select subset of mRNAs and pathways. In this proposal we will expand on the cell biological and functional role of mRNA decapping enzymes. We have shown the Dcp2 decapping enzyme selectively modulates the decapping of mRNAs involved in innate immunity and will pursue its role in the innate immune response in Aim1. We have identified a novel class of decapping proteins represented by the mammalian DXO protein, which possesses an unusual intrinsic dual decapping and exonuclease activities. We have already shown DXO preferentially functions on incompletely capped pre-mRNAs in a nuclear pre-mRNA 5'end quality control mechanism, and now have evidence it also functions as a "canonical" decapping enzyme disproportionally modulating a subset of mRNAs involved in cytoskeletal architecture and cell migration. We will pursue the role of DXO in mRNA decapping and cell migration in Aim2. In Aim3, we will build on our ongoing efforts to identify additional mRNA decapping enzymes and decipher the functional role of six new Nudix family proteins we recently demonstrated contain decapping activity in vitro, Nudt2, Nudt3, Nudt12, Nudt15, Nudt17 and Nudt19. We will initially focus on the evolutionarily conserved Nudt3 protein where preliminary data indicates it is a bona fide decapping enzyme in cells. Collectively, this work will provide novel insights into a fundamental post-transcriptional regulatory mechanism involved in gene expression and a framework for innovative approaches for therapeutic intervention in pathological conditions.