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mRNA稳定性的微小改变也可能产生深远的后果，并可能表现为临床表型，如异常表达的原癌基因的能力所示，其可能导致恶性肿瘤。尽管mRNA稳定性在基因表达控制中的重要性，但直到最近才在控制mRNA周转及其最终生理后果的组分的鉴定和表征方面取得进展。我们的工作重点是研究mRNA降解过程中的核酸酶，特别是mRNA 5 '端去帽及其细胞生物学意义。我们现在已经确定了多个确认和推定的脱帽酶，这似乎调节一个选择的mRNA和途径的子集。在这个提议中，我们将扩大mRNA去帽酶的细胞生物学和功能作用。我们已经证明Dcp2脱帽酶选择性地调节参与先天免疫的mRNA的脱帽，并将在Aim1中发挥其在先天免疫应答中的作用。我们已经确定了一类新的脱帽蛋白为代表的哺乳动物DXO蛋白，它具有不寻常的内在双重脱帽和核酸外切酶的活动。我们已经显示DXO在核前mRNA 5 '端质量控制机制中优先作用于不完全加帽的前mRNA，并且现在有证据表明它也作为“典型”去帽酶功能性地调节参与细胞骨架结构和细胞迁移的mRNA的子集。我们将继续研究DXO在Aim2中mRNA脱帽和细胞迁移中的作用。在Aim3中，我们将继续努力鉴定其他mRNA去帽酶，并破译我们最近证明的六种新的Nuidt家族蛋白的功能作用，这些蛋白包括体外去帽活性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去帽酶。总的来说，这项工作将提供新的见解，一个基本的转录后调控机制参与基因表达和框架的创新方法，在病理条件下的治疗干预。

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.