Characterization of Ars2 function in RNA processing

点击翻译按钮获取中文摘要

The long term goal of my research program is to address how different families of RNA transcripts are recognized and correctly processed to mature RNAs with distinct destinations and functions and to understand how the different types of RNA contribute to stem and progenitor cell behavior. The generation of mature RNA in the nucleus is a highly coordinated multistep process that requires distinct complexes for the biogenesis of different RNA families. RNAPII transcripts include at least 4 different types of RNA, each with its own processing requirements. How different families of RNAPII transcripts are recognized and processed to generate mature RNA is not understood. My lab discovered a gene called Ars2 that is a critical regulator of RNAPII transcript maturation and surveillance (appendix 2). We were the first to produce a mouse knockout for Ars2 and discovered that it is required for maintenance of stem and progenitor cells. We showed that Ars2 is the mammalian orthologue of the plant SERRATE gene and we predicted that ARS2(protein) would be important for RNA biogenesis. Our publication led to the discovery that ARS2 is an integral part of the nuclear cap complex and is necessary for the biogenesis of several different types of RNAPII transcripts. Therefore understanding ARS2 function is a critical step towards our long term goal. ***The story emerging from our work is that ARS2 has multiple putative elements for binding to both RNA and processing-protein components. Thus ARS2 is poised to act as a key regulator of RNA maturation with the ability to regulate the processing of different RNA molecules. However we do not have a complete understanding of ARS2 protein or RNA interactions. For example, we identified an RRM domain in ARS2. We have shown that the RRM domain is required specifically for replication dependent histone mRNA processing and cell cycle progression, yet mutation of the canonical RNA binding interface does not affect the ability of ARS2 to interact with histone mRNA or histone processing machinery. Similarly there are conserved arginine, glutamate, and proline rich regions highly likely to be forming interactions for which we do not know the function. ***We hypothesize ARS2 is critical nexus of RNA processing that couples the CBC to the appropriate processing machinery. As a first step to address this hypothesis we need to know what ARS2 interacts with and how it interacts with these proteins and RNAs. Our short term aims are 1) to determine the discreet protein interaction surfaces of ARS2 2) to determine the RNA interaction surfaces of ARS2 and 3) to determine which ARS2 interactions underpin ARS2 loss-of-function phenotypes. Our aims are the requisite logical steps towards our long term goal of understanding how ARS2 contributes to stem and progenitor maintenance and differentiation and provide a mechanistic model for the rationale design of in vivo experiments. **