Biochemical, proteomic and microscopic insights into regulation of nucleolar structure and function

点击翻译按钮获取中文摘要

The mammalian nucleolus is a non membrane-bound nuclear organelle that forms around tandem repeats of ribosomal DNA and is best known for its essential role in the coordination of ribosome biogenesis, which supplies the cell with the ribosome complexes required for protein synthesis. This structure is dynamic, disassembling and reassembling throughout each cell cycle in mammalian cells and reorganizing its internal structure in response to various cellular stresses. Recent biochemical and proteomic analyses have revealed a much wider nucleolar functional complexity than was previously appreciated, linking this organelle to roles in cell cycle regulation, DNA damage repair, telomere metabolism, RNA processing and coordination of the cellular response to various stresses. Given that nucleolar dysfunction has been linked to several disease states, including cancer, accelerated aging and viral infection, it is clear that precise coordination of these diverse individual pathways is essential for its proper function.     Despite major advances in recent years, including a more detailed catalogue of nucleolar protein, DNA and RNA components, important questions remain to be answered with regard to which specific factors provide the nucleolus with its structural integrity and how its dynamic organization is regulated. Much also remains to be learned about the full range of biological processes that occur within, or involve, the nucleolus, and the relationship between sub-nucleolar structure and specific functions at the molecular level.     Our interest lies primarily in the structure/function relationship of non-canonical nucleolar components (i.e. those not involved directly in ribosome biogenesis), and we hypothesize that their functions fit within a defined architecture, similar to the structure/function relationship observed for components involved in ribosome biogenesis pathways. The main objectives of this project are thus to characterize nucleolar proteins that mediate non-ribosomal functions and define the regulatory mechanisms that underlie this organelle’s coordinated organization, and we propose to apply a combination of powerful new super-resolution imaging and quantitative proteomic technologies to carry them out.     Understanding the regulation of nucleolar assembly/maintenance and function remains a fundamental question in cell biology. Given that a detailed description of the protein content of the nucleolus has emerged over the past few years and yet we still do not know how their diverse functions are regulated (and in some cases, what their functions actually are) this structure clearly remains a source of significant new discoveries and undoubtedly some more surprises for the foreseeable future.