The role of Stress Granules and G3BP1 in coupling cytosolic and nuclear stress responses

项目总结

Project Summary Ribonucleoprotein (RNP) granules are cellular membrane-less organelles comprised of RNA and RNA binding proteins (RBPs), which form through the biophysical principle of condensation or liquid-liquid phase separation (LLPS). An interesting group of cytosolic RNP granules are stress granules (SGs), that form upon a variety of different stressors. Stress leads to a global translation inhibition, causing exposed untranslating RNAs to condense and aggregate into SGs. Mutations in various SG proteins lead to aberrant and constitutive SGs or RNP aggregates. Such RNP aggregates are associated with amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and various muscular dystrophies. Therefore, it is of high medical need to understand the principles of RNP granule assembly and disassembly. While the properties, mechanisms and functions of SGs are highly studied, nothing is known about if, and how, SGs couple transcriptional and posttranscriptional mechanisms. Therefore, my research objectives focus on characterizing how SGs and/or the SG assembly scaffold protein G3BP1 regulate transcription, thereby coupling cytosolic and nuclear stress responses to maintain cellular homeostasis. In this application, I combine genome-wide, computational and experimental approaches to 1) determine if transcription is affected by the formation of SGs and identify SG target genes, 2) characterize the detailed mechanism by which SGs mediate transcriptional changes, and 3) examine nuclear functions of G3BP1 including possible direct roles in regulating transcription. During the K99 phase, under the mentorship of Dr. Roy Parker and Dr. Robin Dowell, comprehensive approaches using genome-wide data analysis and cellular techniques will be used to determine if SGs regulate transcription, identify SG target genes, and elucidate the detailed mechanism of this regulatory pathway. With support from Dr. Amy Palmer, expertise in analyzing the role of SGs and/or G3BP1 in metal/ion homeostasis will be acquired in order to identify if SGs and/or G3BP1 regulate metal/ion homeostasis during stress response on the transcriptional level. Further, expertise from Dr. John Rinn in studying the role of RNA in chromatin recognition will advance characterizing G3BP1 and the importance of RNA in G3BP1-chromatin binding. Additional K99 training in genomic techniques and computational analysis will be essential for the proposed research and advance my transition into and progress during the independent R00 phase. The results of this proposal will not only lead to identification of important SG and G3BP1 function, but also provide a fundamental understanding of how RNP granules couple cytosolic and nuclear stress responses.