Mechanisms of RNA turnover during the epithelial-mesenchymal transition

Project Summary/Abstract Cells alter their gene expression landscape to change their cellular state. The ability of cells to quickly transit between cell states is essential for many processes in biology—from development to wound healing and regeneration, processes which often go awry in pathological conditions like cancer or fibrosis. Thus, there is a biomedical need to understand the basic mechanisms driving these rapid cellular transitions. The epithelial- mesenchymal transition (EMT) is one such cellular transition that has reiterative roles in human health and disease. While much is known about the transcriptional programs that promote EMT, there are additional levels of gene expression control that impact cell state transitions and by extension EMT. The role of post- transcriptional regulation, and how it drives and contributes to a spectrum of EMT states, is not well understood. Here, we examine the role of post-transcriptional regulation, with emphasis on transcript turnover, during EMT. Neural crest cells undergo a tightly regulated EMT and offer a tractable model system in which to investigate the basic mechanisms of RNA turnover during EMT. We hypothesize that, in addition to pro-EMT transcriptional activation, transcripts that inhibit EMT (anti- EMT) or serve to maintain a previous cellular state must be degraded to drive EMT and cell state transitions. Using neural crest EMT as a model system, we seek to test this hypothesis by answering the following questions: 1) How are anti-EMT and residual transcripts targeted for turnover; and 2) What are the targets of RNA turnover during EMT and how does specific RNA turnover contribute to hybrid EMT states? To answer these questions, we will: 1) Apply a combination of unbiased multi-omic and candidate gene approaches to identify the RNA-binding proteins that promote RNA turnover during EMT; and 2) Apply RNA-sequencing approaches to broadly identify the targets of RNA turnover, the mechanism of how they are turned over, and how this contributes to hybrid EMT states. This Proposal seeks to understand the mechanisms of RNA turnover during EMT. The results of these studies will greatly advance current understanding of the basic cellular mechanisms driving EMT, providing novel targets for modulating EMT in human health and disease.