Uncovering novel mechanisms of the CELF/Bruno protein ETR-1 in apoptosis

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PROJECT SUMMARY/ABSTRACT: Programmed cell death or apoptosis is a natural developmental process. Failure of apoptosis can lead to developmental abnormalities, cancer (uncontrolled growth) and autoimmune diseases, while excessive apoptosis contributes to neurodegenerative diseases like Alzheimer's and Parkinson's. New players in the various stages of apoptosis (initiation, execution, and engulfment) continue to be identified, indicating that our understanding of the mechanism by which apoptosis occurs and is regulated is still lacking. C. elegans is an ideally suited genetic system to address apoptotic research questions because the transparent animals allows real time, in vivo, observation of apoptosis in the germline (physiological or stress-induced germline apoptosis). We recently identified a well-conserved RNA-binding protein (RBP) in C. elegans belonging to the highly conserved CELF/Bruno protein family, ETR-1, as playing a role in germline apoptosis. Preliminary findings show that depletion of ETR-1 results in accumulation of germline apoptotic cells and that a member of the apoptotic engulfment pathway is a potential mRNA target of ETR-1. The overall objective of this proposed study is to elucidate ETR-1's function during germline apoptosis, and the mechanism by which ETR-1 acts during apoptosis. The central hypothesis guiding the proposed work is that ETR-1 functions in a RNA-binding dependent manner during the early stages of physiological germline apoptosis to regulate execution and also in the later stage of engulfment. The rationale for this research is that successful completion will contribute to our fundamental understanding of apoptosis at multiple levels. To test the central hypothesis, we have devised two specific aims. Specific Aim 1 will focus on determining the role of ETR-1 in either physiological or stress- induced apoptosis through examining the kinetics of apoptosis upon ETR-1 depletion and the tissue specific requirement of ETR-1 in the gonad as related to apoptosis. Specific Aim 2 will focus on understanding the function of the RNA Recognition Motif (RRM) domains of ETR-1 during germline apoptosis. The proposed work is innovative because we will be elucidating in vivo the role for a novel apoptotic player in an intact multicellular organism, and identifying mRNA targets for a previously uncharacterized RNA-binding protein. Completion of these aims will provide a more thorough understanding of the process of apoptosis, and how apoptosis is properly controlled. Another important long-term goal of this proposal is to foster undergraduate student interest in the area of biomedical research. This proposal will facilitate substantial participation of underrepresented minority students in their early career years at Howard University, a major HBCU (Historically Black Colleges and Universities). This research has strong