Mechanisms that Protect Transcripts from Nonsense-mediate mRNA Decay

University Of Nebraska-Lincoln, Lincoln NE

Investigators

Abstract

Intellectual Merit. A key step in regulating gene expression is the rate at which specific mRNA molecules are degraded. The protein synthesis machinery translates single mRNAs repeatedly to produce multiple proteins. In part, the amount of protein produced is dependent on the mRNA lifespan because this determines how much of each type of mRNA is available for translation and how many times each mRNA is translated. Each mRNA has a specific lifespan, and for many mRNAs, lifespan is modulated in response to environmental or intracellular changes. mRNA decay rates are determined by interactions between cis-elements within the mRNAs and the mRNA decay machinery. RNA binding proteins can mediate these interactions. However little is known about how these interactions lead to functional changes in the rate at which an mRNA is degraded. The objective of this project is to identify the mechanisms that permit wild type mRNAs with nonsense-mediated mRNA decay (NMD) targting signals to evade the NMD pathway. NMD is a specialized pathway that is responsible for the recognition and rapid degradation of mRNAs with premature stop codons and some wild type mRNAs as well. However, not all wild type mRNAs with NMD targeting cis-elements are degraded by the NMD pathway. The mechanism responsible for protection of these mRNAs from NMD is unknown. The hypothesis that protection from NMD is mediated by RNA binding proteins which interfere with the NMD pathway and thus redirect these mRNAs for decay by the default pathways will be tested using both biochemical and genetic tools in the yeast Saccharomyces cerevisiae. This research will provide valuable new insight into how the NMD pathway is regulated and serve as a paradigm for how mRNA decay regulators modulate the decay of specific mRNAs by influencing the mRNA decay machinery. Broader Impact. The research will increase our understanding of the mechanisms regulating gene expression at the mRNA level. The new knowledge of the mechanisms regulating mRNA decay that will be generated by this project is expected to lead to a new set of tools for controlling gene expression. The project will also have an impact on human resource development through the direct training of a Postdoctoral Researcher, a Graduate Student, Undergraduate Students and High School Students in a lab with a proven track record of providing meaningful research experiences for trainees. Participants will work on an important, fundamental biological problem using integrative computational and molecular genetics approaches developed for the powerful model organism Saccharomyces cerevisiae. The high school students will be recruited though the Young Nebraska Scientists and Nebraska College Preparatory Academy programs which emphasizes broadening participation of underrepresented groups in STEM disciplines.