Molecular mechanisms regulating Poly(ADP-ribosyl)ation pathway in living cells

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Developmental processes are tightly regulated, and their disruption leads to pathologies. Chromatin factors regulate developmental processes by controlling the chromatin state of specific loci to coordinate expression of multiple developmental genes. Much remains to be learned about how chromatin is programmed and how active or inactive domains are maintained during development. Poly(ADP-ribose) polymerase 1 (PARP1) and poly(ADP-ribose) glycohydrolase (PARG) (PAR enzymes) play a vital role during organismal development by controlling chromatin state and transcription. In this project, researchers will use the PAR pathway as a model to understand how cells undergo quick, localized and reversible chromatin reprogramming to fine tune gene activity. The findings will enhance our knowledge of developmental gene regulation and facilitate new methodology for reprogramming genes, for example through activation of PAR enzymes present in repressed chromatin loci. This project will reinforce the research environment at University of North Dakota by providing local high school and undergraduate students of different backgrounds with new opportunities to learn fundamental and biomedical aspects of developmental processes.This project will focus on the study of molecular mechanisms of PARG enzyme regulation, using Drosophila as a model. The research will be driven by the hypothesis that regulation of PARG activity is crucial for tissue-specific and cell cycle-specific differences in poly(ADP-ribosyl)ation rates. The preliminary data show that PARG, which does not have a DNA-binding motif, has two distinct roles in chromatin: 1) PARP1-independent binding to gene body of silent genes, likely to repress their expression; 2) binding of PARP1-occupied active loci, likely to maintain their expression in cooperation with PARP1. This project will focus on characterizing the molecular mechanism targeting and regulating PAR enzymes in living cells in steady-state conditions and in mutant backgrounds. The experiments will probe 1) what mechanisms recruit PAR enzymes to specific loci and 2) what triggers and fine-tunes PAR-dependent processes, including underlying mechanisms. The outcomes will advance understanding of the PAR pathway and how it might be modulated in new ways.This project is jointly funded by the Genetic Mechanisms program in the Molecular and Cellular Biosciences Division of the Directorate for Biological Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.