The coordinated regulation of gene expression is a fundamental process in biology. In this proposal, we explore the role of poly (ADP-ribose) polymerase-1 (PARP-1) and its associated factors in the chromatin- dependent control of transcription in response to cellular signaling by a steroid hormone, estrogen, and a cytokine, tumor necrosis factor alpha (TNF?). PARP-1 is an abundant, chromatin-associated enzyme that catalyzes the polymerization of poly (ADP-ribose) (PAR) chains on target proteins from donor nicotinamide adenine dinucleotide (NAD+) molecules. PARP-1 plays key roles in a variety of physiological and pathological systems, including hormonal signaling, metabolism, inflammation, differentiation, adipogenesis, carcinogenesis, development, and aging. The long-term objective of these studies is to achieve a better understanding of the chromatin-dependent molecular mechanisms underlying signal-regulated transcription by PARP-1 and its associated factors. Our broad hypothesis is that the gene regulatory activities of PARP-1 are determined by: (1) the local chromatin environment (e.g., chromatin composition, histone modifications), (2) physical and functional interactions among PARP-1, transcription factors (e.g., ER?, NF-?B), histone-modifying coregulators, and components of chromatin, (3) the targets of PARP-1 enzymatic activity, and (4) the availability of NAD+ in the nucleus. We will test this hypothesis as it relates to estrogen- and TNF?-dependent gene regulation by using an integrated approach that combines a complementary set of tools from biochemistry, molecular biology, cell biology, chemical biology, and genomics. Specifically, we will determine (1) the chromatin-dependent molecular mechanisms of PARP-1 localization and activity at target gene promoters, including the role of the histone variants H2A.Z and H3.3;(2) the effects of PARP-1-dependent site- specific PARylation on the activity and function of chromatin-regulating proteins, including the histone demethylase KDM5B and the histone methyltransferase Ezh2;and (3) the mechanisms by which NAD+ production by the nuclear NAD+ synthase nicotinamide mononucleotide adenylyltransferase-1 (NMNAT-1) regulates PARP-1 enzymatic activity at target gene promoters. Collectively, these studies will provide new insights into the molecular mechanisms of PARP-1's gene regulatory activities in the context of chromatin, especially in relation to estrogen and TNF? signaling, and nuclear NAD+ biosynthesis and availability. Given the important role of PARP-1 in human disease, as well as its potential "drugability", our studies could lead to new ways to exploit these factors as therapeutic targets.
PARP-1 is an abundant nuclear enzyme that controls gene expression programs in a variety of signaling- and stress-related biological responses, including hormonal signaling, metabolism, inflammation, differentiation, adipogenesis, carcinogenesis, development, and aging. PARP-1 enzymatic activity can be targeted through chemical inhibition, and PARP inhibitors have shown promise in clinical trials for various cancers and inflammation-related diseases. Our proposed studies will shed new light on the molecular mechanisms of signal-dependent gene regulation by PARP-1 in key biological systems and may suggest better ways to target PARP-1 to prevent, diagnose, and treat human diseases.
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|Luo, Xin; Kraus, W Lee (2012) On PAR with PARP: cellular stress signaling through poly(ADP-ribose) and PARP-1. Genes Dev 26:417-32|
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|Gibson, Bryan A; Kraus, W Lee (2011) Small molecules, big effects: a role for chromatin-localized metabolite biosynthesis in gene regulation. Mol Cell 41:497-9|
|Krishnakumar, Raga; Kraus, W Lee (2010) The PARP side of the nucleus: molecular actions, physiological outcomes, and clinical targets. Mol Cell 39:8-24|
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|Krishnakumar, Raga; Kraus, W Lee (2010) PARP-1 regulates chromatin structure and transcription through a KDM5B-dependent pathway. Mol Cell 39:736-49|
|Zhang, Tong; Kraus, W Lee (2010) SIRT1-dependent regulation of chromatin and transcription: linking NAD(+) metabolism and signaling to the control of cellular functions. Biochim Biophys Acta 1804:1666-75|
|Zhang, Tong; Berrocal, Jhoanna G; Frizzell, Kristine M et al. (2009) Enzymes in the NAD+ salvage pathway regulate SIRT1 activity at target gene promoters. J Biol Chem 284:20408-17|
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