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Nuclear IMPDH2 controls the DNA damage response by modulating PARP1 activity

ABSTRACT: Nuclear metabolism and DNA damage response are intertwined processes, but the precise molecular connections remain elusive. Here, we delve into this crosstalk using as a model triple-negative breast cancer (TNBC), a subtype often prone to DNA damage accumulation. We reveal that the de novo purine synthesis enzyme Inosine monophosphate dehydrogenase 2 (IMPDH2) is enriched on chromatin in TNBC when compared to other subtypes. IMPDH2 chromatin localization is DNA damage dependent and IMPDH2 repression leads to DNA damage accumulation. On chromatin, IMPDH2 interacts and modulates Poly [ADP-ribose] polymerase 1 (PARP1) activity by controlling nuclear availability of nicotinamide adenine dinucleotide (NAD+) -a shared metabolic cofactor- to fine-tune the DNA damage response. However, when IMPDH2 is restricted to the nucleus, it depletes nuclear NAD+, leading to PARP1 cleavage and cell death. Our study identifies a non-canonical nuclear role for IMPDH2 that act as convergence point of nuclear metabolism and DNA damage response. # Contributed equally *Corresponding authors: sara.sdelci@crg.eu; marta.garciacao@crg.eu

ORGANISM(S): Homo sapiens

PROVIDER: GSE271269 | GEO | 2024/09/16

REPOSITORIES: GEO

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Nuclear IMPDH2 controls the DNA damage response by modulating PARP1 activity

Project description:Recent studies have highlighted the critical role of metabolism in the response to DNA damage. However, the precise metabolic interactions that are set in motion to tune this fundamental process remain largely unknown. In this study, we investigated the role of nuclear metabolism in the DNA damage response using triple-negative breast cancer as a model. By comparing the chromatin-associated proteome of different breast cancer subtypes, we observed that the purine synthesis enzyme Inosine monophosphate dehydrogenase 2 (IMPDH2) is enriched in the chromatin of triple-negative breast cancer cells, which are often prone to DNA damage accumulation. Downregulation, depletion, or inhibition of IMPDH2 leads to accumulation of DNA damage. IMPDH2 chromatin localization is DNA damage dose dependent and happens at a late stage of the DNA damage repair. On chromatin, IMPDH2 interacts with PARP1. The enzymatic function of IMPDH2, which consumes NAD+, modulates PARP1 activity, thus mediating a pondered DNA damage response. However, forcing the nuclear localization of exogenous IMPDH2 provokes a dramatic NAD+ depletion that results in PARP1 cleavage and consequent cytoplasmic translocation, which mediates apoptosis. Our study identifies a moonlighting role for IMPDH2 in the control of nuclear ATP and NAD+ level, which fine-tune the activation of PARP1 and regulates the DNA damage response.

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Nuclear IMPDH2 controls the DNA damage response by modulating PARP1 activity

Project description:Nuclear IMPDH2 controls the DNA damage response by modulating PARP1 activity

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