UCO (B. Schumacher group): Longevity assurance mechanisms and the DNA damage response
i. Objective of research: To characterize longevity assurance mechanisms in the DNA damage response.
ii. Current state of the art: DNA repair defects promote cancer development, impair developmental growth and accelerate ageing. The ageing process can be slowed and lifespan extended when the insulin-like signaling (IIS) is dampened. In C. elegans this leads to the activation of the FOXO transcription factor DAF-16 that promotes longevity. We have determined that IIS is downregulated in response to persistent DNA damage that blocks transcription and that the ensuing activation of DAF-16 promotes developmental growth and tissue maintenance when responding to DNA damage. The specific transcription response to DNA damage is determined by recognition of promoter elements by the GATA transcription factor EGL-27 that interacts with DAF-16. Using proteomics, phosphoproteomics and lipidomics, we recently provided a comprehensive assessment of processes that respond to persistent DNA damage in an organism. We found striking parallels between the alterations following UV-induced DNA damage and the proteome changes observed during natural ageing of C. elegans. The assessment of signaling mechanisms placed the IIS at the center of proteostatic and metabolic alteration in the DNA damage response.
iii. Research methodology and approach: We will investigate the role of signaling networks in the DNA damage response and in DNA damage-driven ageing. We will focus on elucidating the central role of DAF-16 in regulating the maintenance of tissues when DNA lesions persist. Our phosphor-proteome analysis indicates that several signaling pathways converge on the regulation of DAF-16. Indeed, reduced activity of the ERK1/2 MAPK mpk-1 results in exacerbated DAF-16 activity and elevated resistance to DNA damage (Bianco and Schumacher, unpublished) while the GATA EGL-27 is required for the DAF-16-mediated DNA damage response. The critical signaling pathways identified by phosphoproteomic network analysis are in addition to IIS the EGF- and AMPK-like pathways. We will use available genetic mutants that abrogate or constitutively activate IIS, EGF and AMPK signaling and determine the level of DAF-16 activation by following the kinetics of DAF-16::GFP nuclear translocalization in vivo. We will assess how the outcome of the DNA damage response is influenced by assessing developmental growth as well as adult tissue maintenance and lifespan. We will use chromatin-immunoprecipitation (ChIP) of DAF-16 to address how promoter binding might be affected by EGF and AMPK signaling. We will furthermore use established proteomics and lipidomics to test the consequences on metabolic alterations and the distinct processes we identified in the DNA damage response and that are implicated in regulating the ageing process including chromatin remodeling, autophagy, protein synthesis, folding and degradation, and fatty acid and glucose metabolism.
iv. Originality and innovative aspects of the ESR project: This project will provide targetable signaling pathways that modulate tissue maintenance and health during DNA damage-driven ageing.
v. Integration of the ESR project to the overall research program: Our ESR will assess the impact of genome instability on nutrient-sensing pathways (with the Auwerx group) and mitochondrial dysfunction (with Tavernarakis group) and with LXRepair for the application of miniaturized DNA repair assays in C. elegans.