Aging can be generally characterized as the long-term loss of tissue architecture, function and regenerative capacity. In the previous funding period, we explored the effects of two key challenges to long-term tissue maintenance using a novel system to delete the ATR checkpoint kinase in adult mice. We showed 1) that exhaustion of regenerative potential through stem cell attrition and increased replicative demand accelerates the appearance of age-related pathologies, and 2) that failure to suppress the accumulation of highly-damaged cells can dominantly inhibit tissue regeneration. This later mechanism putatively serves as a tissue renewal checkpoint that prevents regeneration until damaged cells can be effectively cleared. Finally, our preliminary results indicate that delayed renewal is immediately followed by a highly stimulatory phase that ultimately accelerates degeneration. Herein, we propose to further develop these research areas by defining the physiological conditions that promote replication-associated DNA damage and correlating this damage with debilitated stem cell potential. To accomplish this goal, hypomorphic ATR suppression will be used to convert transient replication abnormalities into more long-lived intermediates (double strand breaks). This system will permit the identification of both cell populations and genomic loci that are selectively susceptible to replication abnormalities during compensatory renewal. In addition, we propose to use our ATR-conditional system to characterize how DNA-damaged cells coordinate the distinct phases of regeneration through extrinsic factors. These factors include ones that that inhibit renewal and those that subsequently stimulate it. In aggregate, these studies will determine how urgent episodes of compensatory renewal are regulated and how these events can lead to the decline of long-term renewal potential.

Public Health Relevance

Age-associated pathologies are a major contributor to morbidity and mortality in the United States. Occurrence of these diseases is strongly influenced by the effectiveness of organ maintenance and tissue regeneration. In this proposal, we describe experiments to both better define the causes of debilitated regenerative potential with age and investigate the mechanisms used to renew tissues following acute loss of tissue integrity.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Research Project (R01)
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Study Section
Cellular Mechanisms in Aging and Development Study Section (CMAD)
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Velazquez, Jose M
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University of Pennsylvania
Schools of Medicine
United States
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Shastri, Nishita; Tsai, Yu-Chen; Hile, Suzanne et al. (2018) Genome-wide Identification of Structure-Forming Repeats as Principal Sites of Fork Collapse upon ATR Inhibition. Mol Cell 72:222-238.e11
Kim, Hyoung; George, Erin; Ragland, Ryan et al. (2017) Targeting the ATR/CHK1 Axis with PARP Inhibition Results in Tumor Regression in BRCA-Mutant Ovarian Cancer Models. Clin Cancer Res 23:3097-3108
Enriquez-Rios, Vanessa; Dumitrache, Lavinia C; Downing, Susanna M et al. (2017) DNA-PKcs, ATM, and ATR Interplay Maintains Genome Integrity during Neurogenesis. J Neurosci 37:893-905
George, Erin; Kim, Hyoung; Krepler, Clemens et al. (2017) A patient-derived-xenograft platform to study BRCA-deficient ovarian cancers. JCI Insight 2:e89760
Lee, Youngsoo; Brown, Eric J; Chang, Sandy et al. (2014) Pot1a prevents telomere dysfunction and ATM-dependent neuronal loss. J Neurosci 34:7836-44
Brown, Adam D; Sager, Brian W; Gorthi, Aparna et al. (2014) ATR suppresses endogenous DNA damage and allows completion of homologous recombination repair. PLoS One 9:e91222
Anastassiadis, Theonie; Brown, Eric J (2014) Wild-type RAS: keeping mutant RAS in CHK. Cancer Cell 25:137-8
Yamane, Arito; Robbiani, Davide F; Resch, Wolfgang et al. (2013) RPA accumulation during class switch recombination represents 5'-3' DNA-end resection during the S-G2/M phase of the cell cycle. Cell Rep 3:138-47
Royo, Hélène; Prosser, Haydn; Ruzankina, Yaroslava et al. (2013) ATR acts stage specifically to regulate multiple aspects of mammalian meiotic silencing. Genes Dev 27:1484-94
Ragland, Ryan L; Patel, Sima; Rivard, Rebecca S et al. (2013) RNF4 and PLK1 are required for replication fork collapse in ATR-deficient cells. Genes Dev 27:2259-73

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