PROJECT SUMMARY (CORE C) The Mouse Interventions and Aging Core (Core C) will provide investigators of the Program Project (PPG) with mouse models necessary to achieve their specific aims and will perform mouse lifespan assays, drug treatments and characterize mouse phenotypes. Experiments of this PPG focus on defining the role played by retrotransposable elements in aging, identifying the molecular mechanisms that control retrotransposons and on testing anti-transposon interventions. Retrotransposable elements move by a copy-and-paste mechanism creating DNA breaks, mutations and genomic rearrangements. Furthermore, the transcription of retroelements which comprise ~45% of the genome can take a toll on the host cell. The recent studies by all the three Projects of this PPG indicate that retrotransposons are activated during aging. The central hypothesis of this PPG is that the activation of retroelements contributes to the onset of aging and that pRb and SIRT6 proteins that regulate repressive heterochromatin are the key components of the pathways responsible for repression of LINE-1 (L1). Our preliminary data suggest that treating Sirt6-/- mice with reverse transcriptase inhibitors, which repress L1 retrotransposition, alleviates the premature aging phenotype of these mice, providing support for our hypothesis. Core C Specific Aims will be to: (1) prepare and maintain the Institutional Animal Care and Use Committee protocols for all projects within this PPG; (2) breed and maintain mice for project investigators; (3) examine the effect of aging on retrotransposition in L1 reporter mice; (4) examine the effect of hyperactive L1 on mouse lifespan and pathology; (5) breed pRb deficient mice for Project 1 for analysis of retrotransposon activation; (6) introduce Rb and Suv39h1 genes into livers of old mice using Adeno-Associated virus (AAV); (7) breed brain-specific and adult-onset Sirt6 knockout mice; (8) perform interventions to suppress L1 retrotransposition using nRTIs in wild type and three different Sirt6 deficient mouse models and examine retrotransposon activity and pathology; (9) determine whether nRTIs extend lifespan of wild type and constitutive whole body Sirt6 knockout mice; (10) generate and breed transgenic mice with shRNA to L1 to inhibit L1 transcription. Analyze whether shRNA alleviates age-related pathology of wild type mice and extends lifespan and rescues pathology of constitutive Sirt6 knockout mice; (11) generate and breed mice with Sirt6 separation of function and regulatory site mutations for analysis of retrotransposon activity and the ability to complement Sirt6 knockout phenotype; (12) maintain a database of all mice to ensure efficient distribution of materials and data to project investigators. Maintaining the centralized rodent colonies will standardize husbandry conditions, quality control and biological samples for use across the PPG projects, improve reproducibility of results, and allow the analysis of the same individual animals by several assays and projects, as well as minimize animal use.