Project description:We stably infected IMR90 fibroblasts with lentiviral vectors expressing doxycycline-inducible TRF2dBdM or vector control. Cells were treated with 1mg/ml of doxycycline for 7 days to induce senescence in the cells expressing TRF2dBdM before collecting RNA. IMR90 cells, either young (passage 10, population doubling ~20) or old (passage 24, population doubling ~40-48) were also used as a model of replicative senescence. The transcriptomes were analyzed using RNA microarrays.
Project description:Age-related microangiopathy, also known as small vessel disease (SVD), causes damage to the liver, brain, kidney and retina. Based on the DNA damage theory of aging, we reasoned that genomic instability may underlie an SVD caused by dominant C-terminal variants in TREX1, the most abundant 3’-5’ DNA exonuclease in mammals. C-terminal TREX1 variants cause an adult-onset SVD known as retinal vasculopathy with cerebral leukoencephalopathy (RVCL or RVCL-S). In RVCL, an aberrant, C-terminally truncated TREX1 mislocalizes to the nucleus due to deletion of its ER-anchoring domain. Since RVCL pathology mimics that of the radiation injury, we reasoned that nuclear TREX1 promotes DNA damage. Here, we show that RVCL-associated TREX1 variants cause DNA damage in humans, mice, and Drosophila, and that cells expressing RVCL mutant TREX1 are more vulnerable to DNA damage induced by chemotherapy and cytokines that up-regulate TREX1, leading to depletion of TREX1-high cells in RVCL mice. RVCL-associated TREX1 mutants inhibit homology-directed repair (HDR), causing DNA deletions and vulnerablility to PARP inhibitors. In women with RVCL, we observe early-onset breast cancer, similar to patients with BRCA1/2 variants. Our results provide a new mechanistic basis linking aberrant TREX1 activity to the DNA damage theory of aging, premature senescence, and microvascular disease.
