Investigation of mechanisms underlying cellular senescence and the Senescence-associated secretory phenotype (SASP) during brain ageing

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Brain ageing is associated with neuroinflammation, neurodegeneration and cognitive decline. We have recently shown that neurons can acquire a senescent-like phenotype displaying various senescent hallmarks such as activation of a persistent DNA damage response, Senescence-associated-beta-Galactosidase activity and increased production of both pro-inflammatory cytokines and Reactive Oxygen Species (ROS). Both ROS and pro-inflammatory factors which are produced by senescent cells can be secreted and contribute to induction of senescence in surrounding young cells, a phenomenon termed as the "bystander-effect". However, the senescence bystander effect has not been investigated in the context of neuronal senescence.In this project, we hypothesise that secreted factors from senescent neurons and/or microglia can promote a bystander effect which may accelerate neurodegeneration and functional decline. For that, the student will:1) Compare the composition of the senescent associated secretory phenotype (SASP) in aged microglia and neurons isolated from mice.2) Investigate whether SASP factors from senescent neurons and microglia can induce paracrine senescence and if cell-to-cell contact is required.3) Test whether downregulation of signalling pathways involved in SASP regulation such as p38MAPK and mTORC1 can suppress neuronal/microglia senescence and improve neuronal function in vivo.4) Finally, the student will investigate links between nuclear envelop stability and the SASP in neurons during ageing.The project will use established methods in the team (including confocal microscopy of fixed and live cells, western blotting and immunohistochemistry). SASP and molecular mechanisms will be examined using neuronal cultures, isolated adult neurons and mouse brains. Changes in SASP will be investigated by measuring mRNA levels (PCR, PCR array or RNAseq) and secretion of proteins (antibody arrays). Effect of SASP on neuronal senescence will be studied using a set of well-established markers like Telomere Associated DNA damage Foci (TAF), Sen-beta-Gal, p21 and markers of nuclear envelop maintenance.