Investigating the impact of cellular senescence of neuronal progenitor cells and microglia on cellular functionality and behavior

• Applicant: Privatdozentin Dr. Susanne A. Wolf
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells ; Biological Psychiatry
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269902361

Cellular senescence (CS) is a state of permanent cell-cycle arrest proliferating cells can initiate as a response to stress and damage. Whereas CS in peripheral tissues has been causally linked to a number of age-related pathologies, little is known about the induction of CS in the brain. Neuroinflammatory events, gene toxicity or stress could lead to CS in self-renewing brain cells including microglia (MG) and neuronal progenitor cells (NPCs). In recent years it has been demonstrated that microglia play emerging roles in adult hippocampal neurogenesis and their regulation during chronic stress, aging, and neurodegenerative diseases. Stress-induced MG alterations directly regulate certain aspects of cognitive function and emotional regulation. To date, the mechanisms underlying CS in the brain as well as how senescent cells may affect brain function and pathology remain unclear. I here propose 1) to map CS in NPCs and MG in different brain regions utilizing senescent markers and immunohistochemistry in three mouse models of premature aging: maternal inflammation, in utero stress, and induction of cell specific senescence in either NPCs or MG by genetic manipulation. Telomerase activity determines the capacity of self-renewal in cells; thus it can be used in combination with telomere length as a measure of CS in NPCs and in MG. In our previous studies and in our preliminary work we were able to show that telomerase activity decreases and telomere shorten in NPCs derived from mouse models of maternal inflammation and in utero stress. 2) we will here use telomerase activity/telomere length in NPCs and MG freshly isolated out of different brain regions to confirm the senescent phenotype identified by immunohistochemistry in 1). 3) In order to profile senescent brain cells and to identify senescent associated pathways we will subject freshly isolated MG and NPCs to RNA sequencing. The analysis will be done in parallel in all three mouse models of premature aging. 4) In addition we will measure whether cellular functions including phagocytosis, motility and neurogenesis are affected in our mouse models of premature aging. 5) By cross breeding ERCC1 floxed animals with inducible Cre lines driving the promotor for Nestin or Fraktalkine we induce CS in either NPCs or MG respectively. In addition to cellular function and RNA profiling, we will assess behavior. 6) Finally we like to investigate the potential of voluntary exercise to rescue the phenotype of premature aging on a cellular and behavioral level in all three animal models followed by RNA sequencing of NPCs and MG. In a bioinformatics approach we will compare the data obtained from the two cell types in our three models before and after the intervention to identify pathways that could become targets for a therapeutic approach. Moreover we will provide evidence why voluntary exercise is a valuable add on therapy to prevent CS and thus premature aging.

• DFG Programme: Research Grants