The roles of microglial phagocytosis in ageing-induced synaptic, neuronal and memory loss
Lead Research Organisation:
University of Cambridge
Department Name: Biochemistry
Abstract
During ageing of both mice and humans, the brain loses synapses, white matter and the ability to learn and remember, which can severely limit work, function and quality of life with age. Microglia are brain macrophages that eat (phagocytose) synapses and neurons in specific circumstances. This project tests whether age-induced lose of synapses and memory is due to microglial phagocytosis of these synapses. The project may also investigate the causes of the late developmental loss of synapses (adolescence in humans, 1-4 months in mice). The project will bring together expertise on microglial signalling pathways and function, based in the Brown lab, with a strong interest in adaptations in brain function as humans' age, based in the Eli Lilly Neuroscience group.
P2Y6 is a receptor required for microglial phagocytosis of neurons, and Prof. Brown's lab have found that P2Y6 receptor knockout mice are protected in models of inflammation, Parkinson's and Alzheimer's disease. The P2Y12 receptor is a related receptor required to recruit microglia to stressed neurons. TREM2 is a microglial receptor required for phagocytosis of a variety of targets, possibly including synapses. Mice lose hippocampal synapses, neurons and memory from about 12 months of age, and there is evidence in the literature that this is mediated by microglial phagocytosis of synapses and neurons. In preliminary research, Prof. Brown's lab have found that the P2Y6 receptor is required for microglial phagocytosis of synapses in culture, and that aged mice (16 months) lose long- term memory of novel objects and novel locations, which is prevented in the P2Y6 receptor knockout mice. So we now want to find out whether blocking the P2Y6 or other microglial receptors prevents the synaptic and/or neuronal loss associated with aging.
The goals of this proposal are to:
1) Determine the effects of P2Y6 receptor knockout or inhibition on microglial phagocytosis of synapses in culture,
2) Determine the effects of P2Y6 receptor knockout or inhibition on aging-induced loss of synapses, neurons and memories, and
3) Investigate the role of other microglial receptors (including TREM2 and P2Y12) on microglial phagocytosis of synapses.
The project work may consist of:
a) histological analysis of brains from wt and P2Y6 receptor knockout mice (and potentially also TREM2 and P2Y12 receptor knockout mice) to analyse density of synapses, neurons and myelin in various brain regions at 1, 4, 12 and/or 16 months old, and
b) blocking the P2Y6 receptor from 12 to 16 months of age , either using a P2Y6R inhibitor or induced-knockout of the gene, and measuring: learning and memory at 13 and 16 months, followed by histological analysis of density of synapses, neurons and myelin, and
c) analysis of wild-type and transgenic microglia at 4 and 16 months for: synaptic, neuronal and myelin markers, and general RNA expression by RNAseq.
d) hippocampal brain slices from wt and transgenic mice, imaged for microglial phagocytosis of synapses, neurons and myelin when inflamed, and/or
e) analysis of factor regulating microglial phagocytosis of isolated synapses in vitro.
The project would involve image analysis of fixed brain sections, but also live cell and slice culture work, and characterising signals mediating microglial phagocytosis of isolated synapses. Microglia will be sorted from the aged brain and characterised by RNAseq, requiring bioinformatics and data handling. The student will also learn how to behaviourally characterise aged mice.
This project addresses the BBSRC Strategic Theme: Bioscience for Health, by revealing the biological mechanisms underlying normal brain physiology, in order to sustain wellbeing throughout life.
P2Y6 is a receptor required for microglial phagocytosis of neurons, and Prof. Brown's lab have found that P2Y6 receptor knockout mice are protected in models of inflammation, Parkinson's and Alzheimer's disease. The P2Y12 receptor is a related receptor required to recruit microglia to stressed neurons. TREM2 is a microglial receptor required for phagocytosis of a variety of targets, possibly including synapses. Mice lose hippocampal synapses, neurons and memory from about 12 months of age, and there is evidence in the literature that this is mediated by microglial phagocytosis of synapses and neurons. In preliminary research, Prof. Brown's lab have found that the P2Y6 receptor is required for microglial phagocytosis of synapses in culture, and that aged mice (16 months) lose long- term memory of novel objects and novel locations, which is prevented in the P2Y6 receptor knockout mice. So we now want to find out whether blocking the P2Y6 or other microglial receptors prevents the synaptic and/or neuronal loss associated with aging.
The goals of this proposal are to:
1) Determine the effects of P2Y6 receptor knockout or inhibition on microglial phagocytosis of synapses in culture,
2) Determine the effects of P2Y6 receptor knockout or inhibition on aging-induced loss of synapses, neurons and memories, and
3) Investigate the role of other microglial receptors (including TREM2 and P2Y12) on microglial phagocytosis of synapses.
The project work may consist of:
a) histological analysis of brains from wt and P2Y6 receptor knockout mice (and potentially also TREM2 and P2Y12 receptor knockout mice) to analyse density of synapses, neurons and myelin in various brain regions at 1, 4, 12 and/or 16 months old, and
b) blocking the P2Y6 receptor from 12 to 16 months of age , either using a P2Y6R inhibitor or induced-knockout of the gene, and measuring: learning and memory at 13 and 16 months, followed by histological analysis of density of synapses, neurons and myelin, and
c) analysis of wild-type and transgenic microglia at 4 and 16 months for: synaptic, neuronal and myelin markers, and general RNA expression by RNAseq.
d) hippocampal brain slices from wt and transgenic mice, imaged for microglial phagocytosis of synapses, neurons and myelin when inflamed, and/or
e) analysis of factor regulating microglial phagocytosis of isolated synapses in vitro.
The project would involve image analysis of fixed brain sections, but also live cell and slice culture work, and characterising signals mediating microglial phagocytosis of isolated synapses. Microglia will be sorted from the aged brain and characterised by RNAseq, requiring bioinformatics and data handling. The student will also learn how to behaviourally characterise aged mice.
This project addresses the BBSRC Strategic Theme: Bioscience for Health, by revealing the biological mechanisms underlying normal brain physiology, in order to sustain wellbeing throughout life.
