Molecular triggers of reactive gliosis and neurodegeneration in proteasome depleted neurons: a role for STAT3 signalling in astrocytes
Publication Date
December 15, 2022
Creator
Abstract
Neurodegenerative diseases are devastating disorders with a wide social, economic, and environmental impact. These disorders are classified as proteinopathies due to their commonality of exhibiting protein aggregates in late-stage disease and dysfunction in proteolytic mechanisms. In association with protein aggregates, neuroinflammation, the activation of resident astrocytes and microglia, is key in these disorders and has demonstrated pathological roles. However, there is limited research on how neuronal proteotoxicity impacts on glial cells prior to the accumulation of characteristic intraneuronal inclusions. The Psmc1fl/fl;CaMKIIα-cre mouse model shows a gradual depletion in 26S proteasome in the forebrain and hippocampal neurons resulting in time-dependent proteotoxicity, inflammation, and neurodegeneration. This thesis aimed to examine glial responses in this mouse model during the onset of neuronal dysfunction and neuroinflammation. Firstly, protein expression profiling using SWATH-MS was employed in 2-,3-,4- and 5-week old Psmc1fl/fl;CaMKIIα-cre mice, which revealed several upregulated neuroinflammatory responses at a molecular level, such as the heat-shock response, necroptosis, neutrophil degradation in association with a downregulation in CaMKIIα-cre neuronal components. GFAP, a major astrocyte protein, was consistently upregulated throughout disease progression. Secondly, GFAP, STAT3α and pSTAT3 tyrosine705 expression was quantified to be significantly higher from 3 weeks of age via western blotting and the number of GFAP+/STAT3α+ cells was significantly increased in 3 and 4-week Psmc1fl/fl;CaMKIIα-cre mice, showing a selective increase in astrocytic-STAT3 in the dentate gyrus and CA3 region of these mice. Thirdly, quantitative PCR of astrocytic-STAT3 coupled inflammatory mediators was performed in Psmc1fl/fl;CaMKIIα-cre mice, whereby TNF-α mRNA expression reported consistent significant results. Finally, astrocytic-STAT3 agonists and inhibitors (ADP/ATP/IL-6/TNF-α/CXCL10 and STATTIC) were applied to 3-week-old acute slices, and astrocytic-STAT3 phosphorylation was confirmed through western blot for the cytokines and chemokines (IL-6/CXCL10/TNF-α) however showed no results for ADP/ATP/STATTIC. Collectively, these results suggest Astrocytic-STAT3 phosphorylation precedes neuron degeneration in the Psmc1fl/fl;CaMKIIα-cre mice model which warrants further investigation into the role of astrocytes in neurodegenerative disorders.
Item Type
ethesis
Thesis Type
PhD
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Subjects (LC)
Associated Schools / Departments
School of Life Sciences
eprints ID
71771
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Examined. Molecular triggers of reactive gliosis and neurodegeneration in proteasome depleted neurons: a role for STAT3 signalling in astrocytes
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