Investigating the microglial function of ALS-FTD gene TBK1

Chughtai, Uroosa 2024. Investigating the microglial function of ALS-FTD gene TBK1. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Heterozygous loss-of-function mutations in TANK-binding kinase 1 (TBK1) are a common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two devastating and interlinked neurodegenerative disorders that exist on a continuous ALS-FTD disease spectrum. Whilst neuronal dysfunction and degeneration is central to both diseases, chronic neuroinflammation is a hallmark feature of ALS-FTD and it is increasingly being recognised that non-neuronal cells, such as microglia, can actively contribute to disease pathogenesis. TBK1 is a serine/threonine protein kinase that is highly expressed in microglia and has well-characterised roles in immune and immune-related pathways. As such, ALS-FTD-associated TBK1 mutations may act in microglia to contribute to disease pathogenesis. This thesis aimed to investigate the microglial function of TBK1 and understand how ALS-FTD-associated loss-of-function mutations in TBK1 may intrinsically impair microglial function to contribute to disease pathogenesis. We utilised a combination of immortalised microglial cell lines and human pluripotent stem cell-derived microglia-like cells (hPSC-MG), along with pharmacological TBK1 kinase inhibition and genetic TBK1 deletion, to model microglial TBK1 loss-of-function in vitro. Subsequently, using a combination of unbiased quantitative proteomics and targeted functional assays, we investigated the impact of microglial TBK1 loss-of-function at a molecular and functional level. We found that: (1) The two TBK1 loss-of-function models (pharmacological TBK1 kinase inhibition and genetic TBK1 deletion) differentially impacted microglial function, (2) TBK1 loss-of-function was associated with endocytic dysfunction, (3) TBK1 inhibition was associated with diminished activation of the IRF3-IFN signalling axis, whilst TBK1 deletion resulted in increased cytokine secretion and/or production, and (4) dysregulation of small GTPase signalling may be a mechanistic driver of microglial dysfunction upon TBK1 loss-of-function. Taken together, this thesis demonstrated that TBK1 plays a vital role in the physiological function of microglia and that TBK1 loss-of-function mutations may contribute to ALS-FTD pathogenesis via cell autonomous microglial dysfunction.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Biosciences
Subjects:	Q Science > Q Science (General)
Funders:	Wellcome Trust
Date of First Compliant Deposit:	5 September 2024
Last Modified:	05 Sep 2025 01:30
URI:	https://orca.cardiff.ac.uk/id/eprint/171838

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