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Regulation of lipid metabolism by GATA6: an integrated ‘omics’ approach

Rodrigues, Patricia 2019. Regulation of lipid metabolism by GATA6: an integrated ‘omics’ approach. PhD Thesis, Cardiff University.
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Abstract

The transcription factor GATA6 was recently recognised as a master regulator of the phenotype and function of peritoneal resident macrophages (pResMf), whose deficiency results in dysregulated proliferative renewal during homeostasis and altered inflammatory responses, associated with delays in resolution. Herein, I show using microarray analysis that mice with a myeloid deficiency of Gata6 (Gata6-KOmye mice) have significant changes in genes associated with lipid metabolism, in particular sphingolipids (SL). Three of the most notable alterations were the downregulation of genes responsible for the degradation of glucosylceramides (GlcCer) and sphingomyelins (SM) (Gba2 and Smpd1), as well as a gene involved in the regulation of lysosomal pH, and consequently, lysosomal function. To characterise the metabolic defect, I compared the lipidome of Gata6-KOmye and wild-type (WT) pResMf using a high-resolution LC-MS based global lipidomics approach and replicated my findings using targeted LC-MS/MS. SL showed a high percentage of changes (25% of all lipids levels were altered significantly) with a marked increase in Gata6-KOmye pResMf. SL are important constituents of the plasma membrane in eukaryotes and, as second messengers, modulate apoptosis, cell proliferation and differentiation. Targeted lipidomics by LC-MS/MS showed that the most significantly-increased molecular species were long chain GlcCer and SM. This linked with downregulation of Gba2, Ctse and Smpd1, observed during the microarray analysis, and was confirmed by supressing these pathways, in RAW 264.7 cells, using knockdown (shRNA) approaches. Accumulation of SL metabolites in tissues is implicated in a plethora of patho-physiological complications such as development of neurological dysfunctions, atherosclerosis, diabetes, and heart failure, whilst in cells it correlates with defects in cell migration, cholesterol traffic and efflux, lipid transport, cell activation, proliferation and apoptosis. Overall, I concluded that GATA6 regulates lipid metabolism in pResMf, on both a transcriptional and metabolic level, with particular focus on SL levels. Furthermore,there is indication that this regulation may at least in part control phenotype and function in pResMf through altering SL signalling. Thus, my studies propose GATA6 as a new lipid-regulating transcription factor and highlight the importance of lipid regulation in pResMf biology.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Medicine
Date of First Compliant Deposit: 6 March 2019
Last Modified: 06 Mar 2019 15:27
URI: http://orca-mwe.cf.ac.uk/id/eprint/120173

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