Use this URL to cite or link to this record in EThOS:
Title: Human group IIA secreted phospholipase A₂ : a protein with many functions
Author: Birts, Charles N.
ISNI:       0000 0001 3465 2865
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2007
Availability of Full Text:
Access from EThOS:
Full text unavailable from EThOS. Please try the link below.
Access from Institution:
Fluorescently labelled cysteine mutants were used to show increased binding of hgIIA to PMA activated human THP-1 macrophage cells. Inhibition and competition studies suggest that the hgIIA enzyme is binding via electrostatic interactions to heparan sulphate proteoglycans that show increased cell surface expression on THP-1 activation. On binding, hgIIA is rapidly internalised via an energy-dependent endocytic mechanism. Inhibitory studies and confocal microscopy implicate both the clathrin- and caveolae-mediated endocytic pathways as well as macropinocytosis. Entry via macropinocytosis results in the increase in cell volume, and highlights a possible novel signalling pathway utilised by the hgIIA enzyme. On internalisation, hgIIA accumulates in the nucleus where we have shown using Western blotting that it can act to increase the LPS induced expression of COX-2 in a synergistic manner. All results presented were also observed using the catalytically inactive hgIIA mutant H48N,S74C, demonstrating that in addition to hgIIA's catalytic-dependent role in the antibacterial response, it also possesses other functions independent of activity that allows it to interact with and have subsequent affect on host cell function. The hgIIA protein may thus play a pro-resolving role in inflammation as increased COX-2 levels leads to increased production of the pro-resolving inflammatory mediator prostaglandin D₂. This response would be of beneficial effect in preventing tumour progression as it would reduce macrophage production of pro-inflammatory cytokines and reactive oxygen and nitrogen species that may potentiate tumour development and metastasis. The accumulated evidence suggest that the hgIIA protein has a variety of physiological roles in addition to its antibacterial properties, including acting as a bridging molecule that facilitates the uptake of anionic cell debris, while nuclear targeting affects the expression of genes involved in the inflammatory response.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available