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Title: Quantifying plasma membrane protein reduction during immune activation using mass spectrometry
Author: Stegmann, Monika
ISNI:       0000 0004 6352 9454
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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The communication of immune cells through cell surface receptors is crucial for maintaining immune homeostasis, coordinating the immune response and pathogen clearance. The interaction of cell surface receptors with their cognate ligands is dependent on a key-lock principle and therefore only allows binding of partners in their correct conformational state. Reductive cleavage of labile disulfide bonds is a post-translational modification, capable of controlling protein function by mediating a conformational change. Activation of the immune system leads to the secretion of thiol isomerases that catalyse labile disulfide bond reduction and thereby are able to modulate protein function. A bioinformatics study and a mass spectrometry based screen have shown that many different plasma membrane proteins potentially contain labile disulfide bonds. To identify proteins with biologically relevant labile disulfide bonds it is necessary to quantify the reduction occurring as it is expected that only proteins that are reduced to a substantial amount affect cellular function. In this study, a mass spectrometry based method to screen for proteins with labile disulfide bonds and quantify their reduction in primary cells was developed. It was then applied to study the plasma membrane redox proteome during immune activation and identified several proteins, mainly activating (CD132, gp130) and adhesion (integrins, ICAM1 and CD44) molecules, that are reduced to a major degree during immune activation. Furthermore, functional studies on the shared cytokine receptor gp130 showed that thioredoxin reduction inhibits IL-6 signalling. These observations in conjunction with the literature suggest that labile disulfide bond reduction during immune activation is a mechanism to prevent over-activation of the immune system and excessive accumulation of leukocytes in sites of inflammation. Presenting a method to identify altered redox control of proteins in diseases such as autoimmunity provides the basis for the rational design of novel redox drugs.
Supervisor: Barclay, A. Neil ; Metcalfe, Clive Sponsor: Scatcherd European Scholarship ; Medical Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available