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Title: Involvement of deubiquitinating enzymes in TGF[beta] receptor trafficking and signalling
Author: Chojnowska-Monga, Monika
ISNI:       0000 0004 2734 2051
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2011
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The transforming growth factor-β (TGF β) superfamily of ligands controls a wide range of biological processes, including cellular differentiation, proliferation, motility, adhesion and apoptosis. It exerts its biological processes mainly through the TGF β receptor and downstream Smad proteins. Deregulation of TGF β signalling is associated with a variety of human diseases, including cancer. Ubiquitination is a reversible post-translational modification implicated In a variety of cellular processes, including proteasome-mediated protein degradation, DNA repair, regulation of transcription, endocytosis and receptor trafficking. Reversible ubiquitination tightly regulates the TGF β signaling pathway by controlling the basal expression level of TGF β pathway components, terminating signals after prolonged activation of signalling cascade or regulating activity of transcription factors involved in regulation of TGF β target gene expression. In this study, I assessed the involvement of two deubiquitinating enzymes (DUBs) AMSH (~ssociated molecule with the SH3 domain of STAM) and AMSH-LP (AMSH like protein) in the signalling of the TGF~ superfamily of ligands. I compared cellular localisation of both DUBs in HeLa cells as well as their relative protein levels in HEK293T cells. I performed a comparative analysis of the interactions of both AMSH and AMSH-LP with the components of the Smad family of signal transducers using a yeast two- hybrid approach. I also demonstrated evidence for the role of AMSH and AMSH-LP in the regulation of signalling by the TGF~ superfamily ligands, using a luciferase reporter driven by the TGF β or BMP-responsive promoters. Importantly, I showed differential dependence of AMSH and AMSH-LP effect on TGF~ signalling on their DUB activity. I then tested the importance of endosomal localisation for the role of AMSH and AMSH-LP in TGF β signalling and presented evidence for AMSH regulation of TGF β type I receptor levels. Finally, I report on a comprehensive siRNA screen testing the involvement of other DUBs in these signalling pathways.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available