2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London




Название2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London
страница1/48
Дата01.10.2012
Размер1 Mb.
ТипДокументы
  1   2   3   4   5   6   7   8   9   ...   48


Investigation of the role of the p110 isoform of PI 3-kinase in cell signalling and proliferation


CRISTIANO GONELLA

2011


QUEEN MARY UNIVERSITY OF LONDON

Mile End Road

London


This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London

ABSTRACT




Phosphoinositide 3-kinases (PI3Ks) are signalling enzymes that play important roles in various cellular processes and in disease, such as cancer and auto-immunity. There are several isoforms of PI3K whose individual roles have been studied extensively, amongst other to understand whether any of the PI3K isoforms may represent a target for selective pharmacological intervention in disease.

In this study, I aimed to identify the mechanisms that determine the sensitivity of cancer cell growth and proliferation to inhibition of the p110 isoform of PI3K. p110β is activated downstream G-protein coupled receptors (GPCRs), and occurs in complex with a regulatory subunit named p85 which links this PI3K to tyrosine kinase signalling pathways. The parameters that determine cellular sensitivity to p110 are unclear.

To characterize the role of p110β in signal transduction, its recruitment downstream a model receptor tyrosine kinase (PDGFR, platelet-derived growth factor receptor) and its binding to the different p85 isoforms was investigated. p110β was found to be recruited downstream active PDGFR alongside p110, the other PI3K isoform that acts as the main PI3K isoform downstream such receptor. I also document that there is no preferential association of p110β with p85α or p85β, the two main p85 isoforms.

In a panel of human cancer cell lines, I discovered that cancer cell lines that showed sensitivity to p110β growth and cell signalling inhibition were deficient in expression or function of IRS-1 (insulin receptor substrate-1), although they expressed IRS-1 mRNA, and this molecular trait was further investigated. Using cell transfection and RNA interference (RNAi) techniques I tried to modulate p110β sensitivity in various cellular models. Overexpression of IRS-1 protein in p110β-sensitive cancer cells could not be achieved, likely due to the same inhibitory signalling networks that prevent expression of endogenous IRS-1. Unexpectedly, downregulation of IRS expression by RNAi resulted in a positive effect of p110β inhibition on cell growth and proliferation. Such a growth-stimulating effect of inhibition of p110 was also observed under other conditions. The molecular basis for this effect is not completely clear to date and possible explanations are discussed.

I conclude that p110 has a role as a signalling modulator that, upon specific circumstances, can determine both positive and negative responses in the cellular signalling circuitry and behaviour.

STATEMENT




This thesis is the result of work conducted at the Centre for Cell Signalling, Barts Cancer Institute, Charterhouse Square, Queen Mary University of London, between October 2007 and February 2011. Except where references are given, this thesis contains my own original work in agreement with the regulations of Queen Mary University of London.

Some of the work I performed has been published elsewhere:


Ciraolo, E., Iezzi, M., Marone, R., Marengo, S., Curcio, C., Costa, C., Azzolino, O., Gonella, C., Rubinetto, C., Wu, H., et al. (2008). Phosphoinositide 3-kinase p110beta activity: key role in metabolism and mammary gland cancer but not development. Science signaling 1, ra3.

Guillermet-Guibert, J., Bjorklof, K., Salpekar, A., Gonella, C., Ramadani, F., Bilancio, A., Meek, S., Smith, A.J., Okkenhaug, K., and Vanhaesebroeck, B. (2008). The p110beta isoform of phosphoinositide 3-kinase signals downstream of G protein-coupled receptors and is functionally redundant with p110gamma. Proceedings of the National Academy of Sciences of the United States of America 105, 8292-8297.


In the PNAS work, I contributed to immunoblot analyses of PI3K isoform expression in p110 mutant cells (Fig. 1C). I also provided technical assistance to some parts of the study, as part of my initial training in the Centre for Cell Signalling laboratory. These data are not presented in this thesis.
  1   2   3   4   5   6   7   8   9   ...   48

Похожие:

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconA thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Information Systems

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconGlaeconomics laying the foundations London’s construction industry February 2006 Transport for London London Development Agency Mayor of London Greater London Authority

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London icon1990 Ph. D. Zoology, Imperial College, University of London, London, U. K

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconN. C. Markatos, “Transport Processes Across a Wavy Boundary”, Ph. D. Thesis, University of London, 1973

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconConvened by the Institute of Education, University of London and Beijing Normal University, 3-6 May 2006. Introduction

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconAnd thank-you for considering St George’s, University of London (sgul) /Kingston University (KU) as a place to come and study physiotherapy. We hope the

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconOriginally published by the London Ecology Unit, 1993. The London Ecology Unit was abolished in 2000, and absorbed into the Greater London Authority. The text has been reprinted here, but not revised. Some images have been replaced

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London icon14 General observations 14 The “London Lens” 20 Case study 1: Innovative London ‘high streets’ 21 Case study 2: Tesco in London 25 Unresolved questions 27

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconThis is London’s Economic Development Strategy, prepared by the London Development Agency (lda) on behalf of the Mayor of London. It replaces the 2001 Strategy

2011 queen mary university of london mile End Road London This thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy from the University of London iconA dissertation submitted in partial fulfilment of the requirement for the degree of Bachelor in Adult and Vocational Education (Honours) at the University of South Australia

Разместите кнопку на своём сайте:
Библиотека


База данных защищена авторским правом ©lib.znate.ru 2014
обратиться к администрации
Библиотека
Главная страница