Epithelial PDZ scaffolds: new links in Ca2+ handling

Wade Kruger (2011). Epithelial PDZ scaffolds: new links in Ca2+ handling PhD Thesis, School of Biomedical Sciences, The University of Queensland.

Attached Files (Some files may be inaccessible until you login with your UQ eSpace credentials)
Name Description MIMEType Size Downloads
s40591492_phd_finalthesis.pdf s40591492_phd_finalthesis.pdf application/pdf 24.36MB 7
Author Wade Kruger
Thesis Title Epithelial PDZ scaffolds: new links in Ca2+ handling
School, Centre or Institute School of Biomedical Sciences
Institution The University of Queensland
Publication date 2011-12
Thesis type PhD Thesis
Supervisor Professor Philip Poronnik
Professor Gregory Monteith
Total pages 204
Total colour pages 24
Total black and white pages 180
Language eng
Subjects 1116 Medical Physiology
Abstract/Summary Ca2+ mediated signalling is subject to tight spatial and temporal regulation in order to achieve the appropriate physiological response. It has only been recognised recently that ion channels, transporters and receptors are subject to dynamic regulation at the plasma membrane by the formation of specific molecular complexes that direct functional specificity. These complexes are nucleated and held together by scaffolds and adapter proteins that serve to restrict the lateral mobility of the membrane proteins and anchor them to the cytoskeleton as well as recruiting signalling / regulatory molecules to the complex. The most common scaffold protein module is the PDZ module. The name PDZ is derived from the proteins that were shown initially to have these modules: Postsynaptic density septate junction protein, Disc-large and the epithelia tight junction protein ZO-1. This strategic positioning of functionally related proteins in close proximity scaffolded PDZ proteins allows fast and efficient control of membrane transport processes. One family of PDZ proteins are the Na+/H+ exchanger regulatory factors, of which there are 4 members NHERF-1, -2, -3 and -4. NHERF-1 was the first PDZ scaffold identified for an epithelial transporter. It was shown to direct the formation of a multi-protein complex that mediated cAMP regulated protein kinase (PKA) phosphorylation and inhibition of the Na+/H+ exchanger 3 (NHE3). Initially thought to be specific for epithelial cells, NHERFs have since been identified in many diverse cell types and there is an ever growing list of their binding partners and functions. This thesis describes new and novel roles for NHERF-1 and NHERF-2 in the context of Ca2+ signaling. The first section explored the regulation of the ubiquitous plasma membrane calcium ATPase (PMCA) in colonic epithelial carcinoma cells (HT-29) by NHERF-2. A new transient Ca2+ efflux complex was identified that was formed in response to the activation of M3 muscarinic receptors by acetylcholine. NHERF-2 was shown to play a key role in not only nucleating the PMCA complex, but also in providing a previously uncharacterized mechanism for the regulation of PMCA activity by PKA during muscarinic stimulation. The second section shed further light into the role of NHERF-1 in colon cancer. NHERF-1 is recognised as a marker in various epithelial cell malignancies. Here it was shown that silencing NHERF-1 significantly altered the proliferative capacity of HT-29 cells. Importantly, transactivation of the EGF receptor by neurotensin was inhibited when NHERF-1 was silenced via a mechanism that involved inhibition of Ca2+ signaling.
Keyword calcium signalling
Scaffold Proteins,
PDZ domain
G-protein coupled receptors
Epithelial cells
Additional Notes 29,32,35,44,79,80,82,84,86,87,90,92,105,107,110,111,115,124,125,129,140,167,168,172

Citation counts: Google Scholar Search Google Scholar
Created: Tue, 12 Jun 2012, 15:05:55 EST by Wade Kruger on behalf of Library - Information Access Service