Heterotrimeric G proteins are molecular switches that respond to a wide range of stimuli including light, neurotransmitters, small molecules and peptides. Due to their role in a variety of physiological responses, it is no surprise that over 50% of drugs modulate G protein signaling pathways. While many drugs function at the level of the G protein-coupled receptor, downstream signaling components are increasingly being investigated as drug targets. Therefore, discovery of new components and regulators will help identify new ways to exploit G protein-coupled signaling pathways for therapeutic utility.
Previous attempts to systematically identify new components of G protein pathways have focused on genome-wide knockout screens including gene-deletion mutants. However, these methods are inherently limited because they exclude the essential genes. In this thesis, we present studies to identify new signaling components by systematically analyzing 870 essential genes using repressible-promoter strains. Specifically, we show that the SCFCdc4 E3 ubiquitin ligase complex regulates G protein turnover and catalyzes ubiquitination of the G protein subunit, Gpa1. Also, we demonstrate that Pik1, a phosphatidylinositol (PtdIns) 4-kinase, regulates the mitogen-activated protein kinase (MAPK) cascade and helps maintain signaling fidelity. These findings reveal the essential-genome as an untapped resource for identifying new components and regulators of signal transduction pathways. Furthermore, work on this thesis has expanded our understanding of G protein signaling networks and could lead to future opportunities for drug discovery.
|Advisor:||Dohlman, Henrik G.|
|Commitee:||Bankaitis, Vytas A., Graves, Lee M., Johnson, Gary L., Siderovski, David P.|
|School:||The University of North Carolina at Chapel Hill|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 72/08, Dissertation Abstracts International|
|Keywords:||Essential genes, G proteins, Ubiquitin|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be