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A NOVEL STUDY OF THE G-PROTEIN
AND THE G-PROTEIN COUPLED RECEPTOR IN THE PHOTOTRANSDUCTION OF MOUSE RETINAS
by
Wen Mao
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(NEUROSCIENCE)
Copyright 2011 Wen Mao
Object Description
| Title | A novel study of the G-protein and the G-protein coupled receptor in the phototransduction of mouse retinas |
| Author | Mao, Wen |
| Author email | wen.mao.usc@gmail.com;joywwmao@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Neuroscience |
| School | College of Letters, Arts And Sciences |
| Date defended/completed | 2011-06-15 |
| Date submitted | 2011-07-21 |
| Date approved | 2011-07-22 |
| Restricted until | 2011-07-22 |
| Date published | 2011-07-22 |
| Advisor (committee chair) | Chen, Jeannie |
| Advisor (committee member) |
Alapakkam , Sampath Sucov, Henry |
| Abstract | During the past several years of my PhD studies, I strived to achieve a better understanding of the G-protein mediated phototransduction, particularly in a quantitative approach. Although the general picture of this signal transduction pathway has long been described, we lack accurate information about how individual step is precisely regulated. This work presents novel findings of phototransduction employing a combination of biochemical, electrophysiological, and genetic techniques. ❧ As the major part of my research, we replaced cone transducin-alpha (cTα) for rod transducin-alpha (rTα) in transgenic mouse rods to evaluate how Ga subtype influences signal amplification from different GPCRs, and how this might explain functional differences between rods and cones. We demonstrated biochemically that the exogenous cTα forms a functional heterotrimeric complex with rod Tβ1γ1. The electrophysiological recordings revealed that the light sensitivities were indeed affected by the expression level of G proteins and independent of cell-specific isoforms. ❧ Taking advantages of variant G-protein expressing mice, we further investigated the relationship between transducin translocation pattern and its light activation. Because transducin translocation has been found to be triggered by saturation of the GTPase-activating complex that is proportional to light activation, we examined whether a higher light threshold to trigger translocation was required for a low expressor of transducin. In the cTα transgenic retina, we found out that light sensitivity appeared to be uncoupled from translocation threshold. Thus, additional factors other than transducin activation may contribute to its translocation. ❧ The other part of my work aimed to study recoverin’s influence on rhodopsin phosphorylation in the intact mouse rod photoreceptor cells. Consistent with many in vitro biochemical studies, our findings indicate Rv’s inhibition on rhodopsin phosphorylation by quenching RK activity, which is likely to play an essential role during dark adaption. |
| Keyword | phototransduction; mouse retinas; G-protein; rhodopsin phosphorylation; transgenic |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m |
| Contributing entity | University of Southern California |
| Rights | Mao, Wen |
| Access conditions | The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given. |
| Repository name | University of Southern California Digital Library |
| Repository address | USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA |
| Repository email | cisadmin@usc.edu |
| Archival file | uscthesesreloadpub_Volume71/etd-MaoWen-150.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Full text | A NOVEL STUDY OF THE G-PROTEIN AND THE G-PROTEIN COUPLED RECEPTOR IN THE PHOTOTRANSDUCTION OF MOUSE RETINAS by Wen Mao A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (NEUROSCIENCE) Copyright 2011 Wen Mao |
