Kim, Dong Eun
(2011)
THE ROLE OF THE N-END RULE PATHWAY IN CARDIOVASCULAR DEVELOPMENT, SIGNALING, AND HOMEOSTASIS.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
The N-end rule pathway relates the in vivo half-life of a protein to the identity of its N-terminal residue. The conjugation of arginine (Arg) from Arg-tRNAArg to N-terminal Asp, Glu, or Cys is a universal eukaryotic protein modification that can lead to ubiquitylation and proteasomal degradation of the resulting Arg-conjugated proteins through the N-end rule pathway. The mammalian ATE1 gene encodes Arg-transferase that mediates all known N-terminal arginylation reactions. ATE1-/- embryos die owing to various cardiovascular defects including ventricular hypoplasia, ventricular septal defect, and late angiogenesis. The genomewide functional proteomics previously identified a set of RGS proteins (RGS4, RGS5, and RGS16) as in vivo substrates of ATE1. These RGS proteins are important negative regulators of Gáq-activated signaling for myocardial growth and vascular maturation/integrity. In my first project, I attempted to determine the role of ATE1-dependent posttranslational arginylation in Gáq-dependent cardiac signaling. I constructed and characterized ATE1-/-GáqTg compound mutant mice, where Gáq is exclusively overexpressed in the heart from áMHC promoter. I found that while Gáq overexpression in the heart rescues significantly cardiac defects in ATE1-/- embryonic hearts, it does not cause a noticeable change in vascular defects. These results together suggest that ATE1 controls cardiac development and signaling in part through Gq-activated signaling pathways. In the second project, I generated RGS5 transgenic mouse (TG) strains overexpressing either MC-RGS5 (wild-type, short-lived) or MV-RGS5 (mutant, long-lived) from vascular smooth muscle-specific SM22á promoter to determine the physiological importance of RGS5 proteolysis in Gq signaling of VSMC. Both MC-RGS5 and MV-RGS5 mice were viable and fertile without any visible defects. However, MC-RGS5 femalevmice demonstrated impaired delivery in that newborn pups were often found dead associated with an absence of milk in their stomachs. In contrast, MV-RGS5 mice did not show this phenotype. The mis-regulated RGS5 proteolysis in MC-RGS5 mice may result in the failure in oxytocin-induced uterine and mammary gland smooth muscle contraction. In summary, my research provides an insight into the role of N-end rule pathway in cardiovascular Gq signaling.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
10 January 2011 |
| Date Type: |
Completion |
| Defense Date: |
6 October 2010 |
| Approval Date: |
10 January 2011 |
| Submission Date: |
6 October 2010 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Pharmacy > Pharmaceutical Sciences |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
ATE1; cardiovascular system; GPCR; N-end rule pathway; RGS5; transgenic mice; ubiquitin system |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-10062010-201104/, etd-10062010-201104 |
| Date Deposited: |
10 Nov 2011 20:02 |
| Last Modified: |
15 Nov 2016 13:50 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/9442 |
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