Fibroblast Growth Factors (FGFs) are secreted molecules that activate the RAS/mitogen-activated protein kinase (MAPK) signaling pathway to establish dorsal polarity, maintain the isthmic organizer, and assure proper ventricle formation in the zebrafish. The mechanism of FGF regulation of these processes and the transcription factors involved are still unclear. Expression of the zebrafish PEA3 family of ETS transcription factors, Etv5, Erm, and Pea3, is responsive to FGF signaling, and these factors are likely transcriptional effectors of this pathway. I have determined the role of PEA3 ETS factors in FGF signaling and gene regulation through gain- and loss-of-function studies. Ectopic expression of a constitutively activated form of Etv5 induced FGF target transcripts, dual specificity phosphatase 6 (dusp6) and similar expression to fgfs (sef). The simultaneous knock-down of Etv5, Erm, and Pea3 produced phenotypes reminiscent of the fgf8 mutant, including the disruption of the mid-hindbrain boundary, diminished cardiac progenitors, and left/right patterning defects. Furthermore, the expression of FGF target genes was abolished in Etv5/Erm/Pea3 depleted embryos. To understand how FGF signaling and PEA3 ETS factors control gene expression, the transcriptional regulation of dusp6 was studied in mouse and zebrafish. Conserved Pea3/ETS binding sites were identified within the dusp6 promoter, and reporter assays show that one of these sites is required for dusp6 induction by FGFs in both species. In addition, I demonstrated the interaction of PEA3 ETS factors with the dusp6 promoter both in vitro and in vivo. These results revealed the requirement of ETS factors in transducing FGF signals in developmental processes.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-06302010-114141 |
| Date | 01 October 2010 |
| Creators | Znosko, Wade |
| Contributors | Michael Tsang, Philip Auron, Jeffrey Brodsky, Deborah Chapman, Gerard Campbell |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-06302010-114141/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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