Transcriptional activity is dependent not only on the binding of transcription factors to cis-acting elements, but also on the ability of those factors to recruit a complex hierarchy of proteins to stabilize the basal transcriptional machinery. Oncogenic Ras signaling to the rat prolactin (rPRL) promoter is dependent on the interaction of the proto-oncoprotein c-Ets-1, a member of the Ets family of transcription factors, with the pituitary-specific transcription factor, Pit-1, at a composite Ets/Pit-1 DNA binding element (RRE) in the rPRL promoter. This signaling cascade utilizes a tripartite code comprised of Pit-1 and Ets-1 binding to the unique RRE element, the physical interaction of the Ets-1 Rill TAD with the Pit-1 homeodomain, and Ras-stimulated MAPkinase phosphorylation of threonine 82 in Ets-1. Together this code creates a structural platform for the binding of a transcriptional regulatory complex through which Ras can mediate activation of the rPRL promoter. Recent studies suggest that the phosphorylation of Pit-1 can modulate both Ras signaling and Ets-1/Pit-1 binding. Thus, I hypothesize that the Pit-1/Ets-1 complex binding to the RRE mediates the oncogenic Ras response of the rPRL promoter by recruiting specific transcription regulatory proteins to a unique interaction face. The goals of this proposal are to determine the mechanism by which phosphorylation of Pit-1 inhibits Ras-activation of the rPRL promoter, and to use liquid chromatography/mass spectrometry methods to identify the protein components that are recruited by Ras signaling to the Ets-1/Pit-1 complex. Therefore, these studies are important to my career development as they will allow me to gain expertise in the cutting edge field of proteomics and protein structure-function relationships, which I can then utilize to establish my career as an independent investigator.
| Jean, Annie; Gutierrez-Hartmann, Arthur; Duval, Dawn L (2010) A Pit-1 threonine 220 phosphomimic reduces binding to monomeric DNA sites to inhibit Ras and estrogen stimulation of the prolactin gene promoter. Mol Endocrinol 24:91-103 |
| Jonsen, Matthew D; Duval, Dawn L; Gutierrez-Hartmann, Arthur (2009) The 26-amino acid ss-motif of the Pit-1ss transcription factor is a dominant and independent repressor domain. Mol Endocrinol 23:1371-84 |
| Gutierrez-Hartmann, Arthur; Duval, Dawn L; Bradford, Andrew P (2007) ETS transcription factors in endocrine systems. Trends Endocrinol Metab 18:150-8 |
| Duval, Dawn L; Jonsen, Matthew D; Diamond, Scott E et al. (2007) Differential utilization of transcription activation subdomains by distinct coactivators regulates Pit-1 basal and Ras responsiveness. Mol Endocrinol 21:172-85 |
