The CRE-Like Element Inside the 5′-Upstream Region of the Rat Sodium/Iodide Symporter Gene Interacts with Diverse Classes of b-Zip Molecules that Regulate Transcriptional Activities through Strong Synergy with Pax-8

• Published in: Molecular endocrinology (Baltimore, Md.) Md.), 2004-11, Vol.18 (11), p.2817-2829
• Main Authors: Chun, J. T, Di Dato, V, D’Andrea, B, Zannini, M, Di Lauro, R
• Format: Article
• Language: English
• Subjects: 5' Flanking Region - genetics; Animals; Binding Sites - genetics; Cell Line; Conserved Sequence; Cyclic AMP - metabolism; Cyclic AMP - pharmacology; Cyclic AMP Response Element-Binding Protein - metabolism; Dimerization; DNA-Binding Proteins - metabolism; Electrophoretic Mobility Shift Assay; Gene Expression Regulation; Mutation - genetics; Nuclear Proteins - metabolism; Paired Box Transcription Factors; PAX8 Transcription Factor; Promoter Regions, Genetic - genetics; Rats; Response Elements - genetics; Symporters - genetics; Trans-Activators - metabolism; Transcription Factor AP-1 - metabolism; Transcription Factors - metabolism
• ISSN: 0888-8809; 1944-9917
• DOI: 10.1210/me.2004-0020

We previously demonstrated that transcription of the rat sodium/iodide symporter (NIS) gene is regulated by NUE, an upstream enhancer located between nucleotides −2264 and −2495 of the 5′-flanking region. To elucidate the mechanism of TSH/cAMP-mediated regulation of NIS gene expression, we have characterized the putative cAMP response element (CRE)/activator protein (AP)-1 site (termed NUC) that is closely located between the two Pax-8 (paired box domain transcription factor-8) binding sites within NUE. In two different approaches using either gel supershift analyses or dominant-negative inhibitors of b-Zip molecules, we have shown that NUC can be recognized by several members of the AP-1 and CREB family transcription factors that modulate the transcriptional activity of NUE. Using tethered dimers of b-Zip molecules, we have also demonstrated that specific homo- or heterodimers of AP-1 can synergistically stimulate NUE activity in concert with Pax-8. To demonstrate further that NUC is a bona fide CRE, we made an artificial promoter with the five-time tandem repeat of this sequence (5xNUC). In comparison to the canonical CRE (5xCRE), 5xNUC manifested greater transcriptional activity and broader response to cAMP signaling. Hence, we postulate that the significance of this evolutionally conserved CRE-like site may lie in its broader cell type specificity.