Human chorionic somatomammotropin enhancer function is mediated by cooperative binding of TEF-1 and CSEF-1 to multiple, low-affinity binding sites

Shi Wen Jiang, Miguel A. Trujillo, Norman L. Eberhardt

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

The human chorionic somatomammotropin gene enhancer (CSEn) is composed of multiple enhansons (Enh) that share sequence similarities with those of the simian virus, SV40 enhancer (SVEn). The sequence homology includes two GT-IIC-like (Enh1 and Enh4) and three SphI/II-like enhansons (Enh2, Enh3, and Enh5). We previously showed that transcription enhancer factor 1 (TEF-1) and a 30-kDa placental-specific factor, chorionic somatomammotropin enhancer factor 1 (CSEF-1), bind to Enh4, which plays an essential role in enhancer function. In this study, we demonstrate that TEF-1 and CSEF-1 bind specifically to all the other GT-IIC- and SphI/II-like elements within CSEn with a broad range of binding affinities that vary between 0.005 and 0.15 that of Enh4. Each individual concatenated enhanson was able to stimulate hCS promoter activity in an orientation-independent manner in choriocarcinoma cells (BeWo) with an observed stimulation that was directly proportional to its relative binding affinity for TEF-1 and CSEF-1. These results indicate that CSEn function results from the cooperative interaction of TEF-1 and/or CSEF-1 binding to multiple, low-affinity GT-IIC-and SphI/II-like enhansons within the enhancer.

Original languageEnglish (US)
Pages (from-to)1223-1232
Number of pages10
JournalMolecular Endocrinology
Volume11
Issue number9
DOIs
StatePublished - Jan 1 1997

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

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