Human placental TEF-5 transactivates the human chorionic somatomammotropin gene enhancer.
Human chorionic somatomammotropin (hCS) gene expression in the placenta is controlled by an enhancer (CSEn) containing SV40-related GT-IIC and SphI/SphII enhansons. These enhancers are controlled by members of the transcription enhancer factor-1 (TEF-1) family. Recently TEF-5, whose mRNA is abundant in placenta, was shown to bind cooperatively to a unique, tandemly repeated element in CSEn2, suggesting that TEF-5 regulates CSEn activity. However, expression of TEF-5 using a cDNA lacking the 5'-untranslated region and containing a modified translation initiation site was not accompanied by CSEn activation. Using nested, degenerate PCR primers corresponding to conserved TEF domains, several novel TEF-1-related cDNAs have been cloned from a human placental cDNA library. The open reading frame of one 3033-bp clone was identical to TEF-5 and contained 300- and 1423-bp 5'- and 3'-untranslated regions, respectively. The in vitro generated approximately 53-kDa TEF-5 polypeptide binds specifically to GT-IIC and SphI/SphII oligonucleotides. Overexpression of TEF-5 in BeWo cells using the intact 3033-bp cDNA transactivates the hCS and SV40 enhancers and artificial enhancers comprised of tandemly repeated GT-IIC enhansons, but not OCT enhansons. The data demonstrate that TEF-5 is a transactivator that is likely involved in the transactivation of CSEn enhancer function. Further, the data suggest that elements within the untranslated regions, initiation site, or both control TEF-5 expression in ways that influence its transactivation function.
Jiang
S W
SW
Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Wu
K
K
Eberhardt
N L
NL
D020121:5' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D001483:Base Sequence; D019556:COS Cells / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010920:Placenta / Q000378:metabolism; D010928:Placental Lactogen / Q000235:genetics* / Q000378:metabolism; D011247:Pregnancy; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
D020121:5' Untranslated Regions; D000952:Antigens, Polyomavirus Transforming; D004268:DNA-Binding Proteins; D000091262:TEA Domain Transcription Factors; C106169:TEAD3 protein, human; D014157:Transcription Factors; D010928:Placental Lactogen