Steroidogenic factor-1 and early growth response protein 1 act through two composite DNA binding sites to regulate luteinizing hormone beta-subunit gene expression.
Recent in vivo and in vitro studies have implicated the orphan nuclear receptor, steroidogenic factor-1 (SF-1), and the early growth response protein 1 (Egr-1) in the transcriptional regulation of the luteinizing hormone beta-subunit (LHbeta) gene. We have previously demonstrated the ability of SF-1 to bind to and transactivate the rat LHbeta gene promoter acting at a consensus gonadotrope-specific element (GSE) located at position -127. We have now identified a second functional GSE site at position -59. In addition, based on electrophoretic mobility shift assay, in vitro translated Egr-1 is shown to bind to two putative Egr-1 binding sites (positions -112 and -50), which appear to be paired with the identified GSE sites. By transient transfection assay in pituitary-derived GH3 cells, it was seen that Egr-1 increases promoter activity of region -207/+5 of the rat LHbeta gene promoter through action at both Egr-1 sites. Furthermore, LHbeta gene promoter activity is markedly augmented in the presence of both factors together relative to activity in the presence of SF-1 or Egr-1 alone (150-fold versus 14-fold and 12-fold, respectively). These data define two composite SF-1-Egr-1 response-elements in the proximal LHbeta gene promoter and suggest that SF-1 and Egr-1 act synergistically to increase expression of the LHbeta gene in the gonadotrope.
Halvorson
L M
LM
Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. Halvorson@rascal.med.harvard.edu
Ito
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Jameson
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Chin
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D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002460:Cell Line; D017124:Conserved Sequence / Q000235:genetics; D004268:DNA-Binding Proteins / Q000032:analysis / Q000502:physiology*; D051766:Early Growth Response Protein 1; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D018398:Homeodomain Proteins; D017874:Immediate-Early Proteins; D007986:Luteinizing Hormone / Q000235:genetics*; D051379:Mice; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D010902:Pituitary Gland / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000502:physiology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear; D015682:Retroviridae Proteins, Oncogenic / Q000502:physiology*; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000502:physiology*; D014162:Transfection / Q000235:genetics
D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; C486110:Egr1 protein, rat; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D017874:Immediate-Early Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D015682:Retroviridae Proteins, Oncogenic; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse; C515060:steroidogenic factor 1, rat; D007986:Luteinizing Hormone