Transcription of the Leydig insulin-like gene is mediated by steroidogenic factor-1.
The Leydig insulin-like gene (Ley I-L), a member of the insulin-related gene family, is specifically expressed in pre- and postnatal Leydig cells of the testis and in postnatal theca cells of the ovary. To determine the functional region of the mouse Ley I-L promoter and factors controlling the Ley I-L gene expression, we used 2.1 kb of the 5'-flanking region of the mouse Ley I-L gene to generate chimeric constructs with the chloramphenicol acetyltransferase gene (CAT). Transient transfections of MA10 Leydig cells, LTK- fibroblasts, and F9 embryonic cells by a series of 5'-deleted mouse Ley I-L promoter-CAT constructs revealed that the sequence between nucleotides -157 to +4 directs the transcription of the reporter gene in MA10 but not in LTK- and F9 cells, indicating that the determinants of Leydig cell-specific expression reside within this region. Deoxyribonuclease I (DNase I) footprint analysis revealed that the sequences designated SF-1/1, SF-1/2, and SF-1/3 within three DNase I-protected regions are homologous to the consensus binding site of the steroidogenic factor-1 (SF-1). Competition and antibody studies showed that the three SF-1-binding sites in the Ley I-L promoter have similar binding affinities for SF-1. Furthermore, transient transfections of MA10 cells with mutant reporter constructs, in which SF-1/1 or both SF-1/2 and SF-1/3 were deleted, demonstrated that all three SF-1-binding sites are required for SF-1-mediated stimulation of Ley I-L transcription. Cotransfection of an SF-1-containing expression vector together with a Ley I-L promoter-CAT construct into HeLa cells, which lack the endogenous SF-1 protein, resulted in CAT gene transcription, which indicated that SF-1 can transactivate the Ley I-L promoter. These data demonstrate an essential role of SF-1 in transcriptional activation of the Ley I-L promoter.
Zimmermann
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S
Institute of Human Genetics, University of Göttingen, Germany.
Schwärzler
A
A
Buth
S
S
Engel
W
W
Adham
I M
IM
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation / Q000187:drug effects; D018398:Homeodomain Proteins; D006801:Humans; D007328:Insulin / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000235:genetics; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics*; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D007328:Insulin; C084797:Leydig insulin-like protein; C515057:NR5A1 protein, human; D011506:Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse