Interaction of Ets-1 and the POU-homeodomain protein GHF-1/Pit-1 reconstitutes pituitary-specific gene expression.
The pituitary-specific, POU-homeodomain factor GHF-1/Pit-1 is necessary, but not sufficient, for cell-specific expression of prolactin (PRL), growth hormone (GH), and thyrotropin. Combinatorial interactions of GHF-1 with other factors are likely to be required; however, such factors and their mechanisms of action remain to be elucidated. Here we identify Ets-1 as a factor that functionally and physically interacts with GHF-1 to fully reconstitute proximal PRL promoter activity. In contrast, Ets-2 has no effect, and the alternatively spliced GHF-2/Pit-1beta variant fails to synergize with Ets-1. The Ets-1-GHF-1 synergy requires a composite Ets-1-GHF-1 cis element and is dependent on an Ets-1-specific protein domain. Furthermore, the ancestrally related and GHF-1-dependent GH promoter, which lacks this composite element, does not exhibit this response. Finally, Ets-1, but not Ets-2, binds directly to GHF-1 and GHF-2. These data show that a functional interaction of GHF-1 and Ets-1, acting via a composite DNA element, is required to establish lactotroph-specific PRL gene expression, thus providing a molecular mechanism by which GHF-1 can discriminate between the GH and PRL genes. These results underscore the importance of transcription factors that are distinct from, but interact with, homeobox proteins to establish lineage-specific gene expression.
Bradford
A P
AP
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262, USA.
Wasylyk
C
C
Wasylyk
B
B
Gutierrez-Hartmann
A
A
D000818:Animals; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics*; D013006:Growth Hormone / Q000235:genetics; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D011388:Prolactin / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D050784:Proto-Oncogene Protein c-ets-1; D050787:Proto-Oncogene Protein c-ets-2; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D051381:Rats; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators / Q000378:metabolism; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; C107465:ERF protein, human; C494041:ETS1 protein, human; C494069:ETS2 protein, human; C494043:Ets1 protein, rat; C494071:Ets2 protein, rat; D018398:Homeodomain Proteins; C494187:POU1F1 protein, human; C494186:Pou1f1 protein, rat; D050784:Proto-Oncogene Protein c-ets-1; D050787:Proto-Oncogene Protein c-ets-2; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D011388:Prolactin; D013006:Growth Hormone; D004247:DNA