A PIT-1 Homeodomain Mutant Blocks the Intranuclear Recruitment Of the CCAAT/Enhancer Binding Protein α Required for Prolactin Gene Transcription
| Autor: | Margaret A. Kawecki-Crook, Richard N. Day, Fred Schaufele, Ty C. Voss, John F. Enwright |
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| Rok vydání: | 2003 |
| Předmět: |
Transcription
Genetic Recombinant Fusion Proteins Centromere Green Fluorescent Proteins EMX2 Active Transport Cell Nucleus Biology Article NKX2-3 Prolactin cell Mice Endocrinology Transcription (biology) Heterochromatin Enhancer binding CCAAT-Enhancer-Binding Protein-alpha Animals Humans Promoter Regions Genetic Molecular Biology Transcription factor Cells Cultured Cell Nucleus Homeodomain Proteins Regulation of gene expression Ccaat-enhancer-binding proteins General Medicine Molecular biology Prolactin Rats DNA-Binding Proteins Luminescent Proteins Gene Expression Regulation Pituitary Gland Mutation Transcription Factor Pit-1 Transcription Factors |
| Zdroj: | Molecular Endocrinology. 17:209-222 |
| ISSN: | 1944-9917 0888-8809 |
| DOI: | 10.1210/me.2001-0222 |
| Popis: | The pituitary-specific homeodomain protein Pit-1 cooperates with other transcription factors, including CCAAT/enhancer binding protein α (C/EBPα), in the regulation of pituitary lactotrope gene transcription. Here, we correlate cooperative activation of prolactin (PRL) gene transcription by Pit-1 and C/EBPα with changes in the subnuclear localization of these factors in living pituitary cells. Transiently expressed C/EBPα induced PRL gene transcription in pituitary GHFT1–5 cells, whereas the coexpression of Pit-1 and C/EBPα in HeLa cells demonstrated their cooperativity at the PRL promoter. Individually expressed Pit-1 or C/EBPα, fused to color variants of fluorescent proteins, occupied different subnuclear compartments in living pituitary cells. When coexpressed, Pit-1 recruited C/EBPα from regions of transcriptionally quiescent centromeric heterochromatin to the nuclear regions occupied by Pit-1. The homeodomain region of Pit-1 was necessary for the recruitment of C/EBPα. A point mutation in the Pit-1 homeodomain associated with the syndrome of combined pituitary hormone deficiency in humans also failed to recruit C/EBPα. This Pit-1 mutant functioned as a dominant inhibitor of PRL gene transcription and, instead of recruiting C/EBPα, was itself recruited by C/EBPα to centromeric heterochromatin. Together our results suggest that the intranuclear positioning of these factors determines whether they activate or silence PRL promoter activity. |
| Databáze: | OpenAIRE |
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