Binding of STAT5a and STAT5b to a single element resembling a gamma-interferon-activated sequence mediates the growth hormone induction of the mouse acid-labile subunit promoter in liver cells.
After birth, the endocrine actions of insulin-like growth factor (IGF)-I and -II become increasingly important. In postnatal animals, most of circulating IGFs occur in 150-kDa complexes formed by association of an acid-labile subunit (ALS) with complexes of IGF and IGF-binding protein-3. ALS is synthesized almost exclusively in liver. GH stimulates the transcription of the ALS gene, resulting in increased hepatic mRNA and circulating ALS levels. To map the GH response element, a series of 5'-deletion fragments of the mouse ALS promoter (nt -2001 to -49, A(+1)TG) were inserted in the luciferase reporter plasmid pGL3 and transfected into the H4-II-E rat hepatoma cell line. GH stimulated the activity of promoter fragments with 5'-ends between nucleotide (nt) -2001 and nt -653 by 1.9- to 2.7-fold. This stimulation was abolished by deletion of the region located between nt -653 and nt -483. This region contains two sites, ALS-GAS1 and ALS-GAS2, that resemble the gamma-interferon activated sequence (GAS). Mutation of the ALS-GAS1 site, but not of the ALS-GAS2 site, eliminated the response to GH when assessed in the context of a GH-responsive promoter fragment, indicating that ALS-GAS1 was necessary for GH induction. Three tandem copies of ALS-GAS1 were sufficient to confer GH inducibility to the minimal promoter of the thymidine kinase gene. In electrophoretic mobility shift assays, ALS-GAS1 formed a specific, GH-dependent protein-DNA complex with nuclear extracts from H4-II-E cells. Using antibodies directed against members of the family of signal transducers and activators of transcription (STAT), this complex was shown to be composed of STAT5a and STAT5b. Identical results were obtained when transfections and mobility shift assays were performed in primary rat hepatocytes in which the endogenous ALS gene is expressed. Thus, the transcriptional activation of the mouse ALS gene by GH is mediated by the binding of STAT5 isoforms to a single GAS-like element.
Ooi
G T
GT
Growth and Development Section, Molecular and Cellular Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA.
Hurst
K R
KR
Poy
M N
MN
Rechler
M M
MM
Boisclair
Y R
YR
D000818:Animals; D006528:Carcinoma, Hepatocellular; D002352:Carrier Proteins / Q000187:drug effects / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D006023:Glycoproteins / Q000187:drug effects / Q000235:genetics*; D013006:Growth Hormone / Q000494:pharmacology*; D007371:Interferon-gamma / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D008894:Milk Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects / Q000235:genetics*; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D013002:Somatomedins / Q000187:drug effects / Q000235:genetics; D015534:Trans-Activators / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D006023:Glycoproteins; D008894:Milk Proteins; D009687:Nuclear Proteins; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D013002:Somatomedins; C494080:Stat1 protein, mouse; C494087:Stat3 protein, mouse; C494088:Stat3 protein, rat; C494093:Stat5a protein, mouse; C494094:Stat5a protein, rat; C494096:Stat5b protein, mouse; C494097:Stat5b protein, rat; D015534:Trans-Activators; C075944:insulin-like growth factor binding protein, acid labile subunit; D007371:Interferon-gamma; D013006:Growth Hormone