IFN-gamma increases the hGH gene promoter activity in rat GH3 cells.
OBJECTIVE
To study the effect(s) of interferon gamma (IFN-gamma) on the activity of human growth hormone (hGH) gene promoter in rat pituitary GH3 cells and the molecular mechanism underlying the effect(s).


METHODS
Cell transfection and luciferase reporter gene were used.


RESULTS
IFN-gamma (10(2) and 10(3) U/ml) increased the activity of hGH in GH3 cells. The addition of the mitogen-activated protein kinase inhibitor PD98059 (40 micromol/l) to the cells blocked the stimulatory effect of IFN-gamma. Neither overexpression of Pit-1 nor inhibiting Pit-1 expression affected IFN-gamma induction of hGH promoter activity. To identify the DNA sequence that mediated the effect of IFN-gamma, four deletion constructs of hGH gene promoter were created. The stimulatory effect of IFN-gamma was abolished following deletion of the -250 to -132 fragment.


CONCLUSIONS
IFN-gamma increases the activity of hGH gene promoter in rat pituitary GH3 cells. This stimulatory effect of IFN-gamma appears to require the intracellular mitogen-activated protein kinase-dependent signaling pathway. The effect of IFN-gamma requires the promoter sequence that spans the -250 to -132 fragment of the gene, but is unrelated to Pit-1 protein.
Gong
Feng-Ying
FY
Department of Endocrinology, Beijing Union Medical College Hospital, Chinese Academy of Medical Sciences and Beijing Union Medical College, Beijing, China.
Deng
Jie-Ying
JY
Shi
Yi-Fan
YF
D000818:Animals; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter / Q000235:genetics; D019382:Human Growth Hormone / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics; D014162:Transfection; D001616:beta-Galactosidase / Q000235:genetics
D004268:DNA-Binding Proteins; C494187:POU1F1 protein, human; C494186:Pou1f1 protein, rat; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D019382:Human Growth Hormone; D007371:Interferon-gamma; D008156:Luciferases; D001616:beta-Galactosidase