Effect of interleukin-1 beta on growth hormone gene expression and its possible molecular mechanism in rat MtT/S somatotroph cells / 中国医学科学杂志(英文版)
Chinese Medical Sciences Journal
;
(4): 193-201, 2008.
Article
in English
| WPRIM
| ID: wpr-302671
ABSTRACT
<p><b>OBJECTIVE</b>To elucidate the effect of interleukin-1 beta (IL-1 beta) on human growth hormone (hGH) gene expression in a rat somatotropic pituitary cell line MtT/S.</p><p><b>METHODS</b>Stably transfected MtT/S cells were firstly established by transfecting 484-Luc1 plasmid which contained hGH gene promoter -484 to +30 bp and luciferase reporter gene. The effect of IL-1 beta on hGH gene expression was determined by assaying the luciferase activities. RT-PCR method was also used to determine whether IL-1 recepor mRNA was expressed in MtT/S cells.</p><p><b>RESULTS</b>The 10(3) U/mL IL-1 beta stimulated secretion and synthesis of GH, and promoted the 5'-promoter activity of GH gene in stably transfected MtT/SGL cells with the action of 1.38 times above the control. Among inhibitors of signaling transduction pathways, mitogen-activated protein kinase kinase (MAPKK/MEK) inhibitor PD98059 (40 micromol/L) and p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 (5 micromol/L) completely blocked the stimulatory effect of IL-1 beta, and phosphatidylinositol-3-kinase (PI3-K) inhibitor LY294002 partly abolished the effect of IL-1 beta. Western blot analysis further confirmed the activation of phosphorylated MEK and p38 MAPK in MtT/SGL cells. Neither over-expression of Pit-1 nor inhibition of Pit-1 expression affected induction of hGH promoter activity by IL-1 beta. A series of deletion constructs of hGH promoter were created to identify the DNA sequence that mediated the effect of IL-1 beta, and results showed that the stimulatory effect of IL-1 beta was abolished following deletion of the -196 to -132 bp fragment.</p><p><b>CONCLUSIONS</b>IL-1 beta promotes GH secretion and synthesis in rat MtT/S somatotroph cells. The stimulatory effect of IL-1 beta on hGH gene promoter appears to require the activation of MEK, p38 MAPK, PI3-K, and a fragment of promoter sequence that spans the -196 to -132 bp of the gene, but it may be unlinked with Pit-1 protein.</p>
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Physiology
/
Cell Line
/
Promoter Regions, Genetic
/
Receptors, Interleukin-1
/
Human Growth Hormone
/
Mitogen-Activated Protein Kinase Kinases
/
Cell Biology
/
P38 Mitogen-Activated Protein Kinases
/
Enzyme Inhibitors
/
Transcription Factor Pit-1
Type of study:
Prognostic study
Limits:
Animals
/
Humans
Language:
English
Journal:
Chinese Medical Sciences Journal
Year:
2008
Type:
Article
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