Asian Science Citation Index is committed to provide an authoritative, trusted and significant information by the coverage of the most important and influential journals to meet the needs of the global scientific community.  
ASCI Database
308-Lasani Town,
Sargodha Road,
Faisalabad, Pakistan
Fax: +92-41-8815544
Contact Via Web
Suggest a Journal
Endocrinology
Year: 2009  |  Volume: 150  |  Issue: 7  |  Page No.: 3252 - 3258

Fibroblast Growth Factor-2 Autofeedback Regulation in Pituitary Folliculostellate TtT/GF Cells

G Vlotides, Y. H Chen, T Eigler, S. G Ren and S. Melmed    

Abstract:

To investigate paracrine regulation of pituitary cell growth, we tested fibroblast growth factor (FGF) regulation of TtT/GF folliculostellate (FS) cells. FGF-2, and FGF-4 markedly induced cell proliferation, evidenced by induction of pituitary tumor transforming gene-1 (Pttg1) mRNA expression and percentage of cells in S phase. Signaling for FGF-2-induced FS cell proliferation was explored by specific pharmacological inhibition. A potent inhibitory effect on FGF-2 action was observed by blocking of Src tyrosine kinase with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d] pyrimidine (≥0.1 µm), followed by protein kinase C (PKC) inhibition with GF109203X. Treatment with FGF-2 (30 ng/ml; 10 min) activated phosphorylation of signal transducer and activator of transcription-3, ERK, stress-activated protein kinase/c-Jun N-terminal kinase, Akt, and focal adhesion kinase. Src inhibition with 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d] pyrimidine suppressed FGF-2-induced Akt and focal adhesion kinase, indicating effects downstream of FGF-2-induced Src activation. FGF-2 also markedly induced its own mRNA expression, peaking at 2–4 h, and this effect was suppressed by Src tyrosine kinase inhibition. The PKC inhibitor GF109203X abolished FGF-2 autoinduction, indicating PKC as the primary pathway involved in FGF-2 autoregulation in these cells. In addition to pituitary FGF-2 paracrine activity on hormonally active cells, these results show an autofeedback mechanism for FGF-2 in non-hormone-secreting pituitary FS cells, inducing cell growth and its own gene expression, and mediated by Src/PKC signaling.

View Fulltext    |   Related Articles   |   Back
   
 
 
 
  Related Articles

No Article Found
 
 
 
Copyright   |   Desclaimer   |    Privacy Policy   |   Browsers   |   Accessibility