Tri-iodothyronine and cycloheximide enhance insulin-like growth factor-binding protein-1 gene expression in human hepatoma cells
| Autor: | Mervi Julkunen, Markku Seppälä, Riitta Koistinen, Pekka Leinonen, Maarit Angervo |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
medicine.medical_specialty
medicine.medical_treatment Gene Expression Complement factor I Biology Cycloheximide Cell Line chemistry.chemical_compound Endocrinology Somatomedins Internal medicine Gene expression medicine Humans Secretion RNA Messenger Molecular Biology Triiodothyronine Forskolin Growth factor Molecular biology Insulin-Like Growth Factor Binding Protein 1 Liver chemistry Cell culture Carrier Proteins Half-Life |
| Zdroj: | Journal of Molecular Endocrinology. 10:7-13 |
| ISSN: | 1479-6813 0952-5041 |
| DOI: | 10.1677/jme.0.0100007 |
| Popis: | The growth-regulating actions of IGFs are modulated by their binding proteins (IGFBPs). The serum concentration of IGFBP-1 is down-regulated by insulin, and in-vitro studies have demonstrated that IGFBP-1 secretion from various tissues and cells can be stimulated by theophylline, forskolin, oestrogen and progesterone. We have studied the effects and mechanisms of thyroid hormone action on IGFBP-1 gene expression and secretion by human hepatoma cells in vitro. Tri-iodothyronine dose-dependently enhanced IGFBP-1 secretion in serum-free HepG2 cell cultures after 24–48 h of exposure, as measured by a specific immunofluorometric assay. This was accompanied by an increase (+ 50%) in the amount of IGFBP-1 mRNA, which could be prevented by cycloheximide, a protein synthesis inhibitor. Cycloheximide transiently enhanced (+ 200%) the accumulation of IGFBP-1 mRNA at 3–12 h of incubation, when no effect of tri-iodothyronine was observed. It is concluded that thyroid hormone stimulates IGFBP-1 secretion slowly by enhancing IGFBP-1 gene expression by a protein mediator. The acute stimulation of IGFBP-1 gene transcription by cycloheximide associates this gene with a number of growth-related genes encoding growth- and tumour-associated peptides. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|