Regulation of 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase Gene Expression in FRTL-5 Cells
| Autor: | Maurizio Bifulco, Leonard D. Kohn, Chiara Laezza, Salvatore M. Aloj, Motoyasu Saji, Bruno Perillo, Idolo Tedesco |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
7-Dehydrocholesterol reductase
endocrine system Reporter gene Forskolin Oncogene Coenzyme A Cell Biology Transfection Biology Reductase Biochemistry Molecular biology chemistry.chemical_compound chemistry Transcription (biology) Gene expression Histone octamer Protein kinase A Gene Molecular Biology hormones hormone substitutes and hormone antagonists Protein kinase C |
| Zdroj: | Journal of Biological Chemistry. 270:15237-15241 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.270.25.15237 |
| Popis: | 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity and mRNA levels were significantly reduced in FRTL-5 cells transformed with the Kirsten-Moloney sarcoma virus (KiMol); these cells have lost thyrotropin dependence and express high levels of p21ras. FRTL-5 cells, transformed with a temperature-sensitive mutant of the v-K-ras oncogene (Ats cells: 33°C, permissive; 39°C, nonpermissive), showed significant reduction of HMG-CoA reductase expression when exposed to 33°C. In KiMol cells, as well as in Ats cells at 33°C, the transcription driven by cAMP-responsive element was probed by measuring chloramphenicol acetyl transferase (CAT) levels after transfection with a chimeric plasmid containing the reporter gene linked to the rat reductase promoter. Basal CAT activity in KiMol cells transfected with wild-type promoter was lower than in FRTL-5 cells but was increased by forskolin to the levels attained in thyrotropin-stimulated FRTL-5 cells. Forskolin failed to increase CAT activity in KiMol cells transfected with the plasmid harboring a reductase promoter in which the cAMP-responsive element octamer was mutated to a nonpalindromic sequence. The effect of v-K-ras could be mimicked in FRTL-5 cells by tetradecanoyl phorbol acetate and reverted in KiMol and Ats cells, expressing active Ras protein, by increasing intracellular cAMP and/or by protein kinase C inhibition. The data are consistent with the contention that v-K-ras, through protein kinase C and depletion of intracellular cAMP, is inhibitory for the protein kinase A pathway. This is the first demonstration that active v-K-ras down-regulates HMG-CoA reductase expression. |
| Databáze: | OpenAIRE |
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