Modulation by cellular cholesterol of gene transcription via the cyclic AMP response element

Citation
A. Middleton et al., Modulation by cellular cholesterol of gene transcription via the cyclic AMP response element, BIOCH PHARM, 62(2), 2001, pp. 171-181
Citations number
34
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Pharmacology & Toxicology
Journal title
BIOCHEMICAL PHARMACOLOGY
ISSN journal
0006-2952 → ACNP
Volume
62
Issue
2
Year of publication
2001
Pages
171 - 181
Database
ISI
SICI code
0006-2952(20010715)62:2<171:MBCCOG>2.0.ZU;2-C
Abstract
The effect of rapid changes in cellular cholesterol content on adenosine 3' ,5'-cyclic monophosphate (cAMP) response element-mediated gene transcriptio n was investigated. The study was carried out in Chinese hamster ovary (CHO -K1) cells permanently expressing the human beta (2)-adrenoceptor. Gene tra nscription was quantified using a reporter gene (secreted placental alkalin e phosphatase) under the transcriptional control of cAMP response element ( CRE) sequences. Cellular cholesterol was reduced by 42% or elevated by 47% by incubating cells for 1 hr with methyl-beta -cyclodextrin alone or methyl -beta -cyclodextrin complexed with cholesterol, respectively. There was a s ignificant negative correlation between the free cholesterol content of the cells and CRE-mediated gene expression in response to 10(-6) M isoprenalin e (slope = -4.57 +/- 0.73, P < 0.001), indicating that <beta>(2)-adrenocept or-mediated activation of the CRE is inhibited by cholesterol. Cyclic AMP a ccumulation in response to isoprenaline (10(-12) to 10(-5) M) was also inhi bited in cholesterol-enriched cells and enhanced in cholesterol-depleted ce lls compared to controls (P < 0.05, two-way ANOVA). Cholesterol also inhibi ted serum-mediated enhancement of CRE-driven gene expression, and we presen t data suggesting that the pathway activated by serum and inhibited by chol esterol could be independent of adrenoceptor activation and protein kinase A. We conclude that in CHO-K1 cells cholesterol inhibits at least two proce sses that can stimulate CRE-mediated gene expression. One is isoprenaline a ctivation of cAMP synthesis, the other is activated by serum. These finding s demonstrate that activation of gene transcription by extracellular stimul i could be influenced by cellular cholesterol content. (C) 2001 Elsevier Sc ience Inc. All rights reserved.