Transcriptional regulation of apolipoprotein E expression by cyclic AMP

FEBS Letters
M Andreani-MangeneyG Bereziat

Abstract

Incubation of HepG2 cells in the presence of dibutyryl cAMP (db-cAMP), a cell permeable analogue of cyclic AMP, or forskolin, an agent which elevates intracellular cAMP, resulted in a 50% decrease in apoE mRNA levels within 24 h. Results of nuclear run-on transcription assays showed that db-cAMP down-regulates apoE gene expression at the transcriptional level. By transfection analysis with a plasmid containing the -614/+804 human apoE gene fused to the secreted placental alkaline phosphatase (SPAP) reporter gene, we showed that the SPAP activity was decreased by 50% when HepG2 cells were incubated in the presence of db-cAMP or forskolin, indicating that this promoter region mediated this negative effect. In contrast, when the smaller fragment -200/+1 of apoE promoter was linked to the CAT reporter gene, db-cAMP treatment of HepG2 cells resulted in a 2-fold increase in CAT activity, suggesting that positive cAMP-responsive elements were present in the proximal apoE promoter. These data indicate that transcriptional modulation of apoE gene expression by agents known to elevate the intracellular cAMP level is complex and involves several negative and positive elements located in the -614 to +804 region of the apoE gene whose globa...Continue Reading

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Citations

Aug 11, 2000·Microscopy Research and Technique·M J Bullido, F Valdivieso
Feb 27, 2001·Cell Biochemistry and Function·F BrahimiG Siest
Apr 14, 2005·Journal of Molecular Medicine : Official Organ of the Gesellschaft Deutscher Naturforscher Und Ärzte·Kirsty GreenowDipak P Ramji
Aug 5, 2010·American Journal of Medical Genetics. Part a·János KissPéter Lakatos

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