Alternative splicing of human plasma cholesteryl ester transfer protein mRNA in Caco-2 cells and its modulation by oleic acid.
Cholesteryl ester transfer protein (CETP) is a plasma protein involved in the reverse cholesterol transport and expressed in several human tissues and cell lines. We studied CETP expression in Caco-2 cell line, a model of the human enterocyte epithelium. By reverse-transcriptase polymerase chain reaction, we could demonstrate that in basal condition Caco-2 cells have a low rate of expression of active CETP mRNA. Furthermore, we found that even in this cell line CETP mRNA alternative splicing occurs with deletion of exon 9 sequence. Densitometric analysis of the in vitro amplified fragments showed that under basal conditions about 60% of reverse transcribed CETP cDNA corresponds to exon 9-deleted transcripts. After challenge with 50 microM sodium oleate, there is a approximately 2 fold increase in the transcription rate of the full-length CETP cDNA, as measured by competitive PCR, which is accompanied to an increased activity measured in the cell-conditioned medium. On the contrary, no significant change is seen in the amount of exon 9-deleted cDNA. Consequently, an inversion in the ratio of full-length and exon 9-deleted CETP cDNA is evident, suggesting that sodium oleate selectively enhances the expression of full-length CETP mRNA.
Dessí
M
M
Department of Internal Medicine, University of Tor Vergata, Rome, Italy.
Motti
C
C
Cortese
C
C
Leonardis
E
E
Giovannini
C
C
Federici
G
G
Piemonte
F
F
D017398:Alternative Splicing / Q000187:drug effects*; D001667:Binding, Competitive; D018938:Caco-2 Cells / Q000187:drug effects / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis / Q000187:drug effects / Q000235:genetics*; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins; D006801:Humans; D019301:Oleic Acid / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*
C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins; D012333:RNA, Messenger; D019301:Oleic Acid