Transcriptional factor prolactin regulatory element-binding protein-mediated gene transcription of ABCA1 via 3',5'-cyclic adenosine-5'-monophosphate.
OBJECTIVE
Prolactin regulatory element-binding (PREB) protein is a transcription factor that regulates prolactin promoter activity in the rat anterior pituitary. The PREB protein is not only expressed in the anterior pituitary but also in the cardiovascular system, including vascular smooth muscle cells (SMCs). However, the role of PREB in SMCs is not clearly understood. The ATP-binding cassette transporter A1 (ABCA1) regulates lipid efflux from peripheral cells to apolipoproteins. In the present study, we have examined the role of PREB in regulating ABCA1 expression mediated by 3',5'-cyclic adenosine-5'-monophosphate (cAMP).


RESULTS
PREB was expressed in the rats SMC line CRL-2018. ABCA1 expression was found to be regulated by cAMP, which stimulated the expression of PREB in a dose-dependent manner. Conversely, over-expression of PREB, which was induced by a PREB-expressing adenovirus, increased the expression of the ABCA1 protein in CRL-2018 cells. In addition, PREB stimulated the activity of the luciferase reporter protein that was under the control of the ABCA1 promoter. Chromatin immunoprecipitation assay showed that PREB mediates its transcriptional activity by directly binding to the ABCA1 promoter region. Finally, we used siRNA to inhibit PREB expression in the cells and demonstrated that the knockdown of PREB expression attenuated the effects of cAMP on ABCA1 expression.


CONCLUSIONS
In summary, our data showed that PREB regulates the cAMP-mediated transcription of the ABCA1 gene in vascular SMCs.
Nishiuchi
Yukiko
Y
Division of Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.
Murao
Koji
K
Imachi
Hitomi
H
Nishiuchi
Takamasa
T
Iwama
Hisakazu
H
Ishida
Toshihiko
T
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001053:Apolipoproteins / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D032389:Myocytes, Smooth Muscle / Q000166:cytology; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism*
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D001053:Apolipoproteins; D004268:DNA-Binding Proteins; D020662:Guanine Nucleotide Exchange Factors; C118971:PREB protein, human; C485592:Preb protein, rat; D034741:RNA, Small Interfering; D014157:Transcription Factors; D002784:Cholesterol; D000242:Cyclic AMP