Prolactin regulatory element-binding protein involved in cAMP-mediated suppression of adiponectin gene.
Adiponectin (ApN) has several protective effects against diabetes and atherosclerosis. However, the detailed mechanisms of the regulation of the ApN gene have not yet been clarified. Prolactin regulatory element-binding (PREB) protein has been identified as a factor that regulates insulin gene expression in the pancreas. PREB is located not only in the pancreas but also in adipose tissue; however, its role in adipose tissue is not known. To analyse the effects of PREB on ApN gene transcription, we employed a reporter gene assay and electrophoretic mobility shift assay (EMSA). In the cells expressing or knocking down the PREB, ApN expression was determined. PREB was located mainly in the nuclei of adipose tissue and its cell line, 3T3-L1 cells. The nuclear extract contained ApN promoter-binding activity that was super-shifted by PREB antiserum in EMSA studies. In the 3T3-L1 cells, the co-expression of PREB and the ApN promoter inhibited the activity of the latter. The addition of cAMP to the cells increased PREB expression in a dose-dependent manner. A deletional analysis of the ApN promoter showed that the PREB-responsive cis-element in the ApN promoter mediated the transcriptional effect of PREB, whereas a mutant of this motif in the ApN promoter abrogated the effect of PREB, as well as that of cAMP. Furthermore, cells expressing or knocking down PREB exhibited decreased and increased ApN expression, respectively. These results demonstrate that PREB may contribute to the regulation of ApN gene transcription, in response to cAMP activation in adipocytes.
Li
Junhua
J
Division of Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, Kagawa University, Kita-gun, Kagawa, Japan.
Murao
Koji
K
Imachi
Hitomi
H
Yu
Xiao
X
Muraoka
Tomie
T
Kim
Jae Bum
JB
Ishida
Toshihiko
T
D041721:3T3-L1 Cells; D052242:Adiponectin / Q000235:genetics* / Q000378:metabolism; D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000235:genetics*; D055785:Gene Knockdown Techniques; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D052242:Adiponectin; D004268:DNA-Binding Proteins; D020662:Guanine Nucleotide Exchange Factors; C485591:Preb protein, mouse; D012333:RNA, Messenger; D014157:Transcription Factors; D000242:Cyclic AMP