Transcription factor activating protein-2beta: a positive regulator of monocyte chemoattractant protein-1 gene expression.
We previously reported an association between the activating protein (AP)-2beta transcription factor gene and type 2 diabetes. This gene is preferentially expressed in adipose tissue, and subjects with a disease-susceptible allele of AP-2beta showed stronger AP-2beta expression in adipose tissue than those without the susceptible allele. Furthermore, overexpression of AP-2beta leads to lipid accumulation by enhancing glucose transport and inducing insulin resistance in 3T3-L1 adipocytes. In this study, we found that overexpression of AP-2beta in 3T3-L1 adipocytes accelerated the promoter activity of monocyte chemoattractant protein-1 (MCP-1) and subsequently increased both mRNA and protein expression and protein secretion. Furthermore, knockdown of endogenous AP-2beta by RNA interference reduced the mRNA and the protein expression of MCP-1. EMSAs and chromatin immunoprecipitation assays revealed specific binding of AP-2beta to MCP-1 promoter regions, in vitro and in vivo. Additionally, site-directed mutagenesis of the AP-2 binding site located at -137 to -129 relative to the transcription start site markedly diminished MCP-1 promoter activity, whereas other putative AP-2 binding sites did not. Our results clearly show that AP-2beta directly enhanced MCP-1 secretion by binding to its promoter. Thus, we propose that AP-2beta positively regulates MCP-1 expression; subsequently contributes to the infiltration of macrophages to adipose tissue; and leads to insulin resistance, type 2 diabetes, and cardiovascular diseases.
Kondo
Motoyuki
M
Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan.
Maegawa
Hiroshi
H
Obata
Toshiyuki
T
Ugi
Satoshi
S
Ikeda
Kazuhiro
K
Morino
Katsutaro
K
Nakai
Yukie
Y
Nishio
Yoshihiko
Y
Maeda
Shiro
S
Kashiwagi
Atsunori
A
D041721:3T3-L1 Cells; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015153:Blotting, Western; D018932:Chemokine CCL2 / Q000235:genetics* / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D051379:Mice; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D034741:RNA, Small Interfering; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050656:Transcription Factor AP-2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D018932:Chemokine CCL2; D034741:RNA, Small Interfering; D050656:Transcription Factor AP-2; D004247:DNA