Plasminogen activator inhibitor-1 promoter activity in adipocytes is not influenced by the 4 G/5 G promoter polymorphism and is regulated by a USF-1/2 binding site immediately preceding the polymorphic region.
Plasminogen activator inhibitor-1 (PAI-1) levels were found to be associated with obesity indicating that adipocytes influence PAI-1 plasma levels. In addition, the 4 G/5 G promoter polymorphism of the PAI-1 gene may modulate PAI-1 transcription. We investigated the transcriptional regulation of the human PAI-1 gene in adipocytes and analyzed the genetic contribution of the 4 G/5 G polymorphism. The PAI-1 promoter was analyzed using electrophoretic mobility shift assays (EMSAs) and luciferase reporter gene assays. A putative binding site for the upstream stimulatory factor-1/2 (USF-1/2) at the polymorphic region of the PAI-1 promoter was identified. The binding of USF-1/2 was studied using nuclear extracts prepared from adipocytes and was similar in all the promoter variants as analyzed by EMSA. A 257 bp PAI-1 promoter fragment including the 4 G/5 G site was transcriptionally active in adipocytes and was not influenced by the polymorphism. The present data indicate for the first time that USF-1/2 is transcriptionally active in differentiated adipocytes. However, USF-1/2 binding activity and PAI-1 transcription are not influenced by the 4 G/5 G-allele. These data possibly explain the observation that PAI-1 secretion from adipose tissue is not influenced by the PAI-1 promoter polymorphism.
Zietz
B
B
Department of Internal Medicine I, University of Regensburg, Regensburg, Germany.
Drobnik
W
W
Herfarth
H
H
Buechler
C
C
Schölmerich
J
J
Schäffler
A
A
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002454:Cell Differentiation / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism*; D011110:Polymorphism, Genetic / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D051720:Upstream Stimulatory Factors
D004268:DNA-Binding Proteins; D017395:Plasminogen Activator Inhibitor 1; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; C497183:Usf1 protein, mouse