title: Posttranscriptional regulation of expression of plasminogen activator inhibitor type-1 by cAMP in HepG2 liver cells.
abstract: Altered expression of plasminogen activator inhibitor type-1 (PAI-1), a physiologic fibrinolysis inhibitor, is implicated in atherosclerosis. Cyclic adenosine monophosphate (cAMP) alters PAI-1 expression in several cells. Nevertheless, posttranscriptional regulation of PAI-1 has not been elucidated. To determine whether cAMP affects PAI-1 expression at posttranscriptional level, we determined promoter activity, mRNA levels, 3'-untranslated region (UTR) activity and protein levels of PAI-1 using HepG2 cells. cAMP decreased PAI-1 promoter activity at 24 h and mRNA expression at 4 h while it increased mRNA expression and accumulation of PAI-1 protein into media at 24 h. Human PAI-1 mRNA exists in two subspecies (3.2 and 2.2 kb), and cAMP increased baseline luciferase activity of 3'-UTR of the 3.2 kb PAI-1 mRNA [3'-UTR (+1358-3176)] and 1 kb fragment of 3'-terminus of 3'-UTR of 3.2 kb mRNA [3'-UTR (+2177-3176)]. cAMP increased PAI-1 protein expression despite decrease in promoter activity, presumably by regulating PAI-1 expression at the posttranscriptional level and thereby affecting mRNA stability. The 53-nt fragment in 3'-UTR (+2591 to +2643 nt) was involved in posttranscriptional regulation by cAMP. Thus, cAMP can stabilize 3.2 kb PAI-1 mRNA mediated by specific effects on 3'-UTR, and these effects are associated with increased expression of PAI-1 protein.
authors: Department of Molecular and Cellular Pathobiology and Therapeutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.
authors: Takefumi
authors: T
authors: Asakura
authors: Soichiro
authors: S
authors: Iwaki
authors: Hiromi
authors: H
authors: Okada
authors: Burton E
authors: BE
authors: Sobel
authors: Satoshi
authors: S
authors: Fujii
mesh_terms: D020413:3' Untranslated Regions; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000378:metabolism / Q000494:pharmacology*; D003470:Culture Media / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D008099:Liver / Q000166:cytology / Q000378:metabolism; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions; D003470:Culture Media; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; C051321:SERPINE1 protein, human; D015124:8-Bromo Cyclic Adenosine Monophosphate; D008156:Luciferases