Post-transcriptional regulation of endothelial cell plasminogen activator inhibitor-1 expression during R. rickettsii infection.
Intracellular infection of endothelial cells with Rickettsia rickettsii results in increased steady-state levels of plasminogen activator inhibitor-1 (PAI-1) mRNA. Control mechanisms governing such increased expression in response to this novel stimulus have not been defined. In this study, we compared the stability of PAI-1 mRNA in infected and uninfected endothelial cells (EC) and explored the requirement for de novo host cell protein synthesis in the infection-induced increase of steady-state levels. The half-life of PAI-1 mRNA, which is constitutively expressed in cultured EC, increased from 18 h in uninfected EC to greater than 30 h in EC infected for 24 h, a time point at which increases in steady-state PAI-1 mRNA levels are noted. There was no change in stability of gamma-actin due to infection. Nuclear run-on studies revealed no apparent increase in transcription rate at 4, 18 and 24 h. R. rickettsii -induced increase in PAI-1 mRNA was blocked by the eukaryotic protein synthesis inhibitor, cycloheximide, which suggests that this response requires de novo host cell protein synthesis. These results provide evidence that post-transcriptional control mechanisms are operative in the regulation of PAI-1 during R. rickettsii infection.
Shi
R J
RJ
Vascular Medicine Unit, University of Rochester School of Medicine & Dentistry, Rochester, New York, USA.
Simpson-Haidaris
P J
PJ
Marder
V J
VJ
Silverman
D J
DJ
Sporn
L A
LA
D000199:Actins / Q000378:metabolism; D015152:Blotting, Northern; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000382:microbiology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis; D012284:Rickettsia rickettsii; D012373:Rocky Mountain Spotted Fever / Q000382:microbiology
D000199:Actins; D017395:Plasminogen Activator Inhibitor 1; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D003513:Cycloheximide