Post-transcriptional regulation of plasminogen activator inhibitor type-1 expression in human pleural mesothelial cells.
The plasminogen activator inhibitor type-1 (PAI-1) effectively blocks the activities of free and receptor-bound urokinase-type plasminogen activator. Incubation of cultured human pleural mesothelial (Met5A) cells with TGF-beta increased PAI-1 protein. TGF-beta, phorbol myristate acetate, and the translation inhibitor cycloheximide induced PAI-1 mRNA and slowed its degradation, suggesting that PAI-1 mRNA could be regulated by interaction of a PAI-1 binding protein (PAI-1 mRNABp) with PAI-1 mRNA. We found that an approximately 60 kD cytoplasmic PAI-1 mRNABp is detectable in cytoplasmic extracts of MeT5A human pleural mesothelial and malignant mesothelioma cells. The PAI-1 mRNABp specifically binds to a 33-nt sequence in the 3' untranslated region of PAI-1 mRNA. Insertion of this 33-nt sequence destabilizes otherwise stable beta-globin mRNA, indicating that the binding sequence accelerates decay of endogenous PAI-1 mRNA. Competitive inhibition by overexpression of the 33-nt binding sequence in MeT5A cells reduced PAI-1 mRNA decay and increased PAI-1 protein and mRNA expression, indicating that the PAI-1 mRNABp destabilizes PAI-1 mRNA by its interaction with the endogenous 33-nt binding sequence. Incubation of Met5A cells with TGF-beta attenuated the interaction of the PAI-1 mRNABp with the 33-nt sequence. By conventional and affinity purification, we isolated the PAI-1 mRNABp and confirmed its identity as 6-phospho-d-gluconate-NADP oxidoreductase, which specifically interacts with the full-length and the 33-nt sequence of the PAI-1 mRNA 3' untranslated region. This newly recognized pathway could influence expression of PAI-1 by mesothelial or mesothelioma cells at the level of mRNA stability in the context of pleural inflammation or malignancy.
Texas Lung Injury Institute, The University of Texas Health Science Center at Tyler, 75708, USA. sreerama.shetty@uthct.edu
Sreerama
S
Shetty
Thirunavukkarasu
T
Velusamy
Rashmi S
RS
Shetty
Amarnath S
AS
Marudamuthu
Shwetha K
SK
Shetty
Galina
G
Florova
Torry
T
Tucker
Kathy
K
Koenig
Praveenkumar
P
Shetty
Yashodhar P
YP
Bhandary
Steven
S
Idell
D015152:Blotting, Northern; D015153:Blotting, Western; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004848:Epithelium / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008654:Mesothelioma / Q000235:genetics / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics* / Q000378:metabolism; D010994:Pleura / Q000166:cytology / Q000378:metabolism*; D010997:Pleural Neoplasms / Q000235:genetics / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism
D002273:Carcinogens; D017395:Plasminogen Activator Inhibitor 1; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; C051321:SERPINE1 protein, human; D016212:Transforming Growth Factor beta; D003513:Cycloheximide; D013755:Tetradecanoylphorbol Acetate