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.
Shetty
Sreerama
S
Texas Lung Injury Institute, The University of Texas Health Science Center at Tyler, 75708, USA. sreerama.shetty@uthct.edu
Velusamy
Thirunavukkarasu
T
Shetty
Rashmi S
RS
Marudamuthu
Amarnath S
AS
Shetty
Shwetha K
SK
Florova
Galina
G
Tucker
Torry
T
Koenig
Kathy
K
Shetty
Praveenkumar
P
Bhandary
Yashodhar P
YP
Idell
Steven
S
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