Requirement of TGF-beta receptor-dependent activation of c-Jun N-terminal kinases (JNKs)/stress-activated protein kinases (Sapks) for TGF-beta up-regulation of the urokinase-type plasminogen activator receptor.
We have previously demonstrated that activation of the Ras/Mapk pathways is required for transforming growth factor beta (TGF-beta) induction of TGF-beta(1) expression. Here we examined the role of the Ras/Mapk pathways in TGF-beta induction of urokinase-type plasminogen activator receptor (uPAR) expression in untransformed intestinal epithelial cells (IECs). TGF-beta activated the stress-activated protein kinases (Sapk)/c-Jun N-terminal kinases (JNKs) within 5-10 min, an effect that preceeded TGF-beta induction of uPAR expression in these cells. TGF-beta induction of both JNK1 activity and JunD phosphorylation was blocked by expression of a dominant-negative mutant of the type II TGF-beta receptor (DN TbetaRII), a dominant-negative mutant of MKK4 (DN MKK4), or a dominant-negative mutant of Ras (RasN17), or by the addition of the JNK inhibitor SP600125. TGF-beta also induced AP-1 complex formation at the distal AP-1 site (-184 to -178) of the uPAR promoter within 2 h of TGF-beta addition, consistent with the time-dependent up-regulation of uPAR expression. The primary components present in the TGF-beta-stimulated AP-1 complex bound to the uPAR promoter were Jun D and Fra-2. Moreover, addition of SP600125, or expression of DN MKK4 or DN TbetaRII, blocked TGF-beta up-regulation of uPAR in IECs. Accordingly, our results indicate that TGF-beta activates the Ras/MKK4/JNK1 signaling cascade, leading to induction of AP-1 activity, which, in turn, up-regulates uPAR expression. Our results also indicate that the type II TGF-beta receptor (RII) is required for TGF-beta activation of JNK1 and the resulting up-regulation of uPAR expression.
Yue
Jianbo
J
Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey 17033, USA.
Sun
Baodong
B
Liu
Guangming
G
Mulder
Kathleen M
KM
D000818:Animals; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000187:drug effects / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000187:drug effects / Q000378:metabolism; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism; D015854:Up-Regulation
D004791:Enzyme Inhibitors; C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta; D055293:Receptors, Urokinase Plasminogen Activator; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases