title: Posttranscriptional regulation of urokinase receptor expression by heterogeneous nuclear ribonuclear protein C.
abstract: Interaction of urokinase-type plasminogen activator (uPA) with its receptor, uPAR, is a key regulatory step in uPA-mediated cell proliferation and migration. Our previous studies demonstrated that posttranscriptional stabilization of uPAR mRNA by uPA contributes to the induction of cell surface uPAR expression, and heterogeneous nuclear ribonuclear protein C1 (hnRNPC) binds to a 110 nt sequence of uPAR mRNA 3'-UTR, thereby preventing its degradation. These observations indicate that hnRNPC could be involved in the induction of uPAR expression by uPA. In the present study, we investigated this possibility and confirmed that uPA increased the binding of hnRNPC to the 3'-UTR of uPAR mRNA. Furthermore, uPA induced tyrosine phosphorylation of hnRNPC and uPAR expression through mRNA stabilization. Inhibition of hnRNPC tyrosine phosphorylation abolished its interaction with uPAR mRNA and suppressed mRNA stabilization and cell surface uPAR expression. Deletion experiments revealed that hnRNPC binds to uPAR mRNA through its RNA binding domain (RBD). Site-directed mutagenesis studies further indicated that phosphorylation of tyrosine residue 57 (Y57) present in RBD of hnRNPC by uPA is essential for uPAR 3'-UTR mRNA binding and uPAR expression. Increased hnRNPC interaction with the uPAR mRNA 3'-UTR through phosphorylation of Y57 represents a novel mechanism by which uPA regulates posttranscriptional uPAR mRNA turnover and cell surface uPAR expression.
authors.affiliation: Texas Lung Injury Institute, Department of Specialty Care Services, The University of Texas Health Center at Tyler, 11937 U.S. Highway 271, Tyler, Texas 75708, USA.
authors.forename: Thirunavukkarasu
authors.initials: T
authors.lastname: Velusamy
authors.forename: Praveenkumar
authors.initials: P
authors.lastname: Shetty
authors.forename: Yashodhar P
authors.initials: YP
authors.lastname: Bhandary
authors.forename: Ming-Cheh
authors.initials: MC
authors.lastname: Liu
authors.forename: Sreerama
authors.initials: S
authors.lastname: Shetty
mesh_terms: D001665:Binding Sites / Q000235:genetics; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D034482:Heterogeneous-Nuclear Ribonucleoprotein Group C / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology*; D020871:RNA Stability / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator; D020545:Respiratory Mucosa / Q000378:metabolism / Q000473:pathology; D015854:Up-Regulation / Q000235:genetics; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism / Q000502:physiology
chemical_list: C503635:HNRNPC protein, human; D034482:Heterogeneous-Nuclear Ribonucleoprotein Group C; C524898:PLAUR protein, human; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator