Activation of the Jnk Signaling Pathway by a Dual-Specificity Phosphatase, JSP-1

• Published in: Proceedings of the National Academy of Sciences - PNAS 2001-11, Vol.98 (24), p.13613-13618
• Main Authors: Shen, Yu, Luche, Ralf, Wei, Bo, Gordon, Marcia L., Diltz, Curtis D., Tonks, Nicholas K.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antibodies; Base Sequence; Biochemistry; Biological Sciences; Cells; Cercopithecus aethiops; Cloning, Molecular; COS Cells; Cytokines; DNA, Complementary; Dual-Specificity Phosphatases; Enzymes; Humans; Immunoblotting; Mitogen-Activated Protein Kinase 10; Mitogen-Activated Protein Kinase 8; Mitogen-Activated Protein Kinase 9; Mitogen-Activated Protein Kinase Phosphatases; Mitogen-Activated Protein Kinases - metabolism; Molecular Sequence Data; Phosphatases; Phosphoprotein Phosphatases - genetics; Phosphoprotein Phosphatases - metabolism; Phosphorylation; Physiological regulation; Physiological stimulation; Protein Phosphatase 1; Protein Tyrosine Phosphatases - genetics; Protein Tyrosine Phosphatases - metabolism; Protein-Tyrosine Kinases - metabolism; Proteins; Signal Transduction; Substrate Specificity; Tissue Distribution
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.231499098

The mitogen-activated protein kinases (MAPKs) are integral to the mechanisms by which cells respond to physiological stimuli, such as growth factors, hormones, and cytokines, and to a wide variety of environmental stresses. The MAPKs, which are stimulated by phosphorylation of a TXY motif in their activation loop, are components of signal transduction cascades in which sequential activation of protein kinases culminates in their activation and their subsequent phosphorylation of various effector proteins that mediate the physiological response. MAPKs are also subject to dephosphorylation and inactivation, both by enzymes that recognize the residues of the TXY motif independently and by dual specificity phosphatases, which dephosphroylate both Tyr and Ser/Thr residues. We report the identification and characterization of a novel dual specificity phosphatase. Contrary to expectation, this broadly expressed enzyme did not inactivate MAPKs in transient cotransfection assays but instead displayed the capacity to function as a selective activator of the MAPK Jnk, hence the name, Jnk Stimulatory Phosphatase-1 (JSP-1). This study illustrates a new aspect of the regulation of MAPK-dependent signal transduction and raises the possibility that JSP-1 may offer a different perspective to the study of various inflammatory and proliferative disorders associated with dysfunctional Jnk signaling.