JAK2 and SHP2 reciprocally regulate tyrosine phosphorylation and stability of proapoptotic protein ASK1.
Previously we have shown that tyrosine 718 of ASK1 when phosphorylated is critical for SOCS1 binding and SOCS1-mediated degradation of ASK1. However, the kinase and phosphatase responsible for phosphorylation and dephosphorylation of ASK1 at Tyr-718 are unknown. In this study, we identified JAK2 and SHP2 as a Tyr-718-specific kinase and phosphatase, respectively. Interferon-gamma (IFN-gamma) induced degradation of ASK1 in normal but not in SOCS1-KO endothelial cells (EC). IFN-gamma-induced tyrosine phosphorylation of ASK1 at Tyr-718 was blocked by a JAK2-specific inhibitor. IFN-gamma enhanced the association between JAK2 and ASK1, and the ASK1-JAK2 complex was labile and was stabilized by the proteasomal inhibitor MG132. Furthermore, JAK2, but not JAK1, directly bound to and phosphorylated ASK1 at Tyr-718, leading to an enhanced association of ASK1 with SOCS1 and subsequent ASK1 degradation. Next, we showed that overexpression of the SH2-containing protein-tyrosine phosphatase-2 (SHP2) augmented, whereas a phosphatase-inactive mutant of SHP2 inhibited, TNF-induced ASK1 dephosphorylation. SHP2 associated with ASK1 in response to tumor necrosis factor in EC. An SHP-2 substrate-trapping mutant formed a complex with tyrosine-phosphorylated ASK1, suggesting that ASK1 is a direct SHP2 substrate. Moreover, SHP2 wild type, but not a catalytically inactive mutant, dissociated SOCS1 from ASK1. IFN-gamma-induced ASK1 Tyr(P)-718 was enhanced in mouse EC deficient in SHP2 (SHP2-KO). In contrast, tumor necrosis factor-induced dephosphorylation of ASK1 at Tyr(P)-718 and activation of ASK1-JNK signaling, as well as EC apoptosis, are significantly reduced in SHP2-KO EC. Our data suggest that JAK2-SOCS1 and SHP2 reciprocally regulate ASK1 phosphorylation and stability in response to cytokines.
Yu
Luyang
L
Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520.
Min
Wang
W
Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520; Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou 510060, China. Electronic address: wang.min@yale.edu.
He
Yun
Y
Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520.
Qin
Lingfeng
L
Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520.
Zhang
Haifeng
H
Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520.
Bennett
Anton M
AM
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
Chen
Hong
H
Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104.
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D042783:Endothelial Cells / Q000201:enzymology*; D004795:Enzyme Stability / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D053614:Janus Kinase 2 / Q000235:genetics / Q000378:metabolism*; D048848:MAP Kinase Kinase Kinase 5 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D009097:Multienzyme Complexes; C108944:SOCS1 protein, human; C491590:Socs1 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D048848:MAP Kinase Kinase Kinase 5; C482858:MAP3K5 protein, human; C482859:Map3k5 protein, mouse; C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; C516725:Ptpn11 protein, mouse