Cited by 110Protein Kinase Regulation and GTPase SignalingMelanoma and MAPK PathwaysProtein Tyrosine Phosphatases

The JNKK2-JNK1 fusion protein acts as a constitutively active c-Jun kinase that stimulates c-Jun transcription activity

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Zheng, Chaojun, Xiang, Jialing, Hunter, Tony, Lin, Anning·1999·Journal of Biological Chemistry

Abstract

c-Jun N-terminal protein kinase (JNK), a member of the mitogen-activated protein (MAP) kinase family, regulates gene expression in response to various extracellular stimuli. JNK is activated by JNK-activating kinase (JNKK1 and JNKK2), a subfamily of the dual specificity MAP kinase kinase (MEK) family, through phosphorylation on threonine (Thr) 183 and tyrosine (Tyr) 185 residues. The physiological functions of the JNK pathway, however, are not completely understood. A major obstacle is the lack of specific and activated kinase components that can stimulate the JNK pathway in the absence of any stimulus. Here we show that fusion of JNK1 to its upstream activator JNKK2 resulted in its constitutive activation. In HeLa cells, the JNKK2-JNK1 fusion protein showed significant JNK activity, which was comparable with that of JNK1 activated by many stimuli and activators, including EGF, TNF-alpha, anisomycin, UV irradiation, MEKK1, and small GTP binding proteins Rac1 and Cdc42Hs. Immunoblotting analysis indicated that JNK1 was phosphorylated by JNKK2 in the fusion protein on both Thr(183) and Tyr(185) residues. Like JNKK2, the JNKK2-JNK1 fusion protein was highly specific for the JNK pathway and did not activate either p38 or ERK2. Transient transfection assays demonstrated that the JNKK2-JNK1 fusion protein was sufficient to stimulate c-Jun transcriptional activity in the absence of any stimulus. Immunofluorescence analysis revealed that the JNKK2-JNK1 fusion protein was predominantly located in the nucleus of transfected HeLa cells. These results indicate that the JNKK2-JNK1 fusion protein is a constitutively active Jun kinase, which will facilitate the investigation of the physiological roles of the JNK pathway.

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Crossref · 10.1074/jbc.274.41.28966

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  • JNK1 structures with phosphoacceptor-to-glutamate mutations do not have constitutive activity but do adopt a different activation-loop conformer.

    “While these mutations do not yield constitutive activity (Zheng et al., 1999), they induce a different conformer for the A-loop, allowing us to ask how changing the A-loop conformer impacts the catalytic and peptide-binding sites.”

    From Structural Mechanisms of Allostery and Autoinhibition in JNK Family Kinases (2012) · cites this paper as Zheng et al., 1999

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Authors
Zheng, C., Xiang, J., Hunter, T., & Lin, A.
Affiliations
  • University of Alabama at Birmingham (US)
  • Salk Institute for Biological Studies (US)
Corresponding author
Lin, Anning
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
1999-10
Volume
274
Issue
41
Pages
28966-28971
ISSN
0021-9258 (ISSN-L)
OpenAlex
W2022805818
Cited by
110
References
60
Citations by year
2025: 1 · 2024: 1 · 2023: 1 · 2022: 1 · 2020: 1 · 2018: 1 · 2017: 1 · 2016: 1 · 2015: 3 · 2014: 4 · 2013: 4 · 2012: 7
FWCI
2.62
Type
journal article
Language
en
Open access
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health (5r29ca073740-02)
  • National Cancer Institute (CA 73740)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Kinase Regulation and GTPase Signaling
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Melanoma and MAPK Pathways
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Tyrosine Phosphatases
Keywords
c-Jun N-terminal kinase, JNK1, constitutive kinase activation, MAPK signaling, JNK phosphorylation, Rac1, Cdc42, MEKK1, nuclear localization
MeSH terms
Fluorescent Antibody Technique, Gene Expression Regulation, HeLa Cells, Humans, Nuclear Proteins, Phosphorylation, Protein Kinases, Recombinant Fusion Proteins, Transfection, Signal Transduction, Mitogen-Activated Protein Kinases, Mitogen-Activated Protein Kinase Kinases, JNK Mitogen-Activated Protein Kinases, MAP Kinase Kinase 7

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