title: Widespread JNK-dependent alternative splicing induces a positive feedback loop through CELF2-mediated regulation of MKK7 during T-cell activation.
abstract: Alternative splicing is prevalent among genes encoding signaling molecules; however, the functional consequence of differential isoform expression remains largely unknown. Here we demonstrate that, in response to T-cell activation, the Jun kinase (JNK) kinase MAP kinase kinase 7 (MKK7) is alternatively spliced to favor an isoform that lacks exon 2. This isoform restores a JNK-docking site within MKK7 that is disrupted in the larger isoform. Consistently, we show that skipping of MKK7 exon 2 enhances JNK pathway activity, as indicated by c-Jun phosphorylation and up-regulation of TNF-α. Moreover, this splicing event is itself dependent on JNK signaling. Thus, MKK7 alternative splicing represents a positive feedback loop through which JNK promotes its own signaling. We further show that repression of MKK7 exon 2 is dependent on the presence of flanking sequences and the JNK-induced expression of the RNA-binding protein CELF2, which binds to these regulatory elements. Finally, we found that ∼25% of T-cell receptor-mediated alternative splicing events are dependent on JNK signaling. Strikingly, these JNK-dependent events are also significantly enriched for responsiveness to CELF2. Together, our data demonstrate a widespread role for the JNK-CELF2 axis in controlling splicing during T-cell activation, including a specific role in propagating JNK signaling.
authors.affiliation: Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Martinez
authors.affiliation: Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
authors.forename: Laura
authors.initials: L
authors.lastname: Agosto
authors.affiliation: Department of Cell and Molecular Medicine, University of California at San Diego, San Diego, California 92093, USA;
authors.forename: Jinsong
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Mallory
authors.affiliation: Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennysylvania 19104, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Gazzara
authors.affiliation: Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennysylvania 19104, USA.
authors.forename: Yoseph
authors.initials: Y
authors.lastname: Barash
authors.affiliation: Department of Cell and Molecular Medicine, University of California at San Diego, San Diego, California 92093, USA;
authors.forename: Xiang-Dong
authors.initials: XD
authors.lastname: Fu
authors.affiliation: Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennysylvania 19104, USA.
authors.forename: Kristen W
authors.initials: KW
authors.lastname: Lynch
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D000067878:CELF Proteins / Q000378:metabolism*; D025461:Feedback, Physiological / Q000502:physiology; D005786:Gene Expression Regulation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D019169:Jurkat Cells; D048688:MAP Kinase Kinase 7 / Q000235:genetics* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D020871:RNA Stability / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*
chemical_list: D000067878:CELF Proteins; C117363:CELF2 protein, human; D009419:Nerve Tissue Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D048688:MAP Kinase Kinase 7
keywords: CELF2; JNK; MKK7; alternative splicing; positive feedback