Abstract
Unlike the other MAP3Ks, MEKK1 (encoded by Map3k1) contains a PHD motif. To understand the role of this motif, we have created a knockin mutant of mouse Map3k1 (Map3k1(m) (PHD)) with an inactive PHD motif. Map3k1(m) (PHD) ES cells demonstrate that the MEKK1 PHD controls p38 and JNK activation during TGF-β, EGF and microtubule disruption signalling, but does not affect MAPK responses to hyperosmotic stress. Protein microarray profiling identified the adaptor TAB1 as a PHD substrate, and TGF-β- or EGF-stimulated Map3k1(m) (PHD) ES cells exhibit defective non-canonical ubiquitination of MEKK1 and TAB1. The MEKK1 PHD binds and mediates the transfer of Lys63-linked poly-Ub, using the conjugating enzyme UBE2N, onto TAB1 to regulate TAK1 and MAPK activation by TGF-β and EGF. Both the MEKK1 PHD and TAB1 are critical for ES-cell differentiation and tumourigenesis. Map3k1(m) (PHD) (/+) mice exhibit aberrant cardiac tissue, B-cell development, testis and T-cell signalling.
Keywords:
differentiation; signalling; stem cell; tumourigenesis; ubiquitin.
© 2014 The Authors. Published under the terms of the CC BY 4.0 license.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing / genetics
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Adaptor Proteins, Signal Transducing / metabolism*
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Amino Acid Motifs
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Animals
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Cell Differentiation / physiology
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Cell Transformation, Neoplastic / genetics
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Cell Transformation, Neoplastic / metabolism
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Embryonic Stem Cells / cytology
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Embryonic Stem Cells / metabolism*
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Epidermal Growth Factor / genetics
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Epidermal Growth Factor / metabolism*
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MAP Kinase Kinase 4 / genetics
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MAP Kinase Kinase 4 / metabolism*
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MAP Kinase Kinase Kinase 1 / genetics
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MAP Kinase Kinase Kinase 1 / metabolism*
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MAP Kinase Signaling System / physiology
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Mice
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Mice, Knockout
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Polyubiquitin / genetics
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Polyubiquitin / metabolism
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Protein Binding
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Transforming Growth Factor beta / genetics
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Transforming Growth Factor beta / metabolism*
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Ubiquitination / physiology*
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p38 Mitogen-Activated Protein Kinases / genetics
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p38 Mitogen-Activated Protein Kinases / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Tab1 protein, mouse
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Transforming Growth Factor beta
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Polyubiquitin
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Epidermal Growth Factor
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p38 Mitogen-Activated Protein Kinases
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MAP Kinase Kinase Kinase 1
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MAP Kinase Kinase 4