Abstract
The catalytic activity of the Src homology 2 (SH2) domain-containing tyrosine phosphatase, SHP-2, is required for virtually all of its signaling effects. Elucidating the molecular mechanisms of SHP-2 signaling, therefore, rests upon the identification of its target substrates. In this report, we have used SHP-2 substrate-trapping mutants to identify the major vault protein (MVP) as a putative SHP-2 substrate. MVP is the predominant component of vaults that are cytoplasmic ribonucleoprotein complexes of unknown function. We show that MVP is dephosphorylated by SHP-2 in vitro and it forms an enzyme-substrate complex with SHP-2 in vivo. In response to epidermal growth factor (EGF), SHP-2 associates via its SH2 domains with tyrosyl-phosphorylated MVP. MVP also interacts with the activated form of the extracellular-regulated kinases (Erks) in response to EGF and a constitutive complex between tyrosyl-phosphorylated MVP, SHP-2, and the Erks was detected in MCF-7 breast cancer cells. Using MVP-deficient fibroblasts, we demonstrate that MVP cooperates with Ras for optimal EGF-induced Elk-1 activation and is required for cell survival. We propose that MVP functions as a novel scaffold protein for both SHP-2 and Erk. The regulation of MVP tyrosyl phosphorylation by SHP-2 may play an important role in cell survival signaling.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Cell Line, Tumor
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Cell Survival
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Cells, Cultured
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Culture Media, Serum-Free
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DNA-Binding Proteins*
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Enzyme Activation
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Epidermal Growth Factor / metabolism*
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Fibroblasts / cytology
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Fibroblasts / metabolism
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Humans
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Intracellular Signaling Peptides and Proteins
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Mice
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Mitogen-Activated Protein Kinases / metabolism
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Molecular Sequence Data
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Phosphorylation
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Protein Structure, Tertiary
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Protein Tyrosine Phosphatase, Non-Receptor Type 11
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Protein Tyrosine Phosphatases / genetics
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Protein Tyrosine Phosphatases / metabolism*
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Proto-Oncogene Proteins / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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SH2 Domain-Containing Protein Tyrosine Phosphatases
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Signal Transduction / physiology*
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Transcription Factors*
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Vault Ribonucleoprotein Particles / genetics
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Vault Ribonucleoprotein Particles / metabolism*
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ets-Domain Protein Elk-1
Substances
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Culture Media, Serum-Free
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DNA-Binding Proteins
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ELK1 protein, human
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Elk1 protein, mouse
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Intracellular Signaling Peptides and Proteins
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Proto-Oncogene Proteins
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Recombinant Fusion Proteins
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Transcription Factors
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Vault Ribonucleoprotein Particles
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ets-Domain Protein Elk-1
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major vault protein
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Epidermal Growth Factor
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Mitogen-Activated Protein Kinases
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PTPN11 protein, human
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Protein Tyrosine Phosphatase, Non-Receptor Type 11
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Protein Tyrosine Phosphatases
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Ptpn11 protein, mouse
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SH2 Domain-Containing Protein Tyrosine Phosphatases