Abstract
Mutations in the neurofibromatosis 2 (NF2) gene with the resultant loss of expression of the NF2 tumor suppressor schwannomin are one of the most common causes of benign human brain tumors, including schwannomas and meningiomas. Previously we demonstrated that the hepatocyte growth factor-regulated tyrosine kinase substrate (HRS) strongly interacts with schwannomin. HRS is a powerful regulator of receptor tyrosine kinase trafficking to the degradation pathway and HRS also binds STAM. Both of these actions for HRS potentially inhibit STAT activation. Therefore, we hypothesized that schwannomin inhibits STAT activation through interaction with HRS. We now show that both schwannomin and HRS inhibit Stat3 activation and that schwannomin suppresses Stat3 activation mediated by IGF-I treatment in the human schwannoma cell line STS26T. We also find that schwannomin inhibits Stat3 and Stat5 phosphorylation in the rat schwannoma cell line RT4. Schwannomin with the pathogenic missense mutation Q538P fails to bind HRS and does not inhibit Stat5 phosphorylation. These data are consistent with the hypothesis that schwannomin requires HRS interaction to be fully functionally active and to inhibit STAT activation.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acute-Phase Proteins / antagonists & inhibitors
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Acute-Phase Proteins / physiology
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Amino Acid Sequence
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Animals
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Cell Division / drug effects
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DNA-Binding Proteins / antagonists & inhibitors
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DNA-Binding Proteins / metabolism
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DNA-Binding Proteins / physiology*
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Endosomal Sorting Complexes Required for Transport
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Humans
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Insulin-Like Growth Factor I / pharmacology
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Milk Proteins*
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Molecular Sequence Data
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Neurilemmoma / genetics
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Neurilemmoma / metabolism
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Neurilemmoma / pathology
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Neurofibromatosis 2 / genetics*
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Neurofibromin 2 / biosynthesis
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Neurofibromin 2 / chemistry
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Neurofibromin 2 / immunology
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Neurofibromin 2 / physiology*
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Peptides / chemistry
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Peptides / immunology
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Phosphoproteins / physiology*
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Phosphorylation
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Rats
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STAT3 Transcription Factor
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STAT5 Transcription Factor
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Signal Transduction / physiology*
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Soft Tissue Neoplasms / genetics
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Soft Tissue Neoplasms / metabolism
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Soft Tissue Neoplasms / pathology
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Trans-Activators / antagonists & inhibitors
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Trans-Activators / metabolism
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Trans-Activators / physiology*
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Tumor Cells, Cultured
Substances
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Acute-Phase Proteins
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DNA-Binding Proteins
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Endosomal Sorting Complexes Required for Transport
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Milk Proteins
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Neurofibromin 2
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Peptides
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Phosphoproteins
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STAT3 Transcription Factor
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STAT3 protein, human
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STAT5 Transcription Factor
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Stat3 protein, rat
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Trans-Activators
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hepatocyte growth factor-regulated tyrosine kinase substrate
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Insulin-Like Growth Factor I