Abstract
Ret is a receptor tyrosine kinase involved in several neoplastic and developmental diseases affecting the thyroid gland and tissues of neuroectodermal origin. Different ret mutations are associated with different disease phenotypes. Gain-of-function of ret is caused by gene rearrangements in thyroid papillary carcinomas and by point mutations in multiple endocrine neoplasia (MEN) type 2A syndrome (MEN2A), in familial medullary thyroid carcinoma (FMTC), and in the more severe MEN2B syndrome. Conversely, Hirschsprung's disease (HSCR) is associated with loss of function of ret. Recently, it has been shown that glial cell line-derived neurotrophic factor (GDNF), by binding to the accessory molecule GDNFR-alpha, acts as a functional ligand of Ret and stimulates its tyrosine kinase and biological activity. To ascertain whether the biological effects of ret mutations are modulated by GDNF, we have investigated the responsiveness to GDNF of ret mutants in cell lines coexpressing GDNFR-alpha and MEN2A-, MEN2B-, FMTC-, or HSCR-associated ret mutants. Here, we show that triggering of GDNF affected only ret/MEN2B, i.e. it stimulated ret/MEN2B mitogenic and kinase activities, as well as its ability to phosphorylate Shc, a bona fide Ret substrate. In contrast, ret mutants associated with MEN2A or FMTC (carrying Cys634 or Cys620 mutations) were unresponsive to GDNF. HSCR mutations, by affecting either the extracellular or the intracellular Ret domain, impaired responsiveness to GDNF. These data suggest that the phenotype of human diseases caused by ret mutations can be differentially influenced by GDNF.
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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3T3 Cells
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Adaptor Proteins, Signal Transducing*
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Adaptor Proteins, Vesicular Transport*
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Animals
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Cell Line
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Drosophila Proteins*
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Glial Cell Line-Derived Neurotrophic Factor
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Glial Cell Line-Derived Neurotrophic Factor Receptors
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Hirschsprung Disease / genetics*
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Humans
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Immunosorbent Techniques
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Mice
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Multiple Endocrine Neoplasia Type 2a / genetics*
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Mutation*
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Nerve Growth Factors*
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / pharmacology*
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Phosphatidylinositol Diacylglycerol-Lyase
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Phosphorylation
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Proteins / metabolism
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Proto-Oncogene Proteins / genetics*
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-ret
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Receptor Protein-Tyrosine Kinases / genetics*
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Receptor Protein-Tyrosine Kinases / metabolism
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Recombinant Proteins
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Shc Signaling Adaptor Proteins
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Signal Transduction
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Src Homology 2 Domain-Containing, Transforming Protein 1
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Transfection
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Type C Phospholipases / pharmacology
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Tyrosine / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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Adaptor Proteins, Vesicular Transport
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Drosophila Proteins
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GDNF protein, human
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Gdnf protein, mouse
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Glial Cell Line-Derived Neurotrophic Factor
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Glial Cell Line-Derived Neurotrophic Factor Receptors
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Nerve Growth Factors
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Nerve Tissue Proteins
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Proteins
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Proto-Oncogene Proteins
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Recombinant Proteins
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SHC1 protein, human
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Shc Signaling Adaptor Proteins
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Shc1 protein, mouse
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Src Homology 2 Domain-Containing, Transforming Protein 1
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Tyrosine
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Proto-Oncogene Proteins c-ret
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Receptor Protein-Tyrosine Kinases
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Ret protein, Drosophila
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Ret protein, mouse
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Type C Phospholipases
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Phosphatidylinositol Diacylglycerol-Lyase