Abstract
Familial amyloidotic polyneuropathy (FAP) is a neurodegenerative disorder characterized by the extracellular deposition of transthyretin (TTR), especially in the PNS. Given the invasiveness of nerve biopsy, salivary glands (SG) from FAP patients were used previously in microarray analysis; mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1) was down-regulated in FAP. Results were validated by RT-PCR and immunohistochemistry both in SG and in nerve biopsies of different stages of disease progression. MKP-3 was also down-regulated in FAP SG biopsies. Given the relationship between MKPs and MAPKs, the latter were investigated. Only extracellular signal-regulated kinases 1/2 (ERK1/2) displayed increased activation in FAP SG and nerves. ERK1/2 kinase (MEK1/2) activation was also up-regulated in FAP nerves. In addition, an FAP transgenic mouse model revealed increased ERK1/2 activation in peripheral nerve affected with TTR deposition when compared to control animals. Cultured rat Schwannoma cell line treatment with TTR aggregates stimulated ERK1/2 activation, which was partially mediated by the receptor for advanced glycation end-products (RAGE). Moreover, caspase-3 activation triggered by TTR aggregates was abrogated by U0126, a MEK1/2 inhibitor, indicating that ERK1/2 activation is essential for TTR aggregates-induced cytotoxicity. Taken together, these data suggest that abnormally sustained activation of ERK in FAP may represent an early signaling cascade leading to neurodegeneration.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amyloid Neuropathies, Familial / enzymology*
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Amyloid Neuropathies, Familial / physiopathology
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Animals
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Caspase 3
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Caspases / metabolism
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism
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Cell Death / drug effects
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Cell Death / physiology
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Cell Line, Tumor
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Dual Specificity Phosphatase 1
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Dual Specificity Phosphatase 6
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Enzyme Activation / drug effects
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Enzyme Activation / physiology
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Enzyme Inhibitors / pharmacology
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Extracellular Signal-Regulated MAP Kinases / genetics
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Extracellular Signal-Regulated MAP Kinases / metabolism*
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Gene Expression Profiling
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Gene Expression Regulation, Enzymologic / physiology*
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Humans
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Immediate-Early Proteins / genetics
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Immediate-Early Proteins / metabolism
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MAP Kinase Kinase 1 / genetics
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MAP Kinase Kinase 1 / metabolism
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MAP Kinase Signaling System / physiology*
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Mice
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Mice, Transgenic
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Neurotoxins / metabolism
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Oligonucleotide Array Sequence Analysis
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Peripheral Nerves / enzymology*
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Peripheral Nerves / pathology
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Peripheral Nerves / physiopathology
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Phosphoprotein Phosphatases / genetics
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Phosphoprotein Phosphatases / metabolism
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Prealbumin / metabolism
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Protein Phosphatase 1
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Protein Tyrosine Phosphatases / genetics
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Protein Tyrosine Phosphatases / metabolism
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Rats
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Reverse Transcriptase Polymerase Chain Reaction
Substances
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Cell Cycle Proteins
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Enzyme Inhibitors
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Immediate-Early Proteins
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Neurotoxins
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Prealbumin
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Extracellular Signal-Regulated MAP Kinases
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MAP Kinase Kinase 1
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Phosphoprotein Phosphatases
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Protein Phosphatase 1
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DUSP1 protein, human
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DUSP6 protein, human
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Dual Specificity Phosphatase 1
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Dual Specificity Phosphatase 6
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Dusp1 protein, mouse
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Dusp1 protein, rat
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Dusp6 protein, mouse
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Dusp6 protein, rat
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Protein Tyrosine Phosphatases
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CASP3 protein, human
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Casp3 protein, mouse
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Casp3 protein, rat
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Caspase 3
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Caspases