Cited by 97Genetics and Neurodevelopmental DisordersNeuroscience and Neuropharmacology ResearchProtein Kinase Regulation and GTPase Signaling

Aberrant early-phase ERK inactivation impedes neuronal function in fragile X syndrome

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Kim, Soong Ho, Markham, Julie A., Weiler, Ivan Jeanne, Greenough, William T.·2008·Proceedings of the National Academy of Sciences

Abstract

Fragile X syndrome (FXS) has so far resisted efforts to define the basic cellular defects caused by the absence of a single protein, fragile X mental retardation protein (FMRP), because the patients have a wide variety of symptoms of varying severity. Immature-appearing dendritic spines on neurons found in FXS patients and fmr1 -KO mice suggest a role for FMRP in modulating production of synaptic structural proteins. We isolated cortical synaptoneurosomes from WT and KO mice and studied MAPK pathway activation after group I metabotropic glutamate receptor (mGluR) stimulation. Here, we show that ERK in KO synaptoneurosomes is rapidly dephosphorylated upon mGluR1/5 stimulation, whereas it is phosphorylated in WT mice, suggesting that aberrant activation of phosphatases occurs in KO synapses in response to synaptic stimulation. In KO synapses, protein phosphatase 2A (PP2A) is overactivated after mGluR1 stimulation, and tyrosine phosphatase is overactivated after mGluR5 stimulation, causing the rapid deactivation of ERK. ERK activation can be restored in KO by pretreatment with phosphatase blockers; blocking of PP2A by okadaic acid could successfully restore normal ERK activation in KO synaptoneurosomes. We propose that overactivation of phosphatases in synapses may be a key deficit in FXS, which affects synaptic translation, transcription, and synaptic receptor regulation.

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Crossref · 10.1073/pnas.0800257105

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  • Molecular signaling pathways that orchestrate protein synthesis, spine shape, and synaptic plasticity, such as mTOR and ERK, are impaired in fragile X syndrome, possibly because some FMRP target mRNAs encode members of second messenger cascades converging on ERK.

    “The molecular signaling pathways orchestrating protein synthesis, spine shape, and synaptic plasticity, such as mTOR and ERK (Figure 2), are also impaired in FXS (72,(87)(88)(89), possibly because some FMRP target mRNAs encode members of second messenger cascades converging on ERK (88,89).”
  • Fragile X leads to hyperactivity in the protein phosphatase PP2a, which inactivates MAPK, an enzyme with impaired activity in oligomer-exposed neurons.

    “Fragile X also leads to hyperactivity in the protein phosphatase PP2a (Kim et al., 2008) which inactivates MAPK, an enzyme with impaired activity in oligomer-exposed neurons (Tong et al., 2001).”

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Research works printed but not linked: 1

  1. [19]Weiler IJ. In: The Molecular Basis of Fragile X Syndrome. Sung YJ, Denman RB, editors. Kerala, India: Research Signpost; 2005. pp. 201–215. [Google Scholar]

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Authors
Kim, S. H., Markham, J. A., Weiler, I. J., & Greenough, W. T.
Affiliations
  • *Beckman Institute,
  • University of Illinois Urbana-Champaign (US)
Venue
Proceedings of the National Academy of Sciences
Published
2008-03-18
Volume
105
Issue
11
Pages
4429-4434
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W2167656355
Cited by
97
References
43
Citations by year
2024: 3 · 2023: 7 · 2022: 4 · 2021: 6 · 2020: 4 · 2019: 4 · 2018: 5 · 2017: 10 · 2016: 4 · 2015: 6 · 2014: 2 · 2013: 5 · 2012: 9
FWCI
5.32
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health
  • National Institute of Mental Health (MH-35321, R01MH035321, R37MH035321)
  • Eunice Kennedy Shriver National Institute of Child Health and Human Development (HD07333, T32HD007333)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetics and Neurodevelopmental Disorders
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Kinase Regulation and GTPase Signaling
Keywords
fragile X syndrome, FMRP, MAPK signaling, group I metabotropic glutamate receptors, mGluR1, mGluR5, protein phosphatase 2A, protein tyrosine phosphatase, synaptoneurosomes, synaptic plasticity, dendritic spines, Fmr1 knockout mice, okadaic acid
MeSH terms
Animals, Enzyme Activation, Fragile X Syndrome, Neurons, Synapses, Time Factors, Protein Serine-Threonine Kinases, Receptors, Metabotropic Glutamate, Mice, Knockout, Mitogen-Activated Protein Kinase Kinases, Extracellular Signal-Regulated MAP Kinases, Mice, Fragile X Messenger Ribonucleoprotein 1

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