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Dissecting Cell-Autonomous Function of Fragile X Mental Retardation Protein in an Auditory Circuit by In Ovo Electroporation
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Fragile X mental retardation protein expression in Alzheimer's disease

Abigail J Renoux1, Nicholas M Carducci2, Arya A Ahmady2

  • 1Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, MI, USA ; Department of Neurology, University of Michigan , Ann Arbor, MI, USA.

Frontiers in Genetics
|December 3, 2014
PubMed

Insights

Reduced Fragile X mental retardation protein (FMRP) expression is linked to FXTAS, not Alzheimer's disease. Studies found normal FMRP levels in Alzheimer's brains, suggesting FMRP decrease isn't a primary cause of AD.

Area of Science:

  • Neuroscience
  • Genetics
  • Molecular Biology

Background:

  • Fragile X mental retardation protein (FMRP) regulates translation of target mRNAs, including amyloid precursor protein (APP).
  • Elevated APP levels are implicated in Alzheimer's disease (AD) pathogenesis.
  • FMRP levels in AD brains and models are not well understood.

Purpose of the Study:

  • To investigate FMRP expression in Alzheimer's disease (AD) autopsy brain samples and mouse models.
  • To compare FMRP levels in AD and control brains.
  • To explore the relationship between FMRP and APP in Fragile X-associated tremor/ataxia syndrome (FXTAS).

Main Methods:

  • Western blot analysis of FMRP and APP expression.
  • Comparison of FMRP levels in post-mortem brain tissues (frontal cortex, cerebellum) from AD patients, FXTAS patients, and controls.
  • Analysis of FMRP and APP in a double transgenic mouse model of AD (APP/PS1) and in FXTAS patient samples.

Main Results:

  • FMRP expression was similar in aged APP/PS1 AD model mice and their littermate controls.
  • FMRP levels were comparable in frontal cortex and cerebellum samples from AD patients and controls.
  • FXTAS patients exhibited reduced FMRP expression in cortex and cerebellum compared to controls and AD patients.
  • APP levels were increased in the cerebellum, but not cortex, of FXTAS patients.

Conclusions:

  • Decreased FMRP expression is unlikely to be a primary driver of Alzheimer's disease.
  • Reduced FMRP is characteristic of FXTAS, correlating with its neurodegenerative symptoms.
  • APP dysregulation may occur in FXTAS, but its role in AD pathogenesis via FMRP is not supported by these findings.
Keywords:
APPAlzheimer’s diseaseFMRPfragile Xmouse models

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