Cellular, molecular and functional characterisation of YAC transgenic mouse models of Friedreich ataxia.

Sara Anjomani Virmouni,Sahar Al-Mahdawi,Mark A Pook,Chiranjeevi Sandi,Annalisa Pastore

doi:10.1371/journal.pone.0107416

Sara Anjomani Virmouni, Sahar Al-Mahdawi + Show 3 more

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https://doi.org/10.1371/journal.pone.0107416

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Journal: PloS one	Publication Date: Sep 8, 2014
Citations: 50	License type: CC BY 4.0

Affiliation: Brunel University London

Abstract

BackgroundFriedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder, caused by a GAA repeat expansion mutation within intron 1 of the FXN gene. We have previously established and performed preliminary characterisation of several human FXN yeast artificial chromosome (YAC) transgenic FRDA mouse models containing GAA repeat expansions, Y47R (9 GAA repeats), YG8R (90 and 190 GAA repeats) and YG22R (190 GAA repeats).Methodology/Principal FindingsWe now report extended cellular, molecular and functional characterisation of these FXN YAC transgenic mouse models. FXN transgene copy number analysis of the FRDA mice demonstrated that the YG22R and Y47R lines each have a single copy of the FXN transgene while the YG8R line has two copies. Single integration sites of all transgenes were confirmed by fluorescence in situ hybridisation (FISH) analysis of metaphase and interphase chromosomes. We identified significant functional deficits, together with a degree of glucose intolerance and insulin hypersensitivity, in YG8R and YG22R FRDA mice compared to Y47R and wild-type control mice. We also confirmed increased somatic GAA repeat instability in the cerebellum and brain of YG22R and YG8R mice, together with significantly reduced levels of FXN mRNA and protein in the brain and liver of YG8R and YG22R compared to Y47R.Conclusions/SignificanceTogether these studies provide a detailed characterisation of our GAA repeat expansion-based YAC transgenic FRDA mouse models that will help investigations of FRDA disease mechanisms and therapy.

Highlights

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder, caused by a GAA repeat expansion mutation within intron 1 of the FXN gene, resulting in reduced levels of frataxin protein [1]
Copy number of the FXN transgene Copy number variation of the FXN transgene was investigated in YG8R, YG22R, Y47R and wild type (WT) tail biopsy genomic DNA samples using real-time PCR and unquenching of fluorescent probes for the target sequence
The results indicated that YG22R and Y47R mice had a single copy of the FXN transgene whereas the YG8R mice generally showed two copies of the FXN transgene (Fig. 1a)

Summary

Introduction

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder, caused by a GAA repeat expansion mutation within intron 1 of the FXN gene, resulting in reduced levels of frataxin protein [1]. To investigate FRDA molecular disease mechanisms and therapy, we have previously established three human FXN YAC transgenic mouse models: Y47R, containing normal-sized (GAA) repeats, and YG8R and YG22R, which initially contained expanded GAA repeats of 90–. Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder, caused by a GAA repeat expansion mutation within intron 1 of the FXN gene. We have previously established and performed preliminary characterisation of several human FXN yeast artificial chromosome (YAC) transgenic FRDA mouse models containing GAA repeat expansions, Y47R (9 GAA repeats), YG8R (90 and 190 GAA repeats) and YG22R (190 GAA repeats)

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