Identification of a functional non-coding variant in the GABAA receptor α2 subunit of the C57BL/6J mouse reference genome

Major implications for neuroscience research

Megan Mulligan, Timothy Abreo, Sarah M. Neuner, Cory Parks, Christine E. Watkins, M. Trevor Houseal, Thomas M. Shapaker, Michael Hook, Haiyan Tan, Xusheng Wang, Jesse Ingels, Junmin Peng, Lu Lu, Catherine C. Kaczorowski, Camron D. Bryant, Gregg E. Homanics, Robert Williams

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

GABA type-A (GABA-A) receptors containing the α2 subunit (GABRA2) are expressed in most brain regions and are critical in modulating inhibitory synaptic function. Genetic variation at the GABRA2 locus has been implicated in epilepsy, affective and psychiatric disorders, alcoholism and drug abuse. Gabra2 expression varies as a function of genotype and is modulated by sequence variants in several brain structures and populations, including F2 crosses originating from C57BL/6J (B6J) and the BXD recombinant inbred family derived from B6J and DBA/2J. Here we demonstrate a global reduction of GABRA2 brain protein and mRNA in the B6J strain relative to other inbred strains, and identify and validate the causal mutation in B6J. The mutation is a single base pair deletion located in an intron adjacent to a splice acceptor site that only occurs in the B6J reference genome. The deletion became fixed in B6J between 1976 and 1991 and is now pervasive in many engineered lines, BXD strains generated after 1991, the Collaborative Cross, and the majority of consomic lines. Repair of the deletion using CRISPR-Cas9-mediated gene editing on a B6J genetic background completely restored brain levels of GABRA2 protein and mRNA. Comparison of transcript expression in hippocampus, cortex, and striatum between B6J and repaired genotypes revealed alterations in GABA-A receptor subunit expression, especially in striatum. These results suggest that naturally occurring variation in GABRA2 levels between B6J and other substrains or inbred strains may also explain strain differences in anxiety-like or alcohol and drug response traits related to striatal function. Characterization of the B6J private mutation in the Gabra2 gene is of critical importance to molecular genetic studies in neurobiological research because this strain is widely used to generate genetically engineered mice and murine genetic populations, and is the most widely utilized strain for evaluation of anxiety-like, depression-like, pain, epilepsy, and drug response traits that may be partly modulated by GABRA2 function.

Original languageEnglish (US)
Article number188
JournalFrontiers in Genetics
Volume10
Issue numberMAR
DOIs
StatePublished - Jan 1 2019

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GABA-A Receptors
Neurosciences
Inbred C57BL Mouse
Genome
Research
Protein Subunits
Brain
Mutation
Epilepsy
Clustered Regularly Interspaced Short Palindromic Repeats
Anxiety
Genotype
Corpus Striatum
Messenger RNA
RNA Splice Sites
Population Genetics
Mood Disorders
Base Pairing
Pharmaceutical Preparations
Introns

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Genetics
  • Genetics(clinical)

Cite this

Identification of a functional non-coding variant in the GABAA receptor α2 subunit of the C57BL/6J mouse reference genome : Major implications for neuroscience research. / Mulligan, Megan; Abreo, Timothy; Neuner, Sarah M.; Parks, Cory; Watkins, Christine E.; Houseal, M. Trevor; Shapaker, Thomas M.; Hook, Michael; Tan, Haiyan; Wang, Xusheng; Ingels, Jesse; Peng, Junmin; Lu, Lu; Kaczorowski, Catherine C.; Bryant, Camron D.; Homanics, Gregg E.; Williams, Robert.

In: Frontiers in Genetics, Vol. 10, No. MAR, 188, 01.01.2019.

Research output: Contribution to journalArticle

Mulligan, M, Abreo, T, Neuner, SM, Parks, C, Watkins, CE, Houseal, MT, Shapaker, TM, Hook, M, Tan, H, Wang, X, Ingels, J, Peng, J, Lu, L, Kaczorowski, CC, Bryant, CD, Homanics, GE & Williams, R 2019, 'Identification of a functional non-coding variant in the GABAA receptor α2 subunit of the C57BL/6J mouse reference genome: Major implications for neuroscience research', Frontiers in Genetics, vol. 10, no. MAR, 188. https://doi.org/10.3389/fgene.2019.00188
Mulligan, Megan ; Abreo, Timothy ; Neuner, Sarah M. ; Parks, Cory ; Watkins, Christine E. ; Houseal, M. Trevor ; Shapaker, Thomas M. ; Hook, Michael ; Tan, Haiyan ; Wang, Xusheng ; Ingels, Jesse ; Peng, Junmin ; Lu, Lu ; Kaczorowski, Catherine C. ; Bryant, Camron D. ; Homanics, Gregg E. ; Williams, Robert. / Identification of a functional non-coding variant in the GABAA receptor α2 subunit of the C57BL/6J mouse reference genome : Major implications for neuroscience research. In: Frontiers in Genetics. 2019 ; Vol. 10, No. MAR.
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