This HA/HA mutant mouse strain may be useful in studies of the effects of alcohol and anesthesia, behavior, learning and memory.
Gregg E Homanics, University of Pittsburgh
These mutant mice carry substitutions of serine to histidine at amino acid position 270 and leucine to alanine at amino acid position 277 of exon 9. The point mutations confer alcohol and anesthesia insensitivity, while retaining near-normal GABA sensitivity. Approximately half of the homozygous mutant mice (from heterozygous crosses) die between birth and weaning. Homozygotes that survive to adulthood are fertile, normal in size and do not display any gross physical abnormalities. Mutant gene product (mRNA) is detected by RT-PCR analysis of whole brain total RNA. The alpha2 subunit protein levels did not differ between mice homozygous for the mutation and wildtype mice in the cortex and hippocampus. Homozygotes exhibit enhanced fear conditioning, reduced sensitivity to anesthesia (isoflurane), increased alcohol consumption without typical conditioned taste aversion, reduced ethanol induced stimulation of motor activity, and recover more slowly from ethanol?induced hypnosis. Dentate gyrus granule neurons exhibit decreased decay time constant (miniature inhibitory
postsynaptic current) and in response to isoflurane, prolongation of the decay phase is decreased. Male mutants showed increased avoidance of bitter taste (quinine). Homozygotes display some enhanced learning and memory.
The targeting vector was designed (by site-directed mutagenesis) to substitute a serine to histidine at amino acid position 270 and leucine to alanine at amino acid position 277 of exon 9. An FRT-flanked PGKneo cassette was inserted downstream of exon 9. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl+-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting male chimeric animals were crossed to C57BL/6J female mice. Heterozygous mice were crossed to B6.Cg-Tg(ACTFLPe)9205Dym/J (actin-FLPe) to remove the neo cassette and leave a single FRT site downstream of exon 9. The mice were backcrossed to C57BL/6J for 5 generations and the Flpe transgene was subsequently bred out. Upon arrival at The Jackson Laboratory the mice were bred to C57BL/6J for at least 1 generation to establish the colony.
|Allele Name||targeted mutation 1.1, Gregg E Homanics|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Gabra2, gamma-aminobutyric acid (GABA) A receptor, subunit alpha 2|
|Strain of Origin||(129X1/SvJ x 129S1/Sv)F1-Kitl+|
|Molecular Note||The targeting vector was designed (by site-directed mutagenesis) to substitute a serine to histidine at amino acid position 270 and leucine to alanine at amino acid position 277 of exon 9. An FRT-flanked PGKneo cassette was inserted downstream of exon 9. Flp-mediated recombination removed the neo cassette and left a single FRT site downstream of exon 9.|
While maintaining a live colony, these mice can be bred as heterozygotes. Approximately half of homozygotes die between birth and weaning, survivors are fertile, normal in size and do not display any gross physical abnormalities.
When using the B6.129-Gabra2tm1.1Geh/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #012942 in your Materials and Methods section.