Testing the silence of mutations: Transcriptomic and behavioral studies of GABA(A) receptor α1 and α2 subunit knock-in mice.
Knock-in mice were constructed with mutations in the α1 (H(270), A(277)) and α2 (H(270), A(277)) subunits of the GABAA receptor, which resulted in receptors that lacked modulation by ethanol but retained normal responses to GABA in vitro. A key question is whether these mutant receptors also function normally in vivo. Perturbation of brain function was evaluated by gene expression profiling in the cerebral cortex and by behavioral pharmacology experiments with GABAergic drugs. Analysis of individual transcripts found only six transcripts that were changed in α1 knock-in mice and three in the α2 mutants (p<0.05, corrected for multiple comparisons). Two transcripts that are sensitive to neuronal activity, Arc and Fos, increased about 250% in the α2 mutants, and about 50% in the α1 mutants. Behavioral effects (loss of righting reflex, rotarod) of flurazepam and pentobarbital were not different between α2 mutants and wild-type, but they were enhanced for α1 knock-in mice. These results indicate that introduction of these mutations in the α2 subunit of the GABAA receptor does not produce marked perturbation of brain function, as measured by gene expression and GABAergic behavioral responses, but the same mutations in the α1 subunit produce more pronounced changes, especially in GABAergic function.
Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, 1 University Station, A4800, Austin, TX 78712, United States.
R A
RA
Harris
E
E
Osterndorff-Kahanek
I
I
Ponomarev
G E
GE
Homanics
Y A
YA
Blednov
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D005479:Flurazepam / Q000494:pharmacology / Q000627:therapeutic use; D018757:GABA Modulators / Q000494:pharmacology / Q000627:therapeutic use; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D009069:Movement Disorders / Q000188:drug therapy / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010424:Pentobarbital / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism
D003598:Cytoskeletal Proteins; D018757:GABA Modulators; C546241:Gabra1 protein, mouse; C493920:Gabra2 protein, mouse; D009419:Nerve Tissue Proteins; D016760:Proto-Oncogene Proteins c-fos; D011963:Receptors, GABA-A; C092069:activity regulated cytoskeletal-associated protein; D010424:Pentobarbital; D005479:Flurazepam