Antisense suppression of GABA_A receptor β subunit levels in cultured cerebellar granule neurons demonstrates their importance in receptor expression

Abstract

GABAA receptors in the CNS are pentameric molecules composed of α, β, γ, δ, ε and θ subunits. Studies on transfected cells have shown that GABAA receptor β subunit isoforms can direct α1 subunit localization within the cell. To examine the role of selected subunits in governing GABAA receptor expression in neurons, cultures of rat cerebellar granule cells were grown with antisense or sense oligodeoxynucleotides (ODNs) specific for the α1, β2 or γ2 subunits. These subunits are all expressed in granule neurons where they are thought to contribute to an abundant receptor type. Following ODN treatment, subunit expression and distribution were examined by western blotting, immunocytochemistry and RT‐PCR. Treatment of the cultures with the antisense, but not the corresponding sense, ODNs reduced the levels of the targeted subunit polypeptides. In addition, the β2 antisense ODN reduced the level of the α1 subunit polypeptide without altering the level of its mRNA. In contrast, treatment with the β2 subunit antisense ODN did not alter γ2 subunit polypeptide expression, distribution or mRNA level. These findings suggest that the α1 subunit requires a β subunit for assembly into GABAA receptors in cerebellar granule neurons.