Cell surface stability of gamma-aminobutyric acid type A receptors: dependence on protein kinase C activity and subunit composition

Christopher N. Connolly, Josef T. Kittler, Philip Thomas, Julia M. Uren, Nicholas J. Brandon, Trevor G. Smart, Stephen J. Moss

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    Abstract

    Type A gamma-aminobutyric acid receptors (GABA(A)), the major sites of fast synaptic inhibition in the brain, are believed to be composed predominantly of alpha, beta, and gamma subunits, Although cell surface expression is essential for GABA,receptor function, little is known regarding its regulation, To address this issue, the membrane stability of recombinant alpha(1)beta(2) or alpha(1)beta(2)gamma(2) receptors was analyzed in human embryonic kidney cells. alpha(1)beta(2)gamma(2), but not alpha(1)beta(2) receptors were found to recycle constitutively between the cell surface and a microtubule-dependent, perinuclear endosomal compartment. Similar GABA, receptor endocytosis was also seen in cultured hippocampal and cortical neurons. GABA, receptor surface levels were reduced upon protein kinase C (PKC) activation. Like basal endocytosis, this response required the gamma(2) subunit but not receptor phosphorylation. Although inhibiting PKC activity did not block alpha(1)beta(2)gamma(2) receptor endocytosis, it did prevent receptor down-regulation, suggesting that PKC activity may block alpha(1)beta(2)gamma(2) receptor recycling to the cell surface, In agreement with this observation, blocking recycling from endosomes with wortmannin selectively reduced surface levels of gamma(2)-containing receptors, Together, our results demonstrate that the surface stability of GABA(A) receptors can be dynamically and specifically regulated, enabling neurons to modulate cell surface receptor number upon the appropriate cues.

    Original languageEnglish
    Pages (from-to)36565-36572
    Number of pages8
    JournalJournal of Biological Chemistry
    Volume274
    Issue number51
    DOIs
    Publication statusPublished - 17 Dec 1999

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