Modulation of neurosteroid potentiation by protein kinases at synaptic- and extrasynaptic-type GABAA receptors

NEUROPHARMACOLOGY

卷:88

Article

Adams, Joanna M.¹  Thomas, Philip¹  Smart, Trevor G.¹ 

[1] UCL, Dept Neurosci Physiol & Pharmacol, London WC1E 6BT, England

关键词: Neurosteroid;    Protein kinase;    Synaptic GABA(A) receptors;    Extrasynaptic GABA(A) receptors;    Phosphorylation;   

DOI  :  10.1016/j.neuropharm.2014.09.021

来源: Elsevier

【 摘 要 】

GABA(A) receptors are important for inhibition in the CNS where neurosteroids and protein kinases are potent endogenous modulators. Acting individually, these can either enhance or depress receptor function, dependent upon the type of neurosteroid or kinase and the receptor subunit combination. However, in vivo, these modulators probably act in concert to fine-tune GABA(A) receptor activity and thus inhibition, although how this is achieved remains unclear. Therefore, we investigated the relationship between these modulators at synaptic-type alpha 1 beta 3 gamma 2L and extrasynaptic-type alpha 4 beta 3 delta GABA(A) receptors using electrophysiology. For alpha 1 beta 3 gamma 2L, potentiation of GABA responses by tetrahydro-deoxycorticosterone was reduced after inhibiting protein kinase C, and enhanced following its activation, suggesting this kinase regulates neurosteroid modulation. In comparison, neurosteroid potentiation was reduced at alpha 4 beta 3(S408A,S409A)gamma 2L receptors, and unaltered by PKC inhibitors or activators, indicating that phosphorylation of beta 3 subunits is important for regulating neurosteroid activity. To determine whether extrasynaptic-type CABA(A) receptors were similarly modulated, alpha 4 beta 3 delta and alpha 4 beta 3(S408A,S409A)delta receptors were investigated. Neurosteroid potentiation was reduced at both receptors by the kinase inhibitor staurosporine. By contrast, neurosteroid-mediated potentiation at alpha 4(S443A)beta 3(S408A,S409A)delta receptors was unaffected by protein kinase inhibition, strongly suggesting that phosphorylation of alpha 4 and beta 3 subunits is required for regulating neurosteroid activity at extrasynaptic receptors. Western blot analyses revealed that neurosteroids increased phosphorylation of beta 3(S408,S409) implying that a reciprocal pathway exists for neurosteroids to modulate phosphorylation of GABA(A) receptors. Overall, these findings provide important insight into the regulation of GABA(A) receptors in vivo, and into the mechanisms by which GABAergic inhibitory transmission may be simultaneously tuned by two endogenous neuromodulators. (C) 2014 The Authors. Published by Elsevier Ltd.

【 授权许可】

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