Metabotropic, but not allosteric, effects of neurosteroids on GABAergic inhibition depend on the phosphorylation of GABAA receptors
| Autor: | Paul Davies, Parakala Manasa Lakshmi, Yihui Zhang, Jayashree Chadchankar, James J. Doherty, Michael A. Ackley, Amit Modgil, Stephen J. Moss, Thuy N. Vien |
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| Rok vydání: | 2019 |
| Předmět: |
Male
0301 basic medicine Neuroactive steroid Allosteric regulation Hippocampus Biochemistry Mice 03 medical and health sciences Allosteric Regulation Neurobiology GABA receptor Animals Humans Protein phosphorylation GABA-A Receptor Antagonists Phosphorylation Protein kinase A Evoked Potentials Molecular Biology Protein Kinase C Protein kinase C 030102 biochemistry & molecular biology Chemistry GABAA receptor Cell Membrane Cell Biology Receptors GABA-A Cell biology Mice Inbred C57BL Protein Subunits HEK293 Cells 030104 developmental biology Metabotropic receptor Mutagenesis Site-Directed Receptors Progesterone Neurosteroids |
| Zdroj: | J Biol Chem |
| ISSN: | 0021-9258 |
| Popis: | Neuroactive steroids (NASs) are synthesized within the brain and exert profound effects on behavior. These effects are primarily believed to arise from the activities of NASs as positive allosteric modulators (PAMs) of the GABA-type A receptor (GABA(A)R). NASs also activate a family of G protein–coupled receptors known as membrane progesterone receptors (mPRs). Here, using surface-biotinylation assays and electrophysiology techniques, we examined mPRs' role in mediating the effects of NAS on the efficacy of GABAergic inhibition. Selective mPR activation enhanced phosphorylation of Ser-408 and Ser-409 (Ser-408/9) within the GABA(A)R β3 subunit, which depended on the activity of cAMP-dependent protein kinase A (PKA) and protein kinase C (PKC). mPR activation did not directly modify GABA(A)R activity and had no acute effects on phasic or tonic inhibition. Instead, mPR activation induced a sustained elevation in tonic current, which was blocked by PKA and PKC inhibition. Substitution of Ser-408/9 to alanine residues also prevented the effects of mPR activation on tonic current. Furthermore, this substitution abolished the effects of sustained NAS exposure on tonic inhibition. Interestingly, the allosteric effects of NAS on GABAergic inhibition were independent of Ser-408/9 in the β3 subunit. Additionally, although allosteric effects of NAS on GABAergic inhibition were sensitive to a recently developed “NAS antagonist,” the sustained effects of NAS on tonic inhibition were not. We conclude that metabotropic effects of NAS on GABAergic inhibition are mediated by mPR-dependent modulation of GABA(A)R phosphorylation. We propose that this mechanism may contribute to the varying behavioral effects of NAS. |
| Databáze: | OpenAIRE |
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