title: Tyrosine phosphorylation of GABAA receptor γ2-subunit regulates tonic and phasic inhibition in the thalamus.
abstract: GABA-mediated tonic and phasic inhibition of thalamic relay neurons of the dorsal lateral geniculate nucleus (dLGN) was studied after ablating tyrosine (Y) phosphorylation of receptor γ2-subunits. As phosphorylation of γ2 Y365 and Y367 reduces receptor internalization, to understand their importance for inhibition we created a knock-in mouse in which these residues are replaced by phenylalanines. On comparing wild-type (WT) and γ2(Y365/367F)+/- (HT) animals (homozygotes are not viable in utero), the expression levels of GABAA receptor α4-subunits were increased in the thalamus of female, but not male mice. Raised δ-subunit expression levels were also observed in female γ2(Y365/367F) +/- thalamus. Electrophysiological analyses revealed no difference in the level of inhibition in male WT and HT dLGN, while both the spontaneous inhibitory postsynaptic activity and the tonic current were significantly augmented in female HT relay cells. The sensitivity of tonic currents to the δ-subunit superagonist THIP, and the blocker Zn(2+), were higher in female HT relay cells. This is consistent with upregulation of extrasynaptic GABAA receptors containing α4- and δ-subunits to enhance tonic inhibition. In contrast, the sensitivity of GABAA receptors mediating inhibition in the female γ2(Y356/367F) +/- to neurosteroids was markedly reduced compared with WT. We conclude that disrupting tyrosine phosphorylation of the γ2-subunit activates a sex-specific increase in tonic inhibition, and this most likely reflects a genomic-based compensation mechanism for the reduced neurosteroid sensitivity of inhibition measured in female HT relay neurons.
authors.affiliation: Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, United Kingdom.
authors.forename: Francesca
authors.initials: F
authors.lastname: Nani
authors.forename: Damian P
authors.initials: DP
authors.lastname: Bright
authors.forename: Raquel
authors.initials: R
authors.lastname: Revilla-Sanchez
authors.forename: Verena
authors.initials: V
authors.lastname: Tretter
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Moss
authors.forename: Trevor G
authors.initials: TG
authors.lastname: Smart
mesh_terms: D000777:Anesthetics / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002461:Cell Line, Transformed; D005260:Female; D005829:Geniculate Bodies / Q000166:cytology* / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000235:genetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*
chemical_list: D000777:Anesthetics; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D014443:Tyrosine
references.citation: Br J Pharmacol. 2002 Aug;136(7):965-74
references.pmid: 12145096
references.citation: Neuroscience. 2012 Dec 13;226:397-410
references.pmid: 22989919
references.citation: Int Rev Neurobiol. 1996;39:1-52
references.pmid: 8894843
references.citation: Methods Enzymol. 1991;201:477-82
references.pmid: 1943774
references.citation: Proc Natl Acad Sci U S A. 2006 Oct 10;103(41):15230-5
references.pmid: 17005728
references.citation: Brain Res. 1991 Apr 5;545(1-2):142-50
references.pmid: 1650273
references.citation: J Biol Chem. 2010 Dec 31;285(53):41795-805
references.pmid: 20940303
references.citation: Eur J Neurosci. 1990;2(5):414-29
references.pmid: 12106029
references.citation: Proc Natl Acad Sci U S A. 2009 Nov 24;106(47):20039-44
references.pmid: 19903874
references.citation: J Physiol. 2010 Apr 15;588(Pt 8):1251-68
references.pmid: 20176630
references.citation: Nat Neurosci. 2007 Apr;10(4):469-77
references.pmid: 17351635
references.citation: Science. 2010 Mar 19;327(5972):1515-8
references.pmid: 20299596
references.citation: Mol Cell Neurosci. 2003 Jan;22(1):87-97
references.pmid: 12595241
references.citation: Prog Neurobiol. 1994 Feb;42(3):393-441
references.pmid: 7520185
references.citation: J Neurosci. 2000 Mar 15;20(6):2202-8
references.pmid: 10704495
references.citation: Annu Rev Biochem. 1997;66:511-48
references.pmid: 9242916
references.citation: J Physiol. 2002 Oct 1;544(Pt 1):3-18
references.pmid: 12356876
references.citation: J Physiol. 2003 Aug 1;550(Pt 3):785-800
references.pmid: 12807990
references.citation: J Neurosci. 2005 Dec 14;25(50):11553-63
references.pmid: 16354913
references.citation: Nat Neurosci. 1999 Oct;2(10):873-7
references.pmid: 10491606
references.citation: Nat Protoc. 2007;2(11):2826-41
references.pmid: 18007618
references.citation: Nat Rev Neurosci. 2005 Jul;6(7):565-75
references.pmid: 15959466
references.citation: J Comp Neurol. 2002 Apr 29;446(2):179-97
references.pmid: 11932935
references.citation: J Biol Chem. 1999 Jul 9;274(28):19613-6
references.pmid: 10391897
references.citation: J Neurosci. 2000 May 1;20(9):3067-75
references.pmid: 10777770
references.citation: Curr Top Med Chem. 2002 Aug;2(8):795-816
references.pmid: 12171572
references.citation: Curr Opin Neurobiol. 2011 Oct;21(5):726-33
references.pmid: 21752634
references.citation: Br J Pharmacol. 1991 Aug;103(4):1837-9
references.pmid: 1655141
references.citation: Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3616-21
references.pmid: 18305175
references.citation: Nature. 1995 Sep 28;377(6547):344-8
references.pmid: 7566089
references.citation: Neurochem Res. 2001 Sep;26(8-9):907-13
references.pmid: 11699942
references.citation: Nat Neurosci. 1998 May;1(1):23-8
references.pmid: 10195104
references.citation: Nat Neurosci. 2005 Sep;8(9):1179-87
references.pmid: 16116450
references.citation: J Physiol. 2009 May 15;587(Pt 10):2115-25
references.pmid: 19332484
references.citation: J Neurophysiol. 2005 Dec;94(6):4491-501
references.pmid: 16162835
references.citation: J Comp Neurol. 2000 May 15;420(4):481-98
references.pmid: 10805922
references.citation: J Physiol. 1998 Mar 15;507 ( Pt 3):639-52
references.pmid: 9508826
references.citation: Epilepsy Res. 2006 Sep;71(1):47-53
references.pmid: 16829043
references.citation: J Pharmacol Exp Ther. 2003 May;305(2):541-8
references.pmid: 12606703
references.citation: Nature. 2001 Jan 4;409(6816):88-92
references.pmid: 11343119
references.citation: Psychopharmacology (Berl). 2000 Jan;147(4):362-70
references.pmid: 10672629
references.citation: J Neurosci. 1994 Nov;14(11 Pt 2):7077-86
references.pmid: 7525894
references.citation: J Biol Chem. 2004 Oct 29;279(44):45833-43
references.pmid: 15317810
references.citation: Nat Neurosci. 2005 Jun;8(6):797-804
references.pmid: 15895085
references.citation: Neuron. 1990 Dec;5(6):781-8
references.pmid: 1702644
references.citation: Br J Pharmacol. 1990 Apr;99(4):643-54
references.pmid: 2163276
references.citation: Trends Neurosci. 1994 Dec;17(12):517-25
references.pmid: 7532336
references.citation: Neuropharmacology. 2005 Oct;49(5):573-86
references.pmid: 15950994
references.citation: Brain Res. 2001 Aug 10;910(1-2):55-66
references.pmid: 11489254
references.citation: J Neurosci. 2007 Mar 7;27(10):2560-9
references.pmid: 17344393
references.citation: Mol Pharmacol. 1999 Jul;56(1):110-5
references.pmid: 10385690
references.citation: Eur J Neurosci. 2004 Oct;20(7):1928-36
references.pmid: 15380015
references.citation: J Neurosci. 2000 Nov 1;20(21):7914-21
references.pmid: 11050111
references.citation: Neuron. 2011 May 12;70(3):385-409
references.pmid: 21555068
references.citation: Neuroscience. 2000;101(4):815-50
references.pmid: 11113332