Behavioral Characterization of Knockin Mice with Mutations M287L and Q266I in the Glycine Receptor α1 Subunit

Blednov, Yuri A.; Benavidez, Jill M.; Homanics, Gregg E.; Harris, R. Adron

doi:10.1124/jpet.111.185124

Cited by 35 publications

(54 citation statements)

References 42 publications

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“…The use of GLIC as a template for homology modeling of GlyR has been supported by two recent studies: 1) it was possible to combine the ligandbinding domain of GlyR with the TM domain of GLIC and obtain a functional chimera that gates in response to glycine (Duret et al, 2011); and 2) mutations in the TM domain of GLIC that made it resemble GlyR resulted in the enhancement of sensitivity to potentiation by ethanol at concentrations in the range of intoxication (Howard et al, 2011). The behavioral tests performed in these knockin mice are presented in a companion article (Blednov et al, 2012) …”

Section: Introductionmentioning

confidence: 84%

“…We conclude that this role of taurine is probably minimal, given that ␣1(M287L) homomeric GlyRs are insensitive to taurine, and yet the glycinergic function in heterozygous ␣1 M/L knockin mice is not as compromised as in ␣1 Q/I knockin mice (Blednov et al, 2012). The effect of ethanol on the ␣1(M287L) GlyRs expressed in oocytes showed variations in different batches of oocytes when carried out in normal buffer, at times exhibiting no differences from the WT, and at other times, a slight reduction.…”

mentioning

confidence: 99%

“…The behavioral tests of the knockin mice (Blednov et al, 2012) reflect and expand some of these observations.…”

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confidence: 99%

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Characterization of Two Mutations, M287L and Q266I, in the α1 Glycine Receptor Subunit That Modify Sensitivity to Alcohols

Borghese

Blednov

et al. 2011

J Pharmacol Exp Ther

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Glycine receptors (GlyRs) are inhibitory ligand-gated ion channels. Ethanol potentiates glycine activation of the GlyR, and putative binding sites for alcohol are located in the transmembrane (TM) domains between and within subunits. To alter alcohol sensitivity of GlyR, we introduced two mutations in the GlyR ␣1 subunit, M287L (TM3) and Q266I (TM2). After expression in Xenopus laevis oocytes, both mutants showed a reduction in glycine sensitivity and glycine-induced maximal currents. Activation by taurine, another endogenous agonist, was almost abolished in the M287L GlyR. The ethanol potentiation of glycine currents was reduced in the M287L GlyR and eliminated in Q266I. Physiological levels of zinc (100 nM) potentiate glycine responses in wild-type GlyR and also enhance the ethanol potentiation of glycine responses. Although zinc potentiation of glycine responses was unchanged in both mutants, zinc enhancement of ethanol potentiation of glycine responses was absent in M287L GlyRs. The Q266I mutation decreased conductance but increased mean open time (effects not seen in M287L). Two lines of knockin mice bearing these mutations were developed. Survival of homozygous knockin mice was impaired, probably as a consequence of impaired glycinergic transmission. Glycine showed a decreased capacity for displacing strychnine binding in heterozygous knockin mice. Electrophysiology in isolated neurons of brain stem showed decreased glycine-mediated currents and decreased ethanol potentiation in homozygous knockin mice. Molecular models of the wildtype and mutant GlyRs show a smaller water-filled cavity within the TM domains of the Q266I ␣1 subunit. The behavioral characterization of these knockin mice is presented in a companion article (J Pharmacol Exp Ther 340:317-329, 2012).

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Section: Introductionmentioning

confidence: 84%

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confidence: 99%

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Characterization of Two Mutations, M287L and Q266I, in the α1 Glycine Receptor Subunit That Modify Sensitivity to Alcohols

Borghese

Blednov

et al. 2011

J Pharmacol Exp Ther

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“…Behavioral characterizations of GlyR KI mice Blednov et al, 2012), including D80A homozygotes (Hirzel et al, 2006), have shown that impairments in GlyR function are accompanied by changes in startle responses. Here, we compared this behavior in the heterozygotic D80A KI and WT mice.…”

Section: Behavioral Tests In Glyr Ki Micementioning

confidence: 99%

“…Startle responses elicited by a series of auditory stimuli were record as previously described Blednov et al, 2012). First, mice were placed in Plexiglas holding chamber for a 5-minute acclimation period.…”

Section: Acoustic Startle Responsementioning

confidence: 99%

Mutation of a Zinc-Binding Residue in the Glycine Receptor α1 Subunit Changes Ethanol Sensitivity In Vitro and Alcohol Consumption In Vivo

McCracken

Blednov

Trudell

et al. 2012

J Pharmacol Exp Ther

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Ethanol is a widely used drug, yet an understanding of its sites and mechanisms of action remains incomplete. Among the protein targets of ethanol are glycine receptors (GlyRs), which are potentiated by millimolar concentrations of ethanol. In addition, zinc ions also modulate GlyR function, and recent evidence suggests that physiologic concentrations of zinc enhance ethanol potentiation of GlyRs. Here, we first built a homology model of a zinc-bound GlyR using the D80 position as a coordination site for a zinc ion. Next, we investigated in vitro the effects of zinc on ethanol action at recombinant wild-type (WT) and mutant a1 GlyRs containing the D80A substitution, which eliminates zinc potentiation. At D80A GlyRs, the effects of 50 and 200 mM ethanol were reduced as compared with WT receptors. Also, in contrast to what was seen with WT GlyRs, neither adding nor chelating zinc changed the magnitude of ethanol enhancement of mutant D80A receptors. Next, we evaluated the in vivo effects of the D80A substitution by using heterozygous Glra1(D80A) knock-in (KI) mice. The KI mice showed decreased ethanol consumption and preference, and they displayed increased startle responses compared with their WT littermates. Other behavioral tests, including ethanol-induced motor incoordination and strychnine-induced convulsions, revealed no differences between the KI and WT mice. Together, our findings indicate that zinc is critical in determining the effects of ethanol at GlyRs and suggest that zinc binding at the D80 position may be important for mediating some of the behavioral effects of ethanol action at GlyRs.

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Gene Targeting Studies of Hyperexcitability and Affective States of Alcohol Withdrawal in Rodents

Greenberg

Crabbe

2016

International Review of Neurobiology

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Behavioral Characterization of Knockin Mice with Mutations M287L and Q266I in the Glycine Receptor α1 Subunit

Cited by 35 publications

References 42 publications

Characterization of Two Mutations, M287L and Q266I, in the α1 Glycine Receptor Subunit That Modify Sensitivity to Alcohols

Characterization of Two Mutations, M287L and Q266I, in the α1 Glycine Receptor Subunit That Modify Sensitivity to Alcohols

Mutation of a Zinc-Binding Residue in the Glycine Receptor α1 Subunit Changes Ethanol Sensitivity In Vitro and Alcohol Consumption In Vivo

Gene Targeting Studies of Hyperexcitability and Affective States of Alcohol Withdrawal in Rodents

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