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David J Hinkle

Publications and source records attributed to David J Hinkle.

3 recordsLinked to original sources
PubMed2003

Beta subunit phosphorylation selectively increases fast desensitization and prolongs deactivation of alpha1beta1gamma2L and alpha1beta3gamma2L GABA(A) receptor currents.

We studied the effects of phosphorylation by protein kinase A (PKA) on GABA(A) receptors (alpha1beta1gamma2L andalpha1beta3gamma2L) transiently expressed in HEK 293T cells. Under conditions favorable for PKA activation, currents obtained using whole-cell patch clamp of lifted cells displayed increased rate and extent of the fast phases of desensitization, decreased rate of current deactivation after GABA removal, and prolongation of brief IPSC-like currents. Mutation of serine residues (beta1 S409, beta3 S407, beta3 S408) revealed that only beta1 S409 and beta3 S408 were critical for the modulatory effect of PKA on GABA(A) receptor currents. Additionally, repeated pulse inhibition was increased in receptors after mutation of the critical serine to glutamate and decreased when the serine was mutated to alanine. These data demonstrate that PKA phosphorylation modulated GABA(A) receptor currents by increasing fast phases of macroscopic desensitization and suggest a role for PKA in regulating GABAergic IPSC duration.

Cell Line↗
PubMed2002

Functional characterization of the new human GABA(A) receptor mutation beta3(R192H).

We screened 124 individuals for single nucleotide polymorphisms of the alpha1, beta3 and gamma2 genes of the GABA(A) receptor in the regions corresponding to the ligand-binding domains on the protein level. In a patient with chronic insomnia, a missense mutation was found in the gene of the beta3 subunit. This mutation results in the substitution of the amino acid residue arginine for histidine in position 192 (beta3(R192H)). The patient was found to be heterozygous for this mutation. Functional analysis of human alpha1beta3(R192H)gamma2S GABA(A) receptors using ultra fast perfusion techniques revealed a slower rate of the fast phase of desensitization compared with alpha1beta3gamma2S GABA(A) receptors. Additionally, current deactivation [a major determinant of inhibitory postsynaptic current (IPSC) duration] was faster in the mutated receptors. This raises the possibility of decreased GABAergic inhibition contributing to insomnia, as some members of the patient's family also suffer from insomnia. The mutation beta3(R192H) might, therefore, be linked to this condition. The intron/exon boundaries of the alpha1 subunit gene were also established and three additional variants were found in the alpha1 and beta3 genes.

Animals↗