GABA(A) receptor subunit alteration-dependent diazepam insensitivity in the cerebellum of phospholipase C-related inactive protein knockout mice.
The GABA(A) receptor, a pentamer composed predominantly of alpha, beta, and gamma subunits, mediates fast inhibitory synaptic transmission. We have previously reported that phospholipase C-related inactive protein (PRIP) is a modulator of GABA(A) receptor trafficking and that knockout (KO) mice exhibit a diazepam-insensitive phenotype in the hippocampus. The alpha subunit affects diazepam sensitivity; alpha1, 2, 3, and 5 subunits assemble with any form of beta and the gamma2 subunits to produce diazepam-sensitive receptors, whereas alpha4 or alpha6/beta/gamma2 receptors are diazepam-insensitive. Here, we investigated how PRIP is implicated in the diazepam-insensitive phenotype using cerebellar granule cells in animals expressing predominantly the alpha6 subunit. The expression of alpha1/beta/gamma2 diazepam-sensitive receptors was decreased in the PRIP-1 and 2 double KO cerebellum without any change in the total number of benzodiazepine-binding sites as assessed by radioligand-binding assay. Since levels of the alpha6 subunit were increased, the alpha1/beta/gamma2 receptors might be replaced with alpha6 subunit-containing receptors. Then, we further performed autoradiographic and electrophysiologic analyses. These results suggest that the expression of alpha6/delta receptors was decreased in cerebellar granule neurons, while that of alpha6/gamma2 receptors was increased. PRIP-1 and 2 double KO mice exhibit a diazepam-insensitive phenotype because of a decrease in diazepam-sensitive (alpha1/gamma2) and increase in diazepam-insensitive (alpha6/gamma2) GABA(A) receptors in the cerebellar granule cells.
Mizokami
Akiko
A
Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, and Station for Collaborative Research, Kyushu University, Fukuoka, Japan.
Tanaka
Hiroto
H
Ishibashi
Hitoshi
H
Umebayashi
Hisanori
H
Fukami
Kiyoko
K
Takenawa
Tadaomi
T
Nakayama
Keiichi I
KI
Yokoyama
Takeshi
T
Nabekura
Junichi
J
Kanematsu
Takashi
T
Hirata
Masato
M
D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D003975:Diazepam / Q000494:pharmacology*; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques; D021122:Protein Subunits / Q000502:physiology; D011869:Radioligand Assay; D011963:Receptors, GABA-A / Q000502:physiology*
D002352:Carrier Proteins; C546241:Gabra1 protein, mouse; C546172:Gabra6 protein, mouse; C546280:Gabrg2 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; C513987:PRIP-1 phospholipase C-related protein, mouse; D021122:Protein Subunits; D011963:Receptors, GABA-A; D003975:Diazepam