title: Mutation (Ser284Leu) of neuronal nicotinic acetylcholine receptor alpha 4 subunit associated with frontal lobe epilepsy causes faster desensitization of the rat receptor expressed in oocytes.
abstract: To date five mutations in two major constituents of neuronal nicotinic acetylcholine receptor (nAChR) in the brain, i.e. alpha4 and beta2 subunits, have been identified to be associated with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Among them, only Ser284Leu, a point mutation in alpha4 subunit identified in ADNFLE as well as in a sporadic case with nocturnal frontal lobe epilepsy, remains to be characterized electrophysiologically. We examined the properties of rat nAChR harboring Ser284Leu reconstituted on Xenopus oocytes. Currents elicited in response to application of acetylcholine to oocytes expressing wild type or mutant nAChR were measured by a standard two-microelectrode voltage clamp method. Compared with wild-type nAChR, the mutant nAChR had a comparable EC(50) value for acetylcholine whereas it showed faster desensitization and lower Cs(+)/Na(+) permeability ratio. Ser284Phe, a putative mutation constructed for comparison, exhibited similar properties. These findings indicate that Ser(284) plays an important role in gating of nAChR along with Thr(276) and Ser(280), and suggest that mutation at Ser(284) could reduce nAChR activity similar to other mutations of alpha4 subunit found in ADNFLE.
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, 10-1, 6-chome Hakozaki Higashi-ku, 812-8581, Fukuoka, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Matsushima
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hirose
authors.forename: Hiromi
authors.initials: H
authors.lastname: Iwata
authors.forename: Goryu
authors.initials: G
authors.lastname: Fukuma
authors.forename: Minako
authors.initials: M
authors.lastname: Yonetani
authors.forename: Chiaki
authors.initials: C
authors.lastname: Nagayama
authors.forename: Wakako
authors.initials: W
authors.lastname: Hamanaka
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Matsunaka
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Ito
authors.forename: Sunao
authors.initials: S
authors.lastname: Kaneko
authors.forename: Akihisa
authors.initials: A
authors.lastname: Mitsudome
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sugiyama
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D017034:Epilepsy, Frontal Lobe / Q000235:genetics* / Q000378:metabolism; D005260:Female; D007930:Leucine / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D009865:Oocytes / Q000378:metabolism; D051381:Rats; D011978:Receptors, Nicotinic / Q000096:biosynthesis* / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000235:genetics; D014162:Transfection; D014981:Xenopus
chemical_list: D000109:Acetylcholine; D007930:Leucine; D011978:Receptors, Nicotinic; D011994:Recombinant Proteins; D012694:Serine