title: Regulation of activity of P2X7 receptor by its splice variants in cultured mouse astrocytes.
abstract: Of purinergic receptors, P2X7 receptor (P2X7R, defined as a full-length receptor) has unique characteristics, and its activation leads to ion channel activity and pore formation, causing cell death. Previously, we demonstrated that P2X7R expressed by nonstimulated astrocyte cultures obtained from SJL-strain mice exhibits constitutive activation, implying its role in maintenance of cellular homeostasis. To obtain novel insights into its physiological roles, we examined whether constitutive activation of P2X7R is regulated by expression of its splice variants in such resting astrocytes, and whether their distinct expression profiles in different mouse strains affect activation levels of astrocytic P2X7Rs. In SJL- and ddY-mouse astrocytes, spontaneous YO-PRO-1 uptake, an indicator of pore activity of P2X7R, was detected, but the uptake by the formers was significantly greater than that by the latter. Between the two mouse strains, there was a difference in their sensitivity of YO-PRO-1 uptake to antagonists, but not in the expression levels and sequences of P2X7R and pannexin-1. Regarding expression of splice variants of P2X7R, expression of P2X7R variant-3 (P2X7R-v3) and -4 (P2X7R-v4), but not variant-2 and -k, was lower in SJL-mouse astrocytes than in ddY-mouse ones. On transfection of P2X7R-v3 and -v4 into SJL-mouse astrocytes, the pore activity was attenuated as in the case of the HEK293T cell-expression system. These findings demonstrate that basal activity of P2X7R expressed by resting astrocytes is negatively regulated by P2X7R-v3 and -v4, and that their distinct expression profiles result in the different activation levels of astrocytic P2X7Rs in different mouse strains.
authors.affiliation: Department of Environmental Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto, Japan.
authors.forename: Yuuka
authors.initials: Y
authors.lastname: Kido
authors.forename: Chiyo
authors.initials: C
authors.lastname: Kawahara
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Terai
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ohishi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Miki
authors.initials: M
authors.lastname: Hayakawa
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kamatsuka
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nishida
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nagasawa
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism*; D001583:Benzoxazoles / Q000378:metabolism; D001921:Brain / Q000166:cytology; D002229:Carbenoxolone / Q000494:pharmacology; D002478:Cells, Cultured; D017630:Connexins / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D051379:Mice; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D020033:Protein Isoforms / Q000235:genetics*; D011806:Quinolinium Compounds / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000235:genetics / Q000378:metabolism*; D013045:Species Specificity; D014162:Transfection
chemical_list: D001583:Benzoxazoles; D017630:Connexins; D004791:Enzyme Inhibitors; D009419:Nerve Tissue Proteins; C503631:Panx1 protein, mouse; D020033:Protein Isoforms; D011806:Quinolinium Compounds; D012333:RNA, Messenger; D058486:Receptors, Purinergic P2X7; C089813:YO-PRO 1; C017199:2',3'-dialdehyde ATP; D000255:Adenosine Triphosphate; D002229:Carbenoxolone
keywords: P2X7 receptor; astrocyte; mouse strain; splice variant