MISC（査読の無い研究業績） - 沼田 朋大
-
若年性ミオクロニーてんかん(JME)責任遺伝子の同定
鈴木 俊光, Delgado-Escueta A.V, Aguan Kripamoy, Shi Jun, 原 雄二, 西田 基宏, 沼田 朋大, 竹内 環, Bai Dongsheng, 井上 有史, 大澤 真木子, 兼子 直, 小国 弘量, 森 泰生, 山川 和弘
てんかん研究 ( (一社)日本てんかん学会 ) 23 ( 1 ) 43 - 44 2005年02月
未設定
-
TRPM7チャネルは、細胞膨張によって活性化されて容積調節に関与する
沼田 朋大, 清水 貴浩, 岡田 泰伸
日本生理学会大会発表要旨集 ( 一般社団法人 日本生理学会 ) 2005 S76 - S76 2005年
未設定
In animal cells, it is known that under hypoosmotic conditions, an intracellular Ca<SUP>2+</SUP> increase initially occurs followed by a regulatory volume decrease (RVD) which is attained by effluxes of K<SUP>+</SUP>, Cl<sup>−</SUP> and organic osmolytes and the resulting extraction of osmotically obliged water. The present study was performed to identify the volume-regulatory Ca<SUP>2+</SUP> influx pathway under hypoosmotic conditions in HeLa cells. Whole-cell recordings showed that osmotic swelling activates TRPM7-like cation currents. The currents showed outward rectification and sharp sensitivity to Mg<SUP>2+</SUP>, Gd<SUP>3+</SUP>, SKF96365 and ruthenium red (RR). These TRPM7 channel blockers also inhibited the intracellular Ca<SUP>2+</SUP> increase in response to osmotic swelling and the following RVD. RT-PCR studies demonstrated expression of TRPM7 mRNA in HeLa cells. The siRNA silencing of TRPM7 significantly suppressed not only expression of TRPM7 mRNA but also whole-cell TRPM7-like channel currents, Ca<SUP>2+</SUP> influx and RVD in HeLa cells upon a hypotonic challenge. Thus, we conclude that the endogenous activity of swelling-activated cation channel exhibits the properties identical to the hallmark biophysical and pharmacological features of TRPM7, and that the TRPM7 channel plays an important role in the RVD process by serving as the volume-regulatory Ca<SUP>2+</SUP> influx pathway in the human epithelial cells. <b>[Jpn J Physiol 55 Suppl:S76 (2005)]</b>
-
若年性ミオクローヌスてんかん原因遺伝子の単離に向けて(Towards the identification of genes responsible for juvenile myoclonic epilepsy)
鈴木 俊光, Delgado-Escueta Av, Aguan K, 原 雄二, 西田 基宏, Numata T, 竹内 環, Bai D, 井上 有史, 大沢 真木子, 兼子 直, 小国 弘量, 森 泰生, 山川 和弘
神経化学 ( 日本神経化学会 ) 43 ( 2-3 ) 512 - 512 2004年08月
未設定
-
ミトコンドリア仲介性アポトーシス誘導時のアニオンチャネル活性化における活性酸素の役割
清水 貴浩, 沼田 朋大, 岡田 泰伸
日本生理学会大会発表要旨集 ( 一般社団法人 日本生理学会 ) 2004 S83 - S83 2004年
未設定
Apoptosis is essential for normal tissue development and homeostasis. The apoptotic volume decrease (AVD), which is induced by KCl efflux due to activation of K<SUP>+</SUP> and Cl<sup>−</SUP> channels, is an early-phase, prerequisite component of apoptosis. We previously demonstrated that volume-sensitive Cl<sup>−</SUP> currents are activated after application either of a mitochondrion-mediated inducer, staurosporine (STS), or of a death receptor-mediated inducer, TNF-α or Fas ligand, in HeLa cells without showing cell swelling. Here, we investigated a role of reactive oxygen species (ROS) in STS-induced activation of Cl<sup>−</SUP> channel. STS was found to increase the intracellular ROS level by using 2', 7'-dichlorofluorescein diacetate. The rise in ROS was inhibited by a ROS scavenger, N-acetyl-cysteine (NAC), or an NAD(P)H oxidase inhibitor, diphenylene-iodonium chloride (DPI). In the presence of NAC or DPI, STS failed to activate Cl<sup>−</SUP> currents. In addition, extracellular application of hydrogen peroxide directly increased Cl<sup>−</SUP> currents, which exhibited properties identical to those of volume-sensitive Cl<sup>−</SUP> currents. NAC and DPI could abolish the AVD induced by STS. STS-induced caspase-3 activation and reduction of cell viability were also suppressed by NAC and DPI. These results suggest that ROS is a key mediator for activation of volume-sensitive Cl<sup>−</SUP> channel during a mitochondrion-mediated apoptosis. <b>[Jpn J Physiol 54 Suppl:S83 (2004)]</b>