Effects of hydrophobic compounds on anion channels expressed in pancreatic duct cells

疏水性化合物对胰管细胞表达的阴离子通道的影响

基本信息

批准号：
15590196
负责人：
SOHMA Yoshiro
金额：
$ 2.37万
依托单位：
Osaka Medical College
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15590196/
关键词：
CFTR ion channel anion gating hydrophobic compound pancreatic duct cell cholesterol bicarbonate secretion 膵臓外分泌重炭酸イオン bicarbonate secretion pancreatic duct

项目摘要

Anion conductance in pancreatic duct cells is mainly underlied by Cystic Fibrosis Transmembrane-conductance Regulator (CFTR) anion channels. In this study, we investigated the effects of hydrophobic compounds on CFTR channels using patch-clamp technique.Small negatively-charged hydrophobic aromatic compounds like aromatic carboxylic acids induced both a decrease in single channel conductance and an increase in open probability (Po) simultaneously. On the other hand, small electro-neutral hydrophobic aromatic compounds increased Po without decreasing single channel conductance. These results suggested that the small aromatic compounds bind to a hydrophobic binding site inside the channel pore with a fast kinetics leading to reduce the single channel conductance, and also increase Po by binding to another site located in the intracellular side of CFTR channel.We also investigated mechanisms of ATP-dependent gating of CFTR channel as well as effects of cholesterol on the CFTR gating. Our … More results for the ATP-dependent gating strongly supported the "nucleotide binding domain (NBD) dimmerization hypothesis" that two NBDs make a dimmer with two ATP molecules in their interface, leading to open the channel pore, and the sequential hydrolysis of ATP binding to NBD2 breaks the dimmer, leading to channel closing. We also found that cholesterol content in plasma membrane changed the gating kinetics of CFTR channel significantly. Totally our results suggested that cholesterol affects rate of the ATP hydrolysis at the nucleotide binding domain via changing the mechanical resistance to the conformational change of the membrane spanning domains during channel pore gating.Taken together, the present study showed that effects of hydrophobic compounds on CFTR widely varied dependent on its peculiar characteristics of each compound, not their common feature of ‘hydrophobicity', which suggested us the existence of a complicated feed back system via lipid metabolism. Our novel findings for ATP-dependent gating significantly contribute to understanding of gating mechanisms of CFTR itself and other ABC transporters as well.We also performed some basic studies for epithelial BK_<Ca> channels and GABA_A channels expressed in peripheral tissue, which are important for the next step in this research field. Less

胰管细胞中的阴离子电导主要由囊性纤维化跨膜传导调节剂（CFTR）阴离子通道底部。在这项研究中，我们使用贴片钳技术研究了疏水化合物对CFTR通道的影响。小收集的疏水芳香族化合物（如芳族羧酸）诱导了单个通道电导率的降低，又降低了开放概率的增加（PO）。另一方面，小的电性疏水芳香族化合物增加了PO，而不会降低单通道电导。 These results suggested that the small aromatic compounds bind to a hydrophobic binding site inside the channel pore with a fast kinetics leading to reduce the single channel conductance, and also increase Po by binding to another site located in the intracellular side of CFTR channel.We also investigated mechanisms of ATP-dependent gating of CFTR channel as well as effects of cholesterol on the CFTR gating. Our … More results for the ATP-dependent gating strongly supported the "nucleotide binding domain (NBD) dimmerization hypothesis" that two NBDs make a dimmer with two ATP molecules in their interface, leading to open the channel pore, and the sequential hydrolysis of ATP binding to NBD2 breaks the dimmer, leading to channel closing.我们还发现，质膜中的胆固醇含量显着改变了CFTR通道的门控动力学。完全我们的结果表明，胆固醇通过改变机械阻力对通道孔隙门控孔的构象变化的机械阻力来影响核结合结构域的ATP水解速率。参与通道孔隙的膜跨度。进行综合，本研究表明，疏水化合物对CFTR对CFTR的依赖性的影响而不是其特征的特征，而不是其相关特征，而不是其相关特征，而不是其相关的特征，而不是它们的传统特征，而不是'''，而不是其特征的特征。通过脂质代谢的复杂馈电系统。我们对ATP依赖门控的新发现显着有助于了解CFTR本身和其他ABC转运蛋白的门控机制。我们还为上皮BK_>通道和GABA_A通道进行了一些基础研究，在外围组织中表达的GABA_A通道，这对于该研究领域的下一步非常重要。较少的