Functinal regulation of cardiac ATP-sensitive potassium channel by actin cytoekeleton

肌动蛋白细胞骨架对心脏 ATP 敏感钾通道的功能调节

基本信息

批准号：
08670774
负责人：
FURUKAWA Tetsushi
金额：
$ 1.66万
依托单位：
Tokyo Medical and Dental University, Medical Research Institute
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

Previously, we had reported that ATP-sensitive potassium channel (K_<ATP> channel)^- required intracellular ATP to maintain its activity and that this effect of ATP is similar to ATP action on polymerization/depolymerization of actin cytoskeleton. Thus, we examined functional modulation of K_<ATP> channel by cytoskeleton.Actin disruptors diminished K_<ATP> channel activity, while actin stabilizer maintained channel activity. Disruptors or stabilizers of microtubules did not affect K_<ATP> channel activity. Direct application of polymerized form of actin (F-actin) recovered lost channel activity. PIP_2, which binds to all actin binding proteins and inhibits their actin severing activity, act for maintainance of channel activity and recevered prtially lost channel activity. These data indicate that K_<ATP> channel activity was functionally modulated by the status of actin cytoskeleton.Next, we sought using yeast two hybrid system protein that would interact with nucleotide binding domain (NBD) of sulfonylurea receptor (SUR), a target of intracellular regulation of K_<ATP> channel. An unknown protein was found to interact with NBD1 of cardiac type SUR,(SUR2a), whose transcript are present ubiquitously and most predominantly in the heart. Isolation of full-length of cDNA revealed that there were four isoforms due to alternative splicing. In each isoform, there was a region that had high sequence homology to cytochrome C.Thus, K_<ATP> channel might be regulated by intracellular oxidization reaction.Currently, we are on the way to examine functional role of interaction of NBD1 in SUR2a and the unknown protein that we found.

此前，我们报道了ATP敏感性钾通道（K_<ATP>通道）^-需要细胞内ATP来维持其活性，并且ATP的这种作用类似于ATP对肌动蛋白细胞骨架聚合/解聚的作用。因此，我们检查了细胞骨架对 K_<ATP> 通道的功能调节。肌动蛋白干扰剂减弱了 K_<ATP> 通道活性，而肌动蛋白稳定剂则维持通道活性。微管的干扰剂或稳定剂不影响K_<ATP>通道活性。直接应用聚合形式的肌动蛋白（F-肌动蛋白）恢复了失去的通道活性。 PIP_2 与所有肌动蛋白结合蛋白结合并抑制其肌动蛋白切断活性，用于维持通道活性并恢复部分失去的通道活性。这些数据表明 K_<ATP> 通道活性受到肌动蛋白细胞骨架状态的功能调节。接下来，我们寻求使用酵母二杂合系统蛋白，该蛋白会与磺酰脲受体 (SUR) 的核苷酸结合域 (NBD) 相互作用，磺酰脲受体 (SUR) 是K_<ATP>通道的细胞内调节。一种未知的蛋白质被发现与心脏类型 SUR (SUR2a) 的 NBD1 相互作用，其转录物普遍存在且主要存在于心脏中。全长 cDNA 的分离表明，由于选择性剪接，存在四种亚型。在每个亚型中，都有一个与细胞色素C具有高度序列同源性的区域。因此，K_<ATP>通道可能受到细胞内氧化反应的调节。目前，我们正在研究NBD1在SUR2a和SUR2a中相互作用的功能作用。我们发现的未知蛋白质。