Liu Xiao, Spicarová Zuzana, Rydholm Susanna, Li Juan, Brismar Hjalmar, Aperia Anita
Department of Woman and Child Health, Karolinska Institutet, Astrid Lindgren Children's Hospital, Q2:09, SE-171 76 Stockholm, Sweden.
J Biol Chem. 2008 Apr 25;283(17):11461-8. doi: 10.1074/jbc.M706942200. Epub 2008 Feb 26.
Na,K-ATPase and inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) can form a signaling microdomain that in the presence of ouabain triggers highly regular calcium oscillations. Downstream effects include NF-kappaB activation. Here we report that ankyrin B (Ank-B), expressed in most mammalian cells, plays a pivotal role in the function of the Na,K-ATPase/IP3R signaling microdomain. In studies performed on a monkey kidney cell line, we show that Ank-B co-precipitates with both Na,K-ATPase and IP3R. We identify the N terminus tail of the Na,K-ATPase catalytic subunit and the N-terminal portion 1-604 of the IP3R as novel binding sites for Ank-B. Knockdown of Ank-B with small interfering RNA reduced the expression of Ank-B to 15-30%. This down-regulation of Ank-B attenuated the interaction between Na,K-ATPase and IP3R, reduced the number of cells responding to pm doses of ouabain with calcium oscillations, altered the calcium oscillatory pattern, and abolished the ouabain effect on NF-kappaB. In contrast, Ank-B down-regulation had no effect on the ion transporting function of Na,K-ATPase and no effect on the distribution and apparent mobility of Na,K-ATPase in the plasma membrane.
钠钾ATP酶与肌醇1,4,5 - 三磷酸(IP3)受体(IP3R)可形成一个信号微结构域,在哇巴因存在的情况下触发高度规则的钙振荡。下游效应包括核因子κB(NF-κB)的激活。在此我们报告,在大多数哺乳动物细胞中表达的锚蛋白B(Ank-B)在钠钾ATP酶/IP3R信号微结构域的功能中起关键作用。在对一种猴肾细胞系进行的研究中,我们发现Ank-B与钠钾ATP酶和IP3R都能共沉淀。我们确定钠钾ATP酶催化亚基的N末端尾巴以及IP3R的N末端1 - 604部分是Ank-B的新结合位点。用小干扰RNA敲低Ank-B可使Ank-B的表达降至15% - 30%。Ank-B的这种下调减弱了钠钾ATP酶与IP3R之间的相互作用,减少了对皮摩尔剂量哇巴因产生钙振荡反应的细胞数量,改变了钙振荡模式,并消除了哇巴因对NF-κB的作用。相比之下,Ank-B的下调对钠钾ATP酶的离子转运功能没有影响,对钠钾ATP酶在质膜中的分布和表观迁移率也没有影响。