In situ co-distribution and functional interactions of SAP97 with sinoatrial isoforms of HCN channels.
In situ co-distribution and functional interactions of SAP97 with sinoatrial isoforms of HCN channels.
复制标题
SAP97 与 HCN 通道窦房亚型的原位共分布和功能相互作用。
DOI：
10.1016/j.yjmcc.2009.01.010
复制
发表时间：
2009
影响因子：
5
通讯作者：
Accili,EricA
中科院分区：
文献类型：
--
作者：
Peters,ChristianJ;Chow,SarahS;Angoli,Damiano;Nazzari,Hamed;Cayabyab,FranciscoS;Morshedian,Ala;Accili,EricA
窦房结是一个专门的心肌细胞区域，负责成人心脏的重复活动。与心脏的其他区域相比，窦房结受到严重的神经支配，并且该区域的特化心肌细胞从自主神经系统接收神经和激素输入，这导致心率的变化。响应自主输入的窦房搏动频率的关键调节器是超极化激活的环核苷酸门控（HCN）通道，其是一种混合阳离子通道，其活性通过cAMP与其细胞质侧的结合而增加。HCN通道定位于窦房肌细胞的细胞表面上的不同区域或“热点”，但这些区域如何形成，它们是否对应于特定的信号传导结构域和特定的HCN同种型以及其中的其他蛋白质尚不清楚。在本文中，我们表明，HCN 2和HCN 4亚型共分布的衔接蛋白SAP 97，一个重要组成部分，不同的斑点在兔心脏的窦房结。HCN 4，而不是HCN 2，也与突触后标记物β-连环蛋白共分布，从而鉴定该组织内的不同组织结构域。此外，我们表明，使用异源表达系统，全细胞膜片钳电生理学和成像，SAP 97功能上与HCN相互作用的方式，依赖于PDZ兼容的C-末端结合基序，但它对Ifbehavior的影响是HCN亚型和上下文依赖性。总之，数据表明SAP 97有助于在兔窦房结中的特定结构域内HCN通道的同种型特异性组织。
The sinoatrial node is a region of specialized cardiomyocytes that is responsible for the repetitive activity of the adult heart. The sinoatrial node is heavily innervated compared to the other regions of the heart, and the specialized cardiomyocytes of this region receive neural and hormonal input from the autonomic nervous system, which leads to changes in heart rate. A key regulator of sinoatrial beating frequency in response to autonomic input is the hyperpolarization-activated cyclic nucleotide gated (HCN) channel, a mixed cationic channel whose activity is increased by the binding of cAMP to its cytoplasmic side. HCN channels localize to distinct regions or “hot spots” on the cell surface of sinoatrial myocytes, but how these regions are formed, whether they correspond to specific signaling domains and the specific HCN isoforms and other proteins therein are not known. In this paper, we show that both HCN2 and HCN4 isoforms co-distribute with the adapter protein SAP97, an important component of distinct punctae in the sinoatrial node of the rabbit heart. HCN4, but not HCN2, also co-distributes with the post-synaptic marker β-catenin, thus identifying diverse organized domains within this tissue. Furthermore, we show, using heterologous expression systems, whole-cell patch clamp electrophysiology and imaging, that SAP97 interacts functionally with HCN in a manner that depends upon the PDZ compatible binding motif of the C-terminus, but that its effects on Ifbehaviour are HCN isoform and context dependent. Together, the data suggest that SAP97 contributes to isoform specific organization of HCN channels within specific domains in the sinoatrial node of the rabbit.