Akt phosphorylation and arrhythmogenic modification of the cardiac sodium channel

Akt 磷酸化和心脏钠通道的致心律失常修饰

基本信息

批准号：
18590757
负责人：
MAKITA Naomasa
金额：
$ 2.53万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18590757/
关键词：
Akt phosphorylation Na channel Lethal arrhythmias リン酸化シグナルトランスジェニック動物

项目摘要

Akt is a serine-threonine phosphatase implicated in wide variety of signal transductions including cell proliferation and apoptosis. Selective overexpression of Akt in mice heart results in cardiac hypertrophy, but occasionally, some transgenic mice die suddenly with unknown causes before the cardiac hypertrophy is fully established, suggesting life-threatening arrhythmias during Akt-induction. The purpose of the study was to elucidate the biophysical and biochemical mechanisms underlying Akt-induced cardiac hypertrophy and lethal arrhythmias. We focused on cardiac Na channel Navl.5, because Navl.5, unlike other cardiac ion channels, has two Akt phosphorylation recognition sequences (RXRXXT/S). Navl.5 was coexpressed in HEK 293 cells together with Akt or its phosphorylation deficient mutant Akt-3A (K179A+T308A+S478A), and the biophysical properties were determined by whole-cell patch clamp technique. Current density of Nav.15 was significantly increased by Akt but not by Akt-3A. Voltage-dependence of the activation curve, but not inactivation, was significantly shifted in the depolarizing direction. Furthermore, coimmunoprecipitation of FLAG-tagged Nav.15 with anti-phosphorylated-Akt antibodies revealed that Akt but not Akt-3A increased the association of Akt with cardiac Na channel. These results suggest that Akt modified the biophysical properties and expression levels of Na channel, leading to induce of lethal arrhythmias. Further study including in vivo ECG recording in Aid transgenic mice are required to elucidate the mechanistic link between cardiac Akt signaling pathway and the lethal arrhythmias.

AKT是一种丝氨酸 - 硫代磷酸酶，其中涉及各种信号转导，包括细胞增殖和凋亡。小鼠心脏中AKT的选择性过表达会导致心脏肥大，但偶尔，某些转基因小鼠在完全确定心脏肥大之前突然死于未知原因，这表明在AKT诱导过程中会威胁生命。该研究的目的是阐明Akt诱导的心脏肥大和致命性心律不齐的生物物理和生化机制。我们专注于心脏NA通道NAVL.5，因为NAVL.5与其他心脏离子通道不同，具有两个AKT磷酸化识别序列（RXRXXT/S）。 NAVL.5在HEK 293细胞中与AKT或其磷酸化缺陷突变体AKT-3A（K179A+T308A+S478A）共表达，并且通过全细胞贴片夹技术确定了生物物理性能。 NAV的当前密度15显着增加了AKT，但AKT-3A的密度不高。激活曲线的电压依赖性（而不是灭活）在去极化方向上显着移动。此外，抗磷酸化的Akt抗体对标记为标记的NAV的共免疫沉淀显示，AKT而不是AKT-3A增加了AKT与心脏NA通道的关联。这些结果表明AKT改变了Na通道的生物物理特性和表达水平，从而导致致命性心律不齐。需要进一步的研究，包括辅助转基因小鼠中的体内心电图记录，以阐明心脏AKT信号通路和致命性心律失常之间的机械联系。