Overexpression of human KCNA5 increases IK(V) and enhances apoptosis
Overexpression of human KCNA5 increases IK(V) and enhances apoptosis
复制标题
DOI：
10.1152/ajpcell.00050.2004
复制
发表时间：
2004-09-01
影响因子：
5.5
通讯作者：
Yuan, JXJ
中科院分区：
文献类型：
--
作者：
Brevnova, EE;Platoshyn, O;Yuan, JXJ
凋亡细胞收缩是细胞凋亡的早期标志，受K+外排和K+通道活性的调节。肺动脉平滑肌细胞（PASMC）的凋亡抑制和K+通道下调与肺血管内侧肥大和肺动脉高压的发生有关。本研究的目的是验证KCNA5（编码延迟整流器电压门控K+ (Kv)通道）的过表达增加K+电流并促进细胞凋亡的假设。瞬时转染KCNA5可使COS-7和PASMC中KCNA5通道蛋白水平升高25 ~ 34倍，+60 mV时Kv通道电流（I-K(V)）升高24 ~ 29倍。在kcna5转染的COS-7细胞中，staurosporine （ST）介导的caspase-3活性增加和细胞凋亡百分比均增强，而与空载体转染的细胞相比，基础凋亡（没有ST刺激）保持不变。然而，在大鼠PASMC中，单独转染KCNA5除了增强st介导的细胞凋亡外，还导致基底细胞凋亡显著增加。此外，st诱导的凋亡细胞收缩在转染KCNA5的COS-7细胞和大鼠PASMC中显著加速，用4-氨基吡啶（4-AP）阻断KCNA5通道减少通过KCNA5通道的K+电流，抑制KCNA5转染的COS-7细胞中st诱导的凋亡。人KCNA5基因的过表达增加K+电流（即K+外排或损失），加速凋亡体积减少（AVD），增加caspase-3活性，诱导细胞凋亡。通过KCNA5基因转移诱导PASMC细胞凋亡可能是预防肺血管壁增厚进展和治疗特发性肺动脉高压（IPAH）患者的重要策略。
Apoptotic cell shrinkage, an early hallmark of apoptosis, is regulated by K+ efflux and K+ channel activity. Inhibited apoptosis and downregulated K+ channels in pulmonary artery smooth muscle cells (PASMC) have been implicated in development of pulmonary vascular medial hypertrophy and pulmonary hypertension. The objective of this study was to test the hypothesis that overexpression of KCNA5, which encodes a delayed-rectifier voltage-gated K+ (Kv) channel, increases K+ currents and enhances apoptosis. Transient transfection of KCNA5 caused 25- to 34-fold increase in KCNA5 channel protein level and 24- to 29-fold increase in Kv channel current (I-K(V)) at +60 mV in COS-7 and rat PASMC, respectively. In KCNA5-transfected COS-7 cells, staurosporine (ST)-mediated increases in caspase-3 activity and the percentage of cells undergoing apoptosis were both enhanced, whereas basal apoptosis ( without ST stimulation) was unchanged compared with cells transfected with an empty vector. In rat PASMC, however, transfection of KCNA5 alone caused marked increase in basal apoptosis, in addition to enhancing ST-mediated apoptosis. Furthermore, ST-induced apoptotic cell shrinkage was significantly accelerated in COS-7 cells and rat PASMC transfected with KCNA5, and blockade of KCNA5 channels with 4-aminopyridine (4-AP) reduced K+ currents through KCNA5 channels and inhibited ST-induced apoptosis in KCNA5-transfected COS-7 cells. Overexpression of the human KCNA5 gene increases K+ currents (i.e., K+ efflux or loss), accelerates apoptotic volume decrease (AVD), increases caspase-3 activity, and induces apoptosis. Induction of apoptosis in PASMC by KCNA5 gene transfer may serve as an important strategy for preventing the progression of pulmonary vascular wall thickening and for treating patients with idiopathic pulmonary arterial hypertension (IPAH).