Tianjin Key Labortory of Drug Targeting and Bioimaging, Tianjin University of Technology , Tianjin, China.
School of Chemistry and Chemical Engineering, Tianjin University of Technology , Tianjin, China.
Channels (Austin). 2021 Dec;15(1):262-272. doi: 10.1080/19336950.2021.1882112.
The slowly activating delayed rectifier K current () plays a key role in the repolarization of ventricular action potential in the human heart and is formed by the pore-forming α-subunit encoded by KCNQ1 (Kv7.1) and β-subunit encoded by KCNE1. Evidence suggested that was regulated through protein kinase C (PKC) pathway, but the mechanism is controversial. This study was designed to identify the specific PKC isoform involved in the long-term regulation of current. The current was recorded using whole-cell patch-clamp technique in human embryonic kidney (HEK) 293B cell co-transfected with human KCNQ1/KCNE1 genes. The results revealed that both chronic activation of Ang II and PMA reduced the current in a long-term regulation (about 24 hours). Further evidence showed that PKCε knockdown by siRNA antagonized the AngII-induced chronic inhibition on the current, whereas knockdown of cPKC (PKCα and PKCβ) attenuated the inhibition effect of PMA on the current. Moreover, the forward transport inhibition of the channel with brefeldin A alleviated the Ang II-induced chronic inhibition on current, while the channel endocytosis inhibition with dynasore alleviated both Ang II and PMA-induced chronic inhibition on current. The above results showed that PKCε activation promoted the channel endocytosis and inhibited the channel forward transport to the plasma membrane, while cPKC activation only promoted the channel endocytosis, which both down regulated the channel current.
缓慢激活延迟整流钾电流（）在人心室动作电位复极化中起关键作用，由 KCNQ1（Kv7.1）编码的孔形成α亚基和 KCNE1 编码的β亚基组成。有证据表明，通过蛋白激酶 C（PKC）途径调节，但机制存在争议。本研究旨在确定参与调节的特定 PKC 同工型。使用全细胞膜片钳技术在共转染人 KCNQ1/KCNE1 基因的人胚肾（HEK）293B 细胞中记录电流。结果表明，慢性 Ang II 激活和 PMA 均可长期调节（约 24 小时）电流。进一步的证据表明，siRNA 敲低 PKCε 可拮抗 Ang II 诱导的电流慢性抑制，而 cPKC（PKCα 和 PKCβ）的敲低可减弱 PMA 对电流的抑制作用。此外，用布雷菲德菌素 A 抑制通道正向转运可减轻 Ang II 诱导的电流慢性抑制，而用 dynasore 抑制通道内吞作用可减轻 Ang II 和 PMA 诱导的电流慢性抑制。上述结果表明，PKCε 的激活促进了通道内吞作用，并抑制了通道向质膜的正向转运，而 cPKC 的激活仅促进了通道内吞作用，均下调了通道电流。
