Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, USA.
Circ Res. 2011 Mar 18;108(6):704-15. doi: 10.1161/CIRCRESAHA.110.235747. Epub 2011 Jan 27.
Remodeling of connexin (Cx)43 gap junctions (GJs) is linked to ventricular arrhythmia.
A peptide mimetic of the carboxyl terminal (CT) of Cx43, incorporating a postsynaptic density-95/disks-large/ZO-1 (PDZ)-binding domain, reduces Cx43/ZO-1 interaction and GJ size remodeling in vitro. Here, we determined: (1) whether the Cx43-CT mimetic αCT1 altered GJ remodeling following left ventricular (LV) injury in vivo; (2) whether αCT1 affected arrhythmic propensity; and (3) the mechanism of αCT1 effects on arrhythmogenicity and GJ remodeling.
A cryoinjury model generating a reproducible wound and injury border zone (IBZ) in the LV was used. Adherent methylcellulose patches formulated to locally release αCT1 (< 48 hours) were placed on cryoinjuries. Relative to controls, Cx43/ZO-1 colocalization in the IBZ was reduced by αCT1 by 24 hours after injury. Programmed electric stimulation ex vivo and optical mapping of voltage transients indicated that peptide-treated hearts showed reduced inducible arrhythmias and increased ventricular depolarization rates 7 to 9 days after injury. At 24 hours and 1 week after injury, αCT1-treated hearts maintained Cx43 in intercalated disks (IDs) in the IBZ, whereas by 1 week after injury, controls demonstrated Cx43 remodeling from IDs to lateralized distributions. Over a postinjury time course of 1 week, αCT1-treated IBZs showed increased Cx43 phosphorylation at serine368 (Cx43-pS368) relative to control tissues. In biochemical assays, αCT1 promoted phosphorylation of serine368 by protein kinase (PK)C-ε in a dose-dependent manner that was modulated by, but did not require ZO-1 PDZ2.
αCT1 increases Cx43-pS368 in vitro in a PKC-ε-dependent manner and in the IBZ in vivo acutely following ventricular injury. αCT1-mediated increase in Cx43-pS368 phosphorylation may contribute to reductions in inducible-arrhythmia following injury.
连接蛋白 (Cx)43 缝隙连接 (GJ) 的重构与室性心律失常有关。
Cx43 羧基末端 (CT) 的肽模拟物，包含一个后突触密度-95/盘状结构域大/ZO-1 (PDZ) 结合域，可减少体外 Cx43/ZO-1 相互作用和 GJ 大小重构。在这里，我们确定：(1) Cx43-CT 模拟物 αCT1 是否在体内左心室 (LV) 损伤后改变 GJ 重塑；(2) αCT1 是否影响心律失常倾向；(3) αCT1 对致心律失常性和 GJ 重塑的作用机制。
使用一种在 LV 中产生可重复的创伤和损伤边界区 (IBZ) 的冷冻损伤模型。将定制的可附着甲基纤维素贴片（<48 小时）置于冷冻损伤处，以局部释放 αCT1。与对照组相比，αCT1 在损伤后 24 小时内降低了 IBZ 中的 Cx43/ZO-1 共定位。离体程控电刺激和电压瞬态光学映射表明，肽处理后的心脏在损伤后 7 至 9 天显示出可诱导性心律失常减少和心室去极化率增加。在损伤后 24 小时和 1 周时，αCT1 处理的心脏在 IBZ 中保留了 Cx43 位于闰盘 (IDs) 中，而在 1 周后，对照组显示 Cx43 从 IDs 重塑为侧向分布。在 1 周的损伤后时间过程中，αCT1 处理的 IBZ 中 Cx43 丝氨酸 368 磷酸化（Cx43-pS368）相对于对照组织增加。在生化测定中，αCT1 以剂量依赖性方式促进蛋白激酶 (PK)C-ε 磷酸化丝氨酸 368，这种作用被但不依赖于 ZO-1 PDZ2 调节。
αCT1 以 PKC-ε 依赖性方式在体外增加 Cx43-pS368，并在体内急性损伤后立即在 IBZ 中增加。αCT1 介导的 Cx43-pS368 磷酸化增加可能有助于减少损伤后的可诱导性心律失常。
