Hemichannels formed by connexins mediate the exchange of ions and signaling molecules between the cytoplasm and the extracellular milieu. Under physiological conditions hemichannels have a low open probability, but in certain pathologies their open probability increases, which can result in cell damage. Pathological conditions are characterized by the production of a number of proinflammatory molecules, including 4-hydroxynonenal (4-HNE), one of the most common lipid peroxides produced in response to inflammation and oxidative stress. The aim of this work was to evaluate whether 4-HNE modulates the activity of Cx46 hemichannels. We found that 4-HNE (100 μM) reduced the rate of 4',6-diamino-2-fenilindol (DAPI) uptake through hemichannels formed by recombinant human Cx46 fused to green fluorescent protein, an inhibition that was reversed partially by 10 mM dithiothreitol. Immunoblot analysis showed that the recombinant Cx46 expressed in HeLa cells becomes carbonylated after exposure to 4-HNE, and that 10 mM dithiothreitol reduced its carbonylation. We also found that Cx46 was carbonylated by 4-HNE in the lens of a selenite-induced cataract animal model. The exposure to 100 μM 4-HNE decreased hemichannel currents formed by recombinant rat Cx46 in Xenopus laevis oocytes. This inhibition also occurred in a mutant expressing only the extracellular loop cysteines, suggesting that other Cys are not responsible for the hemichannel inhibition by carbonylation. This work demonstrates for the first time that Cx46 is post-translationally modified by a lipid peroxide and that this modification reduces Cx46 hemichannel activity.

中文翻译：

---

4-Hydroxynonenal 通过其羰基化诱导 Cx46 半通道抑制。


由连接蛋白形成的半通道介导细胞质和细胞外环境之间的离子和信号分子的交换。在生理条件下，半通道的开放概率较低，但在某些病理条件下，其开放概率会增加，这可能会导致细胞损伤。病理状况的特征是产生许多促炎分子，包括 4-羟基壬烯醛 (4-HNE)，它是响应炎症和氧化应激而产生的最常见的脂质过氧化物之一。这项工作的目的是评估 4-HNE 是否调节 Cx46 半通道的活性。我们发现 4-HNE (100 μM) 通过与绿色荧光蛋白融合的重组人 Cx46 形成的半通道降低了 4',6-二氨基-2-fenilindol (DAPI) 的摄取率，这种抑制作用可被 10 mM 部分逆转二硫苏糖醇。免疫印迹分析表明，HeLa 细胞中表达的重组 Cx46 在暴露于 4-HNE 后发生羰基化，并且 10 mM 二硫苏糖醇降低了其羰基化。我们还发现，在亚硒酸盐诱发的白内障动物模型的晶状体中，Cx46 被 4-HNE 羰基化。暴露于 100 μM 4-HNE 会降低非洲爪蟾卵母细胞中重组大鼠 Cx46 形成的半通道电流。这种抑制也发生在仅表达细胞外环半胱氨酸的突变体中，表明其他半胱氨酸不负责羰基化的半通道抑制。这项工作首次证明 Cx46 被脂质过氧化物进行翻译后修饰，并且这种修饰降低了 Cx46 半通道活性。