A unique mode of keratinocyte death requires intracellular acidification
A unique mode of keratinocyte death requires intracellular acidification
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DOI：
10.1073/pnas.2020722118
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发表时间：
2021-04-27
影响因子：
11.1
通讯作者：
Amagai, Masayuki
中科院分区：
文献类型：
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作者：
Matsui, Takeshi;Kadono-Maekubo, Nanako;Amagai, Masayuki
角质层(SC)是最外层的表皮，由不能存活的无核角质形成细胞组成，称为角质形成细胞，起到保护屏障的作用。颗粒上层角质形成细胞(SG1细胞)执行细胞死亡的确切方式在很大程度上仍不清楚。在这里，我们使用活体成像结合细胞内钙离子和pH响应的荧光探针，旨在剖析SG1在体内的死亡过程。我们发现，在SG1细胞死亡之前，持续的(？60min)钙离子升高和迅速诱导的细胞内酸化。一旦这种细胞内的离子变化被启动，它们就会持续下去，不可逆转地将SG1细胞转化为角质细胞。对分离的小鼠SG1细胞的时间推移成像显示，细胞内的酸化对于角质形成细胞形成特有的角质形成颗粒和核DNA的降解是必不可少的。此外，活体成像显示，SG1细胞表现出钙离子升高的数量和细胞内酸化的时间都受到瞬时受体电位阳离子通道V3的严格调控。在分离的SG1细胞中，用全细胞膜片钳分析证实了该蛋白的功能活性。这些发现为更好地理解角质形成细胞特异性死亡模式下的独特分子机制提供了理论框架，即角膜下垂。
The stratum corneum (SC), the outermost epidermal layer, consists of nonviable anuclear keratinocytes, called corneocytes, which function as a protective barrier. The exact modes of cell death executed by keratinocytes of the upper stratum granulosum (SG1 cells) remain largely unknown. Here, using intravital imaging combined with intracellular Ca2*- and pH-responsive fluorescent probes, we aimed to dissect the SG1 death process in vivo. We found that SG1 cell death was preceded by prolonged (?60 min) Ca2* elevation and rapid induction of intracellular acidification. Once such intracellular ionic changes were initiated, they became sustained, irreversibly committing the SG1 cells to corneocyte conversion. Time-lapse imaging of isolated murine SG1 cells revealed that intracellular acidification was essential for the degradation of keratohyalin granules and nuclear DNA, phenomena specific to SC corneocyte formation. Furthermore, intravital imaging showed that the number of SG1 cells exhibiting Ca2* elevation and the timing of intracellular acidification were both tightly regulated by the transient receptor potential cation channel V3. The functional activity of this protein was confirmed in isolated SG1 cells using whole-cell patch-clamp analysis. These findings provide a theoretical framework for improved understanding of the unique molecular mechanisms underlying keratinocyte-specific death mode, namely corneoptosis.