Multiple pathways are involved in DNA degradation during keratinocyte terminal differentiation.
Multiple pathways are involved in DNA degradation during keratinocyte terminal differentiation.
复制标题
DOI：
10.1038/cddis.2014.145
复制
发表时间：
2014-04-17
影响因子：
9
通讯作者：
中科院分区：
文献类型：
--
作者：
细胞核的丢失是角质形成细胞终末分化的关键步骤。为了阐明所涉及的机制，我们重点关注两个特征事件：聚丝蛋白原 N 端片段的核转位和 caspase-14 依赖性 caspase 激活 DNase (ICAD) 抑制剂的降解。首先，我们证明表皮胰蛋白酶释放丝聚合蛋白原（FLG-N）的 55 kDa N 端片段，并且 FLG-N 易位到细胞核中。有趣的是，这些细胞呈 TUNEL 阳性。 FLG-N 和第一个聚丝蛋白结构域之间的胰蛋白酶敏感区富含 Arg 的突变消除了这些变化。此外，caspase-14 引起 ICAD 的有限蛋白水解，随后在 TUNEL 阳性细胞核中积累了 caspase 激活的 DNase (CAD)。两种蛋白酶的敲低导致皮肤等效模型中残余核的显着增加。免疫组织化学研究表明，特应性皮炎和牛皮癣患者皮损皮肤角化不全区域的 caspase-14 和胰岛蛋白酶均显着下调。总的来说，我们的结果表明，角质形成细胞终末分化过程中至少有两条途径参与 DNA 降解过程。
Loss of the nucleus is a critical step in keratinocyte terminal differentiation. To elucidate the mechanisms involved, we focused on two characteristic events: nuclear translocation of N-terminal fragment of profilaggrin and caspase-14-dependent degradation of the inhibitor of caspase-activated DNase (ICAD). First, we demonstrated that epidermal mesotrypsin liberated a 55-kDa N-terminal fragment of profilaggrin (FLG-N) and FLG-N was translocated into the nucleus. Interestingly, these cells became TUNEL positive. Mutation in the mesotrypsin-susceptible Arg-rich region between FLG-N and the first filaggrin domain abolished these changes. Furthermore, caspase-14 caused limited proteolysis of ICAD, followed by accumulation of caspase-activated DNase (CAD) in TUNEL-positive nuclei. Knockdown of both proteases resulted in a significant increase of remnant nuclei in a skin equivalent model. Immunohistochemical study revealed that both caspase-14 and mesotrypsin were markedly downregulated in parakeratotic areas of lesional skin from patients with atopic dermatitis and psoriasis. Collectively, our results indicate that at least two pathways are involved in the DNA degradation process during keratinocyte terminal differentiation.