Adducin Is Required for Desmosomal Cohesion in Keratinocytes*
Adducin Is Required for Desmosomal Cohesion in Keratinocytes*
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DOI：
10.1074/jbc.m113.527127
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发表时间：
2014-04
期刊：
影响因子：
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通讯作者：
Vera Rötzer;A. Breit;J. Waschke;V. Spindler
中科院分区：
文献类型：
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作者：
Vera Rötzer;A. Breit;J. Waschke;V. Spindler
背景：皮质肌动蛋白细胞骨架是角质形成细胞黏附所必需的，其机制尚不清楚。结果：肌动蛋白结合蛋白内收蛋白调节桥粒黏附，是水疱性皮肤病天疱疮自身抗体的保护性蛋白激酶C磷酸化的靶点。结论：内收蛋白通过调节桥粒促进黏附，是天疱疮保护途径的一部分。意义：皮质肌动蛋白调节桥粒粘连的新机制。内收蛋白是一种组织皮质肌动蛋白细胞骨架的蛋白质，是RhoA和PKC信号转导的靶点。然而，细胞间凝聚力的作用尚不清楚。我们发现内收蛋白沉默导致肌动蛋白细胞骨架的破坏，减少了人角质形成细胞的细胞间黏附，并通过减少桥粒黏附分子Desmoglein(DSG)3的膜掺入而降低其水平。由于在自身抗体介导的寻常型天疱疮(PV)中观察到细胞凝聚力丧失和Dsg3耗尽，我们使用了PV患者的抗体部分。检测到丝氨酸726处内收蛋白的快速磷酸化对这些自身抗体的反应。为了机械地将自身抗体结合和内收蛋白磷酸化联系起来，我们评估了几个与疾病相关的信号分子的作用。丝氨酸726的内收蛋白磷酸化依赖于钙离子内流和PKC，但不依赖于p38MAPK和PKA。内收蛋白的磷酸化是保护性的，因为磷酸化缺陷的突变导致细胞凝聚力的丧失和Dsg3的断裂。因此，PKC对细胞黏附既有积极的影响，也有消极的影响，因为它在天疱疮中对细胞解离的作用是公认的。我们还评估了RhoA对内收蛋白磷酸化的影响，因为RhoA的激活被证明可以阻止天疱疮自身抗体诱导的细胞解离。我们的数据表明，RhoA激活的保护作用依赖于内收蛋白的存在及其在丝氨酸726处的磷酸化。这些实验为RhoA和PKC介导的角质形成细胞内收蛋白磷酸化调节桥粒黏附提供了新的机制。
Background: The cortical actin cytoskeleton is necessary for keratinocyte adhesion by unclear mechanisms. Results: The actin-binding protein adducin modulates desmosomal adhesion and is a target of protective PKC phosphorylation in response to autoantibodies of the blistering skin disease pemphigus. Conclusion: Adducin promotes adhesion by regulating desmosomes and is part of a protective pathway in pemphigus. Significance: Novel mechanism how cortical actin modulates desmosomal adhesion. Adducin is a protein organizing the cortical actin cytoskeleton and a target of RhoA and PKC signaling. However, the role for intercellular cohesion is unknown. We found that adducin silencing induced disruption of the actin cytoskeleton, reduced intercellular adhesion of human keratinocytes, and decreased the levels of the desmosomal adhesion molecule desmoglein (Dsg)3 by reducing its membrane incorporation. Because loss of cell cohesion and Dsg3 depletion is observed in the autoantibody-mediated blistering skin disease pemphigus vulgaris (PV), we applied antibody fractions of PV patients. A rapid phosphorylation of adducin at serine 726 was detected in response to these autoantibodies. To mechanistically link autoantibody binding and adducin phosphorylation, we evaluated the role of several disease-relevant signaling molecules. Adducin phosphorylation at serine 726 was dependent on Ca2+ influx and PKC but occurred independent of p38 MAPK and PKA. Adducin phosphorylation is protective, because phosphorylation-deficient mutants resulted in loss of cell cohesion and Dsg3 fragmentation. Thus, PKC elicits both positive and negative effects on cell adhesion, since its contribution to cell dissociation in pemphigus is well established. We additionally evaluated the effect of RhoA on adducin phosphorylation because RhoA activation was shown to block pemphigus autoantibody-induced cell dissociation. Our data demonstrate that the protective effect of RhoA activation was dependent on the presence of adducin and its phosphorylation at serine 726. These experiments provide novel mechanisms for regulation of desmosomal adhesion by RhoA- and PKC-mediated adducin phosphorylation in keratinocytes.