Apoptotic mechanism in pemphigus autoimmunoglobulins-induced acantholysis - possible involvement of the EGF receptor
Apoptotic mechanism in pemphigus autoimmunoglobulins-induced acantholysis - possible involvement of the EGF receptor
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DOI：
10.1080/08916930600971836
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发表时间：
2006-11-01
期刊：
影响因子：
3.5
通讯作者：
Milner, Yoram
中科院分区：
文献类型：
--
作者：
Frusic-Zlotkin, Marina;Raichenberg, Dorin;Milner, Yoram
天疱疮是一种自身免疫性皮肤病，其特征是循环自身抗体，导致皮肤和粘膜起泡和糜烂。循环自身抗体与表皮细胞膜结合并引起细胞间脱离（棘层松解），导致表皮组织损伤和细胞死亡。寻常型天疱疮自身抗体 (PV-IgG) 的主要靶标是桥粒钙粘蛋白桥粒糖蛋白 3 (Dsg3)，它是桥粒的组成部分，介导细胞间粘附。关于 PV-IgG 诱导棘层松解的机制存在多种假说，但实际机制尚不清楚。我们之前曾报道过 PV-IgG 介导的表皮组织和细胞损伤中的细胞凋亡诱导作为棘层松解和细胞死亡的可能机制（Wang 等人 2004, Apoptosis, 9: 131-143）。 在这项研究中，我们研究了 EGFR 和细胞内信号转导途径在 PV-IgG 诱导的细胞凋亡中的参与。我们在此表明，PV-IgG 诱导体外培养的角质形成细胞中 EGFR 的激活/自磷酸化。特异性酪氨酸激酶抑制剂 AG1478 消除了 EGFR 自身磷酸化、细胞死亡、FasL 出现和棘层松解，所有这些均由 PV-IgG 平行诱导，证实了 EGFR 参与了该 Fas 凋亡级联反应。 EGFR 激活后，其下游底物、MAP 激酶 ERK 和转录因子 c-Jun 被磷酸化，以及 EGFR 内化。通过分别使用特异性抑制剂 AG1478 和 PD98059 药理灭活 EGFR 和 ERK 激酶活性，阻断 PV-IgG 诱导的 EGFR、ERK 和 c-Jun 磷酸化以及细胞凋亡（通过流式细胞术和 caspase 3 活性测量）。 PV-IgG 对 EGFR 的长时间激活导致该受体急剧内化，可能降低细胞发出生存信号的能力。这表明 EGFR 的激活以及随后的内化对于通过 ERK/c-Jun 途径进行细胞内凋亡信号转导，从而导致棘层松解至关重要。我们的实验数据表明，EGFR 有助于在角质形成细胞培养物中转导细胞凋亡/棘层松解信号，以响应 PV-IgG 治疗。 PV-IgG与细胞表面受体结合引起的棘层松解作用始于并依赖于细胞表面受体（EGFR）对细胞内信号通路（ERK通路）的激活和细胞凋亡诱导（FasR通路），随后导致主要的细胞与细胞分离（棘层松解）和细胞死亡。
Pemphigus is an autoimmune cutaneous disease characterized by circulating autoantibodies that cause blistering and erosions on skin and mucous membranes. Circulating autoantibodies bind to epidermal cell membrane and cause cell-cell detachment (acantholysis), leading to epidermal tissue damage and cell death. The principal target of pemphigus vulgaris autoantibodies (PV-IgG) is desmosomal cadherin desmoglein 3 (Dsg3), a constituent of desmosomes, mediating cell-cell adhesion. Several hypotheses for the mechanisms of acantholysis induction by PV-IgG exist, but the actual mechanism is not clear as yet. We have previously reported on apoptosis induction in PV-IgG-mediated epidermal tissue and cell damage as a possible mechanism of acantholysis and cell death (Wang et al. 2004, Apoptosis, 9: 131-143).In this study we investigated the involvement of the EGFR and intracellular signal transduction pathways in the PV-IgG-induced apoptosis. We show here that PV-IgG induced activation/autophosphorylation of EGFR in cultured keratinocytes in vitro. The specific tyrosine kinase inhibitor AG1478 abrogated EGFR autophosphorylation, cell death, FasL appearance and acantholysis, all induced by PV-IgG, in parallel, confirming the involvement of EGFR in this Fas apoptotic cascade. Activation of EGFR was followed by phosphorylation of its downstream substrates, MAP kinase ERK and transcription factor c-Jun, and internalization of EGFR. Pharmacological inactivation of the EGFR and ERK kinase activities, by use of specific inhibitors AG1478 and PD98059 respectively, blocked PV-IgG-induced phosphorylation of EGFR, ERK and c-Jun and cellular apoptosis, measured by flow cytometry and caspase 3 activity. Prolonged activation of EGFR by PV-IgG led to dramatic internalization of this receptor, possibly reducing the ability of the cell to perform survival signals. This suggests that activation of EGFR, followed by its internalization, is pivotal for intracellular apoptotic signal transduction via ERK/c-Jun pathways, leading to acantholysis.Our experimental data indicate that the EGFR is instrumental in transducing apoptotic/acantholytic signals in keratinocytes cultures in response to PV-IgG treatment. The acantholytic effect caused by PV-IgG binding to cell surface receptors begins with and depends on cell surface receptor (EGFR) activation of intracellular signaling pathways (ERK pathway) and apoptosis induction (FasR pathway), which later lead to major cell-cell separation (acantholysis) and cell death.