Arthritis and Tissue Degeneration Program, Hospital for Special Surgery, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 2013 Jul 9;110(28):11433-8. doi: 10.1073/pnas.1302553110. Epub 2013 Jun 25.
Protein ectodomain shedding by ADAM17 (a disintegrin and metalloprotease 17), a principal regulator of EGF-receptor signaling and TNFα release, is rapidly and posttranslationally activated by a variety of signaling pathways, and yet little is known about the underlying mechanism. Here, we report that inactive rhomboid protein 2 (iRhom2), recently identified as essential for the maturation of ADAM17 in hematopoietic cells, is crucial for the rapid activation of the shedding of some, but not all substrates of ADAM17. Mature ADAM17 is present in mouse embryonic fibroblasts (mEFs) lacking iRhom2, and yet ADAM17 is unable to support stimulated shedding of several of its substrates, including heparin-binding EGF and Kit ligand 2 in this context. Stimulated shedding of other ADAM17 substrates, such as TGFα, is not affected in iRhom2(-/-) mEFs but can be strongly reduced by treating iRhom2(-/-) mEFs with siRNA against iRhom1. Activation of heparin-binding EGF or Kit ligand 2 shedding by ADAM17 in iRhom2(-/-) mEFs can be rescued by wild-type iRhom2 but not by iRhom2 lacking its N-terminal cytoplasmic domain. The requirement for the cytoplasmic domain of iRhom2 for stimulated shedding by ADAM17 may help explain why the cytoplasmic domain of ADAM17 is not required for stimulated shedding. The functional relevance of iRhom2 in regulating shedding of EGF receptor (EGFR) ligands is established by a lack of lysophasphatidic acid/ADAM17/EGFR-dependent crosstalk with ERK1/2 in iRhom2(-/-) mEFs, and a significant reduction of FGF7/ADAM17/EGFR-stimulated migration of iRhom2(-/-) keratinocytes. Taken together, these findings uncover functions for iRhom2 in the regulation of EGFR signaling and in controlling the activation and substrate selectivity of ADAM17-dependent shedding events.
ADAM17（一种解整合素和金属蛋白酶 17）通过各种信号通路快速进行翻译后激活蛋白细胞外结构域脱落，从而成为 EGFR 信号和 TNFα 释放的主要调节因子，但对于其潜在机制知之甚少。在这里，我们报告最近在造血细胞中被鉴定为 ADAM17 成熟所必需的无活性的类糜蛋白酶蛋白 2（iRhom2）对于 ADAM17 一些但不是所有底物快速脱落的激活至关重要。在缺乏 iRhom2 的小鼠胚胎成纤维细胞（mEFs）中存在成熟的 ADAM17，但在这种情况下，ADAM17 无法支持其几种底物（包括肝素结合的表皮生长因子和 Kit 配体 2）的刺激脱落。在 iRhom2(-/-)mEFs 中，其他 ADAM17 底物（如 TGFα）的刺激脱落不受影响，但用针对 iRhom1 的 siRNA 处理 iRhom2(-/-)mEFs 可强烈降低其脱落。在 iRhom2(-/-)mEFs 中，ADAM17 激活肝素结合的表皮生长因子或 Kit 配体 2 脱落可以通过野生型 iRhom2 挽救，但不能通过缺乏其 N 端细胞质结构域的 iRhom2 挽救。iRhom2 的细胞质结构域对于 ADAM17 刺激脱落的需求可能有助于解释为什么 ADAM17 的细胞质结构域对于刺激脱落不是必需的。缺乏 iRhom2 会导致 iRhom2(-/-)mEFs 中 lysophasphatidic acid/ADAM17/EGFR 与 ERK1/2 之间缺乏赖氨酸/ADAM17/EGFR 依赖性相互作用，以及 iRhom2(-/-)角化细胞中 FGF7/ADAM17/EGFR 刺激迁移的显著减少，从而确立了 iRhom2 在调节表皮生长因子受体（EGFR）配体脱落中的功能相关性。综上所述，这些发现揭示了 iRhom2 在调节 EGFR 信号以及控制 ADAM17 依赖性脱落事件的激活和底物选择性中的作用。
