Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Invest Ophthalmol Vis Sci. 2013 Jan 7;54(1):132-40. doi: 10.1167/iovs.12-11130.
During mammalian embryonic eyelid closure ADAM17 has been proposed to play a role as a transactivator of epidermal growth factor receptor (EGFR) signaling by shedding membrane bound EGFR ligands. However, ADAM17 also sheds numerous other ligands, thus implicating ADAM17 in additional molecular pathways. The goal of this study was to experimentally establish the role of ADAM17 and determine ADAM17-mediated pathways essential for the embryonic eyelid closure.
Wild-type (WT) and woe mice, carrying a hypomorphic mutation in Adam17, were evaluated using H&E and scanning electron microscopy. Expressions of ADAM17, EGFR, and the phosphorylated form EGFR-P were evaluated using immunohistochemistry. BrdU and TUNEL assays were used to evaluate cell proliferation and apoptosis, respectively. In vitro scratch assays of primary cultures were used to evaluate cell migration. Clinical and histologic analyses established if the hypermorphic Egfr(Dsk5) allele can rescue the woe embryonic eyelid closure.
woe mice exhibited a failure to develop the leading edge of the eyelid and consequently failure of the embryonic eyelid closure. Expression of ADAM17 was identified in the eyelid epithelium in the cells of the leading edge. ADAM17 is essential for epithelial cell migration, but does not play a role in proliferation and apoptosis. EGFR was expressed in both WT and woe eyelid epithelium, but the phosphorylated EGFR-P form was detected only in WT. The Egfr(Dsk5) allele rescued woe eyelid closure defects, but also rescued woe anterior segment defects and the absence of meibomian glands.
We provide in vivo genetic evidence that the role of ADAM17 during embryonic eyelid closure is to transactivate EGFR signaling.
在哺乳动物胚胎眼睑闭合过程中，ADAM17 被认为通过脱落膜结合的表皮生长因子受体（EGFR）配体来充当 EGFR 信号的转激活剂。然而，ADAM17 还脱落许多其他配体，因此 ADAM17 涉及其他分子途径。本研究的目的是通过实验确定 ADAM17 的作用，并确定对胚胎眼睑闭合至关重要的 ADAM17 介导的途径。
使用 H&E 和扫描电子显微镜评估携带 Adam17 功能缺失突变的野生型（WT）和 woe 小鼠。使用免疫组织化学评估 ADAM17、EGFR 和磷酸化形式 EGFR-P 的表达。BrdU 和 TUNEL 测定分别用于评估细胞增殖和细胞凋亡。原代培养的体外划痕试验用于评估细胞迁移。临床和组织学分析确定 hypermorphic Egfr(Dsk5)等位基因是否可以挽救 woe 胚胎眼睑闭合。
woe 小鼠表现出眼睑前缘发育不良，因此胚胎眼睑闭合失败。ADAM17 在眼睑上皮细胞的前缘细胞中表达。ADAM17 对于上皮细胞迁移是必需的，但在增殖和凋亡中不起作用。EGFR 在 WT 和 woe 眼睑上皮中均有表达，但磷酸化 EGFR-P 形式仅在 WT 中检测到。Egfr(Dsk5)等位基因挽救了 woe 眼睑闭合缺陷，但也挽救了 woe 前节缺陷和缺乏睑板腺。
我们提供了体内遗传证据，表明 ADAM17 在胚胎眼睑闭合过程中的作用是转激活 EGFR 信号。
