Epithelial-to-mesenchymal transition (EMT) is a dramatic change in cellular physiology during development and metastasis which involves coordination between cell signaling, adhesion, and membrane protrusions. These processes all involve dynamic changes in the plasma membrane, yet how membrane lipid content regulates membrane function during developmental EMT remains incompletely understood. By screening for differential expression of lipid-modifying genes over the course of EMT in avian neural crest, we have identified the ceramide-producing enzyme neutral sphingomyelinase 2 (nSMase2) as a critical regulator of a developmental EMT. nSMase2 expression begins at the onset of EMT, and in vivo knockdown experiments demonstrate that nSMase2 is necessary for neural crest migration. Further, we find that nSMase2 promotes Wnt and BMP signaling, and is required to activate the mesenchymal gene expression program. Mechanistically, we show that nSMase2 is sufficient to induce endocytosis, and that inhibition of endocytosis mimics nSMase2 knockdown. Our results support a model in which nSMase2 is expressed at the onset of neural crest EMT to produce ceramide and induce membrane curvature, thus increasing endocytosis of Wnt and BMP signaling complexes and activating pro-migratory gene expression. These results highlight the critical role of plasma membrane lipid metabolism in regulating transcriptional changes during developmental EMT programs.

中文翻译：

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质膜脂质含量的时间变化诱导内吞作用，调节发育上皮向间质转化

上皮-间质转化（EMT）是发育和转移过程中细胞生理学的巨大变化，涉及细胞信号传导，粘附和膜突出之间的协调。这些过程都涉及质膜的动态变化，但在发育EMT过程中膜脂质含量如何调节膜功能的知识仍不完全清楚。通过筛选在EMT过程中禽神经rest中脂质修饰基因的差异表达，我们已经确定了产生神经酰胺的酶中性鞘磷脂酶2（nSMase2）是发育EMT的关键调节剂。nSMase2表达始于EMT发作，并在体内组合式实验表明，nSMase2是神经c迁移所必需的。此外，我们发现nSMase2促进Wnt和BMP信号传导，并且是激活间充质基因表达程序所必需的。从机制上讲，我们显示nSMase2足以诱导内吞作用，而对内吞作用的抑制作用类似于nSMase2的敲低。我们的结果支持一个模型，其中nSMase2在神经c EMT发作时表达，以产生神经酰胺并诱导膜弯曲，从而增加Wnt和BMP信号复合物的内吞作用并激活促迁移基因表达。这些结果突出了质膜脂质代谢在发育EMT程序中调节转录变化的关键作用。