Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Epithelial Biology Center , Vanderbilt University Medical Center, Nashville, TN 37232, USA.
J Cell Sci. 2021 Sep 15;134(18). doi: 10.1242/jcs.255927. Epub 2021 Sep 17.
In polarized MDCK cells, disruption of the tyrosine-based YXXΦ basolateral trafficking motif (Y156A) in the epidermal growth factor receptor (EGFR) ligand epiregulin (EREG), results in its apical mistrafficking and transformation in vivo. However, the mechanisms underlying these dramatic effects are unknown. Using a doxycycline-inducible system in 3D Matrigel cultures, we now show that induction of Y156A EREG in fully formed MDCK cysts results in direct and complete delivery of mutant EREG to the apical cell surface. Within 3 days of induction, ectopic lumens were detected in mutant, but not wild-type, EREG-expressing cysts. Of note, these structures resembled histological features found in subcutaneous xenografts of mutant EREG-expressing MDCK cells. These ectopic lumens formed de novo rather than budding from the central lumen and depended on metalloprotease-mediated cleavage of EREG and subsequent EGFR activity. Moreover, the most frequent EREG mutation in human cancer (R147stop) resulted in its apical mistrafficking in engineered MDCK cells. Thus, induction of EREG apical mistrafficking is sufficient to disrupt selective aspects of polarity of a preformed polarized epithelium. This article has an associated First Person interview with the first author of the paper.
在极化的 MDCK 细胞中，表皮生长因子受体 (EGFR) 配体表皮调节素 (EREG) 中基于酪氨酸的 YXXΦ 基底外侧运输基序 (Y156A) 的破坏导致其在顶部分泌错误和体内转化。然而，这些显著影响的机制尚不清楚。使用 3D Matrigel 培养物中的强力霉素诱导系统，我们现在表明，在完全形成的 MDCK 小囊中诱导 Y156A EREG 会导致突变型 EREG 直接和完全递送到顶细胞表面。在诱导后 3 天内，在突变型而非野生型 EREG 表达小囊中检测到异位管腔。值得注意的是，这些结构类似于在突变型 EREG 表达的 MDCK 细胞的皮下异种移植物中发现的组织学特征。这些异位管腔是从头形成的，而不是从中央管腔出芽形成的，并且依赖于 EREG 的金属蛋白酶介导的切割和随后的 EGFR 活性。此外，人类癌症中最常见的 EREG 突变 (R147stop) 导致其在工程化 MDCK 细胞中的顶部分泌错误。因此，诱导 EREG 顶部分泌错误足以破坏预先形成的极化上皮选择性极性的某些方面。本文附有该论文第一作者的第一人称采访。
