Mammary epithelial tubes elongate through MAPK-dependent coordination of cell migration
Mammary epithelial tubes elongate through MAPK-dependent coordination of cell migration
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DOI：
10.1242/dev.127944
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发表时间：
2016-03-15
期刊：
影响因子：
4.6
通讯作者：
Ewald, Andrew J.
中科院分区：
文献类型：
--
作者：
Huebner, Robert J.;Neumann, Neil M.;Ewald, Andrew J.
乳腺分支的形态发生受受体酪氨酸激酶(RTK)的调节。我们试图确定这些RTK信号如何改变小鼠的增殖和迁移，以完成小鼠的管状延长。这两种行为都会发生，但很难确定它们对体内伸长的相对贡献，因为乳腺脂肪细胞散射光线，限制了光学成像的深度。因此，我们利用3D培养在可实验的环境中研究伸长。我们首先使用抗体来定位RTK信号，并发现磷酸化的ERK1/2(PERK)在延长的导管前部附近的细胞中空间上富含，而磷酸化的AKT无处不在。接下来，我们观察到细胞从细长导管的后部到前部的迁移速度的梯度，前部的特征是高活性和最快的细胞。此外，伸长管道内的细胞既有突起，也有向管子伸长方向迁移的方向。相比之下，类器官体内的细胞是各向同性的突起。接下来，我们测试了扩散和迁移的要求。早期抑制增殖阻止了迁移细胞的产生，而晚期抑制增殖并没有阻止导管的持续延长。相比之下，对MEK或rac1信号的药理抑制可以显著地阻止细胞迁移和导管的延长。最后，有条件地诱导MEK活性足以诱导细胞集体迁移和导管延长。我们的数据提示了一种导管延长的模型，在该模型中，依赖RTK的增殖创造了高活性的活动细胞，其集体迁移强烈地需要MEK和rac1信号。
Mammary branching morphogenesis is regulated by receptor tyrosine kinases (RTKs). We sought to determine how these RTK signals alter proliferation and migration to accomplish tube elongation in mouse. Both behaviors occur but it has been difficult to determine their relative contribution to elongation in vivo, as mammary adipocytes scatter light and limit the depth of optical imaging. Accordingly, we utilized 3D culture to study elongation in an experimentally accessible setting. We first used antibodies to localize RTK signals and discovered that phosphorylated ERK1/2 (pERK) was spatially enriched in cells near the front of elongating ducts, whereas phosphorylated AKT was ubiquitous. We next observed a gradient of cell migration speeds from rear to front of elongating ducts, with the front characterized by both high pERK and the fastest cells. Furthermore, cells within elongating ducts oriented both their protrusions and their migration in the direction of tube elongation. By contrast, cells within the organoid body were isotropically protrusive. We next tested the requirement for proliferation and migration. Early inhibition of proliferation blocked the creation of migratory cells, whereas late inhibition of proliferation did not block continued duct elongation. By contrast, pharmacological inhibition of either MEK or Rac1 signaling acutely blocked both cell migration and duct elongation. Finally, conditional induction of MEK activity was sufficient to induce collective cell migration and ductal elongation. Our data suggest a model for ductal elongation in which RTK-dependent proliferation creates motile cells with high pERK, the collective migration of which acutely requires both MEK and Rac1 signaling.