Control of endothelial cell polarity and sprouting angiogenesis by non-centrosomal microtubules.
Control of endothelial cell polarity and sprouting angiogenesis by non-centrosomal microtubules.
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DOI：
10.7554/elife.33864
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发表时间：
2018-03-16
期刊：
影响因子：
7.7
通讯作者：
Akhmanova A
中科院分区：
文献类型：
--
作者：
Martin M;Veloso A;Wu J;Katrukha EA;Akhmanova A
微管控制细胞极化的不同方面。在具有放射状微管系统的细胞中，中心体和细胞核的相对位置在建立不对称性方面起着关键作用。在这里，我们表明中心体的丢失对内皮细胞在2D和3D环境中极化和移动的能力没有影响。相反，由微管负端结合蛋白CAMSAP2稳定的非中心体微管需要在2D基质上定向迁移，并在软3D基质中建立极化细胞形态。在体内斑马鱼血管发育过程中，CAMSAP2对持续内皮细胞的萌发也很重要。在没有CAMSAP2的情况下，中心体耗尽可以部分挽救3D中的细胞极化，这表明在这些条件下，中心体抑制了细胞的极性。我们认为，CAMSAP2保护的非中心体微管是通过在单细胞突起中丰富微管来建立细胞不对称性所必需的。血管网络就像树木一样生长。新芽出现在现有的血管上，在一个被称为血管生成的过程中伸展形成新的分支。负责的细胞是排列在完成的血管内的相同细胞。这些“内皮细胞”通过重新组织自己以面向新芽的方向开始这一过程，改变形状变得不对称，然后开始迁移。在表面之下，一个蛋白质支架网络支撑着每个迁移的细胞。支架包括称为微管的管状纤维，这些纤维向细胞膜延伸，并组织细胞内部。破坏微管会损害血管的形成，但它们的确切作用尚不清楚。一种名为中心体的结构可以在细胞内组织微管。中心体通常被认为像一个指南针，指向细胞移动的方向。微管可以固定在中心体上，这种结构被认为在细胞迁移中发挥着重要作用。然而，许多微管是在没有它的情况下组织起来的；这些微管是由细胞中称为高尔基体的隔室组织的，并由一种名为CAMSAP2的蛋白质稳定下来。Martin等人。现在有报道称，去除细胞的中心体不会影响细胞的迁移，但去除CAMSAP2会影响细胞的迁移。对实验室培养的细胞和活着的动物细胞的形状和运动的分析表明，没有CAMSAP2，细胞不会变得不对称，也不会“极化”，也不会迁移。在一项二维伤口愈合试验中，一张最初从人类脐带血管中生长的细胞被抓伤，然后用显微镜记录细胞在修复损伤时的运动。正常情况下，两边的细胞利用它们的微管沿直线移动，尽管这个过程在没有中心体的细胞中没有受到影响，但在没有CAMSAP2的细胞中是这样。在三维分析中可以看到更惊人的结果。当来自人类脐带的相同血管细胞在胶原凝胶中以球状生长时，它们会形成芽芽，就像它们在体内一样。如果没有CAMSAP2，细胞就不能组织它们的微管，它们不能向一个方向伸长并形成稳定的芽。最后，耗尽CAMSAP2也阻碍了斑马鱼胚胎血管的正常形成。综上所述，这些发现改变了我们对微管如何影响细胞运动的理解，以及中心体对这一过程的重要性。进一步的工作可能会对人类健康产生影响，尤其是在癌症研究方面。肿瘤需要良好的血液供应才能生长，因此了解如何阻止血管形成可能会带来新的治疗方法。微管已经成为癌症治疗的靶点，因此未来的工作可能有助于优化现有药物的使用。
Microtubules control different aspects of cell polarization. In cells with a radial microtubule system, a pivotal role in setting up asymmetry is attributed to the relative positioning of the centrosome and the nucleus. Here, we show that centrosome loss had no effect on the ability of endothelial cells to polarize and move in 2D and 3D environments. In contrast, non-centrosomal microtubules stabilized by the microtubule minus-end-binding protein CAMSAP2 were required for directional migration on 2D substrates and for the establishment of polarized cell morphology in soft 3D matrices. CAMSAP2 was also important for persistent endothelial cell sprouting during in vivo zebrafish vessel development. In the absence of CAMSAP2, cell polarization in 3D could be partly rescued by centrosome depletion, indicating that in these conditions the centrosome inhibited cell polarity. We propose that CAMSAP2-protected non-centrosomal microtubules are needed for establishing cell asymmetry by enabling microtubule enrichment in a single-cell protrusion. Networks of blood vessels grow like trees. Sprouts appear on existing vessels, stretching out to form new branches in a process called angiogenesis. The cells responsible are the same cells that line the finished vessels. These “endothelial cells” start the process by reorganizing themselves to face the direction of the new sprout, changing shape to become asymmetrical, and then they begin to migrate. Beneath the surface, a network of protein scaffolding supports each migrating cell. The scaffolding includes tube-like fibers called microtubules that extend towards the cell membrane and organize the inside of the cell. Destroying microtubules damages blood vessel formation, but their exact role remains unclear. A structure called the centrosome can organize microtubules within cells. The centrosome was generally believed to act like a compass, pointing in the direction that the cell will move. Microtubules can anchor to the centrosome, and this structure is thought to play an important role in cell migration. Yet, many microtubules organize without it; these microtubules instead are organized by a compartment of the cell called the Golgi apparatus and are stabilized by a protein named CAMSAP2. Martin et al. now report that removing the cells’ centrosomes did not affect cell migration, but getting rid of CAMSAP2 did. Analysis of cell shape and movement in cells grown in the laboratory and in living animals revealed that cells cannot become asymmetrical, or “polarize”, and migrate without CAMSAP2. In a two-dimensional wound-healing assay, a sheet of cells originally grown from the vessels of a human umbilical cord was scratched, and a microscope was then used to record the cell’s movement as they repaired the injury. Normally, the cells on either side move in a straight line using their microtubules, and though the process was not affected in cells without centrosomes, it was in those without CAMSAP2. Even more striking results were seen in three-dimensional assays. When the same blood vessel cells from human umbilical cords are grown as spheres inside collagen gels, they form sprouts as they would in the body. Without CAMSAP2, the cells could not organize their microtubules and they were unable to elongate in one direction and form stable sprouts. Lastly, depleting CAMSAP2 also prevented the normal formation of blood vessels in zebrafish embryos. Taken together, these findings change our understanding of how microtubules affect cell movement and how important the centrosome is for this process. Further work could have an impact on human health, not least in cancer research. Tumors need a good blood supply to grow, so understanding how to block blood vessel formation could lead to new treatments. Microtubules are already a target for cancer therapy, so future work could help to optimize the use of existing drugs.