Pac-man motility of kinetochores unleashed by laser microsurgery.
Pac-man motility of kinetochores unleashed by laser microsurgery.
复制标题
激光显微手术释放动粒的吃豆人运动。
DOI：
10.1091/mbc.e12-04-0314
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发表时间：
2012
影响因子：
3.3
通讯作者：
Oldenbourg,Rudolf
中科院分区：
文献类型：
--
作者：
LaFountainJr,JamesR;Cohan,ChristopherS;Oldenbourg,Rudolf
我们报告的实验直接在活细胞中，揭示了调节动粒功能的张力。起重机蝇（Nephrotoma suturalis）精母细胞的X和Y性染色体表现出非典型的分离机制，其中每个单价体保持K-纤维的两极。在分裂后期，每一个都保持一个领先的纤维（缩短）到一个极点，一个尾随的纤维（延长）到另一个极点。我们利用这种有趣的行为来研究X-Y着丝粒在后期能够支持的运动状态。我们使用激光微束来切断单价体沿着姐妹染色单体凝聚的平面，或者敲除单价体的两个动粒中的一个，以使一个或两个动粒从其姐妹的K纤维的阻力影响中释放出来。被释放的带有染色体臂的动粒向极方向移动的速度比正常的快至少两倍。此外，荧光斑点显微镜显示，分离的动粒转换其功能状态从反向吃豆人吃豆人运动的结果，他们从机械张力释放。我们的结论是，动粒可以表现出吃豆人运动，即使他们的正常行为是由牵引纤维力学。通过阻力损失释放动粒能动性进一步证明了动粒受到张力敏感调节的新兴模型。
We report on experiments directly in living cells that reveal the regulation of kinetochore function by tension. X and Y sex chromosomes in crane fly (Nephrotoma suturalis) spermatocytes exhibit an atypical segregation mechanism in which each univalent maintains K-fibers to both poles. During anaphase, each maintains a leading fiber (which shortens) to one pole and a trailing fiber (which elongates) to the other. We used this intriguing behavior to study the motile states that X-Y kinetochores are able to support during anaphase. We used a laser microbeam to either sever a univalent along the plane of sister chromatid cohesion or knock out one of a univalent's two kinetochores to release one or both from the resistive influence of its sister's K-fiber. Released kinetochores with attached chromosome arms moved poleward at rates at least two times faster than normal. Furthermore, fluorescent speckle microscopy revealed that detached kinetochores converted their functional state from reverse pac-man to pac-man motility as a consequence of their release from mechanical tension. We conclude that kinetochores can exhibit pac-man motility, even though their normal behavior is dominated by traction fiber mechanics. Unleashing of kinetochore motility through loss of resistive force is further evidence for the emerging model that kinetochores are subject to tension-sensitive regulation.