Sung Hsin-Ho, Telley Ivo A, Papadaki Piyi, Ephrussi Anne, Surrey Thomas, Rørth Pernille
Temasek Life Sciences Laboratory, 1 Research Link, The National University of Singapore, Singapore.
Dev Cell. 2008 Dec;15(6):866-76. doi: 10.1016/j.devcel.2008.10.006.
Ensconsin is a conserved microtubule-associated protein (MAP) that interacts dynamically with microtubules, but its cellular function has remained elusive. We show that Drosophila ensconsin is required for all known kinesin-1-dependent processes in the polarized oocyte without detectable effects on microtubules. ensconsin is also required in neurons. Using a single molecule assay for kinesin-1 motility in Drosophila ovary extract, we show that recruitment to microtubules and subsequent motility is severely impaired without ensconsin. Ensconsin protein is enriched at the oocyte anterior and apically in polarized epithelial cells, although required for localization of posterior determinants. Par-1 is required for ensconsin localization and directly phosphorylates it at conserved sites. Our results reveal an unexpected function of a MAP, promoting productive recruitment of a specific motor to microtubules, and an additional level of kinesin regulation. Furthermore, spatial control of motor recruitment can provide additional regulatory control in Par-1 and microtubule-dependent cell polarity.
Ensconsin是一种保守的微管相关蛋白（MAP），它与微管动态相互作用，但其细胞功能仍不清楚。我们发现，果蝇的Ensconsin是极化卵母细胞中所有已知的驱动蛋白-1依赖性过程所必需的，而对微管没有可检测到的影响。在神经元中也需要Ensconsin。使用果蝇卵巢提取物中驱动蛋白-1运动的单分子检测方法，我们发现没有Ensconsin时，微管募集和随后的运动能力会严重受损。Ensconsin蛋白在极化上皮细胞的卵母细胞前部和顶端富集，尽管它是后部决定因子定位所必需的。Par-1是Ensconsin定位所必需的，并在保守位点直接使其磷酸化。我们的结果揭示了一种微管相关蛋白的意外功能，即促进特定马达蛋白有效募集到微管上，以及驱动蛋白调节的一个额外水平。此外，马达蛋白募集的空间控制可以在Par-1和微管依赖性细胞极性中提供额外的调节控制。
