Wang C, Asai D J, Robinson K R
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA.
J Neurobiol. 1995 Jun;27(2):216-26. doi: 10.1002/neu.480270208.
Dynein and kinesin have been implicated as the molecular motors that are responsible for the fast transport of axonal membranous organelles and vesicles. Experiments performed in vitro with partially reconstituted preparations have led to the hypothesis that kinesin moves organelles in the anterograde direction and dynein moves them in the retrograde direction. However, the molecular basis of transport directionality remains unclear. In the experiments described here, carboxylated fluorescent beads were injected into living Mauthner axons of lamprey and the beads were observed to move in both the anterograde and retrograde directions. The bead movement in both directions required intact microtubules, occurred at velocities approaching organelle fast transport in vivo, and was inhibited by vanadate at concentrations that inhibit organelle fast transport. When living axons were injected with micromolar concentrations of vanadate and irradiated at 365 nm prior to bead injections, a treatment that results in the V1 photolysis of dynein, the retrograde movement of the beads was specifically abolished. Neither the ultraviolet irradiation alone nor the vanadate alone produced the retrograde-specific inhibition. These results support the hypothesis that dynein is required for retrograde, but not anterograde, transport in vivo.
动力蛋白和驱动蛋白被认为是负责轴突膜性细胞器和囊泡快速运输的分子马达。在体外使用部分重组制剂进行的实验提出了一种假说，即驱动蛋白使细胞器沿顺行方向移动，而动力蛋白使它们沿逆行方向移动。然而，运输方向性的分子基础仍不清楚。在本文所述的实验中，将羧化荧光珠注入七鳃鳗的活迈纳轴突中，观察到珠子沿顺行和逆行方向移动。两个方向的珠子移动都需要完整的微管，其速度接近体内细胞器的快速运输速度，并且在抑制细胞器快速运输的浓度下被钒酸盐抑制。当向活轴突中注入微摩尔浓度的钒酸盐并在注入珠子之前用365nm波长的光照射时（这种处理会导致动力蛋白的V1光解），珠子的逆行运动被特异性消除。单独的紫外线照射或单独的钒酸盐都不会产生逆行特异性抑制。这些结果支持了这样的假说，即在体内逆行运输需要动力蛋白，而顺行运输则不需要。
