Ferhat L, Cook C, Chauviere M, Harper M, Kress M, Lyons G E, Baas P W
Department of Anatomy, The University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
J Neurosci. 1998 Oct 1;18(19):7822-35. doi: 10.1523/JNEUROSCI.18-19-07822.1998.
It is well established that the microtubules of the mitotic spindle are organized by a variety of motor proteins, and it appears that the same motors or closely related variants organize microtubules in the postmitotic neuron. Specifically, cytoplasmic dynein and the kinesin-related motor known as CHO1/MKLP1 are used within the mitotic spindle, and recent studies suggest that they are also essential for the establishment of the axonal and dendritic microtubule arrays of the neuron. Other motors are required to tightly regulate microtubule behaviors in the mitotic spindle, and it is attractive to speculate that these motors might also help to regulate microtubule behaviors in the neuron. Here we show that a homolog of the mitotic kinesin-related motor known as Eg5 continues to be expressed in rodent neurons well after their terminal mitotic division. In neurons, Eg5 is directly associated with the microtubule array and is enriched within the distal regions of developing processes. This distal enrichment is transient, and typically lost after a process has been clearly defined as an axon or a dendrite. Strong expression can resume later in development, and if so, the protein concentrates within newly forming sprouts at the distal tips of dendrites. We suggest that Eg5 generates forces that help to regulate microtubule behaviors within the distal tips of developing axons and dendrites.
有充分证据表明，有丝分裂纺锤体的微管是由多种驱动蛋白组织起来的，而且看起来同样的驱动蛋白或密切相关的变体在有丝分裂后的神经元中组织微管。具体而言，胞质动力蛋白和名为CHO1/MKLP1的驱动蛋白相关分子马达在有丝分裂纺锤体中发挥作用，最近的研究表明，它们对于神经元轴突和树突微管阵列的形成也至关重要。其他驱动蛋白对于紧密调控有丝分裂纺锤体中的微管行为是必需的，推测这些驱动蛋白可能也有助于调控神经元中的微管行为很有吸引力。在此我们表明，名为Eg5的有丝分裂驱动蛋白相关分子马达的一个同源物在啮齿动物神经元终末有丝分裂后很长时间仍持续表达。在神经元中，Eg5直接与微管阵列相关联，并在发育中突起的远端区域富集。这种远端富集是短暂的，通常在一个突起被明确界定为轴突或树突后消失。在发育后期，强表达可能会恢复，如果是这样，该蛋白会集中在树突远端新形成的芽中。我们认为，Eg5产生有助于调控发育中轴突和树突远端微管行为的力。
