Schaar Bruce T, Kinoshita Kazuhisa, McConnell Susan K
Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA.
Neuron. 2004 Jan 22;41(2):203-13. doi: 10.1016/s0896-6273(03)00843-2.
Doublecortin (Dcx) is a microtubule-associated protein that is mutated in X-linked lissencephaly (X-LIS), a neuronal migration disorder associated with epilepsy and mental retardation. Although Dcx can bind ubiquitously to microtubules in nonneuronal cells, Dcx is highly enriched in the leading processes of migrating neurons and the growth cone region of differentiating neurons. We present evidence that Dcx/microtubule interactions are negatively controlled by Protein Kinase A (PKA) and the MARK/PAR-1 family of protein kinases. In addition to a consensus MARK site, we identified a serine within a novel sequence that is crucial for the PKA- and MARK-dependent regulation of Dcx's microtubule binding activity in vitro. This serine is mutated in two families affected by X-LIS. Immunostaining neurons with an antibody that recognizes phosphorylated substrates of MARK supports the conclusion that Dcx localization and function are regulated at the leading edge of migrating cells by a balance of kinase and phosphatase activity.
双皮质素（Dcx）是一种与微管相关的蛋白质，在X连锁无脑回畸形（X-LIS）中发生突变，X-LIS是一种与癫痫和智力迟钝相关的神经元迁移障碍。尽管Dcx能普遍结合非神经元细胞中的微管，但Dcx在迁移神经元的前沿过程和分化神经元的生长锥区域高度富集。我们提供的证据表明，Dcx/微管相互作用受到蛋白激酶A（PKA）和MARK/PAR-1蛋白激酶家族的负调控。除了一个共有MARK位点外，我们在一个新序列中鉴定出一个丝氨酸，该丝氨酸对于PKA和MARK依赖的Dcx微管结合活性的体外调控至关重要。这个丝氨酸在两个受X-LIS影响的家族中发生了突变。用识别MARK磷酸化底物的抗体对神经元进行免疫染色，支持了这样的结论：激酶和磷酸酶活性的平衡在迁移细胞的前沿调节Dcx的定位和功能。
