ＫＩＦ２６Ａの分子遺伝学的研究

已证明激酶超家族蛋白（KIFs）以微管和atp依赖的方式运输各种膜细胞器和蛋白质复合物（Hirokawa和Noda, 2008; Schliwa, 2002）。在之前的研究中，我们发现了激酶蛋白超家族蛋白26A (KIF26A)， KIF26A是一个相当不典型的成员，因为它缺乏atp酶活性。我们发现KIF26A通过直接结合和抑制Grb2来抑制GDNF- ret信号传导，Grb2是GDNF/Akt/ERK信号传导的重要组成部分（Zhou et al., Cell 139, 802-813, 2009）。在本研究中，我们偶尔注意到Kif26a-/-小鼠幼鼠在搬运过程中的超敏和长时间的疼痛反应，并深入研究了其细胞和分子机制。为了了解这种Ca清除障碍的分子基础，我们使用KIF26A敲低系统评估了F11细胞中PMCA的抑制性酪氨酸磷酸化水平。因此，KD细胞中PMCA酪氨酸磷酸化水平显著高于对照细胞，这可以部分解释PMCA失活导致Kif26a-/-神经元Ca清除受损。我们研究了SFK/FAK的激活水平。免疫细胞化学显示，Kif26a-/-神经元抗pFAK的信号明显强于Kif26a+/+神经元。另一方面，针对pSFK （FAK上游的激酶）的免疫细胞化学基本上没有改变。这些数据表明，KIF26A缺乏可能会异常增强sfk到fak的信号转导。

The kinesin superfamily proteins (KIFs) have been shown to transport various membranous organelles and protein complexes in a microtubule- and ATP-dependent manner (Hirokawa and Noda, 2008; Schliwa, 2002). In the previous research, we identified Kinesin superfamily protein 26A (KIF26A), KIF26A is a rather atypical member as it lacks ATPase activity. We found that KIF26A suppressed GDNF-Ret signaling by direct binding and inhibition of Grb2, an essential component of GDNF/Akt/ERK signaling (Zhou et al., Cell 139, 802-813, 2009).In this study, we have occasionally noticed the hypersensitive and prolonged pain response of Kif26a-/- mouse pups during handling, and deeply investigated its cellular and molecular mechanisms.In order to understand the molecular basis of this impairment in Ca clearance, we assessed the level of the inhibitory tyrosine phosphorylation level of PMCA by using a KIF26A knockdown system in F11 cells. As a result, the tyrosine phosphorylation level of PMCA in KD cells was significantly higher than that in control cells, which could partly explain the impairment in Ca clearance in Kif26a-/- neurons via PMCA inactivation. We investigated the levels of SFK/FAK activation. Immunocytochemistry against pFAK in Kif26a-/- neurons revealed a significantly stronger signal than that in Kif26a+/+ neurons. In other hand, immunocytochemistry against pSFK, which is a kinase further upstream to FAK, was largely unaltered. These data suggested the possibility that the SFK-to-FAK signal transduction is abnormally enhanced by KIF26A deficiency.