ＫＩＦ２６Ａの分子遺伝学的研究

已显示驱动蛋白超家族蛋白（KIF）以微管和ATP依赖性方式转运各种膜细胞器和蛋白复合物（Hirokawa和Noda，2008; Schliwa，2002）。在前期的研究中，我们鉴定了驱动蛋白超家族蛋白26 A（KIF 26 A），KIF 26 A是一个非常不典型的成员，因为它缺乏ATP酶活性。我们发现KIF 26 A通过直接结合和抑制Grb 2（GDNF/Akt/ERK信号传导的必要组分）来抑制GDNF-Ret信号传导（Zhou等人，Cell 139，802-813，2009）。在这项研究中，我们偶尔注意到Kif 26 a-/-小鼠幼崽在处理期间的过敏和延长的疼痛反应，并深入研究了其细胞和分子机制。我们通过在F11细胞中使用KIF 26 A敲低系统来评估PMCA的抑制性酪氨酸磷酸化水平。结果表明，KD细胞中PMCA酪氨酸磷酸化水平明显高于对照细胞，这可能部分解释了PMCA失活导致Kif 26 a-/-神经元Ca清除障碍的原因。我们研究了SFK/FAK激活水平。Kif 26 a-/-神经元中pFAK的免疫细胞化学染色显示其信号明显强于Kif 26 a +/+神经元。另一方面，针对pSFK（其是FAK更上游的激酶）的免疫细胞化学在很大程度上未改变。这些数据表明，SFK到FAK信号转导的可能性是异常增强KIF 26 A缺陷。

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.