ＫＩＦ２６Ａの分子遺伝学的研究

运动蛋白超家族蛋白(KIFs)以微管和ATP依赖的方式转运各种膜细胞器和蛋白质复合体(Hirokawa和Noda，2008；Schliwa，2002)。在以前的研究中，我们发现了Kinesin超家族蛋白26A(KIF26A)，KIF26A是一个非常典型的成员，因为它缺乏ATPase活性。我们发现KIF26A通过直接结合和抑制GDNF/Akt/ERK信号的重要成分Grb2来抑制GDNF-Ret信号(周等，Cell 139,802-813,2009)。在本研究中，我们偶尔注意到Kif26a/-小鼠在处理过程中超敏和持续的疼痛反应，并深入研究其细胞和分子机制。为了了解这种损害在钙清除中的分子基础，我们利用KIF26A基因敲除系统在F11细胞中评估了PMCA抑制酪氨酸磷酸化水平的水平。结果显示，KD细胞PMCA酪氨酸磷酸化水平显著高于对照细胞，这可能是PMCA失活导致Kif26a/-神经元钙清除障碍的部分原因。我们研究了SFK/FAK的激活水平。与Kif26a+/+神经元相比，Kif26a-/-神经元中针对pFAK的免疫细胞化学信号明显增强。另一方面，针对PSFK的免疫细胞化学基本上没有改变，PSFK是FAK上游的一种激酶。这些数据提示KIF26A缺乏可能是SFK到FAK信号转导异常增强的可能性。

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.