An Essential Postdevelopmental Role for Lis1 in Mice.
An Essential Postdevelopmental Role for Lis1 in Mice.
复制标题
DOI：
10.1523/eneuro.0350-17.2018
复制
发表时间：
2018-01
期刊：
影响因子：
3.4
通讯作者：
Smith DS
中科院分区：
文献类型：
--
作者：
Hines TJ;Gao X;Sahu S;Lange MM;Turner JR;Twiss JL;Smith DS
Lis1基因突变导致无脑畸形(Lis)，这是一种严重的发育性脑畸形。人们对它在成熟神经系统中的作用知之甚少。Lis1调节微管运动的胞浆动力蛋白1(Dynein)，并且由于在成人神经系统中都有表达，所以Lis1可能调节依赖于动力蛋白的过程，如轴突运输。因此，我们使用他莫昔芬诱导的、Cre-ER介导的重组在成年小鼠中敲除了Lis1。当肌动蛋白启动子被用来驱动Cre-ER的表达(Act-Cre-ER)时，杂合的Lis1敲除(KO)没有引起活性或行为的明显变化，尽管有证据表明在三苯氧胺暴露三周后Cre报告基因广泛重组。相比之下，纯合子的Lis1KO导致雄性和雌性小鼠迅速出现神经症状。一种三苯氧胺给药方案在一周内导致中脑/后脑、三叉神经节和心肌/骨骼肌显著重组；这些小鼠在这段时间内出现严重症状并被处死。不同的三苯氧胺方案导致了中脑/后脑的延迟重组，但在其他组织中没有，也推迟了症状的出现。这表明，中脑/后脑的Lis1缺失是导致严重表型的原因。为了支持这一点，已知的心肺中心所在的脑干区域显示出KO动物轴突功能障碍的迹象。在培养的KO动物背根神经节神经元中，观察到轴突运输缺陷、神经细丝(NF)改变和曲张。由于在使用心脏特异性Cre-ER启动子时没有观察到任何症状，我们提出了在自主神经元中的重要作用，并暗示在KO表型中存在轴突运输缺陷。
LIS1 mutations cause lissencephaly (LIS), a severe developmental brain malformation. Much less is known about its role in the mature nervous system. LIS1 regulates the microtubule motor cytoplasmic dynein 1 (dynein), and as LIS1 and dynein are both expressed in the adult nervous system, Lis1 could potentially regulate dynein-dependent processes such as axonal transport. We therefore knocked out Lis1 in adult mice using tamoxifen-induced, Cre-ER-mediated recombination. When an actin promoter was used to drive Cre-ER expression (Act-Cre-ER), heterozygous Lis1 knockout (KO) caused no obvious change in viability or behavior, despite evidence of widespread recombination by a Cre reporter three weeks after tamoxifen exposure. In contrast, homozygous Lis1 KO caused the rapid onset of neurological symptoms in both male and female mice. One tamoxifen-dosing regimen caused prominent recombination in the midbrain/hindbrain, PNS, and cardiac/skeletal muscle within a week; these mice developed severe symptoms in that time frame and were killed. A different tamoxifen regimen resulted in delayed recombination in midbrain/hindbrain, but not in other tissues, and also delayed the onset of symptoms. This indicates that Lis1 loss in the midbrain/hindbrain causes the severe phenotype. In support of this, brainstem regions known to house cardiorespiratory centers showed signs of axonal dysfunction in KO animals. Transport defects, neurofilament (NF) alterations, and varicosities were observed in axons in cultured DRG neurons from KO animals. Because no symptoms were observed when a cardiac specific Cre-ER promoter was used, we propose a vital role for Lis1 in autonomic neurons and implicate defective axonal transport in the KO phenotype.