Mutations in USP9X Are Associated with X-Linked Intellectual Disability and Disrupt Neuronal Cell Migration and Growth
Mutations in USP9X Are Associated with X-Linked Intellectual Disability and Disrupt Neuronal Cell Migration and Growth
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DOI：
10.1016/j.ajhg.2014.02.004
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发表时间：
2014-03-06
影响因子：
9.8
通讯作者：
Jolly, Lachlan A.
中科院分区：
文献类型：
--
作者：
Homan, Claire C.;Kumar, Raman;Jolly, Lachlan A.
随着最近报道的大量疾病相关DNA变体，提供其功能表征的挑战越来越大。此前，作为208个非综合征性X连锁智力残疾无关家族X染色体大规模系统性重测序的一部分，我们在USP 9 X中发现了三种独特的变异（两种错义和一种蛋白质截短）。为了评估这些变体的功能意义，我们利用了我们产生的Usp 9 x敲除小鼠。Usp 9 x的缺失导致轴突生长和神经元细胞迁移两者的减少。尽管野生型人USP 9 X的过表达挽救了这些缺陷，但所有三种USP 9 X变体都未能挽救轴突生长，导致轴突生长锥中USP 9 X蛋白定位减少，并且（在2/3变体中）未能挽救神经元细胞迁移。有趣的是，在其中一个家族中，先证者随后被鉴定为具有包含ARID 1B（一种已知的ID基因）的微缺失。鉴于我们的研究结果，这是合理的，这两个基因的功能丧失有助于个人的表型。这一案例突出了对全基因组调查的遗传发现的解释的复杂性。我们还对野生型和Usp 9 x敲除胚胎的神经元进行了蛋白质组学分析，并将细胞骨架的破坏确定为Usp 9 x丢失的主要潜在后果。详细的临床评估与USP 9 X变体的所有三个家庭确定肌张力减退和行为和形态缺陷的共同特点，除了ID。我们的数据一起支持参与所有三个USP 9 X变体在ID在这些家庭，并提供可能的细胞和分子机制。
With a wealth of disease-associated DNA variants being recently reported, the challenges of providing their functional characterization are mounting. Previously, as part of a large systematic resequencing of the X chromosome in 208 unrelated families with nonsyndromic X-linked intellectual disability, we identified three unique variants (two missense and one protein truncating) in USP9X. To assess the functional significance of these variants, we took advantage of the Usp9x knockout mouse we generated. Loss of Usp9x causes reduction in both axonal growth and neuronal cell migration. Although overexpression of wild-type human USP9X rescued these defects, all three USP9X variants failed to rescue axonal growth, caused reduced USP9X protein localization in axonal growth cones, and (in 2/3 variants) failed to rescue neuronal cell migration. Interestingly, in one of these families, the proband was subsequently identified to have a microdeletion encompassing ARID1B, a known ID gene. Given our findings it is plausible that loss of function of both genes contributes to the individual's phenotype. This case highlights the complexity of the interpretations of genetic findings from genome-wide investigations. We also performed proteomics analysis of neurons from both the wild-type and Usp9x knockout embryos and identified disruption of the cytoskeleton as the main underlying consequence of the loss of Usp9x. Detailed clinical assessment of all three families with USP9X variants identified hypotonia and behavioral and morphological defects as common features in addition to ID. Together our data support involvement of all three USP9X variants in ID in these families and provide likely cellular and molecular mechanisms involved.