Kharfallah Fares, Guyot Marie Claude, El Hassan Abdul Rahman, Allache Redouane, Merello Elisa, De Marco Patrizia, Di Cristo Graziella, Capra Valeria, Kibar Zoha
Department of Neurosciences, CHU Sainte Justine Research Center, University of Montréal, Montréal, QC H3T 1C5, Canada.
U.O. Neurochirurgia, Istituto Giannina Gaslini, Genova 16147, Italy.
Hum Mol Genet. 2017 Jun 15;26(12):2307-2320. doi: 10.1093/hmg/ddx122.
Scribble1 (Scrib1) is a tumor suppressor gene that has long been established as an essential component of apicobasal polarity (ABP). In mouse models, mutations in Scrib1 cause a severe form of neural tube defects (NTDs) as a result of a defective planar cell polarity (PCP) signaling. In this study, we dissected the role of Scrib1 in the pathogenesis of NTDs in its mouse mutant Circletail (Crc), in cell lines and in a human NTD cohort. While there were no obvious defects in ABP in the Scrib1Crc/Crc neuroepihelial cells, we identified an abnormal localization of the apical protein Par-3 and of the PCP protein Vangl2. These results were concordant with those obtained following a partial knockdown of Scrib1 in MDCK II cells. Par-3 was able to rescue the localization defect of Vangl1 (paralog of Vangl2) caused by partial knockdown of Scrib1 suggesting that Scrib1 exerts its effect on Vangl1 localization indirectly through Par-3. This conclusion is supported by our findings of an apical enrichment of Vangl1 following a partial knockdown of Par-3. Re-sequencing analysis of SCRIB1 in 473 NTD patients led to the identification of 5 rare heterozygous missense mutations that were predicted to be pathogenic. Two of these mutations, p.Gly263Ser and p.Gln808His, and 2 mouse NTD mutations, p.Ile285Lys and p.Glu814Gly, affected Scrib1 membrane localization and its modulating role of Par-3 and Vangl1 localization. Our study demonstrates an important role of Scrib1 in the pathogenesis of NTDs through its mediating effect of Par-3 and Vangl1/2 localization and most likely independently of ABP.
scribble1（Scrib1）是一种肿瘤抑制基因，长期以来一直被认为是顶基极性（ABP）的重要组成部分。在小鼠模型中，Scrib1的突变会导致严重的神经管缺陷（NTDs），这是平面细胞极性（PCP）信号缺陷的结果。在本研究中，我们剖析了Scrib1在其小鼠突变体Circletail（Crc）、细胞系和人类NTD队列中NTD发病机制中的作用。虽然Scrib1Crc/Crc神经上皮细胞的ABP没有明显缺陷，但我们发现顶端蛋白Par-3和PCP蛋白Vangl2的定位异常。这些结果与在MDCK II细胞中部分敲低Scrib1后获得的结果一致。Par-3能够挽救由Scrib1部分敲低引起的Vangl1（Vangl2的旁系同源物）的定位缺陷，这表明Scrib1通过Par-3间接对Vangl1定位发挥作用。我们在部分敲低Par-3后发现Vangl1在顶端富集的结果支持了这一结论。对473名NTD患者的SCRIB1进行重测序分析，发现了5个预测为致病性的罕见杂合错义突变。其中两个突变，p.Gly263Ser和p.Gln808His，以及两个小鼠NTD突变，p.Ile285Lys和p.Glu814Gly，影响了Scrib1的膜定位及其对Par-3和Vangl1定位的调节作用。我们的研究表明，Scrib1通过其对Par-3和Vangl1/2定位的介导作用，在NTD发病机制中发挥重要作用，并且很可能独立于ABP。
