Schulz Yvonne, Wehner Peter, Opitz Lennart, Salinas-Riester Gabriela, Bongers Ernie M H F, van Ravenswaaij-Arts Conny M A, Wincent Josephine, Schoumans Jacqueline, Kohlhase Jürgen, Borchers Annette, Pauli Silke
Institute of Human Genetics, University Medical Center Göttingen, Heinrich-Düker-Weg 12, 37073, Göttingen, Germany.
Hum Genet. 2014 Aug;133(8):997-1009. doi: 10.1007/s00439-014-1444-2. Epub 2014 Apr 13.
Heterozygous loss of function mutations in CHD7 (chromodomain helicase DNA-binding protein 7) lead to CHARGE syndrome, a complex developmental disorder affecting craniofacial structures, cranial nerves and several organ systems. Recently, it was demonstrated that CHD7 is essential for the formation of multipotent migratory neural crest cells, which migrate from the neural tube to many regions of the embryo, where they differentiate into various tissues including craniofacial and heart structures. So far, only few CHD7 target genes involved in neural crest cell development have been identified and the role of CHD7 in neural crest cell guidance and the regulation of mesenchymal-epithelial transition are unknown. Therefore, we undertook a genome-wide microarray expression analysis on wild-type and CHD7 deficient (Chd7 (Whi/+) and Chd7 (Whi/Whi)) mouse embryos at day 9.5, a time point of neural crest cell migration. We identified 98 differentially expressed genes between wild-type and Chd7 (Whi/Whi) embryos. Interestingly, many misregulated genes are involved in neural crest cell and axon guidance such as semaphorins and ephrin receptors. By performing knockdown experiments for Chd7 in Xenopus laevis embryos, we found abnormalities in the expression pattern of Sema3a, a protein involved in the pathogenesis of Kallmann syndrome, in vivo. In addition, we detected non-synonymous SEMA3A variations in 3 out of 45 CHD7-negative CHARGE patients. In summary, we discovered for the first time that Chd7 regulates genes involved in neural crest cell guidance, demonstrating a new aspect in the pathogenesis of CHARGE syndrome. Furthermore, we showed for Sema3a a conserved regulatory mechanism across different species, highlighting its significance during development. Although we postulated that the non-synonymous SEMA3A variants which we found in CHD7-negative CHARGE patients alone are not sufficient to produce the phenotype, we suggest an important modifier role for SEMA3A in the pathogenesis of this multiple malformation syndrome.
CHD7（染色质结构域解旋酶DNA结合蛋白7）的杂合功能丧失突变会导致CHARGE综合征，这是一种影响颅面结构、颅神经和多个器官系统的复杂发育障碍。最近有研究表明，CHD7对于多能迁移神经嵴细胞的形成至关重要，这些细胞从神经管迁移到胚胎的许多区域，并在那里分化为包括颅面和心脏结构在内的各种组织。到目前为止，仅鉴定出少数几个参与神经嵴细胞发育的CHD7靶基因，而CHD7在神经嵴细胞导向和间充质-上皮转化调控中的作用尚不清楚。因此，我们在神经嵴细胞迁移的时间点即第9.5天，对野生型和CHD7缺陷型（Chd7(Whi/+)和Chd7(Whi/Whi)）小鼠胚胎进行了全基因组微阵列表达分析。我们在野生型和Chd7(Whi/Whi)胚胎之间鉴定出98个差异表达基因。有趣的是，许多失调基因参与神经嵴细胞和轴突导向，如信号素和 Ephrin 受体。通过在非洲爪蟾胚胎中对Chd7进行敲低实验，我们在体内发现了参与卡尔曼综合征发病机制的蛋白质Sema3a表达模式异常。此外，我们在45例CHD7阴性的CHARGE患者中有3例检测到非同义SEMA3A变异。总之，我们首次发现Chd7调节参与神经嵴细胞导向的基因，这揭示了CHARGE综合征发病机制的一个新方面。此外，我们还发现Sema3a在不同物种间存在保守的调控机制，凸显了其在发育过程中的重要性。尽管我们推测仅在CHD7阴性的CHARGE患者中发现的非同义SEMA3A变异不足以产生该表型，但我们认为SEMA3A在这种多畸形综合征的发病机制中具有重要的修饰作用。
