INSERM Unité 910, Marseille, France.
Hum Mol Genet. 2010 Dec 15;19(24):4848-60. doi: 10.1093/hmg/ddq415. Epub 2010 Sep 21.
It is a challenge to identify the molecular networks contributing to the neural basis of human speech. Mutations in transcription factor FOXP2 cause difficulties mastering fluent speech (developmental verbal dyspraxia, DVD), whereas mutations of sushi-repeat protein SRPX2 lead to epilepsy of the rolandic (sylvian) speech areas, with DVD or with bilateral perisylvian polymicrogyria. Pathophysiological mechanisms driven by SRPX2 involve modified interaction with the plasminogen activator receptor (uPAR). Independent chromatin-immunoprecipitation microarray screening has identified the uPAR gene promoter as a potential target site bound by FOXP2. Here, we directly tested for the existence of a transcriptional regulatory network between human FOXP2 and the SRPX2/uPAR complex. In silico searches followed by gel retardation assays identified specific efficient FOXP2-binding sites in each of the promoter regions of SRPX2 and uPAR. In FOXP2-transfected cells, significant decreases were observed in the amounts of both SRPX2 (43.6%) and uPAR (38.6%) native transcripts. Luciferase reporter assays demonstrated that FOXP2 expression yielded a marked inhibition of SRPX2 (80.2%) and uPAR (77.5%) promoter activity. A mutant FOXP2 that causes DVD (p.R553H) failed to bind to SRPX2 and uPAR target sites and showed impaired down-regulation of SRPX2 and uPAR promoter activity. In a patient with polymicrogyria of the left rolandic operculum, a novel FOXP2 mutation (p.M406T) was found in the leucine-zipper (dimerization) domain. p.M406T partially impaired the FOXP2 regulation of SRPX2 promoter activity, whereas that of the uPAR promoter remained unchanged. Together with recently described FOXP2-CNTNAP2 and SRPX2/uPAR links, the FOXP2-SRPX2/uPAR network provides exciting insights into molecular pathways underlying speech-related disorders.
确定导致人类言语神经基础的分子网络是一项挑战。转录因子 FOXP2 的突变导致流利言语的掌握困难（发育性言语运动障碍，DVD），而 sushi 重复蛋白 SRPX2 的突变导致罗兰氏（西尔维安）言语区的癫痫，伴有 DVD 或双侧周围性多小脑回。由 SRPX2 驱动的病理生理机制涉及与纤溶酶原激活物受体（uPAR）的修饰相互作用。独立的染色质免疫沉淀微阵列筛选已经确定 uPAR 基因启动子是 FOXP2 结合的潜在靶位点。在这里，我们直接测试了人类 FOXP2 和 SRPX2/uPAR 复合物之间是否存在转录调节网络。通过凝胶阻滞测定进行的计算机搜索确定了 SRPX2 和 uPAR 启动子区域中每个区域的特定有效的 FOXP2 结合位点。在 FOXP2 转染的细胞中，观察到 SRPX2（43.6%）和 uPAR（38.6%）天然转录物的量明显减少。荧光素酶报告基因测定表明，FOXP2 表达导致 SRPX2（80.2%）和 uPAR（77.5%）启动子活性的显著抑制。导致 DVD 的 FOXP2 突变（p.R553H）不能与 SRPX2 和 uPAR 靶位点结合，并显示出 SRPX2 和 uPAR 启动子活性下调受损。在一名左侧 Rolandic 脑盖部多小脑回的患者中，发现了一个新的 FOXP2 突变（p.M406T），位于亮氨酸拉链（二聚化）结构域。p.M406T 部分损害了 FOXP2 对 SRPX2 启动子活性的调节，而对 uPAR 启动子的调节则保持不变。与最近描述的 FOXP2-CNTNAP2 和 SRPX2/uPAR 联系一起，FOXP2-SRPX2/uPAR 网络为言语相关障碍的分子途径提供了令人兴奋的见解。
