Bonkowsky Joshua L, Wang Xu, Fujimoto Esther, Lee Ji Eun, Chien Chi-Bin, Dorsky Richard I
Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah 84108, USA.
BMC Dev Biol. 2008 Oct 24;8:103. doi: 10.1186/1471-213X-8-103.
FOXP2 is a forkhead transcription factor critical for normal development of language in humans, but little is known of its broader function and regulation during central nervous system (CNS) development. We report here that lef1, a member of the Lef/Tcf family of transcription factors activated by Wnt signaling, regulates foxP2 during embryogenesis, and we isolate novel foxP2 enhancers which are lef1-dependent.
Loss, knock down, or inhibition of lef1 led to loss of foxP2 expression. We isolated DNA fragments from the foxP2 genomic region that function as enhancers to drive GFP expression in the CNS during development, including in the telencephalon, diencephalon, eye, tectum, and hindbrain. Three of these enhancers, foxP2-enhancerA.1, foxP2-enhancerB, and foxP2-enhancerD, contain putative Lef1 binding sites, and are regulated by lef1. However, two other genomic fragments containing Lef1 sites failed to function in vivo as enhancers. Chromatin immunoprecipitation confirmed that Lef1 binds to sites in foxP2-enhancerA.1 and foxP2-enhancerB.
This work shows that lef1 is necessary for expression of foxP2 in the tectum, mid-hindbrain boundary, and hindbrain during CNS development, and is the first insight into the upstream regulation of foxP2 during development. We also demonstrate that in silico prediction of potential lef1 binding sites poorly predicts their ability to function in vivo as enhancers. The foxP2 enhancers we identified will allow dissection of foxP2's role during CNS development.
FOXP2是一种对人类语言正常发育至关重要的叉头转录因子，但对其在中枢神经系统（CNS）发育过程中的更广泛功能和调控了解甚少。我们在此报告，lef1是由Wnt信号激活的Lef/Tcf转录因子家族成员，在胚胎发生过程中调节foxP2，并且我们分离出了依赖于lef1的新型foxP2增强子。
lef1的缺失、敲低或抑制导致foxP2表达丧失。我们从foxP2基因组区域分离出DNA片段，这些片段在发育过程中作为增强子驱动CNS中GFP的表达，包括在端脑、间脑、眼睛、顶盖和后脑。这些增强子中的三个，foxP2增强子A.1、foxP2增强子B和foxP2增强子D，包含假定的Lef1结合位点，并受lef1调控。然而，另外两个含有Lef1位点的基因组片段在体内不能作为增强子发挥作用。染色质免疫沉淀证实Lef1与foxP2增强子A.1和foxP2增强子B中的位点结合。
这项工作表明lef1对于CNS发育过程中顶盖、中后脑边界和后脑的foxP2表达是必需的，并且是对发育过程中foxP2上游调控的首次深入了解。我们还证明，对潜在Lef1结合位点的计算机预测很难预测它们在体内作为增强子发挥作用的能力。我们鉴定出的foxP2增强子将有助于剖析foxP2在CNS发育过程中的作用。
