McMahon Riley, Sibbritt Tennille, Aryamanesh Nadar, Masamsetti V Pragathi, Tam Patrick P L
Embryology Research Unit, Children's Medical Research Institute, Sydney, NSW, Australia.
School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Darlington, NSW, Australia.
Front Cell Dev Biol. 2022 Feb 1;9:777652. doi: 10.3389/fcell.2021.777652. eCollection 2021.
The specification of anterior head tissue in the late gastrulation mouse embryo relies on signaling cues from the visceral endoderm and anterior mesendoderm (AME). Genetic loss-of-function studies have pinpointed a critical requirement of LIM homeobox 1 (LHX1) transcription factor in these tissues for the formation of the embryonic head. Transcriptome analysis of embryos with gain-of-function LHX1 activity identified the forkhead box gene, as one downstream target of LHX1 in late-gastrulation E7.75 embryos. Our analysis of single-cell RNA-seq data show is co-expressed with and in the anterior midline tissue of E7.75 mouse embryos, and in the anterior neuroectoderm (ANE) at E8.25 alongside head organizer genes and . To study the role of during early development we used CRISPR-Cas9 gene editing in mouse embryonic stem cells (mESCs) to generate bi-allelic frameshift mutations in the coding sequence of . In an model of the anterior neural tissues derived from -loss of function (LOF) mESCs and extraembryonic endoderm cells, expression of head organizer genes as well as and was reduced, pointing to a need for FOXD4 in regulating early neuroectoderm development. Mid-gestation mouse chimeras harbouring -LOF mESCs displayed craniofacial malformations and neural tube closure defects. Furthermore, our data showed a loss of FOXD4 impacts the expression of cranial neural crest markers and . Our findings have demonstrated that FOXD4 is essential in the AME and later in the ANE for rostral neural tube closure and neural crest specification during head development.
原肠胚晚期小鼠胚胎中头部前部组织的特化依赖于来自脏内胚层和前部中内胚层（AME）的信号线索。基因功能丧失研究已经明确了LIM同源框1（LHX1）转录因子在这些组织中对胚胎头部形成的关键需求。对具有LHX1功能获得性活性的胚胎进行转录组分析，确定叉头框基因是原肠胚晚期E7.75胚胎中LHX1的一个下游靶点。我们对单细胞RNA测序数据的分析表明，在E7.75小鼠胚胎的前部中线组织中与 以及在E8.25时在前部神经外胚层（ANE）中与头部组织者基因 和 共同表达。为了研究 在早期发育中的作用，我们在小鼠胚胎干细胞（mESC）中使用CRISPR-Cas9基因编辑在 的编码序列中产生双等位基因移码突变。在由功能丧失（LOF）的mESC和胚外内胚层细胞衍生的前部神经组织的 模型中，头部组织者基因以及 和 的表达降低，表明在调节早期神经外胚层发育中需要FOXD4。携带LOF mESC的妊娠中期小鼠嵌合体表现出颅面畸形和神经管闭合缺陷。此外，我们的 数据显示FOXD4的缺失影响颅神经嵴标志物 和 的表达。我们的研究结果表明，FOXD4在AME中以及随后在ANE中对于头部发育过程中的 Rostral神经管闭合和神经嵴特化至关重要。
