Popov Ivan K, Kwon Taejoon, Crossman David K, Crowley Michael R, Wallingford John B, Chang Chenbei
Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology, Republic of Korea.
Dev Biol. 2017 Jun 15;426(2):429-441. doi: 10.1016/j.ydbio.2016.05.014. Epub 2016 May 18.
During early vertebrate embryogenesis, cell fate specification is often coupled with cell acquisition of specific adhesive, polar and/or motile behaviors. In Xenopus gastrulae, tissues fated to form different axial structures display distinct motility. The cells in the early organizer move collectively and directionally toward the animal pole and contribute to anterior mesendoderm, whereas the dorsal and the ventral-posterior trunk tissues surrounding the blastopore of mid-gastrula embryos undergo convergent extension and convergent thickening movements, respectively. While factors regulating cell lineage specification have been described in some detail, the molecular machinery that controls cell motility is not understood in depth. To gain insight into the gene battery that regulates both cell fates and motility in particular embryonic tissues, we performed RNA sequencing (RNA-seq) to investigate differentially expressed genes in the early organizer, the dorsal and the ventral marginal zone of Xenopus gastrulae. We uncovered many known signaling and transcription factors that have been reported to play roles in embryonic patterning during gastrulation. We also identified many uncharacterized genes as well as genes that encoded extracellular matrix (ECM) proteins or potential regulators of actin cytoskeleton. Co-expression of a selected subset of the differentially expressed genes with activin in animal caps revealed that they had distinct ability to block activin-induced animal cap elongation. Most of these factors did not interfere with mesodermal induction by activin, but an ECM protein, EFEMP2, inhibited activin signaling and acted downstream of the activated type I receptor. By focusing on a secreted protein kinase PKDCC1, we showed with overexpression and knockdown experiments that PKDCC1 regulated gastrulation movements as well as anterior neural patterning during early Xenopus development. Overall, our studies identify many differentially expressed signaling and cytoskeleton regulators in different embryonic regions of Xenopus gastrulae and imply their functions in regulating cell fates and/or behaviors during gastrulation.
在早期脊椎动物胚胎发育过程中，细胞命运特化通常与细胞获得特定的黏附、极性和/或运动行为相关联。在非洲爪蟾原肠胚中，注定形成不同轴向结构的组织表现出明显的运动性。早期组织者中的细胞集体且定向地向动物极移动，并形成前中内胚层，而原肠胚中期胚胎胚孔周围的背侧和腹后躯干组织分别经历汇聚延伸和汇聚增厚运动。虽然调节细胞谱系特化的因素已得到一定程度的详细描述，但控制细胞运动的分子机制仍未被深入了解。为了深入了解调节特定胚胎组织中细胞命运和运动的基因群，我们进行了RNA测序（RNA-seq），以研究非洲爪蟾原肠胚早期组织者、背侧和腹侧边缘区中差异表达的基因。我们发现了许多已知的信号和转录因子，这些因子在原肠胚形成过程中的胚胎模式形成中发挥作用。我们还鉴定了许多未表征的基因以及编码细胞外基质（ECM）蛋白或肌动蛋白细胞骨架潜在调节因子的基因。在动物帽中，差异表达基因的选定子集与激活素的共表达表明，它们具有不同的阻断激活素诱导的动物帽伸长的能力。这些因子中的大多数不干扰激活素诱导的中胚层诱导，但一种ECM蛋白EFEMP2抑制激活素信号传导，并在活化的I型受体下游起作用。通过聚焦于一种分泌型蛋白激酶PKDCC1，我们通过过表达和敲低实验表明，PKDCC1在非洲爪蟾早期发育过程中调节原肠胚形成运动以及前神经模式形成。总体而言，我们的研究在非洲爪蟾原肠胚的不同胚胎区域中鉴定了许多差异表达的信号和细胞骨架调节因子，并暗示了它们在调节原肠胚形成过程中的细胞命运和/或行为方面的功能。
