Quantitative imaging reveals real-time Pou5f3–Nanog complexes driving dorsoventral mesendoderm patterning in zebrafish

Abstract

Formation of the three embryonic germ layers is a fundamental developmental process that initiates differentiation. How the zebrafish pluripotency factor Pou5f3 (homologous to mammalian Oct4) drives lineage commitment is unclear. Here, we introduce fluorescence lifetime imaging microscopy and fluorescence correlation spectroscopy to assess the formation of Pou5f3 complexes with other transcription factors in real-time in gastrulating zebrafish embryos. We show, at single-cell resolution in vivo, that Pou5f3 complexes with Nanog to pattern mesendoderm differentiation at the blastula stage. Later, during gastrulation, Sox32 restricts Pou5f3–Nanog complexes to the ventrolateral mesendoderm by binding Pou5f3 or Nanog in prospective dorsal endoderm. In the ventrolateral endoderm, the Elabela / Aplnr pathway limits Sox32 levels, allowing the formation of Pou5f3–Nanog complexes and the activation of downstream BMP signaling. This quantitative model shows that a balance in the spatiotemporal distribution of Pou5f3–Nanog complexes, modulated by Sox32, regulates mesendoderm specification along the dorsoventral axis.DOI: http://dx.doi.org/10.7554/eLife.11475.001

Alternative Progenitor Cells Compensate to Rebuild the Coronary Vasculature in Elabela- and Apj-Deficient Hearts

“…Apln is expressed by the endothelial cells themselves, and, in other organs, stimulates endothelial cell migration (del Toro et al, 2010; Papangeli et al, 2016). Ela is expressed non-cell autonomously in zebrafish to stimulate cell motility and nodal signaling during early embryogenesis (Chng et al, 2013; Deshwar et al, 2016; Pauli et al, 2014; Perez-Camps et al, 2016), and to activate angioblast migration toward the midline during vasculogenesis (Helker et al, 2015). Ela also has cardioprotective functions during heart failure (Sato et al, 2017) and is important for suppressing Pre-eclampsia during pregnancy (Ho et al, 2017).…”

Zebrafish Nanog is not required in embryonic cells

“…It has been proposed that Nanog is directly required in embryonic cells (Lee et al 2013;Perez-Camps et al 2016) but this assumption has not been tested. We therefore co-transplanted fluorescently labeled MZ nanog mutant and wild-type cells into wild-type hosts at sphere stage, and tracked their contributions to the host embryos.…”

“…Two subsequent studies analyzed potential roles of zebrafish Nanog in embryonic cells (Lee et al 2013;Perez-Camps et al 2016) . Lee et al (2013) defined a set of genes expressed at the maternal-to-zygotic transition (MZT) whose expression was reduced in nanog morphants.…”

“…Subsequent reviews have interpreted these results to conclude that Nanog is directly required for zygotic genome activation in embryonic cells (Langley et al 2014;Paranjpe & Veenstra 2015;Onichtchouk & Driever 2016;Lee et al 2014) , even though the majority of zygotic genes are activated in nanog morphants (Lee et al 2013;Xu et al 2012) . Perez-Camps et al (2016) reported that morpholino knockdown of nanog caused defects in BMP signaling and target gene expression, and suggested that Nanog acts to promote ventral cell fate specification. Surprisingly, neither study (Perez-Camps et al 2016;Lee et al 2013) mentioned the YSL phenotype of nanog morphants (Xu et al 2012) or tested for direct roles of Nanog in embryonic cells.…”

“…Perez-Camps et al (2016) reported that morpholino knockdown of nanog caused defects in BMP signaling and target gene expression, and suggested that Nanog acts to promote ventral cell fate specification. Surprisingly, neither study (Perez-Camps et al 2016;Lee et al 2013) mentioned the YSL phenotype of nanog morphants (Xu et al 2012) or tested for direct roles of Nanog in embryonic cells.…”