Temporally coordinated signals progressively pattern the anteroposterior and dorsoventral body axes

Abstract

The vertebrate body plan is established through the precise spatiotemporal coordination morphogen signaling pathways that pattern the anteroposterior (AP) and dorsoventral (DV) axes. Patterning along the AP axis is directed by posteriorizing signals Wnt, fibroblast growth factor (FGF), Nodal, and retinoic acid (RA), while patterning along the DV axis is directed by bone morphogenetic proteins (BMP) ventralizing signals. This review addresses the current understanding of how Wnt, FGF, RA and BMP pattern distinct AP and DV cell fates during early development and how their signaling mechanisms are coordinated to concomitantly pattern AP and DV tissues.

Regulation of gastrulation movements by emergent cell and tissue interactions

“…Many embryos possess small regions termed “organizers” that are the source of many morphogens simultaneously, and which function during gastrulation to orchestrate cell fates and morphogenetic behaviors throughout the entire embryo [5,6]. Such global signaling patterns AP and DV body axes, specifies germ layers, patterns tissue sub-types, and regulates gastrulation movements [7]. As this inductive cascade unfolds, new cellular interactions are established: between cells of adjacent germ layers, between neighbors with different positional values along an axis, and at tissue boundaries within the nascent germ layers (see graphical abstract).…”

Dorsal-ventral patterning in amphioxus: current understanding, unresolved issues, and future directions

“…They demonstrated that the dorsal mesoderm (dorsal blastopore lip) of an early gastrula stage amphibian embryo has the ability to instruct the formation of a proper vertebrate body plan. If grafted to the ventral side of a host embryo, this piece of dorsal mesoderm models (reviewed in (De Robertis, 2009;De Robertis and Kuroda, 2004;Niehrs, 2004;Thisse and Thisse, 2015;Tuazon and Mullins, 2015). We now know that although the dorsal organizer is definitively set at the start of gastrulation in vertebrate embryos, the molecular processes that are required for its formation act prior to that.…”

Genetic Mechanisms Regulating the Spatiotemporal Modulation of Proliferation Rate and Mode in Neural Progenitors and Daughter Cells during Embryonic CNS Development

“…Embryonic body patterning and the establishment of A-P and D-V axes span blastula, gastrula and somitogenesis stages of embryonic development. Since A-P and D-V axes are not established all at once, the precise spatio-temporal regulation of morphogens' signaling and distributions are also critical for proper 3D patterning of embryonic body [4].…”

“…Activated receptors then phosphorylate transcription factors Smad2 and Smad3 which are thereby nuclearized and bind their target genes [4,19]. Nodal activity is antagonized by soluble extracellular proteins such as Lefty and Cerberus, which can bind both Nodal and EGF-CFC co-receptor, or only Nodal respectively [19].…”

“…So Nodal acts as a morphogen i.e., concentration-dependent, in mesendoderm patterning but also acts in A-P patterning simultaneously. Whether these two distinct roles are independent or cooperative is yet not clear [4].…”