scholarly journals A mesoderm-independent role for Nodal signaling in convergence & extension gastrulation movements

2019 ◽  
Author(s):  
Margot L.K. Williams ◽  
Lilianna Solnica-Krezel

ABSTRACTDuring embryogenesis, the distinct morphogenetic cell behavior programs that shape tissues are influenced both by the fate of cells and their position with respect to the embryonic axes, making embryonic patterning a prerequisite for morphogenesis. These two essential processes must therefore be coordinated in space and time to ensure proper development, but mechanisms by which patterning information is translated to the cellular machinery that drives morphogenesis remain poorly understood. Here, we address the role of Nodal morphogen signaling at the intersection of cell fate specification, patterning, and anteroposterior (AP) axis extension in zebrafish gastrulae and embryonic explants. AP axis extension is impaired in Nodal-deficient embryos, but it is unclear whether this defect is strictly secondary to their severe mesendoderm deficiencies or also results from loss of Nodal signaling per se. We find that convergence & extension (C&E) gastrulation movements and underlying mediolateral (ML) cell polarization are reduced in the neuroectoderm of Nodal-deficient mutants and exacerbated by simultaneous disruption of Planar Cell Polarity (PCP) signaling, demonstrating at least partially parallel functions of Nodal and PCP. ML polarity of mutant neuroectoderm cells is not fully restored upon transplantation into wild-type gastrulae, demonstrating a cell autonomous, mesoderm-independent role for Nodal in neural cell polarization. This is further demonstrated by the ability of Nodal ligands to promote neuroectoderm-driven C&E of naïve blastoderm explants in a tissue-autonomous fashion. Finally, temporal manipulation of signaling reveals that Nodal contributes to neural C&E in explants after mesoderm is specified and promotes C&E even in the absence of mesoderm. Together these results reveal a mesoderm-independent, cell-autonomous role for Nodal signaling in neural C&E that may cooperate with previously-described mesoderm-dependent mechanisms to drive AP embryonic axis extension.

2017 ◽  
Author(s):  
Margot L K Williams ◽  
Atsushi Sawada ◽  
Terin Budine ◽  
Chunyue Yin ◽  
Paul Gontarz ◽  
...  

Anteroposterior axis extension during vertebrate gastrulation requires cell proliferation, embryonic patterning, and morphogenesis to be spatiotemporally coordinated, but the underlying genetic mechanisms remain poorly understood. Here we define a role for the conserved chromatin factor Gon4l, encoded by ugly duckling (udu), in coordinating tissue patterning and axis extension during zebrafish gastrulation. Although identified as a recessive enhancer of short axis phenotypes in planar cell polarity (PCP) mutants, we found that Gon4l functions in a genetically independent, partially overlapping fashion with PCP signaling to regulate mediolateral cell polarity underlying axis extension in part by promoting notochord boundary formation. We identified direct genomic targets of Gon4l and found that it acts as both a positive and negative regulator of gene expression, including limiting expression of the cell-cell and cell-matrix adhesion molecules EpCAM and Integrinα3b. Excess epcam or itga3b in wild-type gastrulae phenocopied notochord boundary defects of udu mutants, while downregulation of itga3b suppressed them. By promoting formation of this anteroposteriorly aligned boundary and associated cell polarity, Gon4l cooperates with PCP signaling to coordinate morphogenesis with the anteroposterior embryonic axis.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Margot LK Williams ◽  
Lilianna Solnica-Krezel

During vertebrate gastrulation, convergence and extension (C and E) of the primary anteroposterior (AP) embryonic axis is driven by polarized mediolateral (ML) cell intercalations and is influenced by AP axial patterning. Nodal signaling is essential for patterning of the AP axis while planar cell polarity (PCP) signaling polarizes cells with respect to this axis, but how these two signaling systems interact during C and E is unclear. We find that the neuroectoderm of Nodal-deficient zebrafish gastrulae exhibits reduced C and E cell behaviors, which require Nodal signaling in both cell- and non-autonomous fashions. PCP signaling is partially active in Nodal-deficient embryos and its inhibition exacerbates their C and E defects. Within otherwise naïve zebrafish blastoderm explants, however, Nodal induces C and E in a largely PCP-dependent manner, arguing that Nodal acts both upstream of and in parallel with PCP during gastrulation to regulate embryonic axis extension cooperatively.


Science ◽  
2010 ◽  
Vol 329 (5997) ◽  
pp. 1337-1340 ◽  
Author(s):  
Su Kyoung Kim ◽  
Asako Shindo ◽  
Tae Joo Park ◽  
Edwin C. Oh ◽  
Srimoyee Ghosh ◽  
...  

The planar cell polarity (PCP) signaling pathway governs collective cell movements during vertebrate embryogenesis, and certain PCP proteins are also implicated in the assembly of cilia. The septins are cytoskeletal proteins controlling behaviors such as cell division and migration. Here, we identified control of septin localization by the PCP protein Fritz as a crucial control point for both collective cell movement and ciliogenesis in Xenopus embryos. We also linked mutations in human Fritz to Bardet-Biedl and Meckel-Gruber syndromes, a notable link given that other genes mutated in these syndromes also influence collective cell movement and ciliogenesis. These findings shed light on the mechanisms by which fundamental cellular machinery, such as the cytoskeleton, is regulated during embryonic development and human disease.


2004 ◽  
Vol 166 (7) ◽  
pp. 975-981 ◽  
Author(s):  
Chiemi Miyagi ◽  
Susumu Yamashita ◽  
Yusuke Ohba ◽  
Hisayoshi Yoshizaki ◽  
Michiyuki Matsuda ◽  
...  

Zebrafish signal transducer and activator of transcription 3 (STAT3) controls the cell movements during gastrulation. Here, we show that noncell-autonomous activity of STAT3 signaling in gastrula organizer cells controls the polarity of neighboring cells through Dishevelled-RhoA signaling in the Wnt-planar cell polarity (Wnt-PCP) pathway. In STAT3-depleted embryos, although all the known molecules in the Wnt-PCP pathway were expressed normally, the RhoA activity in lateral mesendodermal cells was down-regulated, resulting in severe cell polarization defects in convergence and extension movements identical to Strabismus-depleted embryos. Cell-autonomous activation of Wnt-PCP signaling by ΔN-dishevelled rescued the defect in cell elongation, but not the orientation of lateral mesendodermal cells in STAT3-depleted embryos. The defect in the orientation could be rescued by transplantation of shield cells having noncell-autonomous activity of STAT3 signaling. These results suggest that the cells undergoing convergence and extension movement may sense the gradient of signaling molecules, which are expressed in gastrula organizer by STAT3 and noncell-autonomously activate PCP signaling in neighboring cells during zebrafish gastrulation.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yildiz Koca ◽  
Benjamin E. Housden ◽  
William J. Gault ◽  
Sarah J. Bray ◽  
Marek Mlodzik

AbstractIn all metazoans, a small number of evolutionarily conserved signaling pathways are reiteratively used during development to orchestrate critical patterning and morphogenetic processes. Among these, Notch (N) signaling is essential for most aspects of tissue patterning where it mediates the communication between adjacent cells to control cell fate specification. In Drosophila, Notch signaling is required for several features of eye development, including the R3/R4 cell fate choice and R7 specification. Here we show that hypomorphic alleles of Notch, belonging to the Nfacet class, reveal a novel phenotype: while photoreceptor specification in the mutant ommatidia is largely normal, defects are observed in ommatidial rotation (OR), a planar cell polarity (PCP)-mediated cell motility process. We demonstrate that during OR Notch signaling is specifically required in the R4 photoreceptor to upregulate the transcription of argos (aos), an inhibitory ligand to the epidermal growth factor receptor (EGFR), to fine-tune the activity of EGFR signaling. Consistently, the loss-of-function defects of Nfacet alleles and EGFR-signaling pathway mutants are largely indistinguishable. A Notch-regulated aos enhancer confers R4 specific expression arguing that aos is directly regulated by Notch signaling in this context via Su(H)-Mam-dependent transcription.


2013 ◽  
Vol 3 (1) ◽  
pp. 5-8 ◽  
Author(s):  
Andrea D Belalcazar ◽  
Kristy Doyle ◽  
Justin Hogan ◽  
David Neff ◽  
Simon Collier

Abstract The Drosophila wing consists of a transparent wing membrane supported by a network of wing veins. Previously, we have shown that the wing membrane cuticle is not flat but is organized into ridges that are the equivalent of one wing epithelial cell in width and multiple cells in length. These cuticle ridges have an anteroposterior orientation in the anterior wing and a proximodistal orientation in the posterior wing. The precise topography of the wing membrane is remarkable because it is a fusion of two independent cuticle contributions from the dorsal and ventral wing epithelia. Here, through morphological and genetic studies, we show that it is the dorsal wing epithelium that determines wing membrane topography. Specifically, we find that wing hair location and membrane topography are coordinated on the dorsal, but not ventral, surface of the wing. In addition, we find that altering Frizzled Planar Cell Polarity (i.e., Fz PCP) signaling in the dorsal wing epithelium alone changes the membrane topography of both dorsal and ventral wing surfaces. We also examined the wing morphology of two model Hymenopterans, the honeybee Apis mellifera and the parasitic wasp Nasonia vitripennis. In both cases, wing hair location and wing membrane topography are coordinated on the dorsal, but not ventral, wing surface, suggesting that the dorsal wing epithelium also controls wing topography in these species. Because phylogenomic studies have identified the Hymenotera as basal within the Endopterygota family tree, these findings suggest that this is a primitive insect character.


2002 ◽  
Vol 2 ◽  
pp. 434-454 ◽  
Author(s):  
Jeffrey D. Axelrod ◽  
Helen McNeill

Epithelial cells and other groups of cells acquire a polarity orthogonal to their apical–basal axes, referred to as Planar Cell Polarity (PCP). The process by which these cells become polarized requires a signaling pathway using Frizzled as a receptor. Responding cells sense cues from their environment that provide directional information, and they translate this information into cellular asymmetry. Most of what is known about PCP derives from studies in the fruit fly,Drosophila. We review what is known about how cells translate an unknown signal into asymmetric cytoskeletal reorganization. We then discuss how the vertebrate processes of convergent extension and cochlear hair-cell development may relate toDrosophilaPCP signaling.


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