Cell Sheet Morphogenesis: Dorsal Closure in<i>Drosophila melanogaster</i>as a Model System

Kiehart, Daniel P.; Crawford, Jennifer L.; Aristotelous, Andreas C.; Venakides, Stephanos; Edwards, Glenn S.

doi:10.1146/annurev-cellbio-111315-125357

Cited by 91 publications

(132 citation statements)

References 192 publications

(512 reference statements)

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“…Wound healing is well-described mechanism for tissue resiliency (Redd et al, 2004). During dorsal closure, for example, a purse string at the margin of two sheets of epidermis pulls and seals together the tissue (Kiehart et al, 2017…”

Section: Encoded Robustness In the Absence Of Wound Healingmentioning

confidence: 99%

Structural redundancy in supracellular actomyosin networks enables robust tissue folding

Yevick

Miller

Martin

2019

Preprint

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Tissue morphogenesis is strikingly reproducible. Yet, how tissues are robustly sculpted, even under challenging conditions, is unknown. Here, we combined network analysis, experimental perturbations, and computational modeling to determine how network connectivity between hundreds of contractile cells on the ventral side of the Drosophila embryo ensures robust tissue folding. We identified two network properties that mechanically promote robustness. First, redundant supracellular cytoskeletal network paths ensure global connectivity, even with network degradation. By forming many more connections than are required, morphogenesis is not disrupted by local network damage, analogous to the way redundancy guarantees the large-scale function of vasculature and transportation networks. Second, directional stiffening of edges oriented orthogonal to the folding axis promotes furrow formation at lower contractility levels. Structural redundancy and directional network stiffening ensure robust tissue folding with proper orientation.

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Section: Encoded Robustness In the Absence Of Wound Healingmentioning

confidence: 99%

Structural redundancy in supracellular actomyosin networks enables robust tissue folding

Yevick

Miller

Martin

2019

Preprint

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“…Dorsal closure provides a superb place to study this, as the dorsalmost cells of the lateral epidermis assemble a planar-polarized contractile actomyosin cable at their leading edge, anchored cell-to-cell at tricellular junctions. Contraction of this supercellular cable along with pulsed contractions of the more dorsal amnioserosal cells help power closure (reviewed in Hayes and Solon, 2017;Kiehart et al, 2017). Previous analyses of Cno's role in dorsal closure relied on zygotic cno mutants (e.g.…”

Section: Canoe Is Required To Maintain Homeostatic Cell Shapes and Bamentioning

confidence: 99%

“…During dorsal closure, the leading edge (LE) provides an interesting model of balanced contractility. The planar-polarized supercellular actomyosin cable along the LE provides part of the force-generating machinery that powers dorsal closure (reviewed in Hayes and Solon, 2017;Kiehart et al, 2017; though see Ducuing and Vincent, 2016;Pasakarnis et al, 2016). Each border is a separate contractile unit, pulling on its neighbors, but in the wildtype state each cell's cable is equivalently contractile relative to its neighbors, maintaining relatively uniform LE cell widths across the cable.…”

Section: Cno: More Than Just a Junction:cytoskeletal Linkermentioning

confidence: 99%

The Drosophila Afadin and ZO-1 homologs Canoe and Polychaetoid act in parallel to maintain epithelial integrity when challenged by adherens junction remodeling

Manning

Perez-Vale

Schaefer

et al. 2019

Preprint

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During morphogenesis cells must change shape and move without disrupting tissue integrity. This requires cell-cell junctions to allow dynamic remodeling while resisting force generated by the actomyosin cytoskeleton. Multiple proteins play roles in junctional-cytoskeletal linkage, but the mechanisms by which they act remain unclear. Drosophila Canoe maintains adherens junction-cytoskeletal linkage during gastrulation.Canoe's mammalian homolog Afadin plays similar roles in cultured cells, working in parallel with ZO-1 proteins, particularly at multicellular junctions. We took these insights back into the fly embryo, exploring how cells maintain epithelial integrity when challenged by adherens junction remodeling during germband extension and dorsal closure. We found Canoe helps cells maintain junctional-cytoskeletal linkage when challenged by the junctional remodeling inherent in mitosis, cell intercalation and neuroblast invagination, or by forces generated by the actomyosin cable at the leading edge. However, even in the absence of Canoe many cells retain epithelial integrity. This is explained by a parallel role played by the ZO-1 homolog Polychaetoid. In embryos lacking both Canoe and Polychaetoid, cell junctions fail early, with multicellular junctions especially sensitive, leading to widespread loss of epithelial integrity. Our data suggest Canoe and Polychaetoid stabilize Bazooka/Par3 at cell-cell junctions, helping maintain balanced apical contractility and tissue integrity.

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“…Firstly, we focused on the resolution potential, aiming to probe the visualization of the subcellular and suborganellar organization in embryonic neurons. Secondly, we evaluated the potential of imaging multicellular volumes by analysing embryonic dorsal closure (DC), which is a model system for epithelial morphogenesis as well as wound healing (Redd et al, 2004;Kiehart et al, 2017). Since DC requires interactions and rearrangement of two tissues, epidermis and amnioserosa, information beyond the cellular level is needed.…”

Section: Introductionmentioning

confidence: 99%

FIB‐SEM imaging properties of Drosophila melanogaster tissues embedded in Lowicryl HM20

Porrati

Grewe

Seybert

et al. 2018

Journal of Microscopy

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Summary Lowicryl resins enable processing of biological material for electron microscopy at the lowest temperatures compatible with resin embedding. When combined with high‐pressure freezing and freeze‐substitution, Lowicryl embedding supports preservation of fine structural details and fluorescent markers. Here, we analysed the applicability of Lowicryl HM20 embedding for focused ion beam (FIB) scanning electron microscopy (SEM) tomography of Drosophila melanogaster embryonic and larval model systems. We show that the freeze‐substitution with per‐mill concentrations of uranyl acetate provided sufficient contrast and an image quality of SEM imaging in the range of similar samples analysed by transmission electron microscopy (TEM). Preservation of genetically encoded fluorescent proteins allowed correlative localization of regions of interest (ROI) within the embedded tissue block. TEM on sections cut from the block face enabled evaluation of structural preservation to allow ROI ranking and thus targeted, time‐efficient FIB‐SEM tomography data collection. The versatility of Lowicryl embedding opens new perspectives for designing hybrid SEM‐TEM workflows to comprehensively analyse biological structures. Lay Description Focused ion beam scanning electron microscopy is becoming a widely used technique for the three‐dimensional analysis of biological samples at fine structural details beyond levels feasible for light microscopy. To withstand the abrasion of material by the ion beam and the imaging by the scanning electron beam, biological samples have to be embedded into resins, most commonly these are very dense epoxy‐based plastics. However, dense resins generate electron scattering which interferes with the signal from the biological specimen. Furthermore, to improve the imaging contrast, epoxy embedding requires chemical treatments with e.g. heavy metals, which deteriorate the ultrastructure of the biological specimen. In this study we explored the applicability of an electron lucent resin, Lowicryl HM 20, for focused ion beam scanning electron microscopy. The Lowicryl embedding workflow operates at milder chemical treatments and lower temperatures, thus preserving the sub‐cellular and sub‐organellar organization, as well as fluorescent markers visible by light microscopy. Here we show that focus ion beam scanning electron microscopy of Lowicryl‐embedded fruit flies tissues provides reliable imaging revealing fine structural details. Our workflow benefited from use of transmission electron microscopy for the quality control of the ultrastructural preservation and fluorescent light microscopy for localization of regions of interest. The versatility of Lowicryl embedding opens up new perspectives for designing hybrid workflows combining fluorescent light, scanning, and transmission electron microscopy techniques to comprehensively analyze biological structures.

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Cell Sheet Morphogenesis: Dorsal Closure inDrosophila melanogasteras a Model System

Cited by 91 publications

References 192 publications

Structural redundancy in supracellular actomyosin networks enables robust tissue folding

Structural redundancy in supracellular actomyosin networks enables robust tissue folding

The Drosophila Afadin and ZO-1 homologs Canoe and Polychaetoid act in parallel to maintain epithelial integrity when challenged by adherens junction remodeling

FIB‐SEM imaging properties of Drosophila melanogaster tissues embedded in Lowicryl HM20

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