scholarly journals Myosin II activity is not required for Drosophila tracheal branching morphogenesis

2017 ◽  
Author(s):  
Amanda Ochoa-Espinosa ◽  
Stefan Harmansa ◽  
Emmanuel Caussinus ◽  
Markus Affolter
Keyword(s):  
Cell Migration ◽  
Myosin Ii ◽  
Branching Morphogenesis ◽  
Stalk Cell ◽  
Germ Band ◽  
Tracheal System ◽  
Tip Cell ◽  
Dorsal Branch ◽  
Cell Intercalation ◽  
Tip Cells

AbstractThe Drosophila tracheal system consists of an interconnected network of monolayered epithelial tubes that ensures oxygen transport in the larval and adult body. During tracheal dorsal branch (DB) development, individual DBs elongate as a cluster of cells, led by tip cells at the front and trailing cells in the rear. Branch elongation is accompanied by extensive cell intercalation and cell lengthening of the trailing stalk cells. While cell intercalation is governed by Myosin II (MyoII)-dependent forces during tissue elongation in the Drosophila embryo leading to germ-band extension, it remained unclear whether MyoII plays a similar active role during tracheal branch elongation and intercalation. Here, we use a nanobody-based approach to selectively knock-down MyoII in tracheal cells. Our data shows that despite the depletion of MyoII function, tip cells migration and stalk cell intercalation (SCI) proceeds at a normal rate. Therefore, our data confirms a model in which DB elongation and SCI in the trachea occurs as a consequence of tip cell migration, which produces the necessary forces for the branching process.Summary statementBranch elongation during Drosophila tracheal development mechanistically resembles MyoII-independent collective cell migration; tensile forces resulting from tip cell migration are reduced by cell elongation and passive stalk cell intercalation.AbbreviationsDBDorsal branchDCDorsal closureE-CadE-CadherinGBEGerm-band extensionMRLCMyosin regulatory light chainMyoIIMyosin IISCIstalk cell intercalationSqhSpaghetti squashSxllSex lethalTCTip cellTrTracheomere

scholarly journals Tip-Cell Migration Controls Stalk-Cell Intercalation during Drosophila Tracheal Tube Elongation

2008 ◽  
Vol 18 (22) ◽  
pp. 1727-1734 ◽  
Author(s):  
Emmanuel Caussinus ◽  
Julien Colombelli ◽  
Markus Affolter
Keyword(s):  
Cell Migration ◽  
Tracheal Tube ◽  
Stalk Cell ◽  
Tip Cell ◽  
Cell Intercalation

scholarly journals Identification and functional analysis of endothelial tip cell–enriched genes

Blood ◽  
2010 ◽  
Vol 116 (19) ◽  
pp. 4025-4033 ◽  
Author(s):  
Raquel del Toro ◽  
Claudia Prahst ◽  
Thomas Mathivet ◽  
Geraldine Siegfried ◽  
Joshua S. Kaminker ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Basement Membrane ◽  
Cell Fate ◽  
Stalk Cell ◽  
Matrix Remodeling ◽  
Retinal Endothelial Cells ◽  
Tip Cell ◽  
Mouse Mutants ◽  
Membrane Components ◽  
Tip Cells

Abstract Sprouting of developing blood vessels is mediated by specialized motile endothelial cells localized at the tips of growing capillaries. Following behind the tip cells, endothelial stalk cells form the capillary lumen and proliferate. Expression of the Notch ligand Delta-like-4 (Dll4) in tip cells suppresses tip cell fate in neighboring stalk cells via Notch signaling. In DLL4+/− mouse mutants, most retinal endothelial cells display morphologic features of tip cells. We hypothesized that these mouse mutants could be used to isolate tip cells and so to determine their genetic repertoire. Using transcriptome analysis of retinal endothelial cells isolated from DLL4+/− and wild-type mice, we identified 3 clusters of tip cell–enriched genes, encoding extracellular matrix degrading enzymes, basement membrane components, and secreted molecules. Secreted molecules endothelial-specific molecule 1, angiopoietin 2, and apelin bind to cognate receptors on endothelial stalk cells. Knockout mice and zebrafish morpholino knockdown of apelin showed delayed angiogenesis and reduced proliferation of stalk cells expressing the apelin receptor APJ. Thus, tip cells may regulate angiogenesis via matrix remodeling, production of basement membrane, and release of secreted molecules, some of which regulate stalk cell behavior.

scholarly journals Tracheal tube fusion in Drosophila involves release of luminal exosomes from multivesicular bodies

2021 ◽  
Author(s):  
Carolina Camelo ◽  
Anna Koerte ◽  
Thea Jacobs ◽  
Peter Robin Hiesinger ◽  
Stefan Luschnig
Keyword(s):  
Tracheal Tube ◽  
Extracellular Vesicles ◽  
Multivesicular Bodies ◽  
Tracheal Lumen ◽  
Tracheal System ◽  
Tip Cell ◽  
Luminal Membrane ◽  
Lysosome Related Organelles ◽  
Tip Cells ◽  
Development Of Organs

Fusion of endothelial or epithelial tubes is essential for the development of organs like the vertebrate vasculature or the insect tracheal system, but the mechanisms underlying the formation of tubular connections (anastomoses) are not well understood. Tracheal tube fusion in Drosophila is mediated by tip cells that transform into lumenized toroids to connect adjacent tubes. This process depends on the Munc13-4 orthologue Staccato (Stac), which localizes to tip-cell-specific lysosome-related organelles (LROs). We show that tracheal LROs display features of multivesicular bodies (MVBs) and that the tracheal lumen contains membranous extracellular vesicles (EVs), a subset of which carries Stac/Munc13-4 and is associated with tracheal anastomosis sites. The presence of LROs and luminal Stac-EVs depends on the tip-cell-specific GTPase Arl3, suggesting that Stac-EVs derive from fusion of MVBs with the luminal membrane in tip cells during anastomosis formation. The GTPases Rab27 and Rab35 cooperate downstream of Arl3 to promote Stac-MVB formation and tube fusion. We propose that Stac-MVBs act as membrane reservoirs that facilitate lumen fusion in tip cells, in a process regulated by Arl3, Rab27, Rab35, and Stac/Munc13-4.

scholarly journals The transcription factors KNIRPS and KNIRPS RELATED control cell migration and branch morphogenesis during Drosophila tracheal development

Development ◽  
1998 ◽  
Vol 125 (24) ◽  
pp. 4959-4968 ◽  
Author(s):  
C.K. Chen ◽  
R.P. Kuhnlein ◽  
K.G. Eulenberg ◽  
S. Vincent ◽  
M. Affolter ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Cell Migration ◽  
Egf Receptor ◽  
Regulatory Element ◽  
Control Cell ◽  
Terminal Branch ◽  
Migration Behavior ◽  
Related Activity ◽  
Tracheal System ◽  
Dorsal Branch

Cell migration during embryonic tracheal system development in Drosophila requires DPP and EGF signaling to generate the archetypal branching pattern. We show that two genes encoding the transcription factors KNIRPS and KNIRPS RELATED possess multiple and redundant functions during tracheal development. knirps/knirps related activity is necessary to mediate DPP signaling which is required for tracheal cell migration and formation of the dorsal and ventral branches. Ectopic knirps or knirps related expression in lateral tracheal cells respecifies their anteroposterior to a dorsoventral migration behavior, similar to that observed in the case of ectopic DPP expression. In dorsal tracheal cells knirps/knirps related activity represses the transcription factor SPALT; this repression is essential for secondary and terminal branch formation. However, in cells of the dorsal trunk, spalt expression is required for normal anteroposterior cell migration and morphogenesis. spalt expression is maintained by the EGF receptor pathway and, hence, some of the opposing activities of the EGF and DPP signaling pathways are mediated by spalt and knirps/knirps related. Furthermore, we provide evidence that the border between cells acquiring dorsal branch and dorsal trunk identity is established by the direct interaction of KNIRPS with a spalt cis-regulatory element.

scholarly journals Unravelling the distinct contribution of cell shape changes and cell intercalation to tissue morphogenesis: the case of the Drosophila trachea

Open Biology ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 200329
Author(s):  
Sandra Casani ◽  
Jordi Casanova ◽  
Marta Llimargas
Keyword(s):  
Cell Elongation ◽  
Cell Shape ◽  
Convergent Extension ◽  
Experimental Conditions ◽  
Full Extension ◽  
Tracheal System ◽  
Dorsal Branch ◽  
Respective Contribution ◽  
Pulling Force ◽  
Cell Intercalation

Intercalation allows cells to exchange positions in a spatially oriented manner in an array of diverse processes, spanning convergent extension in embryonic gastrulation to the formation of tubular organs. However, given the co-occurrence of cell intercalation and changes in cell shape, it is sometimes difficult to ascertain their respective contribution to morphogenesis. A well-established model to analyse intercalation, particularly in tubular organs, is the Drosophila tracheal system. There, fibroblast growth factor (FGF) signalling at the tip of the dorsal branches generates a ‘pulling’ force believed to promote cell elongation and cell intercalation, which account for the final branch extension. Here, we used a variety of experimental conditions to study the contribution of cell elongation and cell intercalation to morphogenesis and analysed their mutual requirements. We provide evidence that cell intercalation does not require cell elongation and vice versa. We also show that the two cell behaviours are controlled by independent but simultaneous mechanisms, and that cell elongation is sufficient to account for full extension of the dorsal branch, while cell intercalation has a specific role in setting the diameter of this structure. Thus, rather than viewing changes in cell shape and cell intercalation as just redundant events that add robustness to a given morphogenetic process, we find that they can also act by contributing to different features of tissue architecture.

scholarly journals The Role of Heparan Sulfate and Neuropilin 2 in VEGFA Signaling in Human Endothelial Tip Cells and Non-Tip Cells during Angiogenesis In Vitro

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 926
Author(s):  
Marchien G. Dallinga ◽  
Yasmin I. Habani ◽  
Alinda W. M. Schimmel ◽  
Geesje M. Dallinga-Thie ◽  
Cornelis J. F. van Noorden ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Heparan Sulfate ◽  
Splice Variant ◽  
Cell Formation ◽  
Stalk Cell ◽  
Vegf Receptor ◽  
Tip Cell ◽  
Sprout Formation ◽  
Tip Cells

During angiogenesis, vascular endothelial growth factor A (VEGFA) regulates endothelial cell (EC) survival, tip cell formation, and stalk cell proliferation via VEGF receptor 2 (VEGFR2). VEGFR2 can interact with VEGFR2 co-receptors such as heparan sulfate proteoglycans (HSPGs) and neuropilin 2 (NRP2), but the exact roles of these co-receptors, or of sulfatase 2 (SULF2), an enzyme that removes sulfate groups from HSPGs and inhibits HSPG-mediated uptake of very low density lipoprotein (VLDL), in angiogenesis and tip cell biology are unknown. In the present study, we investigated whether the modulation of binding of VEGFA to VEGFR2 by knockdown of SULF2 or NRP2 affects sprouting angiogenesis, tip cell formation, proliferation of non-tip cells, and EC survival, or uptake of VLDL. To this end, we employed VEGFA splice variant 121, which lacks an HSPG binding domain, and VEGFA splice variant 165, which does have this domain, in in vitro models of angiogenic tip cells and vascular sprouting. We conclude that VEGFA165 and VEGFA121 have similar inducing effects on tip cells and sprouting in vitro, and that the binding of VEGFA165 to HSPGs in the extracellular matrix does not seem to play a role, as knockdown of SULF2 did not alter these effects. Co-binding of NRP2 appears to regulate VEGFA–VEGFR2-induced sprout initiation, but not tip cell formation. Finally, as the addition of VLDL increased sprout formation but not tip cell formation, and as VLDL uptake was limited to non-tip cells, our findings suggest that VLDL plays a role in sprout formation by providing biomass for stalk cell proliferation.

scholarly journals Contribution of Filopodia to Cell Migration: A Mechanical Link between Protrusion and Contraction

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Fei Xue ◽  
Deanna M. Janzen ◽  
David A. Knecht
Keyword(s):  
Cell Migration ◽  
Actin Polymerization ◽  
Myosin Ii ◽  
Temporal Distribution ◽  
Leading Edge ◽  
Distal Portion ◽  
Actin Binding ◽  
Actin Networks ◽  
Motile Cells ◽  
A Cell

Numerous F-actin containing structures are involved in regulating protrusion of membrane at the leading edge of motile cells. We have investigated the structure and dynamics of filopodia as they relate to events at the leading edge and the function of the trailing actin networks. We have found that although filopodia contain parallel bundles of actin, they contain a surprisingly nonuniform spatial and temporal distribution of actin binding proteins. Along the length of the actin filaments in a single filopodium, the most distal portion contains primarily T-plastin, while the proximal portion is primarily bound byα-actinin and coronin. Some filopodia are stationary, but lateral filopodia move with respect to the leading edge. They appear to form a mechanical link between the actin polymerization network at the front of the cell and the myosin motor activity in the cell body. The direction of lateral filopodial movement is associated with the direction of cell migration. When lateral filopodia initiate from and move toward only one side of a cell, the cell will turn opposite to the direction of filopodial flow. Therefore, this filopodia-myosin II system allows actin polymerization driven protrusion forces and myosin II mediated contractile force to be mechanically coordinated.

ribbon encodes a novel BTB/POZ protein required for directed cell migration in Drosophila melanogaster

Development ◽  
2001 ◽  
Vol 128 (15) ◽  
pp. 3001-3015 ◽  
Author(s):  
Pamela L. Bradley ◽  
Deborah J. Andrew
Keyword(s):  
Cell Migration ◽  
Wnt Signaling ◽  
Signaling Pathways ◽  
Egf Receptor ◽  
Tracheal System ◽  
Directed Cell Migration ◽  
Posterior Migration ◽  
And Function ◽  
Dorsal Epidermis ◽  
Anterior Posterior

During development, directed cell migration is crucial for achieving proper shape and function of organs. One well-studied example is the embryonic development of the larval tracheal system of Drosophila, in which at least four signaling pathways coordinate cell migration to form an elaborate branched network essential for oxygen delivery throughout the larva. FGF signaling is required for guided migration of all tracheal branches, whereas the DPP, EGF receptor, and Wingless/WNT signaling pathways each mediate the formation of specific subsets of branches. Here, we characterize ribbon, which encodes a BTB/POZ-containing protein required for specific tracheal branch migration. In ribbon mutant tracheae, the dorsal trunk fails to form, and ventral branches are stunted; however, directed migrations of the dorsal and visceral branches are largely unaffected. The dorsal trunk also fails to form when FGF or Wingless/WNT signaling is lost, and we show that ribbon functions downstream of, or parallel to, these pathways to promote anterior-posterior migration. Directed cell migration of the salivary gland and dorsal epidermis are also affected in ribbon mutants, suggesting that conserved mechanisms may be employed to orient cell migrations in multiple tissues during development.

scholarly journals Unipolar distributions of junctional Myosin II identify cell stripe boundaries that drive cell intercalation throughout Drosophila axis extension

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Robert J Tetley ◽  
Guy B Blanchard ◽  
Alexander G Fletcher ◽  
Richard J Adams ◽  
Bénédicte Sanson
Keyword(s):  
Myosin Ii ◽  
Interaction Model ◽  
Cell Interaction ◽  
Cell Number ◽  
Cell Polarization ◽  
Convergence And Extension ◽  
Pair Rule Gene ◽  
Cell Intercalation ◽  
Pair Rule ◽  
Cell Cell

Convergence and extension movements elongate tissues during development. Drosophila germ-band extension (GBE) is one example, which requires active cell rearrangements driven by Myosin II planar polarisation. Here, we develop novel computational methods to analyse the spatiotemporal dynamics of Myosin II during GBE, at the scale of the tissue. We show that initial Myosin II bipolar cell polarization gives way to unipolar enrichment at parasegmental boundaries and two further boundaries within each parasegment, concomitant with a doubling of cell number as the tissue elongates. These boundaries are the primary sites of cell intercalation, behaving as mechanical barriers and providing a mechanism for how cells remain ordered during GBE. Enrichment at parasegment boundaries during GBE is independent of Wingless signaling, suggesting pair-rule gene control. Our results are consistent with recent work showing that a combinatorial code of Toll-like receptors downstream of pair-rule genes contributes to Myosin II polarization via local cell-cell interactions. We propose an updated cell-cell interaction model for Myosin II polarization that we tested in a vertex-based simulation.

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