Limits...
Genetic control of cell morphogenesis during Drosophila melanogaster cardiac tube formation.

Medioni C, Astier M, Zmojdzian M, Jagla K, Sémériva M - J. Cell Biol. (2008)

Bottom Line: Our study of cell behavior using three-dimensional and time-lapse imaging and the distribution of cell polarity markers reveals a new mechanism of tubulogenesis in which repulsion of prepatterned luminal domains with basal membrane properties and cell shape remodeling constitute the main driving forces.From these data we propose a model for D. melanogaster cardiac lumen formation, which differs, both at a cellular and molecular level, from current models of epithelial tubulogenesis.We suggest that this new example of tube formation may be helpful in studying vertebrate heart tube formation and primary vasculogenesis.

View Article: PubMed Central - PubMed

Affiliation: Institut de Biologie du Développement de Marseille-Luminy, Centre National de la Recherche Scientifique UMR 6216, Université de la Méditerranée, 13288 Marseille, Cedex 9, France.

ABSTRACT
Tubulogenesis is an essential component of organ development, yet the underlying cellular mechanisms are poorly understood. We analyze here the formation of the Drosophila melanogaster cardiac lumen that arises from the migration and subsequent coalescence of bilateral rows of cardioblasts. Our study of cell behavior using three-dimensional and time-lapse imaging and the distribution of cell polarity markers reveals a new mechanism of tubulogenesis in which repulsion of prepatterned luminal domains with basal membrane properties and cell shape remodeling constitute the main driving forces. Furthermore, we identify a genetic pathway in which roundabout, slit, held out wings, and dystroglycan control cardiac lumen formation by establishing nonadherent luminal membranes and regulating cell shape changes. From these data we propose a model for D. melanogaster cardiac lumen formation, which differs, both at a cellular and molecular level, from current models of epithelial tubulogenesis. We suggest that this new example of tube formation may be helpful in studying vertebrate heart tube formation and primary vasculogenesis.

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Slit–Robo functions are required to form the cardiac lumen. Reconstructed time-lapse Z views (6-min intervals) taken from videos (Videos 2–4, available at http://www.jcb.org/cgi/content/full/jcb.200801100/DC1) illustrating CB shape changes and lumen formation in wild-type (24B-Gal4; UAS actin-GFP; A–L), slit2 mutant (A′–L′), and robo/robo2 double mutant embryos (A″–L″) from stages 14–16 of embryogenesis. Mutant alleles are in 24B-Gal4; UAS actin-GFP background to visualize CB shape. Wild-type CBs change their shape from rounded (not depicted), to pearlike (A), to crescentlike (L), whereas the CBs of both mutants (slit2 or robo/robo2) remain rounded over the entire period (from A′–L′ to A″–L″). (A, A′, and A″) Red dotted lines delimit the CB shape. Note the highly dynamic actin-GFP accumulation at the sites of cell–cell contact. CBs contact first by the “leading edge” domains (D–D″ and E–E″) where accumulation of actin-GFP (arrowheads) is observed. This cell–cell contact is dramatically enlarged in slit2 and robo/robo2 mutants (F–F″ and L–L″, brackets). (L) Red dotted line labels the newly formed lumen, absent in slit2 (L′) and robo/robo2 (L″) mutants. Bars, 5 μm.
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fig2: Slit–Robo functions are required to form the cardiac lumen. Reconstructed time-lapse Z views (6-min intervals) taken from videos (Videos 2–4, available at http://www.jcb.org/cgi/content/full/jcb.200801100/DC1) illustrating CB shape changes and lumen formation in wild-type (24B-Gal4; UAS actin-GFP; A–L), slit2 mutant (A′–L′), and robo/robo2 double mutant embryos (A″–L″) from stages 14–16 of embryogenesis. Mutant alleles are in 24B-Gal4; UAS actin-GFP background to visualize CB shape. Wild-type CBs change their shape from rounded (not depicted), to pearlike (A), to crescentlike (L), whereas the CBs of both mutants (slit2 or robo/robo2) remain rounded over the entire period (from A′–L′ to A″–L″). (A, A′, and A″) Red dotted lines delimit the CB shape. Note the highly dynamic actin-GFP accumulation at the sites of cell–cell contact. CBs contact first by the “leading edge” domains (D–D″ and E–E″) where accumulation of actin-GFP (arrowheads) is observed. This cell–cell contact is dramatically enlarged in slit2 and robo/robo2 mutants (F–F″ and L–L″, brackets). (L) Red dotted line labels the newly formed lumen, absent in slit2 (L′) and robo/robo2 (L″) mutants. Bars, 5 μm.

Mentions: At the onset of dorsal closure, CBs adopt a pearlike shape consecutive to constriction of their domain facing the dorsal midline (Fig. 1, F and F′, compared with Fig. 1, E and E′). Actin-rich cytoplasmic extensions grow from this membrane domain, which constitutes the leading edge of the dorsally migrating CBs (Fig. 1 B, arrowheads). CBs from each of the two rows come progressively into contact at their leading edges and join at the dorsal midline (Fig. 1, B, G, and G′). Subsequently, CBs adopt a crescentlike shape (Fig. 1, H and H′), which allows their bases to join ventrally and thus to close the tube (Fig. 1, I and I′), creating an internal lumen. During this step, which takes ∼60 min (see Fig. 2 and Videos 1 and 2), the dorsal part of CBs detaches from the dorsal ectoderm. Throughout this process, CBs increase their size and keep growing after tube closure; as a result, the lumen enlarges progressively (Fig. 1, D and I). Thus, our in vivo analysis provides for the first time a step by step description of the dynamics of cardiac tube formation. It confirms previous observations (Rugendorff et al., 1994; Haag et al., 1999) made on fixed preparations and provides, in addition, a highly tractable new method for analyzing in vivo CB cell behavior in wild-type and mutant backgrounds.


Genetic control of cell morphogenesis during Drosophila melanogaster cardiac tube formation.

Medioni C, Astier M, Zmojdzian M, Jagla K, Sémériva M - J. Cell Biol. (2008)

Slit–Robo functions are required to form the cardiac lumen. Reconstructed time-lapse Z views (6-min intervals) taken from videos (Videos 2–4, available at http://www.jcb.org/cgi/content/full/jcb.200801100/DC1) illustrating CB shape changes and lumen formation in wild-type (24B-Gal4; UAS actin-GFP; A–L), slit2 mutant (A′–L′), and robo/robo2 double mutant embryos (A″–L″) from stages 14–16 of embryogenesis. Mutant alleles are in 24B-Gal4; UAS actin-GFP background to visualize CB shape. Wild-type CBs change their shape from rounded (not depicted), to pearlike (A), to crescentlike (L), whereas the CBs of both mutants (slit2 or robo/robo2) remain rounded over the entire period (from A′–L′ to A″–L″). (A, A′, and A″) Red dotted lines delimit the CB shape. Note the highly dynamic actin-GFP accumulation at the sites of cell–cell contact. CBs contact first by the “leading edge” domains (D–D″ and E–E″) where accumulation of actin-GFP (arrowheads) is observed. This cell–cell contact is dramatically enlarged in slit2 and robo/robo2 mutants (F–F″ and L–L″, brackets). (L) Red dotted line labels the newly formed lumen, absent in slit2 (L′) and robo/robo2 (L″) mutants. Bars, 5 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2483531&req=5

fig2: Slit–Robo functions are required to form the cardiac lumen. Reconstructed time-lapse Z views (6-min intervals) taken from videos (Videos 2–4, available at http://www.jcb.org/cgi/content/full/jcb.200801100/DC1) illustrating CB shape changes and lumen formation in wild-type (24B-Gal4; UAS actin-GFP; A–L), slit2 mutant (A′–L′), and robo/robo2 double mutant embryos (A″–L″) from stages 14–16 of embryogenesis. Mutant alleles are in 24B-Gal4; UAS actin-GFP background to visualize CB shape. Wild-type CBs change their shape from rounded (not depicted), to pearlike (A), to crescentlike (L), whereas the CBs of both mutants (slit2 or robo/robo2) remain rounded over the entire period (from A′–L′ to A″–L″). (A, A′, and A″) Red dotted lines delimit the CB shape. Note the highly dynamic actin-GFP accumulation at the sites of cell–cell contact. CBs contact first by the “leading edge” domains (D–D″ and E–E″) where accumulation of actin-GFP (arrowheads) is observed. This cell–cell contact is dramatically enlarged in slit2 and robo/robo2 mutants (F–F″ and L–L″, brackets). (L) Red dotted line labels the newly formed lumen, absent in slit2 (L′) and robo/robo2 (L″) mutants. Bars, 5 μm.
Mentions: At the onset of dorsal closure, CBs adopt a pearlike shape consecutive to constriction of their domain facing the dorsal midline (Fig. 1, F and F′, compared with Fig. 1, E and E′). Actin-rich cytoplasmic extensions grow from this membrane domain, which constitutes the leading edge of the dorsally migrating CBs (Fig. 1 B, arrowheads). CBs from each of the two rows come progressively into contact at their leading edges and join at the dorsal midline (Fig. 1, B, G, and G′). Subsequently, CBs adopt a crescentlike shape (Fig. 1, H and H′), which allows their bases to join ventrally and thus to close the tube (Fig. 1, I and I′), creating an internal lumen. During this step, which takes ∼60 min (see Fig. 2 and Videos 1 and 2), the dorsal part of CBs detaches from the dorsal ectoderm. Throughout this process, CBs increase their size and keep growing after tube closure; as a result, the lumen enlarges progressively (Fig. 1, D and I). Thus, our in vivo analysis provides for the first time a step by step description of the dynamics of cardiac tube formation. It confirms previous observations (Rugendorff et al., 1994; Haag et al., 1999) made on fixed preparations and provides, in addition, a highly tractable new method for analyzing in vivo CB cell behavior in wild-type and mutant backgrounds.

Bottom Line: Our study of cell behavior using three-dimensional and time-lapse imaging and the distribution of cell polarity markers reveals a new mechanism of tubulogenesis in which repulsion of prepatterned luminal domains with basal membrane properties and cell shape remodeling constitute the main driving forces.From these data we propose a model for D. melanogaster cardiac lumen formation, which differs, both at a cellular and molecular level, from current models of epithelial tubulogenesis.We suggest that this new example of tube formation may be helpful in studying vertebrate heart tube formation and primary vasculogenesis.

View Article: PubMed Central - PubMed

Affiliation: Institut de Biologie du Développement de Marseille-Luminy, Centre National de la Recherche Scientifique UMR 6216, Université de la Méditerranée, 13288 Marseille, Cedex 9, France.

ABSTRACT
Tubulogenesis is an essential component of organ development, yet the underlying cellular mechanisms are poorly understood. We analyze here the formation of the Drosophila melanogaster cardiac lumen that arises from the migration and subsequent coalescence of bilateral rows of cardioblasts. Our study of cell behavior using three-dimensional and time-lapse imaging and the distribution of cell polarity markers reveals a new mechanism of tubulogenesis in which repulsion of prepatterned luminal domains with basal membrane properties and cell shape remodeling constitute the main driving forces. Furthermore, we identify a genetic pathway in which roundabout, slit, held out wings, and dystroglycan control cardiac lumen formation by establishing nonadherent luminal membranes and regulating cell shape changes. From these data we propose a model for D. melanogaster cardiac lumen formation, which differs, both at a cellular and molecular level, from current models of epithelial tubulogenesis. We suggest that this new example of tube formation may be helpful in studying vertebrate heart tube formation and primary vasculogenesis.

Show MeSH
Related in: MedlinePlus