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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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Aberrant setting of CB membrane domains in slit2 mutant embryos. (A–F) Merged Z views of CBs from slit2 mutant embryos stained with Arm (red), Dg (green), and How (blue) antibodies at different stages of embryogenesis (from stages 13–14 in A to stage 16 in F). A′–F′ show Arm and How, whereas A″–F″ show Dg and How staining. CBs keep their initial rounded shape during all stages of cardiac tube formation. Initially, Arm is correctly localized at the future J domains (arrowheads), but is not completely excluded from the Dg-positive domain as it is in the wild type (A′–C′, compared with Fig. 4, E′ and F′). When CBs join dorsally, Arm shows an extended area of expression compared with the wild type (Fig. 5, E and E′ [arrowheads], compare with Fig. 4, G–H and G′–H′). Finally, in a few cases a lumen can be detected, Arm is localized all along the extended dorsal J domain (Fig. 5 F, compare arrowheads with Fig. 4 J). (G) Schematic representation of CB shape dynamics and membrane domains in slit2 mutant embryos (compare with Fig. 4 K). Step 1 is similar to that of the wild type except that the Arm-positive domain is larger in the mutant, and, as a consequence, Dg and Arm partially colocalize. (2) In the mutant, CBs do not change their shape, do not form a leading edge (3), and make contact by an enlarged Arm-positive J domain. Finally, CBs are either not able to form a lumen (4) or, rarely (5), they show an ectopic small lumen formed ventrally. Bars, 4 μm.
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fig5: Aberrant setting of CB membrane domains in slit2 mutant embryos. (A–F) Merged Z views of CBs from slit2 mutant embryos stained with Arm (red), Dg (green), and How (blue) antibodies at different stages of embryogenesis (from stages 13–14 in A to stage 16 in F). A′–F′ show Arm and How, whereas A″–F″ show Dg and How staining. CBs keep their initial rounded shape during all stages of cardiac tube formation. Initially, Arm is correctly localized at the future J domains (arrowheads), but is not completely excluded from the Dg-positive domain as it is in the wild type (A′–C′, compared with Fig. 4, E′ and F′). When CBs join dorsally, Arm shows an extended area of expression compared with the wild type (Fig. 5, E and E′ [arrowheads], compare with Fig. 4, G–H and G′–H′). Finally, in a few cases a lumen can be detected, Arm is localized all along the extended dorsal J domain (Fig. 5 F, compare arrowheads with Fig. 4 J). (G) Schematic representation of CB shape dynamics and membrane domains in slit2 mutant embryos (compare with Fig. 4 K). Step 1 is similar to that of the wild type except that the Arm-positive domain is larger in the mutant, and, as a consequence, Dg and Arm partially colocalize. (2) In the mutant, CBs do not change their shape, do not form a leading edge (3), and make contact by an enlarged Arm-positive J domain. Finally, CBs are either not able to form a lumen (4) or, rarely (5), they show an ectopic small lumen formed ventrally. Bars, 4 μm.

Mentions: As CB cell shape changes do not occur in slit2 mutant embryos (Figs. 2 and 3), we decided to investigate the involvement of the Slit–Robo pathway in specifying CB membrane domains by analyzing Arm and Dg expressions in slit2 mutant embryos (Fig. 5). As in wild-type embryos, Arm is observed in the J domains (Fig. 5, A′–F′), as well as Dlg (Fig. S2, B and D) and Lgl (not depicted). However, from the onset of CB migration onward, the Arm-positive domain is clearly expanded and maintained, or even increased when CBs come into contact (Fig. 5, E′ and F′). Correlatively, Arm is first found to partially colocalize with Dg (Fig. 5, A–C). During CB migration, Dg is progressively excluded from the Arm-positive domain to become completely absent from this domain (Fig. 5, D–F) in the cases when the two contralateral CBs make contact (mean of 60% of the CBs constituting the mutant cardiac tube can reach this stage), Dg is displaced toward the ventral boundary of the Arm J domain, underlining, in some cases, an ectopic, small lumenlike structure (Fig. 5 F). Interestingly, Dg is also sometimes recovered at the periphery of these lumenlike structures located inside the cytoplasm of the CB cells (Fig. S3 A, arrows, available at http://www.jcb.org/cgi/content/full/jcb.200801100/DC1). Together, these observations suggest that Slit–Robo function is required for setting the nonadherent L domain, which is critical for the formation of a correct lumen (Fig. 5 G).


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)

Aberrant setting of CB membrane domains in slit2 mutant embryos. (A–F) Merged Z views of CBs from slit2 mutant embryos stained with Arm (red), Dg (green), and How (blue) antibodies at different stages of embryogenesis (from stages 13–14 in A to stage 16 in F). A′–F′ show Arm and How, whereas A″–F″ show Dg and How staining. CBs keep their initial rounded shape during all stages of cardiac tube formation. Initially, Arm is correctly localized at the future J domains (arrowheads), but is not completely excluded from the Dg-positive domain as it is in the wild type (A′–C′, compared with Fig. 4, E′ and F′). When CBs join dorsally, Arm shows an extended area of expression compared with the wild type (Fig. 5, E and E′ [arrowheads], compare with Fig. 4, G–H and G′–H′). Finally, in a few cases a lumen can be detected, Arm is localized all along the extended dorsal J domain (Fig. 5 F, compare arrowheads with Fig. 4 J). (G) Schematic representation of CB shape dynamics and membrane domains in slit2 mutant embryos (compare with Fig. 4 K). Step 1 is similar to that of the wild type except that the Arm-positive domain is larger in the mutant, and, as a consequence, Dg and Arm partially colocalize. (2) In the mutant, CBs do not change their shape, do not form a leading edge (3), and make contact by an enlarged Arm-positive J domain. Finally, CBs are either not able to form a lumen (4) or, rarely (5), they show an ectopic small lumen formed ventrally. Bars, 4 μm.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2483531&req=5

fig5: Aberrant setting of CB membrane domains in slit2 mutant embryos. (A–F) Merged Z views of CBs from slit2 mutant embryos stained with Arm (red), Dg (green), and How (blue) antibodies at different stages of embryogenesis (from stages 13–14 in A to stage 16 in F). A′–F′ show Arm and How, whereas A″–F″ show Dg and How staining. CBs keep their initial rounded shape during all stages of cardiac tube formation. Initially, Arm is correctly localized at the future J domains (arrowheads), but is not completely excluded from the Dg-positive domain as it is in the wild type (A′–C′, compared with Fig. 4, E′ and F′). When CBs join dorsally, Arm shows an extended area of expression compared with the wild type (Fig. 5, E and E′ [arrowheads], compare with Fig. 4, G–H and G′–H′). Finally, in a few cases a lumen can be detected, Arm is localized all along the extended dorsal J domain (Fig. 5 F, compare arrowheads with Fig. 4 J). (G) Schematic representation of CB shape dynamics and membrane domains in slit2 mutant embryos (compare with Fig. 4 K). Step 1 is similar to that of the wild type except that the Arm-positive domain is larger in the mutant, and, as a consequence, Dg and Arm partially colocalize. (2) In the mutant, CBs do not change their shape, do not form a leading edge (3), and make contact by an enlarged Arm-positive J domain. Finally, CBs are either not able to form a lumen (4) or, rarely (5), they show an ectopic small lumen formed ventrally. Bars, 4 μm.
Mentions: As CB cell shape changes do not occur in slit2 mutant embryos (Figs. 2 and 3), we decided to investigate the involvement of the Slit–Robo pathway in specifying CB membrane domains by analyzing Arm and Dg expressions in slit2 mutant embryos (Fig. 5). As in wild-type embryos, Arm is observed in the J domains (Fig. 5, A′–F′), as well as Dlg (Fig. S2, B and D) and Lgl (not depicted). However, from the onset of CB migration onward, the Arm-positive domain is clearly expanded and maintained, or even increased when CBs come into contact (Fig. 5, E′ and F′). Correlatively, Arm is first found to partially colocalize with Dg (Fig. 5, A–C). During CB migration, Dg is progressively excluded from the Arm-positive domain to become completely absent from this domain (Fig. 5, D–F) in the cases when the two contralateral CBs make contact (mean of 60% of the CBs constituting the mutant cardiac tube can reach this stage), Dg is displaced toward the ventral boundary of the Arm J domain, underlining, in some cases, an ectopic, small lumenlike structure (Fig. 5 F). Interestingly, Dg is also sometimes recovered at the periphery of these lumenlike structures located inside the cytoplasm of the CB cells (Fig. S3 A, arrows, available at http://www.jcb.org/cgi/content/full/jcb.200801100/DC1). Together, these observations suggest that Slit–Robo function is required for setting the nonadherent L domain, which is critical for the formation of a correct lumen (Fig. 5 G).

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