Apical junctions and cell signalling in epithelia

Woods, Daniel F.; Bryant, Peter J.

doi:10.1242/jcs.1993.supplement_17.25

Cited by 86 publications

(57 citation statements)

References 102 publications

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“…Consistent with earlier studies in vertebrate and insect epithelia, we' found that in embryos PY epitopes were localized to the electron-dense cytoplasmic plaques of the ZA ( Fig. 1) (Takata and Singer, 1988;Tsukita et al, 1991, Woods andBryant, 1993). Optical sections through stained wild-type embryos of different stages revealed that Arm and PY colocalize to a large extent (Fig.…”

Section: Formation Of the Za And Basolateral Membrane Identity In Thesupporting

confidence: 90%

armadillo, bazooka, and stardust are critical for early stages in formation of the zonula adherens and maintenance of the polarized blastoderm epithelium in Drosophila.

Müller

Wieschaus

1996

The Journal of Cell Biology

375

354

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Abstract. Cellularization of the Drosophila embryo resuits in the formation of a cell monolayer with many characteristics of a polarized epithelium. We have used antibodies specific to cellular junctions and nascent plasma membranes to study the formation of the zonula adherens (ZA) in relation to the establishment of basolateral membrane polarity. The same approach was then used as a test system to identify X-linked zygotically active genes required for ZA formation. We show that ZA formation begins during cellularization and that the basolateral membrane domain is established at mid-gastrulation. By creating deficiences for defined regions of the X chromosome, we have identified genes that are required for the formation of the ZA and the generation of basolateral membrane polarity. We show that embryos mutant for both stardust (sdt) and bazooka (baz) fail to form a ZA. In addition to the failure to establish the ZA, the formation of the monolayered epithelium is disrupted after cellularization, resulting in formation of a multilayered cell sheet by mid-gastrulation. SEM analysis of mutant embryos revealed a conversion of cells exhibiting epithelial characteristics into cells exhibiting mesenchymal characteristics. To investigate how mutations that affect an integral component of the ZA itself influence ZA formation, we examined embryos with reduced maternal and zygotic supply of wild-type Arm protein. These embryos, like embryos mutant for both sdt and baz, exhibit an early disruption of ZA formation. These results suggest that early stages in the assembly of the ZA are critical for the stability of the polarized blastoderm epithelium.

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Section: Formation Of the Za And Basolateral Membrane Identity In Thesupporting

confidence: 90%

armadillo, bazooka, and stardust are critical for early stages in formation of the zonula adherens and maintenance of the polarized blastoderm epithelium in Drosophila.

Müller

Wieschaus

1996

The Journal of Cell Biology

375

354

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“…Arthropods, including insects, have septate junctions that are considered to be functional equivalents to tight junctions of vertebrates (47). The tight junction has been shown to be a barrier that prevents materials from going through the intercellular space and maintains cell polarity.…”

Section: Figmentioning

confidence: 99%

Cuticular Pro-phenoloxidase of the Silkworm, Bombyx mori

Asano

Ashida

2001

Journal of Biological Chemistry

113

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Pro-phenoloxidase (proPO) in insects is implicated in the defense against microbes and wounding. The presence of proPO in the cuticle was suggested more than 30 years ago, but it has not been purified. The extract of cuticles of the silkworm, Bombyx mori, was shown to contain two proPO isoforms (F-type and S-type proPOs, which have slightly different mobilities in polyacrylamide gel electrophoresis under nondenaturing conditions). The two isoforms were purified to homogeneity. From hemolymph of the same insect, two types of proPO with the same electrophoretic mobilities as those of cuticular isoforms were separated and were shown to be different at five amino acid residues in one of their subunits. The isoforms in the hemolymph and cuticle were activated by a specific activating enzyme. The resulting active phenoloxidases exhibited almost the same substrate specificities and specific activities toward odiphenols. The substrate specificities and the susceptibilities to inhibitors, including carbon monoxide, indicated that the purified proPO isoforms were not zymogens of laccase-type phenoloxidase. The proPO in hemolymph was shown to be transported to the cuticle. This demonstration was corroborated by the failure to detect proPO transcripts by Northern analysis of total RNA from epidermal cells. In reversed-phase column chromatography, cuticular and hemolymph proPOs gave distinct elution profiles, indicating that some yet to be identified modification occurs in hemolymph proPO and results in the formation of cuticular proPO. There was little transportation of cuticular proPO to the cuticle when it was injected into the hemocoel. The nature of the modification is described in the accompanying paper (Asano, T., and Ashida, M. (2001) J. Biol. Chem. 276, 11113-11125).

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“…In ectodermal epithelia of the wild-type embryo, DE-cadherin was restricted to an apical position of cell-cell contacts, and its distribution was segregated from the territory of fasciclin III, a marker for the septate junction, which is located in the subapico-lateral region (Patel et al 1987;Woods and Bryant 1993;see Fig. 2A).…”

Section: De-cadherin Is Encoded By Shotgunmentioning

confidence: 99%

Zygotic Drosophila E-cadherin expression is required for processes of dynamic epithelial cell rearrangement in the Drosophila embryo.

Uemura¹,

Oda²,

Kraut³

et al. 1996

Genes Dev.

285

217

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Dynamic epithelial reorganization is essential for morphogenesis of various organs. In Drosophila embryos, for example, the Malpighian tubule is generated by cellular rearrangement of a preexisting epithelium and the tracheal network is formed by outgrowth, branching, and fusion of epithelial vesicles. Here we report that the previously identified locus shotgun (shg) encodes DE-cadherin, an epithelial cell-cell adhesion molecule of the classic cadherin type and that zygotic shg mutations rather specifically impair processes of the dynamic epithelial morphogenesis. In the mutants, the Malpighian tubule disintegrated into small spherical structures, and the tracheal network formation was blocked in selected steps. The malformation of these organs could be rescued by overexpression of DE-cadherin cDNA under a heat shock promoter. Unexpectedly, the zygotic null condition did not severely affect general epithelial organization; most epithelial tissues maintained not only their cell-cell associations but also their apicobasal polarity in the mutants. The zygotic null mutant retained a certain level of maternally derived DE-cadherin molecules until the end of embryogenesis. These results suggest that zygotic DE-cadherin expression is critical for the rearrangement processes of epithelial cells, whereas the maternally derived DE-cadherin may serve only for the maintenance of the static architecture of the epithelia. [Key Words: DE-cadherin; tubulogenesis; cell rearrangement; Drosophila]Received November 20, 1995; revised version accepted January 29, 1996.Epithelial cells can reposition themselves without breaking the cell layer. This type of cellular rearrangement plays an important role in the production of tissues or organs of diverse morphology (for review, see Gumbiner 1992). A well-known example is amphibian gastrulation, in which a process of intercellular movement, called convergent extension, causes a dramatic elongation of the mesodermal tissue (Keller et al. 1992). In Drosophila embryos, a similar mechanism operates for morphogenesis of tubular organs. These include Malpighian tubules (MTs) and probably tracheal trees as well, both of which are of ectodermal origin and simple epithelial monolayers. MTs arise from the posterior region of the hindgut {for review, see Skaer 1992Skaer , 1993. Primordia of the tubules first grow out by cell divisions, and when the proliferation is complete, 12-14 cells encircle the lumen. Subsequently the cells start shifting 4Corresponding author. 5Present address:

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Apical junctions and cell signalling in epithelia

Cited by 86 publications

References 102 publications

armadillo, bazooka, and stardust are critical for early stages in formation of the zonula adherens and maintenance of the polarized blastoderm epithelium in Drosophila.

armadillo, bazooka, and stardust are critical for early stages in formation of the zonula adherens and maintenance of the polarized blastoderm epithelium in Drosophila.

Cuticular Pro-phenoloxidase of the Silkworm, Bombyx mori

Zygotic Drosophila E-cadherin expression is required for processes of dynamic epithelial cell rearrangement in the Drosophila embryo.

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