Adherens junction-dependent and -independent steps in the establishment of epithelial cell polarity in Drosophila.
Adherens junctions (AJs) are thought to be key landmarks for establishing epithelial cell polarity, but the origin of epithelial polarity in Drosophila remains unclear. Thus, we examined epithelial polarity establishment during early Drosophila development. We found apical accumulation of both Drosophila E-Cadherin (DE-Cad) and the apical cue Bazooka (Baz) as cells first form. Mutant analyses revealed that apical Baz accumulations can be established in the absence of AJs, whereas assembly of apical DE-Cad complexes requires Baz. Thus, Baz acts upstream of AJs during epithelial polarity establishment. During gastrulation the absence of AJs results in widespread cell dissociation and depolarization. Some epithelial structures are retained, however. These structures maintain apical Baz, accumulate apical Crumbs, and organize polarized cytoskeletons, but display abnormal cell morphology and fail to segregate the basolateral cue Discs large from the apical domain. Thus, although epithelial polarity develops in the absence of AJs, AJs play specific roles in maintaining epithelial architecture and segregating basolateral cues.
Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Tony J C
TJ
Harris
Mark
M
Peifer
D000199:Actins / Q000378:metabolism; D022005:Adherens Junctions / Q000378:metabolism*; D000818:Animals; D019521:Body Patterning; D015820:Cadherins / Q000096:biosynthesis / Q000378:metabolism; D002454:Cell Differentiation; D003433:Crosses, Genetic; D003599:Cytoskeleton / Q000378:metabolism; D004252:DNA Mutational Analysis; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins / Q000096:biosynthesis; D004847:Epithelial Cells / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D005260:Female; D007091:Image Processing, Computer-Assisted; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D010641:Phenotype; D017434:Protein Structure, Tertiary; D013997:Time Factors
D000199:Actins; D015820:Cadherins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; C400774:baz protein, Drosophila