Title | Polarity protein Par3/Bazooka follows myosin-dependent junction repositioning. |
Publication Type | Journal Article |
Year of Publication | 2017 |
Authors | Weng, M, Wieschaus, E |
Journal | Dev Biol |
Volume | 422 |
Issue | 2 |
Pagination | 125-134 |
Date Published | 2017 Feb 15 |
ISSN | 1095-564X |
Keywords | Actomyosin, Adherens Junctions, Animals, Down-Regulation, Drosophila melanogaster, Drosophila Proteins, Epithelial-Mesenchymal Transition, Epithelium, Female, Intracellular Signaling Peptides and Proteins, Male, Membrane Proteins, Mesoderm, Snail Family Transcription Factors |
Abstract | <p>The polarity protein Par3/Bazooka (Baz) has been established as a central component of the apical basal polarity system that determines the position of cell-cell junctions in epithelial cells. Consistent with that view, we show that shortly before gastrulation in Drosophila, Baz protein in the mesoderm is down-regulated from junctional sites in response to Snail (Sna) expression. This down-regulation leads to a specific decrease in adherens junctions without affecting other E-Cadherin pools. However, we further show that, interactions between Baz and junctions are not unidirectional. During apical constriction and the internalization of the mesoderm, down-regulation of Baz is transiently blocked as adherens junctions shift apically and are strengthened in response to tension generated by contractile actomyosin. When such junction remodeling is prevented by down-regulating myosin, Baz is lost prematurely in mesodermal epithelium. During such apical shifts, Baz is initially left behind as the junction shifts position, but then re-accumulates at the new location of the junctions. On the dorsal side of the embryo, a similar pattern of myosin activity appears to limit the basal shift in junctions normally driven by Baz that controls epithelium folding. Our results suggest a model where the sensitivity of Baz to Sna expression leads to the Sna-dependent junction disassembly required for a complete epithelium-mesenchymal transition. Meanwhile this loss of Baz-dependent junction maintenance is countered by the myosin-based mechanism which promotes an apical shift and strengthening of junctions accompanied by a transient re-positioning and maintenance of Baz proteins.</p> |
DOI | 10.1016/j.ydbio.2017.01.001 |
Alternate Journal | Dev Biol |
PubMed ID | 28063874 |
PubMed Central ID | PMC5515594 |
Grant List | K99 HD088764 / HD / NICHD NIH HHS / United States R37 HD015587 / HD / NICHD NIH HHS / United States |