PAPC mediates self/non-self-distinction during Snail1-dependent tissue separation.
Bottom Line: First, PAPC attenuates planar cell polarity signaling at the ectoderm-mesoderm boundary to lower cell adhesion and facilitate cleft formation.It consists of short stretches of adherens junction-like contacts inserted between intermediate-sized contacts and large intercellular gaps.These roles of PAPC constitute a self/non-self-recognition mechanism that determines the site of boundary formation at the interface between PAPC-expressing and -nonexpressing cells.
Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5.Show MeSH
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Mentions: To analyze cell–cell interactions across ectoderm–mesoderm boundaries at high resolution, we performed transmission EM (TEM). At low magnification, Brachet’s cleft appeared as an ECM-filled space of irregular width (Fig. 8 A). Large micrometer-sized gaps were intermixed with narrower contacts (Fig. 8 B), which in turn consisted of intermediate contacts 100–300 nm wide and adherens junction–like close contacts <30 nm wide (Fig. 8, C–E), and compatible with cadherin adhesion (Farquhar and Palade, 1963; Miyaguchi, 2000; Tepass et al., 2000). Close contacts occupied 17 ± 1.5% of the cleft length (n = 12 embryos). At intermediate contacts, membranes of adjacent cells typically ran in parallel, bending sharply when they opened into larger spaces, suggesting that cell adhesion occurred across these contacts.
Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5.