Regulation of cell adhesion during embryonic compaction of mammalian embryos: Roles for PKC and ?-catenin

TCL1 participates in early embryonic development and is overexpressed in human seminomas

“…The mouse zygotic genome is transcriptionally activated soon after the first embryo cleavage (15,20,23). Two additional mitotic divisions then lead the embryo to the 8-cell stage at which its peripheral blastomeres compact and establish tight and gap junctional communications with each other (21,24), eventually resulting in blastocoel cavity formation. Our results indicate that Tcl1-deficient embryos acquire major differentiative traits normally and with the appropriate developmental timing.…”

PKC Regulation of Gametogenesis and Early Development

“…Reports from Capco (1999, 2000) have shown a marked reduction in the nuclear localization of these isotypes after the two-cell stage with the exception that PKC lines the nuclear periphery at the four-cell stage. However, these isotypes appear in unique locations poised to presumably interact during subsequent developmental transitions: At the time of compaction PKC , , , and µ line the cell-cell boundaries to differing extents, and these isotypes are considerably absent from the nucleus (Pauken & Capco, 1999. During the late eight-cell stage just prior to compaction the isotype is greatly enriched in the nuclei (Pauken & Capco, 2000).…”

“…Moreover, when PKC was experimentally activated by the natural agonist (DiC8 a diacylglycerol and natural activator of PKC) it induces PKC to localize at internal cell-cell boundaries. Then -catenin becomes phosphorylated and accumulates at these internal cell-cell boundaries as the blastomeres begin to flatten out on each other during the process of embryonic compaction (Pauken & Capco, 1999). In addition, it was shown that immediately before compaction beginscatenin becomes part of the detergent-resistant cytoskeleton at intercellular boundaries indicative of its association with the adherens junctions that are responsible for adhering and subsequently flattening of the blastomeres later during compaction (Pauken & Capco, 1999).…”

Morphogenesis of the mammalian blastocyst

“…β-catenin, which is phosphorylated on ser/thr residues at the time of compaction, is likely to be a target of this signaling cascade. (Goval et al, 2000;Pauken and Capco, 1999). The cytoskeleton protein ezrin is another good candidate (Louvet-Vallée et al, 2001).…”