Successful compaction from morula to blastula involves:
Compaction to form morula requires establishment of strong cell-cell adhesion mediated by E-cadherin, a calcium-dependent adhesion molecule. Extracellular calcium rigidifies cadherin repeats enabling trans-homophilic binding between blastomeres, intracellularly binding beta-catenin which links to alpha-catenin and actin cytoskeleton. Activation and clustering of this cadherin-catenin complex drives blastomere flattening, polarization, tighter apposition and induction of tight junction formation. Blockage of cadherin or removal of calcium prevents compaction, while calcium ionophores alone with
Ref: Maître JL et al., Nature Cell Biology 2015: E-cadherin beta-catenin regulation of compaction and Hippo mediated cell fate.
