The evolutionary origin of epithelial cell-cell adhesion mechanisms

Area of Science:

• Evolutionary Biology
• Cell Biology
• Biochemistry

Background:

• Simple epithelia form essential organismal barriers and represent early multicellular tissues.
• The classical cadherin/β-catenin/α-catenin complex (CCC) is crucial for cell-cell adhesion.

Purpose of the Study:

• To investigate the evolutionary origins and functional diversification of the CCC.
• To understand the relationship between CCC evolution and epithelial development.

Main Methods:

• Phylogenetic analysis using updated genomic data.
• Comparative review of CCC functional properties across metazoan and non-metazoan taxa.

Main Results:

• The core CCC likely predates the last common ancestor of unikonts and bikonts.
• CCC formation may have constrained the evolution of cadherin and β-catenin sequences in metazoans.
• The ancestral α/β-catenin heterodimer functioned as an actin-binding module, with later gains in α-catenin complexity.

Conclusions:

• The CCC's ancient origins highlight its fundamental role in multicellularity.
• Sequence divergence in α-catenin domains facilitated complex actin cytoskeleton regulation.
• Allosteric regulation of α-catenin may represent a later evolutionary innovation.