Mutations affecting transmembrane segment interactions impair adhesiveness of E-cadherin

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• E-cadherin mediates cell-cell adhesion through lateral clustering.
• Extracellular and cytoplasmic domains are known to influence clustering.
• The role of the transmembrane domain in E-cadherin clustering is largely unknown.

Purpose of the Study:

• To investigate the role of the leucine-rich transmembrane domain of E-cadherin in lateral clustering.
• To determine if self-assembly of the transmembrane domain contributes to E-cadherin-mediated cell adhesion.

Main Methods:

• Analysis of transmembrane domain self-assembly using the ToxR reporter system.
• Introduction of point mutations into the E-cadherin transmembrane domain.
• Transfection of wild-type and mutant E-cadherin into Ltk(-) cells.
• Assessment of cell aggregation and adhesion using cell aggregation assays.

Main Results:

• The transmembrane domain of E-cadherin demonstrates self-assembly properties.
• Specific point mutations disrupting transmembrane segment interactions significantly reduced self-assembly.
• Mutations that impaired self-assembly also led to significantly reduced E-cadherin-mediated cell adhesion.
• Control experiments confirmed unaffected cell-surface expression, catenin interaction, cytoskeletal association, and trypsin resistance.

Conclusions:

• Interactions between E-cadherin transmembrane segments are crucial for self-assembly.
• Transmembrane segment interactions are important for the lateral association of E-cadherin molecules.
• This lateral association is essential for effective E-cadherin-mediated cell-cell adhesion.