The CD3ζ adaptor structure determines functional differences between human and mouse CD16 Fc receptor signaling

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Natural killer (NK) cells utilize the CD16 Fc receptor to identify antibody-coated cells.
• The role of CD16 in human NK cell function is well-established, but its mechanism in mouse NK cells is unclear.

Purpose of the Study:

• To investigate the functional differences of CD16 in human versus mouse NK cells.
• To identify the molecular mechanisms underlying these disparities, focusing on the adaptor molecule CD3ζ.

Main Methods:

• Comparative analysis of CD16 and CD3ζ interactions in human and mouse NK cells.
• Site-directed mutagenesis of CD3ζ transmembrane domain residues.
• Assessment of CD16 receptor complex formation and function.

Main Results:

• Significant functional differences exist between human and mouse CD16 in NK cells.
• Specific residues in the mouse CD3ζ transmembrane domain impede CD16 complex formation and signaling.
• Mutating these mouse CD3ζ residues to their human counterparts restored CD16 function.
• Mouse CD3ζ exhibits a conformation that prevents CD16 association, contrasting with the adaptable human CD3ζ.

Conclusions:

• The transmembrane domain of CD3ζ is a key determinant of CD16 function in NK cells.
• Structural differences in CD3ζ explain the distinct CD16-mediated signaling pathways in mice and humans.
• Understanding these differences is crucial for deciphering NK cell immunity in different species.