Ayu (Plecoglossus altivelis) CD46 isoforms protect the cells from autologous complement attack

Area of Science:

• Immunology
• Marine Biology
• Molecular Biology

Background:

• CD46 (membrane cofactor protein) is a crucial immune regulatory receptor with diverse functions.
• Research on teleost (fish) CD46, particularly its isoforms, is limited.
• Understanding fish CD46 is vital for comparative immunology and aquaculture health.

Purpose of the Study:

• To identify and characterize novel CD46 isoforms in ayu (Plecoglossus altivelis).
• To investigate the functional role of these ayu CD46 (PaCD46) isoforms in immune regulation.
• To explore their potential as complement regulatory proteins.

Main Methods:

• Identification of three PaCD46 isoforms through gene sequencing.
• Phylogenetic analysis to determine evolutionary relationships.
• Western blotting to analyze protein expression and molecular weight.
• Functional assays including hemolysis reduction and cell protection against complement activation.

Main Results:

• Three distinct PaCD46 isoforms were identified, generated by alternative splicing.
• Phylogenetic analysis placed ayu CD46 with other fish and higher animal CD46.
• Western blotting revealed higher molecular weights than predicted, suggesting post-translational modifications.
• Recombinant PaCD46 isoforms reduced serum hemolysis and protected cells from complement-mediated damage.

Conclusions:

• The identified PaCD46 isoforms possess complement regulatory functions.
• These isoforms likely prevent complement-induced damage to self-tissues in ayu.
• This study provides the first evidence of CD46 isoform function in ayu, contributing to fish immunology.