Unglycosylated Mtaa expresses an Mtab-like determinant.

Area of Science:

• Immunology
• Mitochondrial Genetics
• Molecular Biology

Background:

• Antigenic polymorphism in maternally transmitted antigen (Mta) is regulated by a maternally transmitted factor (Mtf), likely located in mitochondria.
• The precise mechanisms by which Mtf generates Mta antigenic polymorphism remain unclear.

Purpose of the Study:

• To investigate the role of posttranslational oligosaccharide addition in the formation of Mta determinants.
• To explore how Mtf contributes to Mta polymorphism through glycosylation.

Main Methods:

• Examined Mta expression on cytotoxic T lymphocyte (CTL) target cells cultured with tunicamycin (TM), an inhibitor of N-linked glycosylation.
• Tested lysis of TM-treated Mtaa targets by Mtab-specific CTL lines.
• Utilized a specific CTL clone (17D5.G2) to assess Mtab-like determinant expression on various Mtaa strains and Mta null cells.

Main Results:

• Eight of 18 Mtab-specific CTL lines lysed TM-treated Mtaa targets.
• A subclone (17D5.G2) lysed TM-treated targets from all tested Mtaa strains, irrespective of H-2K/D haplotype.
• This CTL clone did not lyse TM-treated target cells from Mta null strains, indicating Mtab-like determinant expression is concordant with Mtaa expression.

Conclusions:

• Data suggest an Mtab-like determinant is expressed on unglycosylated Mtaa molecules.
• N-linked oligosaccharides likely inhibit the expression of Mtab-like determinants on Mtaa.
• Mtf may influence Mta polymorphism via glycosylation pathways.