Differential requirement for tapasin in the presentation of leader- and insulin-derived peptide antigens to Qa-1b-restricted CTLs.
| Autor: | Li L; Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA., Sullivan BA, Aldrich CJ, Soloski MJ, Forman J, Grandea AG 3rd, Jensen PE, Van Kaer L |
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| Jazyk: | angličtina |
| Zdroj: | Journal of immunology (Baltimore, Md. : 1950) [J Immunol] 2004 Sep 15; Vol. 173 (6), pp. 3707-15. |
| DOI: | 10.4049/jimmunol.173.6.3707 |
| Abstrakt: | The loading of MHC class I molecules with peptides involves a variety of accessory proteins, including TAP-associated glycoprotein (tapasin), which tethers empty MHC class I molecules to the TAP peptide transporter. We have evaluated the role of tapasin for the assembly of peptides with the class Ib molecule Qa-1b. In normal cells, Qa-1b is predominantly bound by a peptide, the Qa-1 determinant modifier (Qdm), derived from the signal sequence of class Ia molecules. Our results show that tapasin links Qa-1b to the TAP peptide transporter, and that tapasin facilitates the delivery of Qa-1b molecules to the cell surface. Tapasin was also required for the presentation of endogenous Qdm peptides to Qdm-specific, Qa-1b-restricted CTLs. In sharp contrast, tapasin expression was dispensable for the presentation of an insulin peptide to insulin-specific, Qa-1b-restricted CTL isolated from TCR transgenic mice. However, tapasin deficiency significantly impaired the positive selection of these insulin-specific, Qa-1b-restricted transgenic CD8+ T cells. These findings reveal that tapasin plays a differential role in the loading of Qdm and insulin peptides onto Qa-1b molecules, and that tapasin is dispensable for retention of empty Qa-1b molecules in the endoplasmic reticulum, and are consistent with the proposed peptide-editing function of tapasin. (Copyright 2004 The American Association of Immunologists, Inc.) |
| Databáze: | MEDLINE |
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