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Forming a complex with MHC class I molecules interferes with mouse CD1d functional expression.

Gourapura RJ, Khan MA, Gallo RM, Shaji D, Liu J, Brutkiewicz RR - PLoS ONE (2013)

Bottom Line: CD1d molecules are structurally similar to MHC class I, but present lipid antigens as opposed to peptides.Low pH (3.0) acid stripping of MHC class I molecules resulted in increased surface expression of murine CD1d on antigen presenting cells as well as augmented CD1d-mediated antigen presentation to NKT cells.Together, these results suggest that MHC class I molecules can regulate NKT cell function, in part, by masking CD1d.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA.

ABSTRACT
CD1d molecules are structurally similar to MHC class I, but present lipid antigens as opposed to peptides. Here, we show that MHC class I molecules physically associate with (and regulate the functional expression of) mouse CD1d on the surface of cells. Low pH (3.0) acid stripping of MHC class I molecules resulted in increased surface expression of murine CD1d on antigen presenting cells as well as augmented CD1d-mediated antigen presentation to NKT cells. Consistent with the above results, TAP1-/- mice were found to have a higher percentage of type I NKT cells as compared to wild type mice. Moreover, bone marrow-derived dendritic cells from TAP1-/- mice showed increased antigen presentation by CD1d compared to wild type mice. Together, these results suggest that MHC class I molecules can regulate NKT cell function, in part, by masking CD1d.

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Murine MHC class I and CD1d molecules physically associate.(A and B) Lysates from BMDCs (A) or mock-treated and acid-stripped KT4-CD1d1, KT4-CD1d1TD, or KT4-control cells (B) were co-immunoprecipitated with the 1H6 mAb or an isotype control mAb and immunoblotted with an anti-MHC class I mAb. Presence of a MHC class I–specific band in the lane loaded with lysate co-immunoprecipitated with the CD1d-specific mAb 1H6, but not in the lane loaded with lysates treated with an isotype control mAb, shows the association of MHC class I and CD1d molecules. The graphs below (B) indicate relative band intensities. (C) Mock- or acid-treated KT4-CD1d1 cells were lysed to prepare membrane and cytosolic fractions; the association of MHC class I and CD1d was analyzed in both fractions. (D) Confocal microscopy shows co-localization of CD1d (green) and MHC class I (red). (E) KT4-CD1d1, KT4-CD1d1TD and KT4-control cells were mock-infected or infected with a control VV or VV-TAP1 for 4 h. Cells were lysed and co-immunoprecipitated with the 1H6 mAb and immunoblotted with an anti-MHC class I mAb.
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pone-0072867-g004: Murine MHC class I and CD1d molecules physically associate.(A and B) Lysates from BMDCs (A) or mock-treated and acid-stripped KT4-CD1d1, KT4-CD1d1TD, or KT4-control cells (B) were co-immunoprecipitated with the 1H6 mAb or an isotype control mAb and immunoblotted with an anti-MHC class I mAb. Presence of a MHC class I–specific band in the lane loaded with lysate co-immunoprecipitated with the CD1d-specific mAb 1H6, but not in the lane loaded with lysates treated with an isotype control mAb, shows the association of MHC class I and CD1d molecules. The graphs below (B) indicate relative band intensities. (C) Mock- or acid-treated KT4-CD1d1 cells were lysed to prepare membrane and cytosolic fractions; the association of MHC class I and CD1d was analyzed in both fractions. (D) Confocal microscopy shows co-localization of CD1d (green) and MHC class I (red). (E) KT4-CD1d1, KT4-CD1d1TD and KT4-control cells were mock-infected or infected with a control VV or VV-TAP1 for 4 h. Cells were lysed and co-immunoprecipitated with the 1H6 mAb and immunoblotted with an anti-MHC class I mAb.

Mentions: MHC class I molecules have been reported to be physically associated with MHC class II molecules at the cell surface [39]. Although CD1d is structurally similar to MHC class I, its intracellular trafficking is similar to MHC class II molecules. CD1d and MHC class II molecules have also been found to be associated both at cell surface and in endocytic compartments [40,41]. To understand the mechanism of how CD1d-mediated Ag presentation is altered by the acid stripping of cell surface MHC class I, we asked whether CD1d and MHC class I molecules form a complex. We looked for the association of CD1d and MHC class I molecules in BMDCs by immunoprecipitating CD1d and performing a Western blot to detect MHC class I. CD1d and MHC class I molecules were indeed found to be associated in BMDCs (Figure 4A).


Forming a complex with MHC class I molecules interferes with mouse CD1d functional expression.

Gourapura RJ, Khan MA, Gallo RM, Shaji D, Liu J, Brutkiewicz RR - PLoS ONE (2013)

Murine MHC class I and CD1d molecules physically associate.(A and B) Lysates from BMDCs (A) or mock-treated and acid-stripped KT4-CD1d1, KT4-CD1d1TD, or KT4-control cells (B) were co-immunoprecipitated with the 1H6 mAb or an isotype control mAb and immunoblotted with an anti-MHC class I mAb. Presence of a MHC class I–specific band in the lane loaded with lysate co-immunoprecipitated with the CD1d-specific mAb 1H6, but not in the lane loaded with lysates treated with an isotype control mAb, shows the association of MHC class I and CD1d molecules. The graphs below (B) indicate relative band intensities. (C) Mock- or acid-treated KT4-CD1d1 cells were lysed to prepare membrane and cytosolic fractions; the association of MHC class I and CD1d was analyzed in both fractions. (D) Confocal microscopy shows co-localization of CD1d (green) and MHC class I (red). (E) KT4-CD1d1, KT4-CD1d1TD and KT4-control cells were mock-infected or infected with a control VV or VV-TAP1 for 4 h. Cells were lysed and co-immunoprecipitated with the 1H6 mAb and immunoblotted with an anti-MHC class I mAb.
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Related In: Results  -  Collection

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pone-0072867-g004: Murine MHC class I and CD1d molecules physically associate.(A and B) Lysates from BMDCs (A) or mock-treated and acid-stripped KT4-CD1d1, KT4-CD1d1TD, or KT4-control cells (B) were co-immunoprecipitated with the 1H6 mAb or an isotype control mAb and immunoblotted with an anti-MHC class I mAb. Presence of a MHC class I–specific band in the lane loaded with lysate co-immunoprecipitated with the CD1d-specific mAb 1H6, but not in the lane loaded with lysates treated with an isotype control mAb, shows the association of MHC class I and CD1d molecules. The graphs below (B) indicate relative band intensities. (C) Mock- or acid-treated KT4-CD1d1 cells were lysed to prepare membrane and cytosolic fractions; the association of MHC class I and CD1d was analyzed in both fractions. (D) Confocal microscopy shows co-localization of CD1d (green) and MHC class I (red). (E) KT4-CD1d1, KT4-CD1d1TD and KT4-control cells were mock-infected or infected with a control VV or VV-TAP1 for 4 h. Cells were lysed and co-immunoprecipitated with the 1H6 mAb and immunoblotted with an anti-MHC class I mAb.
Mentions: MHC class I molecules have been reported to be physically associated with MHC class II molecules at the cell surface [39]. Although CD1d is structurally similar to MHC class I, its intracellular trafficking is similar to MHC class II molecules. CD1d and MHC class II molecules have also been found to be associated both at cell surface and in endocytic compartments [40,41]. To understand the mechanism of how CD1d-mediated Ag presentation is altered by the acid stripping of cell surface MHC class I, we asked whether CD1d and MHC class I molecules form a complex. We looked for the association of CD1d and MHC class I molecules in BMDCs by immunoprecipitating CD1d and performing a Western blot to detect MHC class I. CD1d and MHC class I molecules were indeed found to be associated in BMDCs (Figure 4A).

Bottom Line: CD1d molecules are structurally similar to MHC class I, but present lipid antigens as opposed to peptides.Low pH (3.0) acid stripping of MHC class I molecules resulted in increased surface expression of murine CD1d on antigen presenting cells as well as augmented CD1d-mediated antigen presentation to NKT cells.Together, these results suggest that MHC class I molecules can regulate NKT cell function, in part, by masking CD1d.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA.

ABSTRACT
CD1d molecules are structurally similar to MHC class I, but present lipid antigens as opposed to peptides. Here, we show that MHC class I molecules physically associate with (and regulate the functional expression of) mouse CD1d on the surface of cells. Low pH (3.0) acid stripping of MHC class I molecules resulted in increased surface expression of murine CD1d on antigen presenting cells as well as augmented CD1d-mediated antigen presentation to NKT cells. Consistent with the above results, TAP1-/- mice were found to have a higher percentage of type I NKT cells as compared to wild type mice. Moreover, bone marrow-derived dendritic cells from TAP1-/- mice showed increased antigen presentation by CD1d compared to wild type mice. Together, these results suggest that MHC class I molecules can regulate NKT cell function, in part, by masking CD1d.

Show MeSH
Related in: MedlinePlus