Chaperone protein HSC70 regulates intercellular transfer of Y chromosome antigen DBY
Sascha Kretschmann, Stefanie Herda, Heiko Bruns, Josefine Russ, Edith D. van der Meijden, Ursula Schlötzer-Schrehardt, Marieke Griffioen, Il-Kang Na, Andreas Mackensen, Anita N. Kremer
Sascha Kretschmann, Stefanie Herda, Heiko Bruns, Josefine Russ, Edith D. van der Meijden, Ursula Schlötzer-Schrehardt, Marieke Griffioen, Il-Kang Na, Andreas Mackensen, Anita N. Kremer
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Research Article Immunology Oncology

Chaperone protein HSC70 regulates intercellular transfer of Y chromosome antigen DBY

Abstract

Recent studies have demonstrated that CD4+ T cells can efficiently reject MHC-II–negative tumors. This requires indirect presentation of tumor-associated antigens on surrounding antigen-presenting cells. We hypothesized that intercellular transfer of proteins is not the sole consequence of cell death–mediated protein release, but depends on heat-shock cognate protein 70 (HSC70) and its KFERQ-like binding motif on substrate proteins. Using human Y chromosome antigen DBY, we showed that mutation of one of its 2 putative binding motifs markedly diminished T cell activation after indirect presentation and reduced protein-protein interaction with HSC70. Intercellular antigen transfer was shown to be independent of cell-cell contact, but relied on engulfment within secreted microvesicles. In vivo, alterations of the homologous KFERQ-like motif in murine DBY hampered tumor rejection, T cell activation, and migration into the tumor and substantially impaired survival. Collectively, we show that intercellular antigen transfer of DBY is tightly regulated via binding to HSC70 and that this mechanism influences recognition and rejection of MHC-II–negative tumors in vivo.

Authors

Sascha Kretschmann, Stefanie Herda, Heiko Bruns, Josefine Russ, Edith D. van der Meijden, Ursula Schlötzer-Schrehardt, Marieke Griffioen, Il-Kang Na, Andreas Mackensen, Anita N. Kremer

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Figure 1

Characterization of putative KFERQ-like motifs in human DBY and retrovirally transduced HeLa cells.

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Characterization of putative KFERQ-like motifs in human DBY and retrovir...
(A) Depicted are the 2 identified KFERQ-like motifs in human DBY (motifs 1 and 2), each of which is displayed in its WT (DBY) and mutated representation (MUT). Letters represent amino acids (one letter code) and numbers give information on the protein position. (B) Schematic representation of human DBX and DBY protein constructs illustrating the relative position of mutated KFERQ-like motifs (red bars), the CD4+ T cell epitope (blue bars), and the fused myc-tag at the C terminus (dashed line). Representation of WT or mutant KFERQ-like motifs is shown on the right. (C) Western blot analysis of retrovirally transduced HeLa cells. (D) Depicted is the mean fluorescence intensity per cell of retrovirally transduced HeLa cells from a single immunofluorescence imaging experiment. Data are shown as mean ± SEM and were quantified using ImageJ software (NIH).