A Critical Analysis of the Role of SNARE Protein SEC22B in Antigen Cross-Presentation

S Julia Wu; Yashar S Niknafs; Stephanie H Kim; Katherine Oravecz-Wilson; Cynthia Zajac; Tomomi Toubai; Yaping Sun; Jayendra Prasad; Daniel Peltier; Hideaki Fujiwara; Israel Hedig; Nathan D Mathewson; Rami Khoriaty; David Ginsburg; Pavan Reddy

doi:10.1016/j.celrep.2017.06.013

A Critical Analysis of the Role of SNARE Protein SEC22B in Antigen Cross-Presentation

Cell Rep. 2017 Jun 27;19(13):2645-2656. doi: 10.1016/j.celrep.2017.06.013.

Authors

Affiliations

¹ Program in Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
² Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
³ Division of Hematology/Oncology, Department of Internal Medicine, Michigan Medicine, Ann Arbor, MI 48109, USA.
⁴ Division of Pediatric Hematology/Oncology, Department of Pediatrics and Communicable Diseases, Michigan Medicine, Ann Arbor, MI 48109, USA.
⁵ Dana Farber Cancer Institute, Harvard University, Cambridge, MA 02215, USA.
⁶ Division of Hematology/Oncology, Department of Internal Medicine, Michigan Medicine, Ann Arbor, MI 48109, USA; Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA; Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
⁷ Program in Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Division of Hematology/Oncology, Department of Internal Medicine, Michigan Medicine, Ann Arbor, MI 48109, USA. Electronic address: reddypr@med.umich.edu.

Abstract

Cross-presentation initiates immune responses against tumors and viral infections by presenting extracellular antigen on MHC I to activate CD8⁺ T cell-mediated cytotoxicity. In vitro studies in dendritic cells (DCs) established SNARE protein SEC22B as a specific regulator of cross-presentation. However, the in vivo contribution of SEC22B to cross-presentation has not been tested. To address this, we generated DC-specific Sec22b knockout (CD11c-Cre Sec22b^fl/fl) mice. Contrary to the paradigm, SEC22B-deficient DCs efficiently cross-present both in vivo and in vitro. Although in vitro small hairpin RNA (shRNA)-mediated Sec22b silencing in bone-marrow-derived dendritic cells (BMDCs) reduced cross-presentation, treatment of SEC22B-deficient BMDCs with the same shRNA produced a similar defect, suggesting the Sec22b shRNA modulates cross-presentation through off-target effects. RNA sequencing of Sec22b shRNA-treated SEC22B-deficient BMDCs demonstrated several changes in the transcriptome. Our data demonstrate that contrary to the accepted model, SEC22B is not necessary for cross-presentation, cautioning against extrapolating phenotypes from knockdown studies alone.

Keywords: RNA-seq; SEC22B; SNARE protein; cross-presentation; dendritic cell; off-target effect.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Animals
Antigen Presentation / immunology*
Cross-Priming / immunology
Mice
Mice, Transgenic
R-SNARE Proteins / immunology*

Substances

R-SNARE Proteins
Sec22B protein, human

Abstract

Publication types

MeSH terms

Substances

Grants and funding