An AXL/LRP-1/RANBP9 complex mediates DC efferocytosis and antigen cross-presentation in vivo

• Published in: The Journal of clinical investigation Vol. 124; no. 3; pp. 1296 - 1308
• Main Authors: Subramanian, Manikandan, Hayes, Crystal D, Thome, Joseph J, Thorp, Edward, Matsushima, Glenn K, Herz, Joachim, Farber, Donna L, Liu, Kang, Lakshmana, Madepalli, Tabas, Ira
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 01.03.2014
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Animals; Antigen Presentation; Apoptosis; Biomedical research; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - virology; Cell culture; Coculture Techniques; Cross-Priming; Cytoskeletal Proteins - metabolism; Dendritic cells; Dendritic Cells - physiology; Female; Hepatitis A Virus Cellular Receptor 2; Herpesviridae Infections - immunology; Herpesviridae Infections - pathology; Herpesvirus 1, Human - immunology; Humans; Immune system; Infections; Jurkat Cells; Lymphocytes; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Multiprotein Complexes - metabolism; Nuclear Proteins - metabolism; Phagocytosis; Physiological aspects; Protein Binding; Protein research; Protein-protein interactions; Proteins; Proto-Oncogene Proteins - metabolism; Receptor Protein-Tyrosine Kinases - metabolism; Receptors, LDL - metabolism; Receptors, Virus - metabolism; Rodents; Studies; Transplants & implants; Tumor Suppressor Proteins - metabolism; Viral infections
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/JCI72051

The phagocytosis of apoptotic cells (ACs), or efferocytosis, by DCs is critical for self-tolerance and host defense. Although many efferocytosis-associated receptors have been described in vitro, the functionality of these receptors in vivo has not been explored in depth. Using a spleen efferocytosis assay and targeted genetic deletion in mice, we identified a multiprotein complex--composed of the receptor tyrosine kinase AXL, LDL receptor-related protein-1 (LRP-1), and RAN-binding protein 9 (RANBP9)--that mediates DC efferocytosis and antigen cross-presentation. We found that AXL bound ACs, but required LRP-1 to trigger internalization, in murine CD8α+ DCs and human-derived DCs. AXL and LRP-1 did not interact directly, but relied on RANBP9, which bound both AXL and LRP-1, to form the complex. In a coculture model of antigen presentation, the AXL/LRP-1/RANBP9 complex was used by DCs to cross-present AC-associated antigens to T cells. Furthermore, in a murine model of herpes simplex virus-1 infection, mice lacking DC-specific LRP-1, AXL, or RANBP9 had increased AC accumulation, defective viral antigen-specific CD8+ T cell activation, enhanced viral load, and decreased survival. The discovery of this multiprotein complex that mediates functionally important DC efferocytosis in vivo may have implications for future studies related to host defense and DC-based vaccines.