Abstract: FR-PO239

Deubiquitinating Enzyme UCH-L1 Controls Dendritic Cell Cross Priming of the CD8+ T Cell Response

Session Information

Category: Cell Biology

  • 202 Apoptosis, Proliferation, Autophagy, Cell Senescence, Cell Transformation

Authors

  • Reinicke, Anna, University Clinic Eppendorf Hamburg, Hamburg, Germany
  • Mühlig, Malte, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
  • Lischke, Timo, DRFZ, Berlin, Germany
  • Kurts, Christian, Institute of Experimental Immunology, Bonn, Germany
  • Mittrücker, Hans-willi, Institute for Immunology, Hamburg, Germany
  • Meyer-Schwesinger, Catherine, University of Hamburg, Hamburg, Germany
Background

The deubiquitinating enzyme Ubiquitin C-terminal Hydrolase-L1 (UCH-L1) is thought to regulate the intracellular pool of ubiquitin and is strictly required for the maintenance of axonal integrity in neurons. Within the kidney, UCH-L1 is de novo expressed in glomerular podocytes in human and rodent glomerulonephritis. Preliminary data demonstrate the expression of UCH-L1 in tubulo-interstitial cells of the kidney. Mice with constitutive UCH-L1-deficiency exhibit an exacerbated course of immune-complex nephritis suggesting that UCH-L1 affects the ability to mount an effective immune response in the kidney. Aims of this study were 1. To identify the origin of tubulo-interstitial UCH-L1-expressing cells in the kidney, 2. To analyze the immunologic phenotype of UCH-L1-deficient mice in response to a bacterial infection, 3. To analyze the role of UCH-L1 in dendritic cells for the degradation and cross-presentation of antigens by the ubiquitin proteasome system.

Methods

Mice with constitutive UCH-L1-deficiency were generated by Cre-Lox technology and back-crossed into the C57BL/6 background. The immunologic phenotype was investigated by challenging UCH-L1-deficient mice and dendritic cell-specific UCH-L1-deficient mice with Listeria monocytogenes. Cross presentation and cross priming assays were performed in vitro and in vivo. The dendritic cell (DC) phenotype and UCH-L1 expression was assessed in naïve and stimulated DCs by FACS, Western, proteasomal and deubiquitinase-based activity assays, and real-time PCR.

Results

In this study we show that UCH-L1 has an immunological function in DC antigen cross presentation. UCH-L1 is expressed in kidney, spleen, and bone-marrow derived DCs and its expression is regulated by the immune stimuli LPS and IFN-gamma. DCs from UCH-L1 knockout mice have reduced ability to cross present cell-associated antigens and mediate deficient CD8 T cell priming following Listeria infection while CD4 T cell priming is unaffected. Intriguingly, UCH-L1 colocalises with an ubiquitin selective segregase, VCP/p97 and in UCH-L1 knockout DCs, is strongly reduced suggesting a role for UCH-L1 in VCP/p97 dependent phagocytosis and sorting of ubiquitinated cargo in the endocytic pathway.

Conclusion

These results demonstrate a hitherto unrecognized role of UCH-L1 in DC-mediated immune responses.