Toso regulates the balance between apoptotic and nonapoptotic death receptor signaling by facilitating RIP1 ubiquitination

Blood. 2011 Jul 21;118(3):598-608. doi: 10.1182/blood-2010-10-313643. Epub 2011 May 25.


The regulation of cellular survival and apoptosis is of critical importance for the immune system to maintain immune homeostasis and to establish tolerance. Here, we demonstrate that the immune specific cell surface molecule Toso exhibits antiapoptotic effects on death receptor signaling by a novel regulatory mechanism involving the adaptor kinase RIP1. The antiapoptotic function of Toso depends on RIP1 ubiquitination and involves the recruitment of the death adaptor FADD to a Toso/RIP1 protein complex. In response to CD95L and TNFα, Toso promotes the activation of MAPK and NF-κB signaling pathways. Because of this relative augmentation of survival versus apoptotic signals, Toso raises the threshold for death receptor-mediated apoptosis. Our analysis of Toso-deficient mice revealed that Toso is essential for TNFα-mediated liver damage. Furthermore, the antiapoptotic function of Toso could be blocked by a Toso-specific monoclonal antibody, opening up new therapeutic prospects for the treatment of immune disorders and hematologic malignancies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology
  • Apoptosis / immunology*
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cell Survival / immunology
  • Fas Ligand Protein / metabolism
  • Fas-Associated Death Domain Protein / metabolism
  • Gene Knockdown Techniques
  • Humans
  • Immune Tolerance / immunology
  • Jurkat Cells
  • Liver Diseases / immunology
  • Liver Diseases / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Nuclear Pore Complex Proteins / genetics
  • Nuclear Pore Complex Proteins / metabolism*
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Signal Transduction / immunology*
  • Tumor Necrosis Factor-alpha / immunology
  • Tumor Necrosis Factor-alpha / metabolism
  • Ubiquitination / physiology*
  • fas Receptor / metabolism


  • AGFG1 protein, human
  • Antibodies, Monoclonal
  • Apoptosis Regulatory Proteins
  • Carrier Proteins
  • FADD protein, human
  • FAS protein, human
  • FCMR protein, human
  • Fas Ligand Protein
  • Fas-Associated Death Domain Protein
  • Fcmr protein, mouse
  • Membrane Proteins
  • Nuclear Pore Complex Proteins
  • RNA-Binding Proteins
  • Tumor Necrosis Factor-alpha
  • fas Receptor