Immunoproteasome assembly and antigen presentation in mice lacking both PA28α and PA28β

Two members of the proteasome activator, PA28α and PA28β, form a heteropolymer that binds to both ends of the 20S proteasome. Evidence in vitro indicates that this interferon‐γ (IFN‐γ)‐inducible heteropolymer is involved in the processing of intracellular antigens, but its functions in vivo remain elusive. To investigate the role of PA28α/β in vivo, we generated mice deficient in both PA28α and PA28β genes. The ATP‐dependent proteolytic activities were decreased in PA28α−/−/β−/− cells, suggesting that ‘hybrid proteasomes’ are involved in protein degradation. Treatment of PA28α−/−/β−/− cells with IFN‐γ resulted in sufficient induction of the ‘immunoproteasome’. Moreover, splenocytes from PA28α−/−/β−/− mice displayed no apparent defects in processing of ovalbumin. These results are in marked contrast to the previous finding that immunoproteasome assembly and immune responses were impaired in PA28β−/− mice. PA28α−/−/β−/− mice also showed apparently normal immune responses against infection with influenza A virus. However, they almost completely lost the ability to process a melanoma antigen TRP2‐derived peptide. Hence, PA28α/β is not a prerequisite for antigen presentation in general, but plays an essential role for the processing of certain antigens.

[1]  A. Vitiello,et al.  Impaired immunoproteasome assembly and immune responses in PA28-/- mice. , 1999, Science.

[2]  K Tanaka,et al.  Tissue distribution of constitutive proteasomes, immunoproteasomes, and PA28 in rats. , 2000, Biochemical and biophysical research communications.

[3]  K Tanaka,et al.  Structure and functions of the 20S and 26S proteasomes. , 1996, Annual review of biochemistry.

[4]  K. Ferrell,et al.  Purification of an 11 S regulator of the multicatalytic protease. , 1992, The Journal of biological chemistry.

[5]  Y. Murakami,et al.  Hybrid proteasomes. Induction by interferon-gamma and contribution to ATP-dependent proteolysis. , 2000, The Journal of biological chemistry.

[6]  S. Matsufuji,et al.  Ornithine decarboxylase is degraded by the 26S proteasome without ubiquitination , 1992, Nature.

[7]  Y. Murakami,et al.  Hybrid Proteasomes , 2000, The Journal of Biological Chemistry.

[8]  P M Kloetzel,et al.  The function of the proteasome system in MHC class I antigen processing. , 2000, Immunology today.

[9]  K Eichmann,et al.  The specificity of proteasomes: impact on MHC class I processing and presentation of antigens , 1999, Immunological reviews.

[10]  K. Tanaka,et al.  Newly identified pair of proteasomal subunits regulated reciprocally by interferon gamma , 1996, The Journal of experimental medicine.

[11]  M. Kasahara,et al.  The MHC class I ligand‐generating system: roles of immunoproteasomes and the interferon‐4gMY‐inducible proteasome activator PA28 , 1998, Immunological reviews.

[12]  久松浩.  Newly Identified Pair of Proteasomal Subunits Regulated Reciprocally by Interferon γ , 1997 .

[13]  C. Slaughter,et al.  Identification, purification, and characterization of a protein activator (PA28) of the 20 S proteasome (macropain). , 1992, The Journal of biological chemistry.

[14]  Keiji Tanaka,et al.  Proteasome activator (PA28) subunits, α, β and γ (Ki antigen) in NT2 neuronal precursor cells and HeLa S3 cells , 1998 .

[15]  K. Tanaka,et al.  Molecular biology of the proteasome. , 1998, Biochemical and biophysical research communications.

[16]  A. Goldberg,et al.  Degradation of cell proteins and the generation of MHC class I-presented peptides. , 1999, Annual review of immunology.

[17]  P. Kloetzel,et al.  A second gene encoding the mouse proteasome activator PA28beta subunit is part of a LINE1 element and is driven by a LINE1 promoter. , 1999, Journal of molecular biology.

[18]  S. Tonegawa,et al.  Altered peptidase and viral-specific T cell response in LMP2 mutant mice. , 1994, Immunity.

[19]  C. Wójcik.  Proteasome activator subunit PA28α and related Ki antigen (PA28γ) are absent from the nuclear fraction purified by sucrose gradient centrifugation , 1999 .

[20]  W. Baumeister,et al.  A Subcomplex of the Proteasome Regulatory Particle Required for Ubiquitin-Conjugate Degradation and Related to the COP9-Signalosome and eIF3 , 1998, Cell.

[21]  K. Rajewsky,et al.  MHC class I expression in mice lacking the proteasome subunit LMP-7. , 1994, Science.

[22]  T. Fujiwara,et al.  Chromosomal localization and immunological analysis of a family of human 26S proteasomal ATPases. , 1998, Biochemical and biophysical research communications.

[23]  J. Neefjes,et al.  The major substrates for TAP in vivo are derived from newly synthesized proteins , 2000, Nature.

[24]  S. Rosenberg,et al.  Identification of Tyrosinase-related Protein 2 as a Tumor Rejection Antigen for the B16 Melanoma , 1997, The Journal of experimental medicine.

[25]  S. Matsufuji,et al.  ATP-Dependent Inactivation and Sequestration of Ornithine Decarboxylase by the 26S Proteasome Are Prerequisites for Degradation , 1999, Molecular and Cellular Biology.

[26]  M. Kasahara,et al.  Growth Retardation in Mice Lacking the Proteasome Activator PA28γ* , 1999, The Journal of Biological Chemistry.

[27]  T. Fujiwara,et al.  Molecular properties of the proteasome activator PA28 family proteins and γ‐interferon regulation , 1997, Genes to cells : devoted to molecular & cellular mechanisms.

[28]  P. Kloetzel,et al.  The proteasome regulator PA28α/β can enhance antigen presentation without affecting 20S proteasome subunit composition , 2000 .

[29]  K. Tanaka,et al.  Subcellular localization of proteasomes and their regulatory complexes in mammalian cells. , 2000, The Biochemical journal.

[30]  Hiroshi Takayanagi,et al.  T-cell-mediated regulation of osteoclastogenesis by signalling cross-talk between RANKL and IFN-γ , 2000, Nature.

[31]  M. Kasahara,et al.  Characterization of the mouse PA28 activator complex gene family: complete organizations of the three member genes and a physical map of the approximately 150-kb region containing the alpha- and beta-subunit genes. , 1998, Journal of immunology.

[32]  M. Rechsteiner,et al.  The proteasome activator 11 S REG (PA28) and class I antigen presentation. , 2000, The Biochemical journal.

[33]  K. Früh,et al.  Antigen presentation by MHC class I and its regulation by interferon gamma. , 1999, Current opinion in immunology.

[34]  P. Kloetzel,et al.  Overexpression of the Proteasome Subunits LMP2, LMP7, and MECL-1, But Not PA28α/β, Enhances the Presentation of an Immunodominant Lymphocytic Choriomeningitis Virus T Cell Epitope1 , 2000, The Journal of Immunology.

[35]  Jonathan W. Yewdell,et al.  Rapid degradation of a large fraction of newly synthesized proteins by proteasomes , 2000, Nature.

[36]  M. Kasahara,et al.  PA28 subunits of the mouse proteasome: primary structures and chromosomal localization of the genes , 1997, Immunogenetics.

[37]  Hans-Georg Rammensee,et al.  A role for the proteasome regulator PA28α in antigen presentation , 1996, Nature.

[38]  Hans-Georg Rammensee,et al.  Coordinated Dual Cleavages Induced by the Proteasome Regulator PA28 Lead to Dominant MHC Ligands , 1996, Cell.

[39]  K. Tanaka,et al.  Simultaneous binding of PA28 and PA700 activators to 20 S proteasomes. , 1998, The Biochemical journal.

[40]  A. Goldberg,et al.  Inhibitors of the proteasome block the degradation of most cell proteins and the generation of peptides presented on MHC class I molecules , 1994, Cell.

[41]  T. Ziv,et al.  26 S Proteasome-mediated Production of an Authentic Major Histocompatibility Class I-restricted Epitope from an Intact Protein Substrate* , 1999, Journal of Biological Chemistry.

[42]  W. Baumeister,et al.  The 26S proteasome: a molecular machine designed for controlled proteolysis. , 1999, Annual review of biochemistry.