Double‐cleavage production of the CTL epitope by proteasomes and PA28: role of the flanking region

Shimbara, Naoki; Nakajima, Hiroto; Tanahashi, Nobuyuki; Ogawa, Kiyoko; Niwa, Shin-ichiro; Uenaka, Akiko; Nakayama, Eiichi; Tanaka, Keiji

doi:10.1046/j.1365-2443.1997.1610359.x

Cited by 59 publications

(52 citation statements)

References 37 publications

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“…Moreover, Dick et al (1996) and Shimbara et al (1997) reported that PA28 is responsible for the generation of the dominant MHC class I-ligand in vitro. These findings suggest that PA28 could play an important role in the generation of antigenic peptides capable of presentation by MHC class I-molecules.…”

Section: Biological Roles Of the Ubiquitinylationproteasome Directed mentioning

confidence: 99%

The proteasome: a protein‐destroying machine

Tanaka

Chiba

1998

Genes to Cells

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Most cellular proteins are targeted for degradation by the proteasome, a eukaryotic ATPdependent protease, after they have been covalently attached to ubiquitin (Ub) in the form of a poly Ub chain functioning as a degradation signal. The proteasome is an unusually large multisubunit proteolytic complex, consisting of a central catalytic machine (called the 20S proteasome) and two terminal regulatory subcomplexes, termed PA700 or PA28, that are attached to both ends of the central portion in opposite orientations, to form enzymatically active proteasomes. The large assembled proteasome acts as a protein-destroying machine responsible for the selective breakdown of numerous ubiquitinylated cellular proteins and certain nonubiquitinylated proteins. To date, proteolysis mediated by the Ub-proteasome pathway has been shown to be involved in a wide variety of biologically important processes, such as the cell cycle, apoptosis, metabolism, signal transduction, immune response and protein quality control, implying that it functions as a previously unrecognized regulatory system for determining the final fate of protein factors involved in these biological reactions.

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Section: Biological Roles Of the Ubiquitinylationproteasome Directed mentioning

confidence: 99%

The proteasome: a protein‐destroying machine

Tanaka

Chiba

1998

Genes to Cells

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“…PA28 accelerates the production of MHC class I ligands from longer precursor peptides by the 20S proteasome in vitro (6). The C-terminal flanking region is critical for efficient production of the T cell epitope (7). It is possible that PA28 activates the 20S proteasome by opening its ␣-ring (8) that is usually closed and through which substrates can pass into the core catalytic portion.…”

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Allele-Selective Effect of PA28 in MHC Class I Antigen Processing

Yamano

Sugahara

Mizukami

et al. 2008

The Journal of Immunology

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PA28 is an IFN-γ-inducible proteasome activator and its genetic ablation causes complete loss of processing of certain Ags, but not all of them. The reason why this occurs and how PA28 influences the formation of peptide repertoires for MHC class I molecules remains unknown. In this study, we show the allele-specific role of PA28 in Ag processing. Retrovirus-transduced overexpression of PA28α decreased expression of Kd (Dd) while it increased Kb and Ld on the cell surface. By contrast, overexpression of PA28αΔC5, a mutant carrying a deletion of its five C-terminal residues and capable of attenuating the activity of endogenous PA28, produced the opposite effect on expression of those MHC class I molecules. Moreover, knockdown of both PA28α and β by small-interfering RNA profoundly augmented expression of Kd and Dd, but not of Ld, on the cell surface. Finally, we found that PA28-associated proteasome preferentially digested within epitopic sequences of Kd, although correct C-terminal flankings were removed, which in turn hampered production of Kd ligands. Our results indicate that whereas PA28 negatively influences processing of Kd (Dd) ligands, thereby, down-regulating Ag presentation by those MHC class I molecules, it also efficiently produces Kb (Ld) epitopes, leading to up-regulation of the MHC molecules.

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“…Similarly, partial truncation of the C-terminal flanking region (TRP2 350 -378 ⌬C 5 pp89 ins ), or truncation of both terminal flanking sequences by 5 residues (TRP2 350 -378 ⌬N 5 / ⌬C 5 pp89 ins ), did not affect PA28 dependence. Nevertheless, the efficiency of epitope precursor generation from the latter peptide was diminished in the presence of PA28, most likely because of the shortening of the flanking sequences (9). Neither complete truncation of the C-terminal flanking residues from the TRP2/pp89 hybrid sequence (TRP2 350 -378 ⌬C 10 pp89 ins ) nor its truncation from the original human TRP2 polypeptide (TRP2 350 -378 ⌬C 10 wt) abolished the PA28-dependent liberation of the precursor peptides (Fig.…”

Section: Resultsmentioning

confidence: 97%

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confidence: 99%

“…In vitro digestion experiments performed by incubating epitope-containing peptides with 20S proteasomes in PA28 presence resulted in an immediate liberation of PA28-dependent epitopes (8 -10). The conclusion drawn from these experiments was that PA28 changes the cleavage behavior of the 20S core in a characteristic manner; without PA28 the proteasome cuts substrates by consecutive and independent single cleavages, whereas association with PA28 results in a strong enhancement of proteasomal double cleavages and an accelerated liberation of MHC class I ligands or their precursors (8,9).A striking example of PA28 action that stand in contrast to the above findings has been provided recently by our analysis of two cytotoxic lymphocyte epitopes, TRP2 288 -296 and TRP2 360 -368 , derived from the melanoma differentiation antigen TRP2 (tyrosine-related protein 2) (11). Melanoma cell lines presented the former epitope, but three of them showed a dramatically diminished presentation of the latter epitope.…”

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The N-terminal Flanking Region of the TRP2360–368 Melanoma Antigen Determines Proteasome Activator PA28 Requirement for Epitope Liberation

Textoris-Taube

Henklein

Pollmann

et al. 2007

Journal of Biological Chemistry

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Proteasomes are known to produce major histocompatibility complex (MHC) class I ligands from endogenous antigens. The interferon-␥-inducible proteasome activator PA28 plays an important role in the generation of MHC ligands by proteasomes. Generation of the HLA-A*0201 restricted melanoma antigen TRP2 360 -368 by the proteasome has been shown to be dependent on the function of PA28 in vitro and in vivo (Sun, Y., Sijts, A. J., Song, M., Janek, K., Nussbaum, A. K., Kral, S., Schirle, M., Stevanovic, S., Paschen, A., Schild, H., Kloetzel, P. M., and Schadendorf, D. (2002) Cancer Res. 62, 2875-2882). Here we analyzed the role of the epitope sequence environment in determining this PA28 dependence. Experiments using the melanoma TRP2 288 -296 epitope and the murine cytomegalovirus-derived pp89 epitope precursor peptide for epitope replacement revealed that the TRP2 360 -368 flanking sequences can transfer PA28 dependence onto otherwise PA28 independent epitopes. Moreover, the N-terminal flanking sequence is sufficient to establish PA28 dependence of an epitope by allowing PA28-induced coordinated dual cleavages. These results show that N-terminal flanking sequences strongly influence epitope generation efficiency and that PA28 function is particularly relevant for the generation of normally poorly excised peptide products.The generation of major histocompatibility complex (MHC) 2 class I ligands and the recognition of MHC class I-ligand complexes by CD8ϩ T cells is an effective tool for the elimination of infected or disordered cells from organisms. The ubiquitin-proteasome system represents the major source for MHC class I-presented peptides exposed to CD8ϩ T cells (1). Ubiquitin-proteasome system-mediated peptide generation is influenced by structural changes in the 20S catalytic core (20S proteasome), which occur by exchange of the standard catalytic subunits by immunosubunits. The ATP-dependent 26S proteasome, composed of a 20S core and a 19S regulatory complex, recognizes substrates by a multi-ubiquitin signal. In contrast, 20S proteasomes can accept larger non-ubiquitinated peptides as substrates for ATP-independent degradation (3). However, 20S proteasomes exist in a latent state within the cells. In consequence, proteasome activity and function is regulated in part by modulating substrate entry by the PA28 complex, which attaches ATP-independent to the outer ␣-rings of the 20S proteasome. Detailed kinetic analysis using fluorogenic peptide substrates has shown that activation of the 20S proteasome by PA28 occurs by facilitating either substrate entry and/or product exit, with no effects on the active sites (3). In support, structural analyses have demonstrated that attachment of the activator to the 20S core leads to the opening of the central gate of the ␣-ring (4).The expression of PA28 is constitutively enhanced in cells with specialized antigen-presenting function and is induced by stimulation of cells with interferon-␥. The presentation of a number of viral MHC class I epitopes is enhanced in the presence...

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Double‐cleavage production of the CTL epitope by proteasomes and PA28: role of the flanking region

Cited by 59 publications

References 37 publications

The proteasome: a protein‐destroying machine

The proteasome: a protein‐destroying machine

Allele-Selective Effect of PA28 in MHC Class I Antigen Processing

The N-terminal Flanking Region of the TRP2360–368 Melanoma Antigen Determines Proteasome Activator PA28 Requirement for Epitope Liberation

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