Differential expression regulation of the alpha and beta subunits of the PA28 proteasome activator in mature dendritic cells

• Published in: The Journal of immunology (1950) Vol. 174; no. 12; pp. 7815 - 7822
• Main Authors: Ossendorp, Ferry, Fu, Nathalie, Camps, Marcel, Granucci, Francesca, Gobin, Sam J P, van den Elsen, Peter J, Schuurhuis, Danita, Adema, Gosse J, Lipford, Grayson B, Chiba, Tomoki, Sijts, Alice, Kloetzel, Peter-M, Ricciardi-Castagnoli, Paola, Melief, Cornelis J M
• Format: Journal Article
• Language: English
• Published: United States 15-06-2005
• Subjects: Animals; Antigen Presentation - genetics; Cell Differentiation - genetics; Cell Differentiation - immunology; Cell Line; Cells, Cultured; Dendritic Cells - cytology; Dendritic Cells - enzymology; Dendritic Cells - immunology; Epitopes, T-Lymphocyte - immunology; Epitopes, T-Lymphocyte - metabolism; Gene Expression Regulation - genetics; Melanoma - immunology; Melanoma - metabolism; Membrane Proteins - immunology; Membrane Proteins - metabolism; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle Proteins - biosynthesis; Muscle Proteins - deficiency; Muscle Proteins - genetics; Muscle Proteins - physiology; Peptide Fragments - immunology; Peptide Fragments - metabolism; Proteasome Endopeptidase Complex; Protein Subunits - biosynthesis; Protein Subunits - deficiency; Protein Subunits - genetics; Protein Subunits - physiology; T-Lymphocytes, Cytotoxic - immunology; T-Lymphocytes, Cytotoxic - metabolism; Up-Regulation - genetics; Up-Regulation - immunology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.174.12.7815

Activation of dendritic cells (DC) by Th-dependent (CD40) or -independent (LPS, CpG, or immune complexes) agonistic stimuli strongly enhances the expression of the proteasome activator PA28alphabeta complex. Upon activation of DC, increased MHC class I presentation occurred of the melanocyte-associated epitope tyrosinase-related protein 2(180-188) in a PA28alphabeta-dependent manner. In contrast to other cell types, regulation of PA28alphabeta expression in DC after maturation was found to be IFN-gamma independent. In the present study, we show that expression of PA28alpha and beta subunits was differentially regulated. Firstly, PA28alpha expression is high in both immature and mature DC. In contrast, PA28beta expression is low in immature DC and strongly increased in mature DC. Secondly, we show the presence of a functional NF-kappaB site in the PA28beta promoter, which is absent in the PA28alpha promoter, indicating regulation of PA28beta expression by transcription factors of the NF-kappaB family. In addition, glycerol gradient analysis of DC lysates revealed elevated PA28alphabeta complex formation upon maturation. Thus, induction of PA28beta expression allows proper PA28alphabeta complex formation, thereby enhancing proteasome activity in activated DC. Therefore, maturation of DC not only improves costimulation but also MHC class I processing. This mechanism enhances the CD8(+) CTL (cross)-priming capacity of mature DC.