Differential expression regulation of the alpha and beta subunits of the PA28 proteasome activator in mature dendritic cells.
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.
Ossendorp
Ferry
F
Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands. f.a.ossendorp@lumc.nl
Fu
Nathalie
N
Camps
Marcel
M
Granucci
Francesca
F
Gobin
Sam J P
SJ
van den Elsen
Peter J
PJ
Schuurhuis
Danita
D
Adema
Gosse J
GJ
Lipford
Grayson B
GB
Chiba
Tomoki
T
Sijts
Alice
A
Kloetzel
Peter-M
PM
Ricciardi-Castagnoli
Paola
P
Melief
Cornelis J M
CJ
D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000201:enzymology* / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics; D008545:Melanoma / Q000276:immunology / Q000378:metabolism; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D021122:Protein Subunits / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
D018984:Epitopes, T-Lymphocyte; D008565:Membrane Proteins; D009124:Muscle Proteins; C085047:PSME1 protein, human; D010446:Peptide Fragments; D021122:Protein Subunits; C500290:peptide SVYDFFVWL; C486207:PSME2 protein, human; D046988:Proteasome Endopeptidase Complex