TY - JOUR
T1 - Rapamycin inhibits proteasome activator expression and proteasome activity
AU - Wang, Xin
AU - Omura, Satoshi
AU - Szweda, Luc I.
AU - Yang, Young
AU - Bérard, Jacques
AU - Seminaro, Johnny
AU - Wu, Jiangping
PY - 1997/11
Y1 - 1997/11
N2 - Rapamycin (RAPA) is a potent immunosuppressive drug, and certain of its direct or indirect targets might be of vital importance to the regulation of an immune response. In this study, we used differential hybridization to search for human genes whose expression was sensitive to RAPA. Seven RAPA-sensitive genes were found and one of them coded a protein with high homology to the α subunit of a proteasome activator (PA28α). This gene was later found to code for the β subunit of the proteasome activator (PA28β). Activated T and B cells had up-regulated PA28β expression at the mRNA level. Such up-regulation could be suppressed by RAPA, FK506, and cyclosporin A. RAPA and FK506 also repressed the up-regulated PA28α messages in phytohemagglutinin (PHA)-stimulated T cells. At the protein level, RAPA inhibited PA28α and PA28β in the activated T cells according to immunoblotting and confocal microscopy. Probably as a consequence, there was a fourfold increase of proteasome activities in the peripheral blood mononuclear cell lysate after the PHA activation. PAPA could inhibit the enhanced part of the proteasome activity. Considering the critical role played by the proteasome in degrading regulatory proteins, our data suggest that the proteasome activator is a relevant and important downstream target of rapamycin, and that the immune response could be modulated through the activity of the proteasome.
AB - Rapamycin (RAPA) is a potent immunosuppressive drug, and certain of its direct or indirect targets might be of vital importance to the regulation of an immune response. In this study, we used differential hybridization to search for human genes whose expression was sensitive to RAPA. Seven RAPA-sensitive genes were found and one of them coded a protein with high homology to the α subunit of a proteasome activator (PA28α). This gene was later found to code for the β subunit of the proteasome activator (PA28β). Activated T and B cells had up-regulated PA28β expression at the mRNA level. Such up-regulation could be suppressed by RAPA, FK506, and cyclosporin A. RAPA and FK506 also repressed the up-regulated PA28α messages in phytohemagglutinin (PHA)-stimulated T cells. At the protein level, RAPA inhibited PA28α and PA28β in the activated T cells according to immunoblotting and confocal microscopy. Probably as a consequence, there was a fourfold increase of proteasome activities in the peripheral blood mononuclear cell lysate after the PHA activation. PAPA could inhibit the enhanced part of the proteasome activity. Considering the critical role played by the proteasome in degrading regulatory proteins, our data suggest that the proteasome activator is a relevant and important downstream target of rapamycin, and that the immune response could be modulated through the activity of the proteasome.
KW - Lactacystin
KW - Lymphocyte activation
KW - Proteasome
KW - Proteasome activator
KW - Rapamycin
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U2 - 10.1002/eji.1830271106
DO - 10.1002/eji.1830271106
M3 - Article
C2 - 9394799
AN - SCOPUS:0030715295
SN - 0014-2980
VL - 27
SP - 2781
EP - 2786
JO - European Journal of Immunology
JF - European Journal of Immunology
IS - 11
ER -