Rapamycin inhibits proteasome activator expression and proteasome activity

Xin Wang, Satoshi Omura, Luc I. Szweda, Young Yang, Jacques Bérard, Johnny Seminaro, Jiangping Wu

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)2781-2786
Number of pages6
JournalEuropean Journal of Immunology
Volume27
Issue number11
DOIs
StatePublished - Nov 1 1997

Keywords

  • Lactacystin
  • Lymphocyte activation
  • Proteasome
  • Proteasome activator
  • Rapamycin

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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