title: Interferon gamma regulates accumulation of the proteasome activator PA28 and immunoproteasomes at nuclear PML bodies.
abstract: PA28 is an interferon (gamma) (IFN(gamma)) inducible proteasome activator required for presentation of certain major histocompatibility (MHC) class I antigens. Under basal conditions in HeLa and Hep2 cells, a portion of nuclear PA28 is concentrated at promyelocytic leukemia oncoprotein (PML)-containing bodies also commonly known as PODs or ND10. IFN(gamma) treatment greatly increased the number and size of the PA28- and PML-containing bodies, and the effect was further enhanced in serum-deprived cells. PML bodies are disrupted in response to certain viral infections and in diseases such as acute promyelocytic leukemia (APL). Like PML, PA28 was delocalized from PML bodies by expression of the cytomegalovirus protein, IE1, and in NB4 cells, an APL model line. Moreover, retinoic acid treatment, which causes remission of APL in patients and reformation of PML-containing bodies in NB4 cells, relocalized PA28 to this site. In contrast, the proteasome, the functional target of PA28, was not detected at PML bodies under basal conditions in HeLa and Hep2 cells, but IFN(gamma) promoted accumulation of 'immunoproteasomes' at this site. These results establish PA28 as a novel component of nuclear PML bodies, and suggest that PA28 may assemble or activate immunoproteasomes at this site as part of its role in proteasome-dependent MHC class I antigen presentation.
authors: Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA.
authors: R P
authors: RP
authors: Fabunmi
authors: W C
authors: WC
authors: Wigley
authors: P J
authors: PJ
authors: Thomas
authors: G N
authors: GN
authors: DeMartino
mesh_terms: D001692:Biological Transport; D016895:Culture Media, Serum-Free; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006367:HeLa Cells; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis / Q000235:genetics; D007371:Interferon-gamma / Q000378:metabolism* / Q000494:pharmacology; D009097:Multienzyme Complexes / Q000378:metabolism*; D009124:Muscle Proteins; D009363:Neoplasm Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D000071156:Promyelocytic Leukemia Protein; D046988:Proteasome Endopeptidase Complex; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D014764:Viral Proteins
chemical_list: D016895:Culture Media, Serum-Free; C088645:IE1 protein, cytomegalovirus; D017874:Immediate-Early Proteins; D009097:Multienzyme Complexes; D009124:Muscle Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C085047:PSME1 protein, human; D000071156:Promyelocytic Leukemia Protein; D011506:Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D014764:Viral Proteins; C070576:PML protein, human; D014212:Tretinoin; D007371:Interferon-gamma; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex