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Proteasomes are eukaryotic ring-shaped or cylindrical particles with multicatalytic protease activities. To clarify the involvement of proteasomes in tumorigenesis of human blood cells, we compared their expression in human hematopoietic malignant tumor cells with that in normal peripheral blood mononuclear cells. Immunohistochemical staining showed considerably increased concentrations of proteasomes in leukemic cells from the bone marrow of patients with various types of leukemia and the predominant localization of these proteasomes in the nuclei. Moreover, enzyme immunoassay and Northern blot analysis indicated that the concentrations of proteasomes and their mRNA levels were consistently much higher in a variety of malignant human hematopoietic cell lines than in resting peripheral lymphocytes and monocytes from healthy adults. Proteasome expression was also greatly increased in normal blood mononuclear cells during blastogenic transformation induced by phytohemagglutinin; their expression increased in parallel with induction of DNA synthesis and returned to the basal level with progress of the cell cycle. Thus, abnormally high expression of proteasomes may play an important role in transformation and proliferation of blood cells and in specific functions of hematopoietic tumor cells.named C2 (12) and C3 (13), from rat liver proteasomes and one component of 35 kDa of Drosophila proteasomes (14) have been determined by cDNA cloning. The overall amino acid sequence of rat C2 closely resembles that of the Drosophila 35-kDa protein, suggesting that these two components function similarly in most eukaryotes and that they evolved from the same ancestral gene. In contrast, no significant homologies of these components with any other known proteins were found by computer analysis, indicating that proteasomes are a novel type of enzyme complex.Proteasomes are ubiquitous in cells of eukaryotes ranging from humans to yeast (1,15,16). Moreover, proteasomes or the related 20S particles have been found in both the cytoplasm and the nuclei of a variety of mammalian cells (8,17,18) and also various lower eukaryotes (14,(19)(20)(21)(22)(23)(24)(25), suggesting that their diverse roles depend on their differential localizations in the cells. However, the exact function of proteasomes is still unknown. One way to obtain information on their physiological role(s) is to study their expression in cells in abnormal states. In this work, we examined the expression of proteasomes in resting and growth-stimulated normal peripheral blood mononuclear cells and in a variety of human hematopoietic tumor cell lines.Proteasomes are multicatalytic proteinase complexes that are thought to be major intracellular proteolytic enzyme complexes responsible for certain types of nonlysosomal pathways of protein breakdown that requires metabolic energy (1). They were found to catalyze the degradation of various proteins in an ATP-dependent fashion (2-4). Moreover, 20S proteasomes were demonstrated to assemble into 26S proteolytic complexes t...

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Proteasomes (multicatalytic proteinase complexes), which are identical to the ubiquitous eukaryotic 20S particles, are localized in both the cytoplasm and the nucleus, but the mechanism of their co‐localization in the two compartments is unknown. On examination of the primary structures of subunits of proteasomes, a consensus sequence for nuclear translocation of proteins, X‐X‐K‐K(R)‐X‐K(R) (where X is any residue), was found to be present in some subunits and to be highly conserved in the subunits of a wide range of eukaryotes. In addition, proteasomal subunits were found to bear a cluster of acidic amino acid residues and also a potential tyrosine phosphorylation site that was located in the same polypeptide chain as the nuclear location signal. These structural properties suggest that two sets of clusters with positive and negative charges serve to regulate the translocation of proteasomes from the cytoplasm to the nucleus, and that phosphorylation of tyrosine in certain subunits may play an additional role in transfer of proteasomes into the nucleus.

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SUMMARY Severe thrombocytopenia and increased vascular permeability are two major characteristics of dengue haemorrhagic fever (DHF). To develop a better understanding of the roles of platelet-associated IgG (PAIgG) and IgM (PAIgM) in inducing thrombocytopenia and its severity of disease in patients with secondary dengue virus infection, the relationship between the PAIgG or PAIgM levels and disease severity as well as thrombocytopenia was examined in 78 patients with acute phase secondary infection in a prospective hospital-based study. The decrease in platelet count during the acute phase recovered significantly during the convalescent phase. In contrast, the increased levels of PAIgG or PAIgM that occurred during the acute phase of these patients decreased significantly during the convalescent phase. An inverse correlation between platelet count and PAIgG or PAIgM levels was found in these patients. Anti-dengue virus IgG and IgM activity was found in platelet eluates from 10 patients in an acute phase of secondary infection. Increased levels of PAIgG or PAIgM were significantly higher in DHF than those in dengue fever (DF). An increased level of PAIgM was associated independently with the development of DHF, representing a possible predictor of DHF with a high specificity. Our present data suggest that platelet-associated immunoglobulins involving antidengue virus activity play a pivotal role in the induction of thrombocytopenia and the severity of the disease in secondary dengue virus infections.

Neutrophil infiltration is the first step in eradication of bacterial infection, but neutrophils rapidly die after killing bacteria. Subsequent accumulation of macrophage lineage cells, such as alveolar macrophages (AMs), is essential to remove dying neutrophils, which are a source of injurious substances. Macrophage lineage cells can promote tissue repair, by producing potential growth factors including hepatocyte growth factor (HGF). However, it remains elusive which factor activates macrophage in these processes. Intratracheal instillation of Pseudomonas aeruginosa caused neutrophil infiltration in the airspace; subsequently, the numbers of total AMs and neutrophil ingested AMs were increased. Bronchoalveolar lavage (BAL) fluid levels of monocyte chemoattractant protein (MCP)-1/CC chemokine ligand-2 (CCL2), a potent macrophage-activating factor, were increased before the increases in the number of AM ingesting neutrophils and HGF levels in BAL fluid. Immunoreactive MCP-1 proteins were detected in alveolar type II epithelial cells and AMs only after P. aeruginosa infection. The administration of anti-MCP-1/CCL2 Abs reduced the increases in the number of AM-ingesting neutrophils and HGF levels in BAL fluid, and eventually aggravated lung tissue injury. In contrast, the administration of MCP-1/CCL2 enhanced the increases in the number of AM ingesting neutrophils and HGF levels in BAL fluid, and eventually attenuated lung tissue injury. Furthermore, MCP-1/CCL2 enhanced the ingestion of apoptotic neutrophils and HGF production by a mouse macrophage cell line, RAW 267.4, in a dose-dependent manner. Collectively, MCP-1/CCL2 has a crucial role in the resolution and repair processes of acute bacterial pneumonia by enhancing the removal of dying neutrophils and HGF production by AMs

We have reported a deficiency of a 91-kDa glycoprotein component of the phagocyte NADPH oxidase (gp91 phox ) in neutrophils, monocytes, and B lymphocytes of a patient with X chromosome-linked chronic granulomatous disease. Sequence analysis of his gp91 phox gene revealed a single-base mutation (C 3 T) at position ؊53. Electrophoresis mobility-shift assays showed that both PU.1 and hematopoietic-associated factor 1 (HAF-1) bound to the inverted PU.1 consensus sequence centered at position ؊53 of the gp91 phox promoter, and the mutation at position ؊53 strongly inhibited the binding of both factors. It was also indicated that a mutation at position ؊50 strongly inhibited PU.1 binding but hardly inhibited HAF-1 binding, and a mutation at position ؊56 had an opposite binding specificity for these factors. In transient expression assay using HEL cells, which express PU.1 and HAF-1, the mutations at positions ؊53 and ؊50 significantly reduced the gp91 phox promoter activity; however, the mutation at position ؊56 did not affect the promoter activity. In transient cotransfection study, PU