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S Nonoyama

Publications and source records attributed to S Nonoyama.

At least 19 recordsLinked to original sources
PubMed2002

Flow cytometric determination of intracytoplasmic Wiskott-Aldrich syndrome protein in peripheral blood lymphocyte subpopulations.

We have produced a novel monoclonal antibody (mAb) directed against Wiskott-Aldrich syndrome protein (WASP) by immunizing mice with the recombinant protein. The mAb designated 5A5 is highly specific to WASP and suitable for Western blot analysis and immunoprecipitation. A flow cytometric assay using the 5A5 mAb identifies expression of intracytoplasmic WASP in lymphocytes from normal individuals. Double staining analysis with cell surface CD3, CD19, and CD56, and intracytoplasmic molecules revealed WASP expression in each subpopulation. With regard to WASP expression in patients with Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT), peripheral blood mononuclear cells (PBMCs) from nine patients and Epstein-Barr virus-transformed B-lymphoblastoid cell lines from seven patients examined did not show WASP expression by flow cytometric analysis. These results were confirmed by Western blot analysis. We conclude that WASP expression in lymphocyte subpopulations from patients with WAS and XLT can be more precisely evaluated by flow cytometry as compared with Western blot analysis. This flow cytometry method is important as a supplement to Western blots, but even more important as an alternative and powerful assay that can contribute to research on WASP as well as diagnosis in a clinical setting.

Animals↗
PubMed2001

Characterization of mutations, including a novel regulatory defect in the first intron, in Bruton's tyrosine kinase gene from seven Korean X-linked agammaglobulinemia families.

In this report, we describe seven mutations, including a novel single base pair substitution in intron 1, of the Bruton's tyrosine kinase (Btk) gene found in 12 Korean patients with X-linked agammaglobulinemia. Various mutations, including three novel genetic alterations, were discovered using single-strand conformation polymorphism analysis and direct DNA sequencing. The effect of the intron 1 point mutation (intron 1 +5G-->A) was further evaluated using reporter constructs. Using luciferase assay experiments, we showed that the transcriptional activity of the mutant was significantly lower than in normal counterparts, indicating that the intronic mutation was functional. In addition, DNase I footprinting analysis showed that a single protected region spanning the position +3 to +15 bp hybridized with a mutant-specific probe, but not with a wild-type probe. EMSA indicated that a distinct nuclear protein has the ability to bind the mutant oligonucleotides to produce a new DNA-protein complex. We also observed decreased expression of Btk proteins in monocytes of patients having the point mutation in intron 1. Taken together with the functional analysis, our results strongly suggest the existence of a novel cis-acting element, which might be involved in the down-regulation of Btk gene transcription. Precise definition of the regulatory defect in the Btk intron 1 may provide valuable clues toward elucidating the pathogenesis of X-linked agammaglobulinemia.

Adolescent↗
PubMed2001

Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency characterized by thrombocytopenia with small platelets, eczema, recurrent infections, autoimmune disorders, IgA nephropathy, and an increased incidence of hematopoietic malignancies. The identification of the responsible gene, WASP (Wiskott-Aldrich Syndrome Protein), revealed clinical heterogeneity of the syndrome, and showed that X-linked thrombocytopenia without, or with only mild immunodeficiency and eczema, is also caused by mutations of WASP. The study of WASP and its mutations demonstrates how a single gene defect can cause multiple and complex clinical symptoms.

Animals↗
PubMed2001

Wiskott-Aldrich syndrome (role of WASP).

Wiskott-Aldrich syndrome (WAS) is an X-linked disorder characterized by thrombocytopenia, eczema and immunodeficiency. WASP, the gene responsible for WAS, has been identified by positional cloning, contains a PH domain, a GBD domain, a proline rich region, and a verprolin/cofilin homology domain. Subsequent studies suggest that WASP is involved in signal transduction and in the regulation of the cytoskeleton.

Actin Depolymerizing Factors↗
PubMed2001

Characterization of soluble CD40 ligand released from human activated platelets.

We report here that soluble CD40 ligand (sCD40L) is released from human platelets when activated with collagen or thrombin. The sCD40L was detectable in the culture supernatants of platelets within 30 min after stimulation in vitro, and reached maximal levels in 3 h. The release was blocked by the metalloproteinase inhibitor, KB8301, indicating that the soluble CD40L is made by cleaving the membrane bound CD40L expressed on activated platelets. The sCD40L was undetectable in the supernatant of the activated platelets obtained from patients with X-linked hyper IgM syndrome (XHIM), who have defects in CD40L gene. Since sCD40L has been shown to have biologic function on the activation of vascular endothelial cells and B cells, these findings suggest that platelets play some roles in both inflammation and humoral immune response by releasing soluble CD40L.

Antibody Formation↗
PubMed2000

Double resonance mechanism of ferromagnetism and magnetotransport in (Ga-Mn)As

We calculate the electronic states of the Mn-doped semiconductors and show that resonant states are formed at the top of the down spin valence band due to magnetic impurities and that they give rise to a strong and long-ranged ferromagnetic coupling between Mn moments. We propose that the coupling of the resonant states, in addition to the intra-atomic exchange interaction between the resonant and nonbonding states, is the origin of the ferromagnetism of (Ga-Mn)As. The mechanism is thus called "double resonance." The resonant states bring about the spin-dependent resistivity to produce magnetoresistive properties in (Ga-Mn)As and their junctions.

Journal Article↗
PubMed2000

Characterization of the gammac chain among 27 unrelated Japanese patients with X-linked severe combined immunodeficiency (X-SCID).

X-linked severe combined immunodeficiency (X-SCID) is a rare fatal disease that is caused by mutations in the gene encoding the gammac chain. In this study, 27 unrelated Japanese patients with X-SCID were examined in terms of their genetic mutations and surface expression of the gammac chain. Among 25 patients examined, excluding two patients with large deletions, 23 different mutations were identified in the IL2RG gene, including 10 novel mutations. One patient bearing an extracellular mutation and all three of the patients bearing intracellular mutations after exon 7 expressed the gammac chain on the cell surface. Overall, 84% of patients lacked surface expression of the gammac chain leading to a diagnosis of X-SCID.

Antibodies, Monoclonal↗
PubMed2000

Mutations of the WASP gene in 10 Japanese patients with Wiskott-Aldrich syndrome and X-linked thrombocytopenia.

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, immunodeficiency, and eczema. X-linked thrombocytopenia (XLT) is a mild form of WAS with isolated thrombocytopenia. Both phenotypes are caused by mutation of the Wiskott-Aldrich syndrome protein (WASP) gene. In this study, we identified mutations of the WASP gene in 10 Japanese patients from 9 unrelated families with WAS/XLT. All XLT patients (n = 3) and one WAS patient had a missense mutation at the PH domain of WASP. Two WAS patients had nonsense mutations. One WAS patient had exon 8 skipping caused by one nucleotide deletion at the acceptor site of intron 7. Three WAS patients had genomic deletions; one of the three had a large genomic deletion involving exons 3 to 7. Codons 45 and 86 seem to be the hot spots of the WASP mutation, because missense mutations in these codons have been reported previously in several WAS/XLT patients in addition to the patients in this report, and patients with the same mutation show a similar clinical phenotype. All other mutations are novel, indicating that the mutations of WASP are heterogeneous. EB virus-transformed cell lines from XLT patients expressed nearly normal amounts of WASP, whereas those from typical WAS patients expressed almost undetectable amounts of WASP. We conclude that the analysis of gene mutation and protein expression of WASP are useful together in assessing the severity of WAS.

Adult↗
PubMed2000

[BLNK deficiency].

Explore the source record for details and available documents.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Wiskott-Aldrich syndrome protein induces actin clustering without direct binding to Cdc42.

WASP (Wiskott-Aldrich syndrome protein) was identified as the gene product whose mutation causes the human hereditary disease Wiskott-Aldrich syndrome. WASP contains many functional domains and has been shown to induce the formation of clusters of actin filaments in a manner dependent on Cdc42. However, there has been no report investigating what domain(s) is(are) important for the function. Here we present for the first time the results of detailed analyses on the domain-function relationship of WASP. First, the C-terminal verprolin-cofilin-acidic domain was shown to be essential for the regulation of actin cytoskeleton. In addition, we found that the clustering of WASP itself is distinct from actin clustering. The partial protein containing the region from the N-terminal pleckstrin homology domain to the basic residue-rich region also clustered especially around the nucleus as wild type WASP without inducing actin clustering. Finally, we obtained the quite unexpected result that a WASP mutant deficient in binding to Cdc42 still induced actin cluster formation, indicating that direct interaction between Cdc42 and WASP is not required for the regulation of actin cytoskeleton. This result may explain why no Wiskott-Aldrich syndrome patients have been identified with a missense mutation in the Cdc42-binding site.

Actin Depolymerizing Factors↗
PubMed1999

Involvement of wiskott-aldrich syndrome protein in B-cell cytoplasmic tyrosine kinase pathway.

Bruton's tyrosine kinase (Btk) has been shown to play a role in normal B-lymphocyte development. Defective expression of Btk leads to human and murine immunodeficiencies. However, the exact role of Btk in the cytoplasmic signal transduction in B cells is still unclear. This study represents a search for the substrate for Btk in vivo. We identified one of the major phosphoproteins associated with Btk in the preB cell line NALM6 as the Wiskott-Aldrich syndrome protein (WASP), the gene product responsible for Wiskott-Aldrich syndrome, which is another hereditary immunodeficiency with distinct abnormalities in hematopoietic cells. We demonstrated that WASP was transiently tyrosine-phosphorylated after B-cell antigen receptor cross-linking on B cells, suggesting that WASP is located downstream of cytoplasmic tyrosine kinases. An in vivo reconstitution system demonstrated that WASP is physically associated with Btk and can serve as the substrate for Btk. A protein binding assay suggested that the tyrosine-phosphorylation of WASP alters the association between WASP and a cellular protein. Furthermore, identification of the phosphorylation site of WASP in reconstituted cells allowed us to evaluate the catalytic specificity of Btk, the exact nature of which is still unknown.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1999

The pleckstrin homology domain of the Wiskott-Aldrich syndrome protein is involved in the organization of actin cytoskeleton.

In this study, we investigated the role of the pleckstrin homology (PH) domain of the Wiskott-Aldrich syndrome protein (WASP) in the regulation of actin cytoskeleton, which is defective in patients with Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). Overexpression of the WASP in COS-7 cells cultured in the presence of fetal calf serum (FCS) resulted in large cluster formation of polymerized actin and WASP in the cytoplasm. In contrast, when the WASP transfected cells were cultured in the absence of FCS, activation with PMA or EGF was required to induce cluster formation. Overexpression of WASP with a missense mutation in the N-terminus of the PH domain failed to induce the large cluster formation in COS-7 cells even in the presence of FCS. We also found that phosphatidylinositol 4,5-bisphosphate (PIP(2)), which is known to regulate the actin cytoskeleton, binds to the PH domain of WASP, and the binding was abolished by the introduction of a missense mutation into the N-terminus but not the C-terminus of the PH domain. Together with the observations that most of the missense mutations observed in patients with WAS and XLT are located within the PH domain, these results indicate that the PH domain of WASP plays important roles in the regulation of actin cytoskeleton and suggested that the binding of PIP(2) to the PH domain is necessary for WASP to function properly.

Actins↗
PubMed1999

A new assay for the analysis of X-chromosome inactivation based on methylation-specific PCR.

The pattern of X-chromosome inactivation in females is currently evaluated by assays of differential methylation in the genes between the active and the inactive X chromosomes, with methylation-sensitive enzymes. We report a new assay in the human androgen receptor (HUMARA) locus involving a methylation-specific polymerase chain reaction (M-PCR) technique, independent of the use of restriction enzymes. The assay involves the chemical modification of DNA with sodium bisulfite and subsequent PCR. By using the assay with specific primers for the methylated allele, we obtained an X-inactivation pattern based on the ratio of the maternal inactive X to the paternal inactive X. These patterns were consistent with those obtained by conventional PCR assay at the same locus in 48 female cases. We also obtained another X-inactivation pattern based on the ratio of the maternal active X to the paternal active X by using specific primers for the unmethylated allele. The latter pattern was complementary to the former pattern, and a combination of these patterns produced a reliable X-inactivation pattern. The assay revealed that 12 (11%) of the 105 normal females had non-random inactivation patterns (>80:20 or <20:80). Four patients with an X; autosome translocation showed extremely non-random patterns, and these results were consistent with those obtained by previous molecular/cytogenetic studies. We conclude that M-PCR provides an accurate assay for X-inactivation and that it can be performed on various DNA samples unsuitable for restriction digestion.

Cell Line, Transformed↗
PubMed1999

Ku in the cytoplasm associates with CD40 in human B cells and translocates into the nucleus following incubation with IL-4 and anti-CD40 mAb.

CD40 plays a critical role in survival, growth, differentiation, and class switching of B lymphocytes. Although Ku is required for immunoglobulin class switching, how CD40 signal transduction is coupled to Ku is still unknown. Here, we show that CD40 directly interacts with Ku through the membrane-proximal region of cytoplasmic CD40. Ku was confined to the cytoplasm in human primary B cells, and the engagement of CD40 on the B cells cultured in the presence of IL-4 resulted in the dissociation of Ku from CD40, translocation of Ku into the nucleus, and increase in the activity of DNA-dependent protein kinase. These findings indicate that Ku is involved in the CD40 signal transduction pathway and may play an important role in the CD40-mediated events.

Antibodies, Monoclonal↗
PubMed1999

WASP is involved in proliferation and differentiation of human haemopoietic progenitors in vitro.

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, immunodeficiency and eczema. X-linked thrombocytopenia (XLT) is a mild form of WAS with isolated thrombocytopenia. Both phenotypes are caused by mutation of the Wiskott-Aldrich syndrome protein (WASP) gene. In this study we investigated the role of WASP in the differentiation of CD34-positive (CD34+) cells isolated from the bone marrow of patients with WAS (n = 5) or with XLT (n = 4). Megakaryocyte colony formation was significantly decreased in patients with WAS when compared with normal controls. The formation of granulocyte-macrophage colonies and erythroid bursts were also decreased in WAS patinets. In contrast, in XLT patients, formation of all these colonies was normal. However, in vitro proplatelet formation of megakaryocytes induced by thrombopoietin was markedly decreased in both XLT and WAS. Electron microscopic examination revealed that megakaryocytes obtained from WAS or XLT patients grown in vitro had abnormal morphologic features, which seemed to be caused by defective actin cytoskeletal organization, including labyrinth-like structures of the demarcation membrane system and deviated distribution of the alpha-granules and demarcation membrane system. These observations indicate that WASP is involved in the proliferation and differentiation of CD34+ haemopoietic progenitor cells probably by its participation in signal transduction and in the regulation of the cytoskeleton.

Blood Platelets↗