Publications by authors named "Kazuko Murata"

Article Synopsis
  • HGF-regulated tyrosine kinase substrate (Hrs) is an essential protein involved in sorting and transporting ubiquitinated membrane proteins to the lysosomes for degradation.
  • A study using genetically modified mice lacking Hrs specifically in B-cells revealed that Hrs deficiency reduced the production of antibodies in response to T-cell activation and impaired B-cell growth when stimulated in vitro.
  • Although the initial development of B-cells in the bone marrow was unaffected, there was a significant loss of transitional and marginal zone B-cells in the spleens of these modified mice, highlighting Hrs's crucial role in the later stages of B-cell development and function.
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Interleukin-21 (IL-21) is overproduced in human intestines affected by inflammatory bowel disease (IBD) and in the gut of mice with DSS-induced colitis. IL-21-deficient mice are largely protected against DSS-induced colitis, indicating that IL-21 plays a key role in the development of IBD. We previously identified a novel IL-21 isoform named IL-21iso.

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The endosomal sorting complex required for transport (ESCRT) proteins form multimolecular complexes that control multivesicular body formation, endosomal sorting, and transport ubiquitinated membrane proteins (including cell-surface receptors) to the endosomes for degradation. There is accumulating evidence that endosomal dysfunction is linked to neural cell degeneration in vitro, but little is known about the relationship between neural disorders and ESCRT proteins in vivo. Here we specifically deleted the hrs gene, ESCRT-0, in the neurons of mice by crossing loxP-flanked hrs mice with transgenic mice expressing the synapsin-I Cre protein (SynI-cre).

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Invariant natural killer T (iNKT) cells are a special subset of alphabeta T cells with invariant TCR, which recognize alpha-galactosylceramide (alpha-GalCer) presented by CD1d. In addition to signals through the invariant TCR upon stimulation with alpha-GalCer, costimulatory signals, such as signals through CD28 and OX40, are indispensable for full activation of iNKT cells. In this study, we investigated the functions of a well-known costimulatory molecule, glucocorticoid-induced TNF receptor (GITR), on Ag-induced iNKT cell activation.

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Abnormally high signals from receptor tyrosine kinases (RTK) are associated with carcinogenesis, and impaired deactivation of RTKs may also be a mechanism in cancer. Hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) is one of the master regulators that sort activated receptors toward lysosomes and shut down their signals. Hrs contains a ubiquitin-interacting motif and is involved in the endosomal sorting of monoubiquitinated membrane proteins, such as growth factor receptor and E-cadherin.

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The OX40 (CD134) molecule is induced primarily during T cell activation and, as we show in this study, is also expressed on CD25+CD4+ regulatory T (Treg) cells. A necessary role for OX40 in the development and homeostasis of Treg cells can be inferred from the reduced numbers of the cells present in the spleens of OX40-deficient mice, and their elevated numbers in the spleens of mice that overexpress the OX40 ligand (OX40L). The homeostatic proliferation of Treg cells following transfer into lymphopenic mice was also found to be potentiated by the OX40-OX40L interaction.

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A cross-sectional study was performed to assess the rates of blood pressure (BP) control to a systolic goal (< 140 mmHg), to a diastolic goal (< 90 mmHg), and to both in a sample of 226 treated hypertensive patients. We also examined the association between obesity, BP control, intensity of treatment defined as dose score (summed ranks of doses of all antihypertensive drugs taken), and number of drugs. Of the 226 treated patients (mean age, 60 years; 20.

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The role of OX40-OX40 ligand (OX40L) interaction in Th cell differentiation remains contentious. In vitro studies have revealed a Th2-biased effect by OX40 signals in T cells. However, in vivo studies demonstrated that OX40-OX40L interaction is involved in responses either Th1 or Th2, or both, which appears to be dependent on the experimental conditions used.

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Langerhans cells (LC) represent the dominant antigen-presenting cells (APC) in the epidermis and thus play an important role in cutaneous immune responses to approaching pathogens. These responses are mediated by several costimulatory molecules after antigenic challenge. OX40 ligand (OX40L), a member of TNF superfamily, is expressed on several APC such as splenic dendritic cells (DC) and activated B cells.

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We previously reported that the STAM family members STAM1 and STAM2 are phosphorylated on tyrosine upon stimulation with cytokines through the gammac-Jak3 signaling pathway, which is essential for T-cell development. Mice with targeted mutations in either STAM1 or STAM2 show no abnormality in T-cell development, and mice with double mutations for STAM1 and STAM2 are embryonically lethal; therefore, here we generated mice with T-cell-specific double mutations for STAM1 and STAM2 using the Cre/loxP system. These STAM1(-/-) STAM2(-/-) mice showed a significant reduction in thymocytes and a profound reduction in peripheral mature T cells.

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The interaction between OX40 and OX40 ligand (OX40L) is suggested to provide T cells with an effective costimulatory signals during T cell-APC interaction. To examine the in vivo effect of constitutive OX40/OX40L interaction during immune regulation, we report the establishment of OX40L-transgenic (OX40L-Tg) mice that constitutively express OX40L on T cells. Markedly elevated numbers of effector memory CD4(+) T cells, but not CD8(+) T cells, were observed in the secondary lymphoid organs of OX40L-Tg mice.

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Human parvovirus B19 (B19) infection during pregnancy is associated with the adverse foetal outcome known as non-immune hydrops fetalis (NIHF). Although B19 is known to infect erythroid-lineage cells in vivo as well as in vitro, the mechanism leading to the occurrence of NIHF is not clear. To investigate the possible involvement of the B19 non-structural protein NS1 in NIHF, three independent lines of transgenic mice were generated that expressed NS1 under the control of the Cre-loxP system and the GATA1 promoter.

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