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Biomedical subjects

Shingo Ichimiya

Publications and source records attributed to Shingo Ichimiya.

24 records · Page 2Linked to original sources
PubMed2002

Improved generation of HLA class I/peptide tetramers.

As a tetrameric major histocompatibility complex (MHC) class I-peptide complex (tetramer) is capable of detecting antigen-specific cytotoxic T lymphocyte (CTL) by flow cytometry, significant information about the generation of in vivo immunity can be obtained. It is, however, difficult to make a soluble wild type of MHC class I heavy chain by the prokaryotic expression system. Therefore, we developed a new method for making soluble mutant HLA-A*2402 heavy chain. In this method, signal sequences were deleted, and the codon was changed to silent mutated nucleotide sequences that bacteria could use as preferable codon. When purified mutant HLA-A*2402 molecules were examined for the protein generation by SDS-polyacrylamide gel electrophoresis (PAGE) and western blotting using anti-HLA class I monoclonal antibody (mAb) as compared with wild type, a large amount of mutant heavy chain could be detected. In contrast, the expression of wild-type stable HLA-A*2402 heavy chain molecule was not detected in this system. Consequently, by using mutant HLA-A*2402/peptide tetramers, CTL precursors (CTLp) that specifically recognize antigenic peptide derived from the X;18 chromosomal translocations of synovial sarcoma were detected in patients' PBL.

Base Sequence↗
PubMed2002

Detection and induction of CTLs specific for SYT-SSX-derived peptides in HLA-A24(+) patients with synovial sarcoma.

To investigate the immunogenic property of peptides derived from the synovial sarcoma-specific SYT-SSX fusion gene, we synthesized four peptides according to the binding motif for HLA-A24. The peptides, SS391 (PYGYDQIMPK) and SS393 (GYDQIMPKK), were derived from the breakpoint of SYT-SSX, and SS449a (AWTHRLRER) and SS449b (AWTHRLRERK) were from the SSX region. These peptides were tested for their reactivity with CTL precursors (CTLps) in 16 synovial sarcoma patients using HLA-A24/SYT-SSX peptide tetramers and also for induction of specific CTLs from four HLA-A24(+) synovial sarcoma patients. Tetramer analysis indicated that the increased CTLp frequency to the SYT-SSX was associated with pulmonary metastasis in synovial sarcoma patients (p < 0.03). CTLs were induced from PBLs of two synovial sarcoma patients using the peptide mixture of SS391 and SS393, which lysed HLA-A24(+) synovial sarcoma cells expressing SYT-SSX as well as the peptide-pulsed target cells in an HLA class I-restricted manner. These findings suggest that aberrantly expressed SYT-SSX gene products have primed SYT-SSX-specific CTLps in vivo and increased their frequency in synovial sarcoma patients. The identification of SYT-SSX peptides may offer an opportunity to design peptide-based immunotherapeutic approaches for HLA-A24(+) patients with synovial sarcoma.

Adolescent↗
PubMed2002

p73 is expressed in human thymic epithelial cells.

The thymus is a heterogeneous immune organ in which immature T-cells develop and eventually specialize to make certain immune responses of their own. Among various types of stromal cells in the thymus, thymic epithelial cells (TECs) have a crucially important function for presenting self-antigens and secreting cytokines to thymocytes for their maturation into T-cells. In this study we show that the p73 gene, a homologue of the tumor suppressor gene p53, was expressed in the nucleus of the human TEC in vivo and in TEC lines in vitro. Because p73 has the capacity to be a transactivator like p53, it may contribute to T-cell development in the context of TEC biology as regulated in the cell cycle and apoptosis.

Cell Line↗
PubMedDate not supplied

Role of the p38 MAP-kinase signaling pathway for Cx32 and claudin-1 in the rat liver.

Liver regeneration and cholestasis are associated with adaptive changes in expression of gap and tight junctions through signal transduction. The roles of stress responsitive MAP-kinase, p38 MAP-kinase, in the signaling pathway for gap junction protein, Cx32, and tight junction protein, claudin-1, were examined in rat liver in vivo and in vitro, including regeneration following partial hepatectomy and cholestasis after common bile duct ligation. Changes in the expression and function of Cx32 and claudin-1 in hepatocytes in vivo were studied using the p38 MAP-kinase inhibitor SB203580. Following partial hepatectomy and common bile duct ligation, down-regulation of Cx32 protein was inhibited by SB203580 treatment. Up-regulation of claudin-1 protein was enhanced by SB203580 treatment after partial hepatectomy but not common bile duct ligation. However, no change of the Ki-67 labeling index (which is a marker for cell proliferation) in the livers treated with SB203580, was observed compared to that without SB203580 treatment. In primary cultures of rat hepatocytes, however, treatment with a p38 MAP-kinase activator, anisomycin, decreased Cx32 and claudin-1 protein levels. p38 MAP-kinase may be an important signaling pathway for regulation of gap and tight junctions in hepatocytes. Changes of gap and tight junctions during liver regeneration and cholestasis are shown to be in part controlled via the p38 MAP-kinase signaling pathway and are independent of cell growth.

Animals↗
PubMedDate not supplied

A gene encoding human gastric signet ring cell carcinoma antigen recognized by HLA-A31-restricted cytotoxic T lymphocytes.

SUMMARY: We previously reported acid-extracted natural antigenic peptide (F4.2 [YSWMDISCWI]) of a gastric signet ring cell carcinoma HST-2 cells, recognized by HLA-A*31012-restricted autologous cytotoxic T lymphocytes, TcHST-2 line. In this study, the full-length cDNA (1101 bp), termed c98, predicting a protein composed of 170 amino acids was obtained. Because TcHST-2 cells could lyse the HLA-A31 antigen (+) allogeneic tumor cells that were introduced with c98 gene, this gene was suggested to possess antigenicity. Beginning at N-terminal 61 amino acid, the N-terminal six amino acid sequence that is completely identical to F4.2 was present in c98; however, a sequence of four amino acids in C-terminal was not found. Nevertheless, this peptide, c98(61-70), seemed to be immunogenic, because cells pulsed with c98(61-70) peptide were lysed in a dose-dependent manner by TcHST-2 cells. The c98 gene was expressed ubiquitously in tumor cells as well as in normal tissues. However, some tumor cells, including HST-2 cells, expressed this antigen in a high content, and such cells were lysed by TcHST-2 cells in the context of HLA-A31 antigen. However, TcHST-2 cells did not lyse cells that expressed lower amounts of c98 than HST-2 cells. These data suggested that c98-gene product and/or c98(61-70) peptides could be used as a candidate for tumor vaccines in cancer immunotherapy.

Amino Acid Sequence↗