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K Sugamura

Publications and source records attributed to K Sugamura.

At least 73 records · Page 4Linked to original sources
PubMed1997

Bcl-2 rescues T lymphopoiesis, but not B or NK cell development, in common gamma chain-deficient mice.

The common cytokine receptor gamma chain (gamma(c)) is an indispensable subunit for the formation of lymphoid-related cytokine receptors, including IL-7 and IL-15 receptors, that mediate nonredundant or critical signals for the differentiation of T and B cells and natural killer (NK) cells, respectively. We introduced the bcl-2 transgene driven by E mu or H-2K promoters into gamma(c)-deficient mice that lack all three lymphoid subclasses. The forced expression of Bcl-2 restored all stages of T lymphopoiesis, but not B or NK cell development, indicating that a primary function of gamma(c)-mediated signals in the T lineage might be to maintain cell survival. Therefore, the development of T, B, and NK cells may be influenced by distinct intracytoplasmic signaling cascades that are activated by coupling of gamma(c)-related receptors.

Animals↗
PubMed1997

Lymphohaematopoietic abnormalities and systemic lymphoproliferative disorder in interleukin-2 receptor gamma chain-deficient mice.

Interleukin-2 (IL-2) receptor gamma chain-deficient mice with a truncated mutation showed the absence or severe reduction of natural killer cells, decreased numbers of T- and B-cells, marked hypoplasia of the thymus and peripheral lymphoid tissues, defective formation of lymphoid follicles and germinal centre in the peripheral lymphoid tissues, and the absence of Peyer's patches in the intestinal mucosa. In addition, marked splenomegaly with extramedullary haematopoiesis, increased level of IgM and decreased levels of IgG and IgE in serum, severe reduction of conventional B cells (B-2) in the peripheral lymphoid tissues, the presence of IgM-producing CD5+ B cells (B-1) and their differentiation into plasma cells and Motto cells in the spleen, and increased production and differentiation of macrophages in various tissues were found in the mutant mice. However, the development of both marginal metallophilic macrophage populations in the spleen and of their related macrophages in the other tissues of the mutant mice was severely impaired. All these abnormalities seem to be induced by the loss-of-function of the IL-2 receptor gamma chain. From 8 weeks of age on, inflammatory changes occurred in the intestines, mesenteric lymph nodes, lungs, liver, and kidneys of the mutant mice. Besides the absence of Hassall's corpuscles, thymic cysts were frequently observed in the mutant mice. These pathological abnormalities suggest that the gamma chain is implicated not only in lymphoid and haematopoietic development but also in thymic epithelial cell ontogeny.

Animals↗
PubMed1997

Induction of IL-1 beta-converting enzyme-independent apoptosis by IL-2 in human T cell lines.

Our previous study demonstrated that IL-2 suppressed growth of human T cell lines, in which the suppression was observed with members among HTLV-I-infected T cell lines independent of IL-2 for growth. In this study, we examined the molecular mechanism of IL-2-induced growth suppression with two HTLV-I-infected T cell lines; TL-OmI expressing endogenously three subunits, i.e. alpha, beta and gamma chains, of the IL-2 receptor, and an MT-1 transfectant expressing the endogenous alpha and gamma chains and exogenous beta chain. Our analysis revealed that IL-2 induced apoptosis in both T cell lines. Experiments with inhibitors for the proteases responsible for apoptosis signals showed that caspase 1 (IL-1 beta-converting enzyme) was not involved in apoptosis induced by IL-2. Other MT-1 sublines introduced with mutant beta chains demonstrated that IL-2-induced apoptosis required signals from both the serine-rich (S) region and acidic (A) region of the IL-2 receptor beta chain, which are essential but not critical for IL-2-mediated cell growth respectively. Collectively, IL-2 functions not only on growth promotion and prevention of apoptosis but also on induction of apoptosis, which may be implicated in physiological regulation of immune reactions by controlling growth and activation of T cells.

Apoptosis↗
PubMed1997

Itk, a T cell-specific tyrosine kinase, is required for CD2-mediated interleukin-2 promoter activation in the human T cell line Jurkat.

We investigated the functional role of Itk, a member of the cytoplasmic tyrosine kinase Tec family, in T cell activation. Stimulation of either CD2 or T cell receptor (TCR)/CD3 on Tcells by monoclonal antibody-mediated cross-linking induced tyrosine phosphorylation of Itk, which was maximal as early as 1 min after stimulation. The tyrosine kinase activity in the anti-Itk immunoprecipitate was significantly activated upon these stimulations. Interleukin-2 (IL-2) promoter activity stimulated by cross-linking of CD2, TCR/CD3, and CD28 with antibodies was significantly reduced by transient expression of an Itk mutant lacking the kinase activity. The reduction paralleled a decrease in tyrosine phosphorylation of endogenous wild-type Itk. Stimulation of CD2 or TCR/CD3 induced activation of the nuclear factor of activated T cells (NFAT), the binding site of which is included in the IL-2 gene promoter. The activation of NFAT was also impaired by expression of the Itk mutant. These results demonstrate that Itk plays a role in IL-2 production, indicating a critical involvement of Itk in the initial stage of T cell activation by mediating signals from the TCR/CD3 complex, CD2, and CD28.

CD2 Antigens↗
PubMed1997

HTLV-I Tax trans-activation and cell growth signaling.

We have cloned two genes for cell surface molecules, capable of delivering the intracellular signals, which are modulated for their expression by Tax. One is the gamma chain of the interleukin-2 (IL-2) receptor which is suggested to be critical for IL-2-dependent growth of human T-cell leukemia virus type I (HTLV-I) infected cells. The gamma chain is upregulated by Tax, like the IL-2 receptor alpha chain. This upregulation may compensate the gamma chain downregulation after IL-2 binding, presumably resulting in more frequent growth of HTLV-I infected T cells. The other is gp34 that was initially identified as a molecule specifically expressed on HTLV-I-infected T cells. gp34 has been demonstrated to bind OX40 which belongs to the tumor necrosis factor (TNF) receptor family. We found that HTLV-I Tax induces expression of gp34 and OX40, and that normal T cell transiently express both gp34 and OX40 upon antigenic stimulation. Collectively, it may be possible that HTLV-I-infected T cells are in a predisposition to growth due to modulated expression by HTLV-I Tax of gp34/OX40 and the gamma chain.

Cell Division↗
PubMed1997

Regulation of IL-2 signaling.

Several tyrosine kinases such as Jak1, Jak3, Lck and Syk are known to participate in IL-2-mediated intracellular signal transduction. Jak1, Lck and Syk are associated with the cytoplasmic domain of the beta chain, whereas Jak3 is associated with the cytoplasmic domain of the gamma chain, which is shared among receptors for IL-2, IL-4, IL-7 and IL-15. We first demonstrated that Jak1 is associated with the alpha chains of receptors for IL-4, IL-7 and IL-15 as well as the IL-2 receptor beta chain. Furthermore, we revealed that two proline residues in the box1 region, which is conserved in the IL-2 receptor beta chain and the alpha chains of the cytokine receptors, are essentially involved in association with Jak1. The MOLT4 transfectants with the box1 mutants of the IL-2 receptor beta chain lacking Jak1 association showed IL-2 responsiveness, in terms of activations of Jak3 and Stat5 and induction of cell growth, indicating that Jak1 is dispensable for IL-2-mediated cell growth signaling, and that Jak1 activation is not required for activation of Jak3 and Stat5 in the MOLT4 transfectants.

Amino Acid Sequence↗
PubMed1996

Cloning of a novel signal-transducing adaptor molecule containing an SH3 domain and ITAM.

We molecularly cloned a cDNA coding for a novel phosphotyrosine molecule with a 70 kDa molecular mass, named STAM (signal transducing adaptor molecule), which is tyrosine-phosphorylated rapidly after stimulation with various cytokines such as IL-2, IL-3, IL-4, IL-7, GM-CSF, EGF and PDGF. STAM contains an SH3 (Src-homology 3) domain and the ITAM (immunoreceptor tyrosine-based activation motif), suggesting that STAM acts as an adaptor molecule involved in signal transducing pathways from the cytokine receptors.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Interleukin 2 (IL-2) receptor expression and sensitivity to diphteria fusion toxin DAB389IL-2 in cultured hematopoietic cells.

The high-affinity interleukin 2 (IL-2) receptor is a heterotrimer consisting of alpha, beta, and gamma subunits. We examined the concentration of subunit mRNA for each of the three protein subunits on human hematopoietic cell lines, human peripheral blood mononuclear cells, and murine fibroblasts transfected with cDNAs encoding the human IL-2 receptor subunits. In most cultured hematopoietic cells, there was abundant gamma subunit message. In contrast, there was variable expression of both alpha and beta subunit message. Sensitivity of cells to the diphtheria fusion toxin DAB389IL-2 was not related to expression of any single IL-2 receptor subunit mRNA. Rather, the greatest sensitivity was observed for cells possessing all three subunit mRNAs. Cells displaying beta and gamma subunit mRNA showed a reduced but significant sensitivity to the fusion toxin. In contrast, cells with alpha and gamma subunit mRNA, but missing the beta subunit mRNA, were insensitive to DAB389IL-2. The data correlate with the requirement for an intermediate or a high-affinity receptor for cell intoxication. A critical concentration of the beta subunit may be required for toxin internalization and killing.

Animals↗
PubMed1996

Differential activity of dexamethasone on IL-2-, IL-4-, or IL-9-induced proliferation of murine factor-dependent T cell lines.

Mouse helper T cell lines were developed that proliferate permanently without Ag and APCs in response to either IL-2, IL-4, or IL-9, three cytokines whose receptors interact with the IL-2R gamma-chain for signal transduction. Depending on the growth factor, a marked difference was observed regarding the ability of dexamethasone (DEX) to inhibit cell proliferation. In three different cell lines, proliferation induced by IL-2 was completely arrested, while that supported by IL-9 was hardly affected. With IL-4, proliferation was also maintained but less markedly than with IL-9. Although DEX was able to induce apoptosis in these cells, the inhibition of IL-2-induced proliferation was not the result of apoptosis, as this process was equally antagonized by all three factors. Moreover, addition of IL-4 or IL-9 to cultures previously incubated with IL-2 and DEX for several days restored cell proliferation. Finally, autonomous cell variants derived from the factor-dependent cell lines were still protected by IL-4 and IL-9 against growth inhibition by DEX. Together, these results indicate that growth stimulation in the presence of glucocorticoids and inhibition of apoptosis involve distinct aspects of cytokine activities.

Animals↗
PubMed1996

Interleukin-4 (IL-4) and IL-13 bind to a shared heterodimeric complex on endothelial cells mediating vascular cell adhesion molecule-1 induction in the absence of the common gamma chain.

Interleukin-4 (IL-4) and IL-13 exert similar, nonadditive effects on endothelial cells, inducing vascular cell adhesion molecule-1 (VCAM-1) expression and subsequent transmigration of eosinophils. The receptor for IL-4 and IL-13 was described as a shared heteromultimeric complex in which the common gamma-chain (gamma c) subunit was essential for activity. Endothelial cell bound both cytokines with high affinity; by flow cytofluorometry and reverse transcription-polymerase chain reaction (RT-PCR), they expressed IL-4 receptor alpha (IL-4R alpha) but did not express the gamma c of the IL-2R. Radioligand cross-linking experiments followed by immunoprecipitation with the monoclonal antibody (MoAb) S697 to the IL-4R alpha showed IL-4-specific binding at 130 kD, the IL-4R alpha, and to a minor extent to a double band coimmunoprecipitated at 65 to 75 kD. [125 I]IL-13 bound predominantly to the 65- to 75- kD band and with a trace amount of binding at 130 kD. However, no ligand-cross-linked receptor was precipitated by the MoAb S697, indicating a cognate novel IL-13-binding subunit. Excess unlabeled IL-4 completely displaced IL-13 binding. Similarly, nonsignaling IL-4 (Y124D)-mutant abolished IL-4- and IL-13-mediated signal transduction. Unlabeled IL-13 competed successfully for IL-4 binding at 65 to 75 kD but was unable to completely displace Il-4 from its binding to the IL-4R alpha. The MoAb TUGh4, specific for the gamma c, failed to precipitate ligand-cross-linked IL-4R and IL-13R. Therefore, the subunit structure of the functional receptors for IL-4 and IL-13 on human endothelial cells does not use or require the common gamma c of the IL-2R.

Amino Acid Sequence↗
PubMed1996

Apoptotic cell death and its relationship to carcinogenesis in colorectal carcinoma.

BACKGROUND: Apoptotic cell death plays an important role in the proliferation and turnover of cells in various tumors. The relationship between apoptosis and cell proliferation was studied to determine each of their roles in colorectal carcinogenesis. METHODS: Apoptotic cells were identified by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. The occurrence of apoptosis was examined in colorectal cancer that had invaded the submucosa. Specimens were obtained from 38 cases of cancer with adenoma and 29 cases of cancer de novo. Apoptotic indices (AIs) as percentages of TUNEL-positive cells relative to the number of tumor cells and Ki-67 labeling indices (PI) were investigated. The relationship between the frequency of apoptosis and the expression of p53 and c-myc proteins was also investigated. RESULTS: In cancer with adenoma, the ratio of AI/PI in adenoma cells was significantly higher than that of cancer cells (P < 0.0001). Mean AIs of cancer with adenoma were significantly higher than those of cancer de novo particularly in the flat-type cancers (P < 0.05). Among p53 negative tumors, the ratio of AI/PI for cancer de novo was significantly lower than that for cancer with adenoma (P < 0.05). AI of cancer de novo was lower than that of cancer with adenoma in cases with overexpression of c-myc protein (P < 0.05), whereas there was no significant difference in the ratio of AI/PI between cancer de novo and cancer with adenoma. CONCLUSIONS: Colorectal carcinogenesis is related to the inhibition of apoptosis and to the augmentation of proliferative activity both in cancer with adenoma and in cancer do novo. A reduction of the rate of apoptosis as compared with that of cell proliferation might explain the rapid-growing nature of cancer de novo particularly in cases with the flat-type appearance.

Antigens, Neoplasm↗
PubMed1996

Retroviral-mediated gene correction for X-linked severe combined immunodeficiency.

X-linked severe combined immunodeficiency (XSCID) is a lethal disease caused by a defect in the gene encoding the common gamma chain (gamma-c) of the receptor for interleukin-2 (IL-2), IL-4, IL-7, IL-9, and IL-15. Allogeneic bone marrow transplantation, the current therapy of choice for this defect, is often complicated by graft-versus-host disease and/or incomplete reconstitution of B-lymphocyte functions. Correction of the gene defect at the level of the autologous lymphohematopoietic progenitors could therefore represent an improvement in the medical management of these patients. To study the feasibility of a gene therapy approach for XSCID, a retroviral vector expressing gamma-c was used to transduce Epstein-Barr virus-transformed B-cell lines derived from patients with XSCID. After transduction, XSCID cells newly expressed gamma-c on the cell surface at levels comparable to those observed on B-cell lines obtained from normal donors. Moreover, the reconstituted gamma-c restored function to the IL-2 and IL-4 receptors as shown by signal transduction mediated by phosphorylation of the JAK1 and JAK3 members of the Janus family of tyrosine kinases and by restoration of cellular proliferation in response to IL-2.

B-Lymphocytes↗
PubMed1996

gamma-c gene transfer into SCID X1 patients' B-cell lines restores normal high-affinity interleukin-2 receptor expression and function.

SCID X1 is characterized by faulty T-cell and natural killer cell differentiation caused by mutation of the gamma-c chain gene encoding a number of multiple cytokine receptors (interleukin-2 [IL-2], IL-4, IL-7, IL-9, and IL-15 receptors). To assess the feasibility of inducing long-term expression and function of the gamma-c chain, Epstein-Barr virus (EBV)-transformed B-cell lines from two patients with SCID X1 were transduced with a Moloney-derived retroviral vector containing the gamma-c chain cDNA. The viral LTR was used as the promoter. Immediately after two cycles of coculture with the psi-crip clone producing the MFG(B2)-gamma-c cDNA vector, gamma-c expression, assessed by detection of the mRNA and membrane protein expression, was found in 15% to 20% of cells. The degree of membrane expression was similar to that in control EBV-B cells. Expression increased steadily over 6 months, becoming detectable in 100% of cells, and remained stable thereafter for a total of 9 months, reflecting positive selection of transduced cells. A study of provirus integration sites showed multiple integration. The expressed gamma-c was functional, because it restored high-affinity IL-2 receptor binding, IL-2 endocytosis, and IL-2-triggered phosphorylation of JAK-3 tyrosine kinase. Similar results were obtained with the two B-cell lines. These results show that efficient gamma-c gene transfer into B-cells lacking functional gamma-c is feasible and results in strong and stable expression of a functional gamma-c chain, apparently conferring a selective growth advantage in culture. Further in vitro studies of gamma-c gene transfer into gamma-c- hematopoietic progenitors are being conducted to assess the feasibility of correcting lymphocyte differentiation defects.

B-Lymphocytes↗
PubMed1996

Expression of the interleukin-2 receptor gamma chain on cord blood mononuclear cells.

Lymphocytes in umbilical cord blood and neonatal peripheral blood have been shown to have less ability in an immune reaction. In our present experimental approach to address this issue, we made use of the cord blood of full-term birth infants to investigate the expression of the interleukin- 2 receptor gamma (IL-2Rgamma) chain that is shared with receptors for IL-4, IL-7, IL-9, and IL-15 as well as IL-2. The gamma chain expression in cord blood lymphocytes was about one-third that in the lymphocytes of adults, whereas no significant difference between cord blood and adult monocytes was observed. A reduced expression of the gamma chain was observed in all of the CD4+ T cells, CD8+ T cells, gamma-delta T cells, B cells, CD16+ natural killer (NK) cells, and CD56(bright) NK cells of the cord blood lymphocytes. The reduced gamma chain expression reached two-thirds of that in adults after 3 days of culture in vitro and in infants 3 days after birth, thus implying that the increase in the gamma chain may significantly contribute to the prevention of neonatal infection.

Adult↗
PubMed1996

Modulation of hematopoiesis in mice with a truncated mutant of the interleukin-2 receptor gamma chain.

The interleukin-2 (IL-2) receptor gamma chain is indispensable for IL-2-, IL-4-, IL-7-, IL-9-, and IL-15-mediated signaling. Mutations of the human gamma chain cause the X-linked severe combined immunodeficiency (XSCID), showing that T and natural killer cells absolutely require the gamma chain for their development in humans. To elucidate the roles of the gamma chain in hematopoiesis, we have generated mice, by gene targeting, that express a form of the gamma chain lacking the cytoplasmic region. Male mice carrying the truncated gamma-chain mutant, which mimics mutations in patients with XSCID, showed a decrease in the number of lymphocytes and an increase in monocytes; the number of T cells was profoundly reduced and no natural killer cells were detected, which is similar to the characteristic of human XSCID. Unlike human XSCID, the levels of B cells were also reduced. In spite of the severe decrease in CD45R+/sIgM+ B cells, the level of IgM in serum of the 8-week-old mutant mice was higher than that of control littermates. Interestingly, the stem cell population with surface phenotypes of CD34, c-kit, and Sca-1 was significantly increased. Furthermore, the colony-forming assay showed that the mutant mice had 15-fold higher numbers of hematopoietic progenitor cells in the spleen as compared with that of controls. These results indicate that functional loss of the gamma chain causes significant effects on the immunological system in mice.

Animals↗
PubMed1996

IL-15 is a novel growth factor for murine gamma delta T cells induced by Salmonella infection.

We have previously shown evidence for the early recruitment of gamma delta T cells during the disease course of primary infections with Listeria monocytogenes or Salmonella choleraesuis in mice. Since gamma delta T cells at this stage of the disease do not produce IL-2, the growth factor for the gamma delta T cells remains unknown. IL-15 is a novel cytokine that uses beta- and gamma-chain of IL-2R for signal transduction, and is produced by activated monocytes/macrophages. In this study, we investigated the proliferative activity of IL-15 for gamma delta T cells appearing after primary infection with S. choleraesuis 31N-1. The gamma delta T cells, which expressed beta- and gamma-chains of IL-2R, proliferated in the presence of rIL-15 and produced appreciable levels of gamma-IFN and IL-4. Addition of anti-IL-2R beta mAb significantly inhibited the IL-15-induced proliferation of the gamma delta T cells. Furthermore, the gamma delta T cells produced gamma-IFN in response to monocyte/macrophage cell line, J774A.1 infected with S. choleraesuis, which expressed an abundant level of IL-15 mRNA. This cytokine production was inhibited significantly by anti-IL-15 Ab. Taken together, these results suggest that IL-15 derived from infected macrophages may contribute to the early activation of gamma delta T cells during salmonellosis.

Animals↗
PubMed1996

Expression of the common cytokine receptor gamma chain by murine dendritic cells including epidermal Langerhans cells.

The common cytokine receptor gamma chain (gamma c) is an indispensable component of interleukin (IL)-2, IL-4, IL-7, IL-9, and IL-15 receptors, and its expression has been detected in several leukocyte populations, including T cells, B cells, monocytes, natural killer cells, and neutrophils. The purpose of this study was to determine whether gamma c receptors are expressed by dendritic cells (DC). Constitutive gamma c mRNA expression was observed by reverse transcription polymerase chain reaction and/or Northern blotting for: (a) Ia+ epidermal Langerhans cells (LC), (b) 4F7+ splenic DC, (c) granulocyte/macrophage colony-stimulated factor-propagated bone marrow-derived DC, and (d) the epidermal-derived DC line, XS52, which retains important functions of epidermal LC. Exposure of XS52 cells to recombinant IL-4 induced a rapid up-regulation of c-myc mRNA expression, and this IL-4-dependent signaling was blocked almost completely by anti-gamma c monoclonal antibody (mAb) TUGm2 in a soluble form. Moreover, c-myc up-regulation was inducible in XS52 cells by the same mAb in an immobilized form. These results imply that molecules recognized by this antibody (i.e. gamma c receptors) are expressed on XS52 cell surfaces. We thus conclude that DC express functional gamma c receptors, which then mediate cytokine-dependent regulation of DC functions.

Animals↗