Teruhisa Otsuka

Association between IL-4 genotype and IL-4 production in the Japanese population.

We have identified that there are only two IL-4 gene haplotypes (I and II) in the Japanese population. There are significant differences among three genotypes (I/I, I/II and II/II) in the IL-4 producing proportion of peripheral Th cells using intracellular cytokine detection assay. These results make it likely that IL-4 genotype could influence the type of immune response.

Role of the vav Proto-oncogene Product (Vav) in Erythropoietin-mediated Cell Proliferation and Phosphatidylinositol 3-Kinase Activity

The vav proto-oncogene product (Vav), which is specifically expressed in hematopoietic cells, contains multiple structural motifs commonly used by intracellular signaling molecules. Although a variety of stimuli including erythropoietin (Epo) have been shown to tyrosine phosphorylate Vav, little is known about the Vav signal transduction pathway. Here, we have investigated the role of Vav in the Epo signaling pathway by characterizing its interaction with other proteins, using the human Epo-responsive cell line, F-36P. Immunoprecipitation and immunoblot analyses have demonstrated that Vav was associated with the Epo receptor (EpoR) in an Epo-independent manner and was tyrosine-phosphorylated after Epo stimulation. Furthermore, two phosphotyrosine proteins (pp70 and pp100) co-immunoprecipitated with the regulatory subunit of phosphatidylinositol 3-kinase (PI3-kinase) (p85) were identified as EpoR and Vav, respectively. The interaction between Vav and p85 was shown to be mediated through the SH2 domains of p85 by an in vitro binding assay and confirmed by the presence of in vitro PI3-kinase activity associated with Vav. Treatment of the cells with antisense-vav and -p85 abrogated Epo-induced cell proliferation and PI3-kinase activity. Finally, we found that JAK2 was associated with Vav in vivo and that Vav could be tyrosine-phosphorylated by activated JAK2 in vitro. These results suggest the possible role of JAK2 for tyrosine phosphorylation of Vav and involvement of Vav and PI3-kinase in Epo-induced proliferative signals.

Association of the interferon-γ receptor variant (Val14Met) with systemic lupus erythematosus

Abstract Genetic factors seem to play a significant role in susceptibility to systemic lupus erythematosus (SLE). The purpose of this study was to investigate whether the amino acid polymorphism (Val14Met) found within the IFN-γ receptor gene (IFNGR1) plays a prominent role in susceptibility to SLE. We found Val14Met located at the COOH terminal of the signal peptide of the IFN-γ receptor. There was a significant difference in this polymorphism frequency between SLE patients and healthy populations. To clarify whether this amino acid substitution resulted in the alteration of the receptor function, we evaluated the induction of HLA-DR antigen expression on B cells by IFN-γ stimulation. There was also a significant difference in the induction of HLA-DR by IFN-γ stimulation between B cells. Furthermore, an intracellular cytokine assay indicated that the Th1/Th2 balance of Th cells bearing the variant receptor shifted to Th2. The genetic polymorphism found within the IFN-γ receptor gene (Val14Met) may result in a shift to Th2, and this shift may increase susceptibility to SLE.

Correlation of telomerase activity with development and progression of adult T-cell leukemia.

Telomerase is an enzyme that adds hexameric TTAGGG nucleotide repeats to the ends of vertebrate chromosomal DNAs (i.e. telomeres) to compensate for losses that occur with each round of DNA replication. Telomerase activity, demonstrable in most human tumors, enables them to maintain telomere stability. Peripheral blood mononuclear cells were sampled from 57 patients seropositive for human T-lymphotropic virus type I (HTLV-I), including 24 asymptomatic viral carriers, ten smoldering type, five chronic type, and 18 acute type adult T-cell leukemia (ATL). Telomerase activity was determined in samples using a modified telomeric repeat amplification protocol. We semiquantitatively determined telomerase activity by serial dilution of each sample. All of 23 samples from acute and chronic type ATL patients were positive, seven of ten (70%) smoldering type patients and seven of 24 (29.2%) asymptomatic viral carriers were positive. Disease progression from asymptomatic viral carrier to acute type correlated with telomerase activity. Two samples from chronic type ATL patients with relatively high telomerase activity progressed to the acute type within 1 month. Serum lactate dehydrogenase level also correlated with telomerase activity. These results indicate that reactivation of telomerase activity is a key event in development and progression of ATL, and telomerase could be a useful marker for predicting the course of disease. Accordingly, ATL could be a good candidate disease for trials of telomerase inhibitors, as novel anticancer drugs.

Detection of human herpesvirus-8 in peripheral blood mononuclear cells from adult Japanese patients with multicentric Castleman's disease.

Summary. Human herpesvirus‐8 (HHV‐8) encodes viral homologues of cellular genes, including viral interleukin 6 (vIL‐6), which induces endogenous human IL‐6 (hIL‐6) secretion. Unregulated overproduction of hIL‐6 in lymph nodes (LN) is thought to be responsible for the systemic manifestations of multicentric Castlemans disease (MCD). In the present study, we assessed the presence of HHV‐8 and HHV‐8‐encoded viral homologues in LN and peripheral blood mononuclear cells (PBMC) from adult Japanese patients with MCD. HHV‐8 DNA was amplified by nested polymerase chain reaction (PCR) and was detected in LN from 13 out of 16 MCD patients (81%). HHV‐8 DNA was also detected in PBMC from six out of seven patients (86%) whose LN were positive for HHV‐8 DNA. Because mRNA could not be successfully extracted from LN sections that were either formalin‐fixed or embedded in paraffin, we examined the expression of mRNA for HHV‐8‐encoded viral homologues, such as vIL‐6, vBCL‐2, vCyclin‐D and viral G‐protein‐coupled receptor (vGPCR) by nested reverse transcription (RT)‐PCR in PBMC from 10 MCD patients. However, mRNA of these HHV‐8‐encoded viral homologues was not detected in any patients tested. Although our results do not indicate a role for HHV‐8‐encoded viral homologues in the pathogenesis of MCD, they do suggest that HHV‐8 infection may be associated with MCD in adult Japanese patients.

MTG8 proto-oncoprotein interacts with the regulatory subunit of type II cyclic AMP-dependent protein kinase in lymphocytes

AML1-MTG8 chimeric oncogene is generated in acute myelogenous leukemia with t(8;21), and seems to be responsible for the pathogenesis of the disease. However, the role of MTG8 is ambiguous. Here we found that MTG8 interacted with the regulatory subunit of type II cyclic AMP-dependent protein kinase (PKA RIIα). The binding site of MTG8 was NHR3 domain, and that of RIIα was the N-terminus for interacting with PKA anchoring proteins (AKAPs). NHR3 contains a putative α-amphipathic helix which is characteristic in binding of AKAPs with RII. Indirect immunofluorescence microscopy showed that MTG8 and RIIα were overlapped at the centrosome-Golgi area in lymphocytes. These findings suggest that MTG8 may function as an AKAP at the centrosome-Golgi area in lymphocytes.

Influence of transplanted dose of CD56+ cells on development of graft-versus-host disease in patients receiving G-CSF-mobilized peripheral blood progenitor cells from HLA-identical sibling donors.

Summary:We investigated effects of variations in the cellular composition of G-CSF-mobilized peripheral blood progenitor cell (G-PBPC) allografts on clinical outcomes of allogeneic PBPC transplantation. We retrospectively analyzed transplanted doses of various immunocompetent cells from 27 HLA-identical sibling donors in relation to engraftment, incidence of graft-versus-host disease (GVHD), and survival. Significant variability was documented in both absolute numbers and relative proportions of CD34+, CD2+, CD3+, CD4high+, CD4+25+, CD8high+, CD19+, CD56+, and CD56+16+ cells contained in these allografts. Stepwise Cox regression analysis revealed that the CD56+ cell dose was significantly inversely correlated with the incidence of GVHD. Thus, there was a significantly higher incidence of grade II acute GVHD in patients receiving a lower CD56+16+ cell dose (hazard ratio (HR) 0.0090; 95% confidence interval (CI), <0.00001–3.38; P=0.031), a higher incidence of chronic GVHD in those receiving allografts with a lower CD56+16+ to CD34+ ratio (HR <0.00001; 95% CI <0.00001–0.0007; P=0.0035), and a higher incidence of extensive chronic GVHD in those receiving allografts with a lower CD56+ to CD34+ ratio (HR <0.00001; 95% CI <0.00001–0.053; P=0.0083). These results suggest that CD56+ cells in G-PBPC allografts from HLA-identical sibling donors may play an important role in preventing the development of GVHD.

Proliferative involvement of ENX-1, a putative human polycomb group gene, in haematopoietic cells.

Homeobox genes have important roles in haematopoiesis and are regulated in an activated state by the trithorax group (trxG) of genes. In a repressed state, they are regulated by the Polycomb group (PcG) of genes. ENX‐1, a putative human PcG gene product, interacts with the proto‐oncogene product Vav. We report an investigation of the role of ENX‐1 in human haematopoiesis. CD34+ cells mobilized to peripheral blood strongly expressed ENX‐1. When stimulated to proliferate, both T and B lymphocytes rapidly up‐regulated ENX‐1. ENX‐1 was expressed in all cell lines of the various lineages examined. When HL‐60 cells were differentiated to mature granulocytes with all‐trans retinoic acid, ENX‐1 was down‐regulated. Moreover, ENX‐1 antisense oligodeoxynucleotide suppressed DNA synthesis in HL‐60 cells. Our data indicate that ENX‐1 is involved in the proliferation of both normal and malignant haematopoietic cells.

The role of telomerase activity in hepatocellular carcinoma

OBJECTIVE:The aim of this study was to clarify the role of telomerase activity in hepatocellular carcinoma (HCC).METHODS:Specimens from both HCC and noncancerous liver were obtained from 39 patients with HCC using a 14-gauge biopsy needle immediately after laparotomy. Telomerase activity was determined using a telomeric repeat amplification protocol assay. The 3+ of telomerase activity in HCC was defined as a high telomerase group, and 2+ or less of HCC telomerase activity was defined as a low telomerase group. In noncancerous liver, 2+ or more of telomerase activity was defined as an increased telomerase group, and 1+ or less of telomerase activity was defined as a nonincreased telomerase group. The correlation between telomerase activity in HCC or noncancerous liver and clinicopathological factors, including prognosis, was investigated.RESULTS:Telomerase activities in HCCs were 0 in one patient, 1+ in two, 2+ in seven, and 3+ in 29 patients. The disease-free survival rate in the high telomerase group was significantly worse than that in the low telomerase group. The des-γ-carboxy prothrombin level in a high telomerase group (median, 330 mAU/ml) was significantly higher than that in the low telomerase group (median, 150 mAU/ml). A multivariate analysis revealed that higher TNM stage, high telomerase activity in HCC, female gender, and high α-fetoprotein value were independent significant factors related to be early recurrence. The incidence of multicentric HCC occurrence in the increased telomerase group (53.3%) tended to be higher than that in the nonincreased telomerase group (27.3%).CONCLUSION:A high telomerase activity in HCC correlated with the potential of HCC to be more malignant, which was expressed as both a high level of des-γ-carboxy prothrombin and an earlier recurrence after hepatectomy than that of HCC with a low telomerase activity.

Differential gene expression of human telomerase-associated protein hTERT and TEP1 in human hematopoietic cells

The maintenance of telomere length is crucial for the survival of cells. Recently, genes for proteins that consist of human telomerase have been cloned and the results have indicated a close relationship between telomerase activity and its gene expression. We studied the mRNA expression of the telomerase-associated genes, hTERT and TEP1, in hematopoietic cells in order to clarify the relation between them and telomerase activity using semiquantitative RT-PCR. In polymorphonuclear cells and monocytes isolated from peripheral blood, which had no detectable telomerase activity, no hTERT mRNA expression was seen. On the other hand, lymphocytes and CD34-positive cells both demonstrated hTERT mRNA expression. TEP1 mRNA was detected in all samples, showing no differential expression. We then assessed hTERT and TEP1 mRNA expression in CD34-positive cells cultured in vitro with growth factors. After 4 weeks of culture, all the cells showed myeloid differentiation and the telomerase activity was downregulated. hTERT mRNA was expressed in CD34-positive cells, but was downregulated in 4-week-cultured cells. TEP1 showed no apparent differential expression. We conclude that hTERT mRNA expression is downregulated in accordance with telomerase downregulation during the course of myeloid differentiation, which suggests that it plays a crucial role in the expression of enzyme activity, while TEP1 has a much smaller role to play, if any.