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Biomedical subjects

Atsushi Inoue

Publications and source records attributed to Atsushi Inoue.

At least 19 recordsLinked to original sources
PubMed2006

Identification of N-arachidonylglycine as the endogenous ligand for orphan G-protein-coupled receptor GPR18.

An orphan G-protein-coupled receptor, GPR18, was cloned on the basis of degenerate-oligonucleotide PCR analysis of HUT 102 cells using primers designed from the conservative regions of the human chemokine receptor. GPR18 was expressed significantly in lymphoid cell lines, but not in non-lymphoid hematopoietic cell lines. Moreover, the expression of the GPR18 gene was higher in peripheral lymphocyte subsets (CD4(+), CD4(+)CD45RA(+), CD4(+)CD45RO(+), CD8(+), and CD19(+)) than in monocytes and lymphoid cell lines, and was increased after stimulation with phytohemagglutinin. By screening using a lipid library, N-arachidonylglycine (NAGly) induced an increase in intracellular Ca(2+) concentration in GPR18-transfected cells, which was significantly greater than that in mock-transfected cells. NAGly also inhibited forskolin-induced cAMP production in a pertussis toxin-sensitive manner in the GPR18-transfected CHO cells. This is the first study to demonstrate that NAGly is a natural ligand for GPR18.

Animals↗
PubMed2006

Antagonist of interferon-inducible protein 10/CXCL10 ameliorates the progression of autoimmune sialadenitis in MRL/lpr mice.

OBJECTIVE: Mononuclear cell infiltration of the salivary glands is a major feature of Sjögren's syndrome (SS) and its animal model. Local generation of chemokines and the presence of chemokine receptors on the infiltrating cells may be involved in this process. We undertook the present study to investigate the expression of chemokines during the development of autoimmune sialadenitis in MRL/lpr mice and the therapeutic effect of chemokine antagonists on sialadenitis. METHODS: NH2-terminal-truncated interferon-inducible protein 10 (IP-10)/CXCL10 analogs were transfected into a nonmetastatic fibroblastoid cell line, MRL/N-1, and injected subcutaneously into MRL/lpr mice, and the effects on sialadenitis were monitored. RESULTS: IP-10 analogs truncated by 5 or more amino acid residues from the N-terminal failed to induce chemotaxis and calcium influx by CXCR3-expressing cells. Of these, the most potent antagonist (AT) (IP-10-AT) was a molecule with methionine added after removal of the 5 N-terminal amino acid residues. Significantly increased expression of the Th1-associated chemokines IP-10, monokine induced by interferon-gamma/CXCL9, and interferon-inducible T cell chemoattractant/CXCL11 was induced in the ductal epithelium by interferon-gamma produced in the salivary glands, whereas expression of the Th2-associated chemokines thymus and activation-regulated chemokine (TARC)/CCL17 and monocyte-derived chemokine/CCL22 was almost undetectable during sialadenitis. Inoculation of IP-10-AT into MRL/lpr mice during the early stage of sialadenitis significantly reduced periductal mononuclear cell infiltration and parenchymal destruction compared with these features in control and TARC-AT-bearing mice. This was due to a significant reduction in infiltration of CXCR3+ T cells, predominantly Th1 cells, resulting in decreased interferon-gamma production. CONCLUSION: We prepared a novel potent IP-10 antagonist and demonstrated its ability to ameliorate the progression of autoimmune sialadenitis. This agent may provide a new therapeutic approach to SS.

Animals↗
PubMed2006

IK cytokine ameliorates the progression of lupus nephritis in MRL/lpr mice.

OBJECTIVE: IK cytokine has been isolated as a factor that inhibits interferon-gamma (IFNgamma)-induced expression of class II major histocompatibility complex (MHC) antigens. Aberrant expression of class II MHC antigens has reportedly been recognized in the target organs of autoimmune diseases and been associated with disease activity. In this study, we investigated whether IK cytokine can ameliorate the progression of lupus nephritis in MRL/lpr mice. METHODS: A truncated IK analog was prepared and transfected into a nonmetastatic fibroblastoid cell line, and then injected subcutaneously into MRL/lpr mice at ages 8 weeks (before the onset of lupus nephritis) and 12 weeks (at the early stage of the disease). RESULTS: An IK cytokine, when it was translated from methionine at position 316, acted as a secretory protein. This truncated IK cytokine (tIK) reduced IFNgamma-induced class II MHC expression in various cells through decreased expression of class II MHC transcription activator. Treatment of MRL/lpr mice with tIK significantly reduced renal damage as compared with control mice. A significant decrease in macrophage and T cell infiltration was found in the kidneys of tIK-treated mice, resulting in decreased production of IFNgamma and interleukin-2. Mice treated with tIK also showed significant reduction of anti-DNA antibodies and circulating immune complexes. A specific reduction of class II MHC expression was observed on B cells and monocytes as well as in the kidney. CONCLUSION: We prepared a potent IK analog and demonstrated its ability to ameliorate the progression of lupus nephritis. This agent may therefore provide a new therapeutic approach for lupus nephritis.

Animals↗
PubMed2006

Molecular design and delivery of siRNA.

Double stranded short interfering RNAs (siRNAs) mediate gene silencing in a sequence specific manner. By virtue of their specific gene silencing activity and owing to the recent discoveries on their plasmid and virus driven expression, siRNAs are being widely adopted in research and therapeutics. Efforts were made to optimize the siRNA expression system for the application in therapy. One major obstacle in developing RNA interference (RNAi) therapy is the delivery of siRNAs to the target cells. Combination of novel molecular targeting technologies, such as recombinant protein technology and ribosome display technology, will enable to deliver gene silencing agents to target cells specifically and efficiently.

Animals↗
PubMed2006

Assessment of head wear more than ten years after total hip arthroplasty: 22-mm zirconia vs. metal heads.

The present retrospective study assessed radiographs to determine socket wear in total hip arthroplasty (THA) with 22-mm zirconia or COP (Cobalt-Chrome alloy rich in Cobalt and Phosphorous) heads, and in cemented stems at more than 10 years after operation. Sockets of ultra high molecular weight polyethylene were used in each of two THA groups (13 hips each) in a clinical trial in our hospital between 1989 and 1990. Three observers carried out masked assessments of the radiographs. Upon final examination, there was no remarkable loosening in the zirconia or COP group, and no case had required revision surgery as of 2005. There was a statistically significant difference between the 2 groups in average annual linear wear, at 0.093 mm/year and 0.046 mm/year in the zirconia and COP groups, respectively. Volume wear and average annual volume wear were also significantly greater in the zirconia group despite its superior mechanical strength and toughness in vitro. Our present findings do not confirm early expectations of lower wear in long-term results of 22-mm zirconia femoral heads used in THA.

Adult↗
PubMed2005

The neuroprotective action of JNK3 inhibitors based on the 6,7-dihydro-5H-pyrrolo[1,2-a]imidazole scaffold.

Imidazole-based structures of p38 inhibitors served as a starting point for the design of JNK3 inhibitors. Construction of a 6,7-dihydro-5H-pyrrolo[1,2-a]imidazole scaffold led to the synthesis of the (S)-enantiomers, which exhibited p38/JNK3 IC50 ratio of up to 10 and were up to 20 times more potent inhibitors of JNK3 than the relevant (R)-enantiomers. The JNK3 inhibitory potency correlated well with inhibition of c-Jun phosphorylation and neuroprotective properties of the compounds in low K+-induced cell death of rat cerebellar granule neurones.

Animals↗
PubMed2005

Antagonist of fractalkine (CX3CL1) delays the initiation and ameliorates the progression of lupus nephritis in MRL/lpr mice.

OBJECTIVE: Lupus nephritis is characterized by immune complex deposition and inflammatory cell infiltration into the renal glomeruli. Local generation of chemokines and the presence of chemokine receptors on the infiltrating cells may be involved in this process. Fractalkine (Fkn)/CX3CL1 and its receptor, CX3CR1, form one such chemokine system. We therefore undertook this study to investigate whether Fkn antagonist inhibits the initiation and progression of lupus nephritis in MRL/lpr mice. METHODS: NH(2)-terminally truncated Fkn/CX3CL1 analogs were transfected into a nonmetastatic fibroblastoid cell line, MRL/N-1, and injected subcutaneously into MRL/lpr mice. RESULTS: Fkn analogs truncated by >/=4 amino acid residues from the N-terminus failed to induce chemotaxis and calcium influx by CX3CR1-expressing cells. Of these, the most potent antagonist (Fkn-AT) lacked the 4 N-terminal amino acid residues. Fkn expression in the glomerulus was significantly increased in 12-week-old MRL/lpr mice. Expression was localized predominantly in the glomerular endothelial cells, but was occasionally observed in the mesangial cells and, to a lesser extent, in the interstitial microvasculature. Inoculation of MRL/lpr mice with Fkn-AT before the onset or during the early stages of lupus nephritis significantly reduced glomerular hypercellularity, glomerulosclerosis, crescent formation, and vasculitis compared with control mice. This seemed to be due to a marked reduction in macrophage accumulation. In contrast, Fkn antagonist did not affect pneumonitis, sialadenitis, lymphadenopathy, or splenomegaly. CONCLUSION: We prepared a novel potent Fkn antagonist and demonstrated its ability to delay the initiation and ameliorate the progression of lupus nephritis. This agent may therefore provide a new therapeutic approach to lupus nephritis.

Animals↗
PubMed2005

Overexpression of Nd1-s, a variant form of new kelch family protein, perturbs the cell cycle progression of fibroblasts.

The murine Nd1 gene encodes two forms of protein, Nd1-L and Nd1-S, both of which share the BTB/POZ domain, but Nd1-S lacks the kelch repeats. Although Nd1-L ubiquitously expresses, localizes in the cytoplasm and functions as a stabilizer of actin filaments, expression and function of Nd1-S were unknown. Here we show that Nd1-S were expressed in all tissues examined and localized in the nucleus as a speckled-like pattern. Furthermore, overexpression of Nd1-S perturbed cell growth of NIH3T3 cells at the G1/S phase of the cell cycle. These results suggest that Nd1-S may play a role in cell cycle progression in the nucleus.

Animals↗
PubMed2005

The influence of dialysate calcium on the therapeutic effects of sevelamer hydrochloride in hemodialysis patients with secondary hyperparathyroidism under treatment of intravenous vitamin d metabolites.

The management of hyperphosphatemia is essential to treat secondary hyperparathyroidism and to prevent ectopic calcification. Sevelamer hydrochloride (sevelamer), a new phosphate binder that contains neither aluminum nor calcium, which could be theoretically beneficial for the management of hyperphosphatemia in dialysis patients with secondary hyperparathyroidism who are receiving intravenous vitamin D metabolites (maxacalcitol or calcitriol). To reduce calcium loads, a dialysate calcium concentration of 2.5 mEq/L is recommended by Kidney Disease Outcome Quality Initiative (K/DOQI) guidelines. In Japan, a dialysate calcium concentration of 3.0 mEq/L prevails. We investigated the influence of dialysate calcium on the therapeutic effect of sevelamer in 40 hemodialysis patients who are under treatment of intravenous vitamin D metabolites for secondary hyperparathyroidism (VD(+)) and compared the results with those of 41 patients who had not received vitamin D metabolites (VD(-)). Serum phosphorus and calcium-phosphorus products showed no significant change by sevelamer in either the VD(+) subgroup of patients receiving hemodialysis with dialysate calcium of 2.5 mEq/L (DCa2.5) or those receiving hemodialysis with dialysate calcium of 3.0 mEq/L (DCa3.0), while serum phosphorus and calcium-phosphorus products decreased in both the VD(-) subgroups. Serum calcium decreased in the DCa2.5 subgroup and did not change in the DCa3.0 subgroup in both the VD(+) and the VD(-) subjects. Parathyroid hormone and alkaline phosphatase increased in the DCa2.5 subgroup and did not change in the Ca 3.0 subgroup in the VD(+) subjects. Serum calcium decreased in both subgroups in the VD(-) subjects. Parathyroid hormone obtained after sevelamer administration in the VD(-) group was within the target range of the K/DOQI guidelines. In conclusion, the concomitant use of sevelamer as a phosphate binder and the dialysate of calcium concentration of 2.5 mEq/L have possibilities for worsening secondary hyperparathyroidism in patients receiving intravenous vitamin D.

Calcitriol↗
PubMed2005

Graves' hyperthyroidism showing transient hypothyroidism during interferon therapy for chronic hepatitis type C.

We report a patient with Graves' disease in whom thyroid function was changed from initial hyperthyroidism to transient hypothyroidism and back to hyperthyroidism during interferon (IFN) therapy. A 43-year-old man was admitted to our hospital to receive IFN treatment for chronic active hepatitis (type C) in June 1998. His thyroid function was normal and testing for thyroid gland antibodies (TSH binding inhibitor immunoglobulins; TBII, anti-thyroglobulin antibodies; TgAb and anti-thyroid peroxidase antibodies; TPOAb) was negative before IFN therapy. The patient had neither history of thyroid disease nor any particular family history. He developed hyperthyroidism four months after its initiation of IFN therapy. When he was hyperthyroid, TBII, the activity of thyroid-stimulating antibodies (TSAb) and thyroid stimulation-blocking antibodies (TSBAb) were 40.2% (normal range, -15 approximately +15.0%), 1201% (normal range, <or=180%) and 52.0% (normal range, <or=45.6%), respectively. Thyroid 99mTc(technetium)-uptake ratio (Tc-UTR) was 1.07% (normal range, 0.5-3.0%). He transiently developed hypothyroidism in December 1998 and recurrent hyperthyroidism in February 1999. When he was hypothyroid, TBII, TSAb and TSBAb were 74.3%, 769% and 95.9%, respectively. To investigate the mechanism of his fluctuating thyroid status, we serially assessed the serum levels of cytokines (TNF-alpha, IFN-gamma, IL-1beta, IL-2, IL-4) and the soluble form of ICAM-1 (sICAM-1) as well as the activities of two types of TSH receptor antibodies (TRAb), TSAb and TSBAb, before and after IFN therapy. There were no characteristic changes of cytokines or sICAM-1 during the follow-up period. The transient hypothyroid state may be explained by two possible mechanisms: one may be due to the shift in the balance between the stimulating and blocking types of TRAb, and the other may be due to the complication of destructive thyroiditis that developed during IFN therapy.

Adult↗
PubMed2004

Expression of DGAT2 in white adipose tissue is regulated by central leptin action.

Acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes catalyze the final step in mammalian triglyceride synthesis, and their functions are considered to be involved in the mechanisms of obesity, insulin resistance, and leptin resistance. Insulin receptor substrate-2 (IRS-2)-deficient mice exhibit obesity-associated with hypertrophic adipocytes and leptin resistance. Screening for transcripts of genes involved in fatty acid and triglyceride synthesis to investigate the mechanism of the hypertrophic change in the adipocytes showed that expression of DGAT2 mRNA was up-regulated in the white adipose tissue (WAT) of Irs2-/- mice, whereas that of DGAT1 was down-regulated. This reciprocal expression of DGAT1 and DGAT2 was also observed in WAT of leptin-deficient ob/ob mice. A high fat diet also resulted in increased DGAT2 and reduced DGAT1 in the WAT of C57BL/6 mice. Induction of adipocyte hypertrophy in vitro up-regulated both DGAT1 and DGAT2 expression in 3T3-L1 cells, suggesting that adipocyte non-autonomous mechanism in vivo is required for the reciprocal changes in expression of DGAT1 and DGAT2. In fact, intracerebroventricular infusion of leptin reduced DGAT2 expression in WAT of Irs2-/- mice and ob/ob mice, independently of DGAT1 expression. We propose the hypothesis that leptin regulates adipocyte size by altering expression patterns of DGAT via central nervous system to determine the levels of triglyceride synthesis.

3T3-L1 Cells↗
PubMed2004

Analysis on a cooperative pathway involving multiple cations in hammerhead reactions.

The hammerhead ribozyme reaction is more complex than might have been expected, perhaps because of the flexibility of RNA, which would have enhanced the potential of RNA during evolution of and in the RNA world. Divalent Mg(2+) ions can increase the rate of the ribozyme-catalyzed reaction by approximately 10(9)-fold as compared to the background rate under standard conditions. However, the role of Mg(2+) ions is controversial since the reaction can proceed in the presence of high concentrations of monovalent ions, such as Li(+), Na(+), and NH(4)(+) ions, in the absence of divalent ions. We thus carried out ribozyme reactions under various conditions, and we obtained parameters that explain the experimental data. On the basis of the analysis, we propose a new pathway in the hammerhead ribozyme reaction in which divalent metal ions and monovalent ions act cooperatively.

Base Sequence↗
PubMed2004

Importance in catalysis of a magnesium ion with very low affinity for a hammerhead ribozyme.

Available evidence suggests that Mg2+ ions are involved in reactions catalyzed by hammerhead ribozymes. However, the activity in the presence of exclusively monovalent ions led us to question whether divalent metal ions really function as catalysts when they are present. We investigated ribozyme activity in the presence of high levels of Mg2+ ions and the effects of Li+ ions in promoting ribozyme activity. We found that catalytic activity increased linearly with increasing concentrations of Mg2+ ions and did not reach a plateau value even at 1 M Mg2+ ions. Furthermore, this dependence on Mg2+ ions was observed in the presence of a high concentration of Li+ ions. These results indicate that the Mg2+ ion is a very effective cofactor but that the affinity of the ribozyme for a specific Mg2+ ion is very low. Moreover, cleavage by the ribozyme in the presence of both Li+ and Mg2+ ions was more effective than expected, suggesting the existence of a new reaction pathway-a cooperative pathway-in the presence of these multiple ions, and the possibility that a Mg2+ ion with weak affinity for the ribozyme is likely to function in structural support and/or act as a catalyst.

Catalysis↗
PubMed2004

Both insulin signaling defects in the liver and obesity contribute to insulin resistance and cause diabetes in Irs2(-/-) mice.

We previously reported that insulin receptor substrate-2 (IRS-2)-deficient mice develop diabetes as a result of insulin resistance in the liver and failure of beta-cell hyperplasia. In this study we introduced the IRS-2 gene specifically into the liver of Irs2(-/-) mice with adenovirus vectors. Glucose tolerance tests revealed that the IRS-2 restoration in the liver ameliorated the hyperglycemia, but the improvement in hyperinsulinemia was only partial. Endogenous glucose production (EGP) and the rate of glucose disappearance (Rd) were measured during hyperinsulinemic-euglycemic clamp studies: EGP was increased 2-fold in the Irs2(-/-) mice, while Rd decreased by 50%. Restoration of IRS-2 in the liver suppressed EGP to a level similar to that in wild-type mice, but Rd remained decreased in the Adeno-IRS-2-infected Irs2(-/-) mice. Irs2(-/-) mice also exhibit obesity and hyperleptinemia associated with impairment of hypothalamic phosphatidylinositol 3-kinase activation. Continuous intracerebroventricular leptin infusion or caloric restriction yielded Irs2(-/-) mice whose adiposity was comparable to that of Irs2(+/+) mice, and both the hyperglycemia and the hyperinsulinemia of these mice improved with increased Rd albeit partially. Finally combination treatment consisting of adenovirus-mediated gene transfer of IRS-2 and continuous intracerebroventricular leptin infusion completely reversed the hyperglycemia and hyperinsulinemia in Irs2(-/-) mice. EGP and Rd also became normal in these mice as well as in mice treated by caloric restriction plus adenoviral gene transfer. We therefore concluded that a combination of increased EGP due to insulin signaling defects in the liver and reduced Rd due to obesity accounts for the systemic insulin resistance in Irs2(-/-) mice.

Adenoviridae↗
PubMed2004

Nature of the chemical bond formed with the structural metal ion at the A9/G10.1 motif derived from hammerhead ribozymes.

We have studied the interaction between metal ions and the metal ion-binding motif in hammerhead ribozymes, as well as the functions of the metal ion at the motif, with heteronuclear NMR spectroscopy. In this study, we employed model RNA systems which mimic the metal ion-binding motif and the altered motif. In Co(NH3)6(III) titrations, we observed large 1H and 31P chemical shift perturbations for the motif and found that outer-sphere complexation of Co(NH3)6(III) is possible for this motif. From the reinvestigation of our previous 15N chemical shift data for Cd(II) binding, in comparison with those of organometallic compounds, we conclude that Cd(II) can form an inner-sphere complex with the nucleobase in the motif. Therefore, the A9/G10.1 site was found to accept both inner-sphere and outer-sphere complexations. The Mg(II) titration for a slightly different motif from the A9/G10.1 site (G10.1-C11.1 to A10.1-U11.1) revealed that its affinity to Mg(II) was drastically reduced, although the ribozyme with this altered motif is known to retain enzymatic activities. This observation suggests that the metal ion at these motifs is not a catalytic center of hammerhead ribozymes.

Cations↗
PubMed2004

Transcriptional downregulation of DC-SIGN in human herpesvirus 6-infected dendritic cells.

DC-SIGN expressed on dendritic cells (DCs) efficiently binds and transmits various pathogens, including human immunodeficiency virus, to lymphoid tissues and permissive cells. Consequently, alteration of DC-SIGN expression may affect susceptibility and resistance to pathogens. The present study shows that infection with human herpesvirus 6 (HHV-6) induces downregulation of DC-SIGN expression on immature DCs. Expression levels of DC-SIGN mRNA and intracellular protein appeared to decrease following infection with HHV-6, indicating that downregulation of surface DC-SIGN occurs at the transcriptional level. Downregulation of DC-SIGN was not induced by inoculation of UV-inactivated HHV-6 or culture supernatant of HHV-6-infected DCs, indicating that replication of HHV-6 in DCs is required for downregulation of DC-SIGN. The present study demonstrates for the first time that expression of DC-SIGN is altered at the transcriptional level by virus infection.

Cell Adhesion Molecules↗