Tetsuya Inazu

Thrombin-induced human platelet aggregation is inhibited by protein-tyrosine kinase inhibitors, ST638 and genistein

We have investigated the involvement of protein‐tyrosine kinases in thrombin‐induced aggregation of human platelets, using ST638 and genistein which are known inhibitors of protein‐tyrosine kinase. Preincubation of platelets with 50 μM of ST638 or 25 μg/ml of genistein completely blocked the platelet aggregation induced with 0.05 unit/ml of thrombin. The increase of protein‐tyrosine phosphorylation bands (135‐, 124‐, 76‐, 64‐, and 60‐kDa) induced with thrombin was also inhibited by these inhibitors in a dose‐dependent manner. These inhibitors also blocked the platelet aggregation and protein‐tyrosine phosphorylation induced with thrombin in aspirin‐treated platelets. Increase of the intracellular Ca2+ concentration induced by thrombin was also inhibited by higher concentrations of genistein. The results suggest that the protein‐tyrosine phosphorylation plays a certain role in platelet activation having some relation to the intracellular Ca2+ concentration.

Amphiregulin is a potent mitogen for the vascular smooth muscle cell line, A7r5

The regulation of amphiregulin, an epidermal growth factor (EGF) family member, and its effect on vascular smooth muscle cells (VSMC) were examined. Amphiregulin mRNA was upregulated by amphiregulin itself as well as alpha-thrombin. Amphiregulin caused an approximate 3-fold increase in DNA synthesis. Its effect on growth was compared with those of other mitogens, and was found to be approximately 3.5-, 2.4-, and 1.0-fold greater than those of endothelin-I (ET-I), alpha-thrombin, and platelet-derived growth factor-AB (PDGF-AB), respectively. As evidenced by Western blot analysis, amphiregulin stimulated the phosphorylation of p42/p44-mitogen-activated protein kinase (MAPK), p38-MAPK, c-Jun NH2-terminal protein kinase (JNK), and Akt/protein kinase B (PKB), respectively. By statistical analysis, the amphiregulin-induced growth effect was significantly decreased by the MAP kinase/ extracellular regulated kinase kinase-1 (MEK-1) inhibitor PD98059, p38-MAPK inhibitor SB203580, and phosphatidylinositol 3-kinase (PI-3 kinase) inhibitor wortmannin, respectively, but was not decreased by JNK inhibitor SP600125. These results suggest that amphiregulin is the most potent mitogen of the mitogens tested, and its growth effect is mediated at least in part through the p42/p44-MAPK, p38-MAPK, and PI-3 kinase-Akt/PKB pathways in VSMC.

Atorvastatin, Etidronate, or Both in Patients at High Risk for Atherosclerotic Aortic Plaques: A Randomized Controlled Trial

Background— Statins are not effective in reducing atherosclerotic plaques of the abdominal aorta, and accumulating evidence suggests that bisphosphonates have the potential to induce the regression of atherosclerotic plaques of the abdominal aorta. Methods and Results— A prospective, randomized, open-label, blinded-end-point trial involving 108 participants with hypercholesterolemia was conducted. Participants received 20 mg atorvastatin daily, 400 mg etidronate daily, or both drugs daily. The primary end point was the percent change in maximal vessel wall thickness of atherosclerotic plaques in the thoracic and abdominal aortas as measured by magnetic resonance imaging after 12 months of treatment. In both the combination therapy and atorvastatin groups, maximal vessel wall thickness of the thoracic aorta was reduced by 13.8% (95% confidence interval, −16.4 to −11.3) and 12.3% (95% confidence interval, −14.9 to −9.7), respectively. These reduction rates were comparable between groups (P=0.61). Meanwhile, in the etidronate group, maximal vessel wall thickness of the thoracic aorta remained unchanged (2.2%; 95% confidence interval, −0.3 to 4.8). Conversely, maximal vessel wall thickness of the abdominal aorta was reduced more effectively in the combination therapy group (−11.4%) than in the atorvastatin group (−0.9%; P<0.001) and the etidronate group (5.5%; P=0.006). Conclusions— Atorvastatin plus etidronate combination therapy for 12 months significantly reduced both thoracic and abdominal aortic plaques, whereas atorvastatin monotherapy reduced only thoracic aortic plaques and etidronate monotherapy reduced only abdominal aortic plaques. The effectiveness of combination therapy in reducing atherosclerotic plaques in the abdominal aorta was significantly greater than for both atorvastatin and etidronate monotherapy. Clinical Trial Registration— URL: http://www.umin.ac.jp/ctr/. Unique identifier: UMIN 000002635.

Cloning and Functional Expression of an E Box-Binding Protein from Rat Granulosa Cells

Abstract Ovarian granulosa cells undergo cell growth and cytodifferentiation during follicular maturation. In a number of tissues, the gene expression that is responsible for the cytodifferentiation is largely dependent on E box(es) located upstream of the responsible genes. In this study, we report on the cloning of cDNA(s) encoding E box (5′-CACGTG-3′)-binding protein from a rat granulosa cell cDNA library using a yeast one-hybrid system. When multiple E box sequences were used as target, we obtained a positive clone that encodes the rat homologue of upstream stimulatory factor 2 (USF2). An analysis of the nucleotide sequence and its deduced amino acid sequence reveals that rat USF2 protein consists of 346 amino acid residues and belongs to the basic helix-loop-helix/leucine zipper protein family. Northern blot analysis shows that rat USF2 mRNA exists as multiple forms between 1.6 and 2.2 kilobases. The size of the cloned insert was identical to that of the transcript of maximal length. Electrophoretic mobility shift assays showed that in vitro-translated rat USF2 specifically binds to the E box. In addition, cotransfection experiments with luciferase-reporter constructs in HepG2 cells reveal that the overexpression of rat USF2 leads to an increase of luciferase activity in the E box sequence-dependent manner. Thus, we report molecular cloning, expression, and functional characterization of full-length rat USF2 cDNA.

The lectin wheat germ agglutinin induces rapid protein-tyrosine phosphorylation in human platelets.

In response to wheat germ agglutinin (WGA), platelet aggregation and stimulation of protein-tyrosine phosphorylation were observed in a dose dependent manner. These reactions were completely inhibited by coexistence of N-acetyl-D-glucosamine with WGA. Upon stimulation by this agonist, protein-tyrosine phosphorylation of seven bands with molecular masses of 140-, 130-, 80-, 76-, 53-, 38- and 35-kDa proteins was observed by immunoblot. These protein-tyrosine phosphorylations were divided into three groups by kinetics. Considering the previous report from our laboratory that thrombin and collagen induced tyrosine phosphorylation in 135-, 124- and 76-kDa proteins (Nakamura, S. and Yamamura, H. (1989) J. Biol. Chem. 264, 7089-7091.), there may be another signal transduction pathway in tyrosine phosphorylation of human platelets.

Reduced Progression to Type 2 Diabetes From Impaired Glucose Tolerance After a 2-Day In-Hospital Diabetes Educational Program : The Joetsu Diabetes Prevention Trial

OBJECTIVE—We assessed the effects of a 2-day in-hospital diabetes educational program in preventing or delaying progression of impaired glucose tolerance (IGT) to type 2 diabetes, including analysis of changes in serum lipids, body weight, and blood pressure after the program. RESEARCH DESIGN AND METHODS—A total of 426 subjects (51 ± 9 years, BMI 24.6 ± 3.9 kg/m2) with newly diagnosed IGT were randomly assigned to three groups, 143 as the short-term hospitalization with diabetes education and support (STH) group, 141 as the nonhospitalization but diabetes education and support (DES) group, and 142 as the neither hospitalization nor education (control) group. RESULTS—The average follow-up was 3.1 years. The incidence of diabetes was 8.0, 10.7, and 13.2 cases per 100 person-years for STH, DES, and control groups, respectively. The incidence of diabetes was 42% lower (95% CI 33–51%) in the STH group and 27% lower (15–37%) in the DES group than in the control group. The incidence of diabetes was 21% lower (10–31%) in the STH group than in the DES group. CONCLUSIONS—The 2-day in-hospital program with diabetes education and support every 3 months was more effective in preventing or delaying the progression from IGT to diabetes than only diabetes education and support every 3 months.

INTERLEUKIN 2 MEDIATES P72SYK ACTIVATION IN PERIPHERAL BLOOD LYMPHOCYTES

The ability of interleukin 2 (IL‐2) to stimulate p72 syk activity in intact porcine peripheral blood lymphocytes was examined. We demonstrated that IL‐2 activated p72 syk in a time‐ and dose‐dependent number, for which its peak time and maximum responsive dose were 5 min and 100 U/ml, respectively. This activation was observed only in cytosolic fractions and not in membrane ones. However, IL‐2 failed to induced calcium mobilization. Moreover, IL‐2‐inducible p72 syk activation was not affected when extra and intracellular calcium was depleted. These data suggest that the IL‐2 signaling pathways through p72 syk in peripheral blood lymphocytes is different, at least in part, from other agonist, such as concanavalin A in polymorphonuclear neutrophils which can trigger both the activation of p72 syk and intracellular calcium mobilization.

Effect of poly-basic amino acids on the phosphorylation of various substrate proteins by cytosolic protein-tyrosine kinase from porcine spleen

Cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) is strongly activated by poly-L-lysine using bovine serum albumin, ovalbumin, phosphorylase b, calmodulin and H1 histone as substrate proteins. However, this polyamine inhibited the enzyme activities when myelin basic protein, tubulin and H2B histone were used as substrate proteins. These stimulatory and inhibitory effects on CPTK-40 are not specific for polylysine, but polyarginine and polyornithine have similar effects on this phosphorylation reaction. Effect of poly-basic amino acids on CPTK-40 seems to be mainly on the substrate proteins, rather than on the enzyme itself.

Generation of Rat Induced Pluripotent Stem Cells Using a Plasmid Vector and Possible Application of a Keratan Sulfate Glycan Recognizing Antibody in Discriminating Teratoma Formation Phenotypes

Induced pluripotent stem cells (iPSCs) offer an invaluable tool for biological research and regenerative medicine. We report establishment of rat iPSCs (riPSCs) using a plasmid vector encoding four transcription factors, Oct3/4, Sox2, c-Myc and Klf4. Although all riPSC clones were generated and cultured under the same conditions, expressed hallmark pluripotency markers and differentiated successfully in vitro, the expression of a keratan sulfate glycan epitope with unique properties defined by R-10G antibody varied in the riPSC clones. In contrast, tumor rejection antigen (TRA)-1-81 epitope expression was comparable. A clone highly reactive to R-10G antibody formed teratomas in vivo consisting of cells from all three germ layers. However, clones expressing a lower level of the epitope defined by R-10G resulted in tumors with rapid growth consisting of undifferentiated cells. Additionally, riPSCs could be successfully differentiated into a neuronal lineage including glutamate neurons that responded to agonist stimulation. These observations demonstrate a glycophenotypic difference that may potentially serve as a useful probe for riPSC evaluation and to study the role of glycans in pluripotency and carcinogenesis in these cells.

Rationale and design of Diabetes Prevention with active Vitamin D (DPVD): a randomised, double-blind, placebo-controlled study

Introduction Recent research suggests that vitamin D deficiency may cause both bone diseases and a range of non-skeletal diseases. However, most of these data come from observational studies, and clinical trial data on the effects of vitamin D supplementation on individuals with pre-diabetes are scarce and inconsistent. The aim of the Diabetes Prevention with active Vitamin D (DPVD) study is to assess the effect of eldecalcitol, active vitamin D analogue, on the incidence of type 2 diabetes among individuals with pre-diabetes. Methods and analysis DPVD is an ongoing, prospective, multicentre, randomised, double-blind and placebo-controlled outcome study in individuals with impaired glucose tolerance. Participants, men and women aged ≥30 years, will be randomised to receive eldecalcitol or placebo. They will also be given a brief (5–10 min long) talk about appropriate calorie intake from diet and exercise at each 12-week visit. The primary end point is the cumulative incidence of type 2 diabetes. Secondary endpoint is the number of participants who achieve normoglycaemia at 48, 96 and 144 weeks. Follow-up is estimated to span 144 weeks. Ethics and dissemination All protocols and an informed consent form comply with the Ethics Guideline for Clinical Research (Japan Ministry of Health, Labour and Welfare). The study protocol has been approved by the Institutional Review Board at Kokura Medical Association and University of Occupational and Environmental Health. The study will be implemented in line with the CONSORT statement. Trial registration number UMIN000010758; Pre-results.