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Biomedical subjects

R Honda

Publications and source records attributed to R Honda.

At least 37 records · Page 2Linked to original sources
PubMed2000

Vascular endothelial growth factor promotes cell-cycle transition from G0 to G1 phase in subcultured endothelial cells of diabetic rat thoracic aorta.

Vascular endothelial growth factor (VEGF) has been claimed to be a major positive regulator of angiogenesis in diabetic retinopathy and atherosclerosis. Diabetic state-induced alteration of the phenotypes and the influence of 12-h pretreatment with VEGF were examined after a further 12-h treatment with only 1% fetal bovine serum in subcultured endothelial cells (EC) derived from rat thoracic aorta. By flow cytometric cell cycle analysis, VEGF showed quite different transition patterns from those of platelet-derived growth factor (PDGF) in 5-day (at the progression phase) cultured normal rat EC even though VEGF belongs to the PDGF family. VEGF promoted cell cycle transition from the G0 to the G1 phase at 3 ng/ml, but at 30 ng/ml, VEGF weakly inhibited it compared with the effect of PDGF. The streptozotocin-diabetic state promoted cell cycle transition of EC from the G0 to the G1 phase. The promotion by the low concentration of VEGF was observed even at the point of 35-day culture (angiogenic EC at the competence phase in normal state). The diabetic state enhanced EC proliferation rather than tube formation, and the tube formation was scarce. The promotion of cell cycle transition by VEGF may aggravate furthermore diabetic angiopathy due to the leaky constitution of blood vessels.

Animals↗
PubMed2000

Glomosporin, a novel antifungal cyclic depsipeptide from Glomospora sp. I. Production, isolation, physico-chemical properties and biological activities.

A novel antifungal cyclic depsipeptide termed glomosporin, which has a fatty acyl side chain, was isolated from a barley solid culture of Glomospora sp. The strain was isolated from fallen pine leaves collected in Fukusima Prefecture, Japan and identified as Glomospora sp. BAUA 2825. Glomosporin was purified by butanol extraction followed by preparative HPLC. Glomosporin showed antimicrobial activity against fungi including clinically important Aspergillus fumigatus.

Animals↗
PubMed1999

In vitro SUMO-1 modification requires two enzymatic steps, E1 and E2.

The SUMO-1 has been identified as a protein that is highly similar to ubiquitin and shown to conjugate to RanGAP1, PML, Sp200 and I kappa B alpha. The conjugation steps are thought to be similar to those of ubiquitination; and human Ubc9, which is homologous to the E2 enzyme for the ubiquitin conjugation step, was identified and shown to be necessary for the conjugation of SUMO-1 to its target protein. Other essential enzymes involved in this modification, however, remain to be clarified. Here we cloned human Sua1 (SUMO-1 activating enzyme) and hUba2, which are human homologs of yeast Saccharomyces cerevisiae Aos1 and Uba2, respectively. The recombinant proteins, Sua1p and hUba2p, formed a complex. In this complex, hUba2 bound SUMO-1 and this complex had the activity of the SUMO-1 activating enzyme. Furthermore, in an in vitro system, RanGAP1 was modified by SUMO-1 in the presence of Sua1p/Uba2p and hUbc9p, showing that the modification of SUMO-1 could be catalyzed by two enzyme steps, although ubiquitination usually requires three enzyme steps.

Amino Acid Sequence↗
PubMed1999

Association of p19(ARF) with Mdm2 inhibits ubiquitin ligase activity of Mdm2 for tumor suppressor p53.

We have demonstrated previously that the oncoprotein Mdm2 has a ubiquitin ligase activity for the tumor suppressor p53 protein. In the present study, we characterize this ubiquitin ligase activity of Mdm2. We first demonstrate the ubiquitination of several p53 point mutants and deletion mutants by Mdm2. The point mutants, which cannot bind to Mdm2, are not ubiquitinated by Mdm2. The ubiquitination of the C-terminal deletion mutants, which contain so-called Mdm2-binding sites, is markedly decreased, compared with that of wild-type p53. The binding of Mdm2 to p53 is essential for ubiquitination, but p53's tertiary structure and/or C-terminal region may also be important for this reaction. DNA-dependent protein kinase is known to phosphorylate p53 on Mdm2-binding sites, where DNA damage induces phosphorylation, and p53 phosphorylated by this kinase is not a good substrate for Mdm2. This suggests that DNA damage-induced phosphorylation stabilizes p53 by inhibiting its ubiquitination by Mdm2. We further investigated whether the tumor suppressor p19(ARF) affects the ubiquitin ligase activity of Mdm2 for p53. The activity of p19(ARF)-bound Mdm2 was found to be lower than that of free Mdm2, suggesting that p19(ARF) promotes the stabilization of p53 by inactivating Mdm2.

Animals↗
PubMed1999

Association of genetic polymorphisms of alcohol-metabolizing enzymes with excessive alcohol consumption in Japanese men.

To evaluate the independent and interactive contributions of alcohol dehydrogenase-2 (ADH2), aldehyde dehydrogenase-2 (ALDH2) and ethanol-induced isozyme cytochrome P450-2E1 (CYP2E1) genes to alcohol consumption large enough to induce health problems, 643 healthy Japanese men aged between 23 and 64 years, recruited from two different occupational groups, were analyzed for genotype and drinking habits. The frequency of excessive alcohol consumers (EAC) who drank 90 ml or more alcohol more than 3 days a week was significantly higher in subjects possessing the ALDH2(1)/ALDH2(1) genotype than in those having ALDH2(1)/ALDH2(2) or ALDH2(2)/ALDH2(2) genotypes. A significant difference was also found in the different genotypes of CYP2E1. Moreover, a borderline significant interaction between the ALDH2 and CYP2E1 genotypes on excessive alcohol consumption was observed, i.e., the group of subjects having the c2 allele of CYP2E1 had a higher frequency of EAC than those having c1/c1 genotypes in the genotype subgroup ALDH2(1)/ALDH2(1), whereas these were not found in the heterozygote and homozygote subgroups of the ALDH2(2) allele. Neither the independent nor interactive genetic effect of ADH2 on excessive alcohol consumption was obvious. In conclusion, Japanese men with the ALDH2(1)/ALDH2(1) genotype and the c2 allele of CYP2E1 are at higher risk of showing excessive alcohol consumption.

Adult↗
PubMed1998

cdc2 kinase-mediated phosphorylation of splicing factor SF2/ASF.

SR proteins are a family of splicing factors which are important components of spliceosomes. Recent studies suggested that phosphorylation of SR protein might be a key event for the regulation of pre-mRNA splicing and is prevalent in metaphase cells. To investigate the role of cdc2 kinase in cell cycle-dependent phosphorylation of SR protein, we examined its phosphorylation of SF2/ASF, a representative SR protein. SF2/ASF was phosphorylated both by recombinant cdc2 kinase, a cdc2-cyclin B complex, and by cdc2 kinase immunoprecipitated from G2/M phase HeLa cells. In vitro phosphorylation and phosphopeptide mapping of several mutant proteins revealed that cdc2 kinase specifically phosphorylates the RS domain of SF2/ASF with serines 227, 238 and presumably 199 as major phosphorylation sites. These findings suggest the possibility that cdc2 kinase takes part in the cell cycle-dependent phosphorylation of SR protein which regulates the function of spliceosomes.

Amino Acid Sequence↗
PubMed1998

Glycated serum stimulation of macrophages in GK- and streptozotocin-rats for the proliferation of primary cultured smooth muscle cells of the aorta.

The purpose of this study was to investigate the actions of intraperitoneal macrophages and aortic endothelial cells (EC) as the cause of proliferation of primary cultured smooth muscle cells (SMC) of the aorta in non-insulin-dependent diabetes mellitus (NIDDM) models, including spontaneously diabetic GK and streptozotocin-diabetic Wistar rats. Conditioned medium derived from macrophages of GK rats increased proliferation of SMC in Wistar rats to a greater extent when compared to normal Wistar rats in conditioned medium. Serum of both GK rats and of Wistar rats which was previously exposed to 16.7 and 25 mM glucose (glycated serum) activated normal macrophages, enhancing SMC proliferation. However, glycated serum and high concentrations of glucose did not affect directly the proliferation of SMC. Conditioned medium from EC of streptozotocin-Wistar rats enhanced SMC proliferation. The enhancing activity of EC in diabetic rats was mimicked by conditioned medium from glycated EC but not from EC treated with the diabetic rat serum nor glycated bovine serum albumin. Cholesterol (39 microg/ml) potentiated the action of glycated serum on macrophages, but neither the action of normal macrophages nor the direct action of SMC was affected. Both the actions of glycated serum and cholesterol were inhibited by a polyclonal platelet-derived growth factor-BB antibody. However, low density lipoprotein (LDL), acetylated LDL and oxidized LDL (25 microg/ml) did not potentiate the action of glycated serum. These results demonstrate that glycated serum in the NIDDM model predominantly activated macrophages, resulting in proliferation of SMC by the release of platelet-derived growth factor-BB. Cholesterol potentiated the actions of glycated serum on macrophages.

Animals↗
PubMed1997

Oncoprotein MDM2 is a ubiquitin ligase E3 for tumor suppressor p53.

The tumor suppressor p53 is degraded by the ubiquitin-proteasome system. p53 was polyubiquitinated in the presence of E1, UbcH5 as E2 and MDM2 oncoprotein. A ubiquitin molecule bound MDM2 through sulfhydroxy bond which is characteristic of ubiquitin ligase (E3)-ubiquitin binding. The cysteine residue in the carboxyl terminus of MDM2 was essential for the activity. These data suggest that the MDM2 protein, which is induced by p53, functions as a ubiquitin ligase, E3, in human papillomavirus-uninfected cells which do not have E6 protein.

Amino Acid Sequence↗
PubMed1997

14-3-3 zeta protein binds to the carboxyl half of mouse wee1 kinase.

To identify proteins which bind to mouse wee1 kinase, the yeast "two-hybrid" system was used with a mouse cDNA library. Using the carboxyl half of weel kinase, the 14-3-3 zeta protein was isolated. Recombinant 14-3-3 zeta was demonstrated to bind to wee1 kinase in vitro. The wee1 kinase phosphorylated by cdc2 kinase also bound to 14-3-3 zeta protein. When both wee1 kinase and 14-3-3 zeta were transfected into COS-1 cells, they formed a complex in a cell. The sequence of wee1 kinase necessary for the binding was tested by a two hybrid system expressing different lengths of peptides derived from wee1 kinase. Both the entire kinase domain and a sequence in the carboxyl terminus was thought to be necessary for the binding. The function of 14-3-3 zeta protein remained to be elucidated in relation to the regulation of G2 to M phase transition through wee1 kinase.

14-3-3 Proteins↗
PubMed1997

Zinc and copper levels in ribs of cadmium-exposed persons with special reference to osteomalacia.

Cadmium (Cd), zinc (Zn), copper (Cu), calcium (Ca), phosphorus (P), and magnesium (Mg) were determined in ribs obtained at autopsy from 38 Cd-exposed and 17 nonexposed subjects to determine how levels of these elements in bone are affected by Cd exposure and whether they are associated with the bone lesions due to Cd exposure, osteomalacia, and osteoporosis. Cd in ribs was significantly higher in the Cd-exposed subjects than in nonexposed subjects. Zn tended to be higher, while Cu, Ca, P, and Mg tended to be lower in the ribs of Cd-exposed subjects, though these differences were not statistically significant. Zn, Ca, P, and Mg were highly correlated with each other in both Cd-exposed and nonexposed groups, but the associations of Ca, P, and Mg in the ribs with Zn concentrations differed in subjects and controls. Ca to Zn ratios were low in the Cd-exposed subjects, and the higher the grade of osteomalacia, the lower the Ca/Zn ratio. The decrease in Ca/Zn ratio was significantly correlated with increases in Cd. Cu showed a significant positive correlation with Cd and significant inverse correlation with Ca, P, and Mg in the Cd-exposed group. Cu and its relation to other elements did not show any association with osteomalacia. In conclusion, Ca/Zn ratio in bone was related to Cd exposure and the degree of osteomalacia in the Cd-exposed subjects.

Aged↗
PubMed1997

RT1.P, rat class Ib genes related to mouse TL: evidence that CD1 molecules but not authentic TL antigens are expressed by rat thymus.

CD1 and TL were once thought to be genetic homologues because of their thymus-specific expression. We investigated their equivalents in the rat to clarify whether their structure and pattern of expression are conserved in rodents. Two rat class Ib genes, containing 3' sequences very similar to mouse TL, were identified and designated RT1.P. Neither of them, however, can encode ordinary class I molecules due to the accumulation of harmful mutations in the 5' regions that are unique to RT1.P, while the 3' TL-like regions still retain protein-coding capacity. Comparison of the structural organization of three types of TL family genes, which include mouse T3/T18-encoding TL antigens, mouse T1/T16, and rat RT1. P1/P2 pseudogenes, revealed the presence of a clear demarcation between the type-specific and TL-specific sequences at intron 3. This finding suggests that recombination plays an important role in creating the TL family genes in rodents. Characteristic features of TL, such as a low level of polymorphism and linkage to the major histocompatibility complex, were also observed in the rat. On the other hand, rat CD1 molecules were expressed at a high level on the surface of thymocytes. Absence of authentic TL antigens and thymic expression of CD1d molecules in the rat suggest the plasticity and conservation of class Ib genes in rodent evolution. Functions of TL may be substituted with CD1 or other class Ib molecules expressed by rat thymus.

Amino Acid Sequence↗
PubMed1997

Concentration of cadmium in rice and urinary indicators of renal dysfunction.

OBJECTIVES: (1) To examine the relation between concentrations of cadmium (Cd) in rice and urinary concentrations of indicators of renal dysfunction and the prevalence of abnormalities in urine in areas polluted by Cd. (2) To establish the maximum allowable concentration of Cd in rice from these findings. METHODS: The target population consisted of 1703 inhabitants (832 men and 871 women) aged over 50 years who consumed home grown rice and had lived in the same hamlet in areas polluted by Cd in the Kakehashi River basin in Ishikawa Prefecture, Japan for at least 30 years. The correlation coefficients between concentrations of Cd in rice and several urinary substances, the prevalence of abnormalities in urine and sex in hamlets polluted by Cd were calculated. Finally, regression analysis was performed for significant indicators to calculate the maximum allowable concentration of Cd in rice based on values in a control group. CONCLUSIONS: Significant correlations between concentration of Cd in rice and concentrations of urinary beta 2-microglobulin, metallothionein, glucose, and aminonitrogen were established. Similarly, there were significant correlations between concentration of Cd in rice and the prevalence of beta 2-microglobulinuria, metallothioneinuria, glucosuria, proteinuria, proteinuria with glucosuria, and aminonitrogenuria. The highest maximum allowable concentration of Cd in rice calculated for these indicators was 0.34 ppm/l and 0.29 ppm/g creatinine. Both values are lower than 0.4 ppm, the tentative limit prescribed by the Japanese government.

Aged↗
PubMed1997

Genotype of cytochrome P450 2E1 and alcohol-related blood pressure elevation in Japanese men.

Three-hundred-and-sixty-seven unrelated Japanese male workers aged between 36 and 61 years were analysed for the genotypes of cytochrome P450 2E1 (CYP2E1), and the association with alcohol-related health effects including blood pressure (BP) elevation. Homozygous for the c1 (wild) gene was found in 204 men (55%), homozygous for the c2 (variant) gene in 17 (5%), and heterozygous in 146 (40%). Arithmetic means of alcohol consumed per week in the genotypes of c1/c1, c1/c2 and c2/c2 were 218, 257 and 211 g, respectively, and were not statistically different. BP was elevated with the increase in alcohol consumption, and was significantly higher in the c2/c2 genotype than in the other genotypes among the subjects consuming 200 g or more of alcohol per week. Serum uric acid did not correlate with alcohol consumption in the whole subjects, but it was also higher in drinkers having the c2/c2 genotype. Although the number of subjects was too small for a definite conclusion to be drawn, these results suggest to some extent that Japanese men having the c2/c2 genotype of CYP2E1 are more sensitive to the pressor effect of alcohol. Further studies are required to confirm this.

Adult↗
PubMed1997

Serum gamma-glutamyl transferase levels and blood pressure falls after alcohol moderation.

Drinkers showing higher serum gamma-glutamyl transferase (GGT) levels tend to have higher blood pressure (BP), independent of the volume of alcohol consumed. To further evaluate the link between alcohol consumption and elevated serum GGT and BP, we observed BP, serum biochemical parameters, plasma pressor hormones and intraplatelet free calcium (Plt. [Ca2+]i) in 40 moderate drinkers who were composed of four categories of 10 each with or without hypertension (> or = 140/90 mmHg) or high serum GGT level (> or = 50 U/L) during four-week alcohol moderation. BP and serum hepatic enzymes including GGT decreased more conspicuously in both normotensive and hypertensive drinkers with high serum GGT. Serum triglyceride was higher and potassium was lower in the drinkers with high serum GGT, and were normalized during alcohol moderation. Serum calcium, Plt. [Ca2+]i and plasma renin activity and cortisol showed some decreases during alcohol moderation, but were not different in the drinkers with different serum GGT and BP levels. No significant changes were observed in plasma catecholamines and aldosterone. These results suggest that BP elevations in moderate drinkers are closely related to hepatic, lipid and electrolyte metabolic alterations induced by alcohol rather than specific pressor agents.

Adult↗
PubMed1996

Ultrasonic assessment of calcaneus in inhabitants in a cadmium-polluted area.

We used ultrasound (US) transmission to evaluate the speed of sound (SOS) and broadband ultrasonic attenuation (BUA) in the calcaneus in 17 male and 18 female inhabitants of a Cd-polluted area and 23 men and 45 women living in a nonpolluted area. Significant decreases in SOS and stiffness (Stiff), which was an index empirically derived from SOS and BUA, were found in Cd-exposed women. To evaluate the usefulness of the US measurements for detecting bone abnormality in Cd-exposed people, we examined the associations with the bone measurements of metacarpus by the previously used microdensitometry (MD) method and the grade of renal tubular damage due to Cd exposure. Bone density estimated by MD, sigmaGS/D, was significantly correlated with BUA, SOS, and Stiff in the Cd-exposed men and with BUA and Stiff in the Cd-exposed women. Further, in the Cd-exposed women, the decreases in BUA and Stiff correlated significantly with the increases in urinary beta 2-microglobulin, while sigmaGS/D by the MD method did not. These results suggest that the measurement of the calcaneus using US is not only radiation free but also can be used as a tool for population surveys aiming to evaluate bone damage in people, especially women, showing renal tubular damage due to environmental Cd exposure.

Aged↗
PubMed1995

Mouse p87wee1 kinase is regulated by M-phase specific phosphorylation.

We have cloned a mouse wee1 kinase cDNA (mwee1). The clone is 2258 bp in length and its open reading frame corresponds to 646 amino acid residues. The molecular weight of this kinase is 87 kDa in SDS-PAGE, which is about 1.7-fold larger than the human p50wee1 kinase reported previously. In a cell cycle, the mouse wee1 kinase is phosphorylated at M-phase, and an in vitro study using a mitotic extract revealed that phosphorylation occurs in the N-terminal domain, which is absent from the human wee1 kinase, resulting in inactivation of the kinase activity. The N-terminal domain or entire molecule is extensively phosphorylated by cdc2-cyclin B kinase. Furthermore, the activity of the wee1 kinase was reduced by phosphorylation with the mitotic extract which contained cdc2-cyclin B kinase.

Amino Acid Sequence↗