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R Kato

Publications and source records attributed to R Kato.

At least 235 records · Page 13Linked to original sources
PubMed1994

KP-10, a novel protein kinase C substrate in intact mouse epidermal cells, is phosphorylated by novel protein kinase C eta and/or zeta.

Recently this group found an endogenous substrate protein for Ca(2+)-independent novel protein kinase C (nPKC), i.e. KP-10 (pI 4.7/25,500 M(r)), in primary cultured mouse epidermal cells [Nishikawa, K. et al. (1992) Cell. Signal. 4, 757-776]. In the present study, the nPKC isozymes which phosphorylate KP-10 in these cells were determined. Western blot analysis revealed that PKC alpha, eta and zeta were present in epidermal cell 105,000 g supernatants and that the content of PKC zeta was much higher than those of PKC alpha and eta. Neither PKC beta, delta nor epsilon was detected in the 105,000 g supernatants. Phosphatidylserine and phorbol 12-myristate 13-acetate (PMA)-dependent KP-10 phosphorylating activity was immunoprecipitated by anti-PKC eta and zeta antibodies, but not by antiPKC alpha antibody. These results suggest that PKC eta and/or zeta phosphorylate KP-10 and play pivotal roles in intracellular signal pathways in intact epidermal cells.

Amino Acid Sequence↗
PubMed1994

Hair growth-stimulating effects of cyclosporin A and FK506, potent immunosuppressants.

Cyclosporin A (CsA), a cyclic endecapeptide, is a T cell-specific immunosuppressant and is successfully used in the field of organ transplantation. Another T cell-specific immunosuppressant, FK506, a more recently discovered macrolide antibiotic, is effective against graft rejection at much lower doses than CsA. Although totally different in structure, both compounds inhibit T cell activation by interfering with the production of interleukin-2 (IL-2) by inhibiting IL-2 gene expression, probably through the inhibition of calcineurin, a Ca2+/calmodulin-dependent phosphatase. Clinical studies have revealed that FK506 induces a variety of side effects in common with CsA. One of the most common side effects of CsA is hypertrichosis. The hair growth stimulating effect of CsA is observed not only in normal but also in pathological conditions of hair growth, i.e. in patients with alopecia areata and also in some patients with male-pattern alopecia. Although hypertrichosis is induced by both topical and oral administration of CsA, there has been no report showing that FK506 induces hypertrichosis. Recently we have found that topical application of FK506 to skins of mice, rats and hamsters markedly stimulates hair growth. This hair growth stimulating effect of FK506 is observed when applied topically but not by oral administration, even with a dose which causes marked immunosuppression. The hair growth stimulating effect of FK506 in normal animals may apparently be unrelated to its immunosuppressive effect. In vitro studies revealed that FK506 directly stimulates hair follicles. Mechanisms of hair growth stimulating effects of FK506 and CsA remain to be elucidated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Inhibition by lithium of cyclic GMP formation without inhibition of nitric oxide generation in the mouse neuroblastoma cell (N1E-115).

We investigated the effects of lithium ion (Li+) on muscarinic receptor-mediated nitric oxide (NO) generation, and guanylate cyclase (GCase) activation using the mouse neuroblastoma clone, N1E-115. The levels of released NO were determined by measuring the levels of nitrite/nitrate in the incubation medium, and the activity of GCase was measured with an assay for cellular cyclic [3H] GMP levels. We determined that Li+ had no effects on muscarinic receptor-activated elevation of nitrite/nitrate levels, which were significantly inhibited by 100 microM L-NG-monomethylarginine, although it has been reported that Li+ inhibits muscarinic receptor-activated cyclic GMP formation in the cells. In addition, Li+ inhibited the cyclic GMP formation induced by an NO donor, sodium nitroprusside (SNP), in both intact cells and a crude cellular homogenate; thus, the inhibition by Li+ of muscarinic receptor-mediated cyclic GMP synthesis appeared to be at the level of GCase, but not NO synthase.

Animals↗
PubMed1994

Localization and developmental changes of tau protein kinase I/glycogen synthase kinase-3 beta in rat brain.

tau protein kinase I (TPKI) purified from bovine brain extract has been shown to phosphorylate tau and to form paired helical filament (PHF) epitopes and was found recently to be identical to glycogen synthase kinase -3 beta (GSK-3 beta). Before elucidating a role of TPKI/GSK-3 beta in PHF formation, it is necessary to investigate the normal function of the enzyme. To study the distribution and developmental changes of the enzyme, specific polyclonal antibodies were prepared against TPKI and GSK-3 alpha. Immunoblot analysis demonstrated that TPKI was nearly specifically localized in the brain of adult rats. The level of TPKI in the rat brain was high at gestational day 18, peaked on postnatal day 8, and then decreased rapidly to a low level, which was sustained up to 2 years. Immunohistochemistry indicated primarily neuronal localization of TPKI. Growing axons were stained most intensely in the developing cerebellum, but the immunoreactivity became restricted to the gray matter in the mature tissue. Parallel fibers had a high level of TPKI and also stained intensely for tau. These findings indicate that tau is one of the physiological substrates of TPKI and suggest that the enzyme plays an important role in the growth of axons during development of the brain.

Animals↗
PubMed1994

Inhibition of two-stage skin carcinogenesis as well as complete skin carcinogenesis by oral administration of TMK688, a potent lipoxygenase inhibitor.

1-([5'-(3''-methoxy-4''-ethoxycarbonyloxyphenyl)-2',4'- pentadienoyl]aminoethyl)-4-diphenylmethoxypiperidine (TMK688) is a potent and orally active 5-lipoxygenase inhibitor having anti-histamine activity in its moiety. Recently, we have found that TMK688 also inhibits epidermal cyclooxygenase activity with a potency similar to its inhibiting 5-lipoxygenase. Oral administration of 30 mg/kg TMK688, a dose which markedly inhibits tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated LTB4 formation in mouse skin, markedly inhibited both TPA-promoted and a non-TPA-type tumor promoter anthralin-promoted skin tumor formation in 7,12-dimethylbenz[a]anthracene (DMBA)-initiated CD-1 mice. The inhibitory effect of TMK688 was not due to any damage inflicted on the initiated cells but due to its antitumor-promoting activity. TMK688 not only inhibited two-stage skin carcinogenesis but also inhibited benzo[a]pyrene-caused complete skin carcinogenesis. Throughout the tumorigenesis experiment, the survival rate of animals was 100% and the TMK688-treated mice looked healthy. The body weight gain of TMK688-treated mice was not significantly different from that of non-treated mice. Both TMK688 and 1-([5'-(3''-methoxy-4''-hydroxyphenyl)-2',4'-pentadienoyl]amino eth yl]-4-diphenylmethoxypiperidine (TMK777), an active metabolite of TMK688 having more potent 5-lipoxygenase inhibitory activity and less potent cyclooxygenase inhibitory activity than TMK688, inhibited epidermal 8-lipoxygenase activity induced by a topical application of TPA to mouse skin. The 8-lipoxygenase inhibitory activity of TMK777 was approximately 5 times more potent than that of TMK688. Indomethacin, a typical cylcloxygenase inhibitor, in topical doses which almost completely inhibit epidermal PGE2 formation, failed to inhibit or only slightly inhibited DMBA-initiated and TPA-promoted skin tumor formation. These results suggest that the cyclooxygenase inhibitory effect of TMK688 is not essential for its anti-tumor promoting activity. Although at present a possible contribution of anti-histamine activity cannot be ruled out completely, the anti-tumor promoting action of TMK688 may most probably be related to its anti-lipoxygenase activity. TMK688 seems to be a promising agent for the prevention of skin carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Construction of aminotransferase chimeras and analysis of their substrate specificity.

Escherichia coli aspartate aminotransferase (AspAT) and E. coli aromatic amino acid aminotransferase (AroAT) have almost identical and high activities toward acidic amino acid substrates. AroAT also has high activity toward aromatic amino acid substrates. The two proteins have 44% amino acid sequence homology. In order to study the mechanism responsible for the different substrate specificities of these aminotransferases, chimeric enzymes of AspAT and AroAT were constructed using homologous recombination in E. coli cells. Five chimeric enzymes were obtained, even though the nucleotide sequence homology between the two parent enzymes was as low as about 50%. The yields of the legitimate chimeric genes were related to the lengths of the homologous region between the two parent genes. Homologous recombination occurred in the region where more than eight nucleotides out of ten were identical. The substrate specificity of the chimeric enzymes suggest that not only the amino acid residues in the active site but also those distant from the active site contribute to the substrate specificity of the parental aminotransferases.

Amino Acid Sequence↗
PubMed1994

Interaction of Escherichia coli RecA protein with ATP and its analogues.

Interactions of Escherichia coli RecA protein with ATP and its analogues in the absence of DNA were studied by circular dichroic (CD) spectroscopy. The binding of RecA protein to ATP increased the CD band of ATP at around 260 nm. The positive CD band of the RecA protein-ATP complex suggested that the bound ATP was in the anti conformation, in accord with X-ray crystallographic data [Story, R.M. and Steitz, T.A. (1992) Nature 355, 374-376]. At pH 7.5 and at 25 degrees C the dissociation constant (Kd) and thermodynamic parameters for the binding of ATP to RecA protein were 18 microM (delta G = -6.5 kcal.mol-1), delta H = 0 kcal.mol-1, and delta S = 22 cal.mol-1.K-1. A non-hydrolyzable ATP analogue, adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S), gave a spectral change similar to that of ATP. The Kd for this analogue, 22 microM, was very close to the Km of ATP. These results in the absence of single-stranded DNA were different from those obtained by kinetic analysis [Weinstock, G.M. et al. (1981) J. Biol. Chem. 256, 8850-8855], which indicated that the inhibition constant of ATP gamma S was much smaller than the Km of ATP in the presence of DNA. For other ATP analogues (dATP, ADP, and dADP), similar spectral changes were observed, and their Kd values ranged from 19 to 54 microM. UTP, dUTP, and TTP also gave CD spectral changes, but not AMP, GTP, dGTP, CTP, and dCTP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1994

Primary structure and molecular basis of polymorphic appearance of an acetyltransferase (AT-II)* in hamsters.

Three hamster clones (clones 1, 2 and 3) were isolated from a genomic library constructed from a homozygote rapid acetylator using a cDNA (hamAT-101) of a monomorphic acetyltransferase (AT-I) as a probe. Clone 1 (13 kbp) was found to contain a gene corresponding to AT-I. The entire coding region was located in an exon and completely identical to that of AT-I cDNA. Clones 2 and 3 (14.5 and 15 kbp) each contained identical information to the AT-I-related protein (AT-B protein). The intronless coding region shared 83.7% of sequence similarly to the AT-I cDNA, and its length was identical to that of the AT-I cDNA. Clone 2 also included a nucleotide sequence identical to the 3'-portion of the AT-I gene, which is located 5'-upstream of the AT-B gene. Restricted fragment lengths of clone 3, which encompassed the entire coding region was expressed in COS-1 cells. The expressed protein migrated at a position identical to that of AT-II purified from a hamster liver on Western blots. AT-B-expressed protein catalysed acetyl CoA-dependent N-acetylation of 2-aminofluorene and p-aminobenzoic acid, but had marginal activities for O-acetylation of 2-N-hydroxyamino-6-methyl-6-methyldipyrido[1,2-a:3',2'-d]imidazole and N-hydroxyarylacetamide-dependent N-acetylation of 4-aminoazobenzene. These results are in good agreement with the data of AT-II purified from hamster livers, indicating that the AT-B gene encodes a polymorphic acetyltransferase (AT-II) in hamsters. Although the AT-II protein was undetectable in slow acetylators, specific mRNA, hybridizing with a selective oligonucleotide probe for the AT-II gene (AT-B), was detected in livers of both homozygous acetylators. Analysis of genomic DNA of a homozygous slow phenotype hamster indicates that AT-II DNA from the slow phenotype has a point mutation which causes premature termination at the 243th (Arg to stop codon) position of the deduced amino acid sequence. PCR-RFLP analysis further confirmed that the point mutation conferred a defective AT-II protein in slow phenotype hamsters.

4-Aminobenzoic Acid↗
PubMed1994

Lack of low Km diazepam N-demethylase in livers of poor metabolizers for S-mephenytoin 4'-hydroxylation.

Metabolism of diazepam was studied in vitro to identify the forms of cytochrome P450 (CYP) responsible for N-demethylation (nordazepam formation) and 3-hydroxylation (temazepam formation), using liver microsomes obtained from extensive (EM) and poor metabolizers (PM) for S-mephenytoin 4'-hydroxylation. Involvement of at least two P450 forms in diazepam N-demethylation was suggested by a biphasic pattern in Lineweaver-Burk and Eadie-Hofstee plots from the EM, whereas a monophasic pattern was observed from the PM liver microsomes. The kinetic parameters for the N-demethylation in the EM group were: Km 1, 19.4 +/- 0.4 microM; Vmax 1, 0.27 +/- 0.04 nmol min-1 per mg protein; Km 2, 346 +/- 34 microM; Vmax2, 1.82 +/- 0.63 nmol min-1 per mg protein (n = 3, mean +/- SD). The PM group showed the mean values of Km and Vmax (Km, 319 +/- 30 microM; Vmax, 1.49 +/- 0.62 nmol min-1 per mg protein) (n = 3) similar to those of Km2 and Vmax2 in the EM group. An antibody raised against CYP2C9 (anti-human CYP2C) strongly inhibited diazepam N-demethylation in EM liver microsomes at a low substrate concentration (20 microM). However, the anti-human CYP2C showed no clear inhibition of N-demethylation in EM liver microsomes at a high substrate concentration (200 microM). Diazepam N-demethylation in PM liver microsomes was not clearly inhibited by the anti-human CYP2C at either the low or high substrate concentrations. These data suggest that different P450 forms mediated diazepam N-demethylation in EM and PM liver microsomes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1994

Stimulation of hair growth by topical application of FK506, a potent immunosuppressive agent.

FK506, a macrolide antibiotic produced by Streptomyces tsukubaensis, is known as a potent T cell-specific immunosuppressant, and is effective against graft rejection after organ transplantation. Topical application of FK506 (0.03-1 mumol) to dorsal skin of CD-1 mice stimulated hair growth in a dose-dependent manner. Unlike topical application, oral administration of 30 mg/kg of FK506, a dose that induces marked immunosuppression, did not stimulate significant hair growth. Topical application of FK506 also stimulated hair growth of rats and Syrian golden hamsters. FK506 stimulated hair growth even in SCID mice that lack both B- and T-cell immunity. Therefore, it is unlikely that the hair growth-stimulatory effect of FK506 results from its immunosuppressive effect. FK506 (0.01-1 microM) stimulated both [3H]thymidine and [3H]glycine uptakes to cultured mouse vibrissae follicles in a concentration-dependent manner. Moreover, when the follicles were treated with FK506 (1 microM) for 16 d, the size of the follicles (length of hair plus follicle) increased slightly but significantly. On the other hand, the size of the non-treated follicles did not increase significantly. These results indicate that FK506 directly stimulates hair follicles. Long-term treatment of mice with FK506, i.e., topical application of 1 mumol FK506 twice a week for 6 months, did not affect body weight gain of mice, and the FK506-treated mice looked healthy. FK506 may be useful as a stimulant of hair growth.

Administration, Topical↗
PubMed1994

Activation of 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b] pyridine by cDNA-expressed human and rat arylsulfotransferases.

Sulfation plays an obligatory role in the activation of N-hydroxy derivatives of carcinogenic arylamine (amide)s and heterocyclic amines. We found that the hepatic sulfotransferase-mediated covalent binding of 3H-labeled 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b] pyridine (N-OH-PhIP) to calf thymus DNA was 3.3 and 12.9 times higher with human cytosol preparation than with male and female rat cytosol preparations, respectively, in the presence of 3'-phosphoadenosine 5'-phosphosulfate. To assess the activating capacities of individual phenol-sulfating sulfotransferases, five different forms, human ST1A2 and ST1A3 and rat ST1A1, ST1B1 and ST1C1, were expressed in heterologous cells. All five sulfotransferases mediated the activation of N-OH-PhIP to DNA-bound products. The extents of the binding, however, differed considerably among these forms. Human ST1A2 and ST1A3 mediated the activation of N-OH-PhIP at 5.2- and 6.2-fold higher rates than did rat ST1C1, a main N-hydroxy-2-acetylaminofluorene-activating sulfotransferase, in rat liver. Extents of the binding of N-OH-PhIP in human hepatic cytosols of different individuals were positively correlated with the contents of immunoreactive ST1A2/3. These results suggest a potential role of human liver sulfotransferases in N-OH-PhIP activation. In contrast, the low sulfotransferase-mediated activation of N-OH-PhIP in rat liver is consistent with the lack of PhIP hepatocarcinogenicity in this species.

Amino Acid Sequence↗
PubMed1994

Serum concentration of 7S collagen and prognosis in patients with the adult respiratory distress syndrome.

BACKGROUND--7S collagen, an N-terminal peptide of type IV collagen, is a primary constituent of the basement membrane. To evaluate whether the serum concentration of 7S collagen reflects the severity of inflammatory lung disease, the serum concentration of 7S collagen was measured in patients with adult respiratory distress syndrome (ARDS) and idiopathic pulmonary fibrosis (IPF). METHODS--A radioimmunoassay was used for the measurement of 7S collagen. Gas exchange abnormality was expressed as the arterial oxygen tension (PaO2) divided by the fractional concentration of inspired oxygen (FiO2). RESULTS--The mean (SD) concentration of 7S collagen was 2.7 (0.9) ng/ml in 10 healthy subjects, 5.0 (1.5) ng/ml in 11 patients with IPF, and 14.8 (9.7) ng/ml in 13 patients with ARDS. Significant differences were observed between the patients with ARDS and both healthy subjects and the patients with IPF. In the patients with ARDS serum concentrations of 7S collagen were strongly related to PaO2/FiO2 (r = -0.61). Moreover, the mean (SD) serum concentration of 7S collagen in the eight patients with ARDS who died (19.5 (10.2) ng/ml) was considerably higher than that of the five who survived (7.1 (2.1) ng/ml). CONCLUSION--These results suggest that serum levels of the 7S fragment of type IV collagen may have some prognostic value in ARDS.

Adolescent↗
PubMed1994

Effects of N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanine (A-4166) on insulin and glucagon secretion in isolated perfused rat pancreas.

N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanine (A-4166) has a structure which differs from those of other known blood glucose-lowering agents including sulfonylureas. It has been shown that oral administration of A-4166 exerts blood glucose-lowering effects in animal in vivo studies. In the present study, we investigated the effects of A-4166 on insulin and glucagon secretion at several glucose concentrations using isolated perfused rat pancreas preparations. Both 3.0 and 30 mumol/l A-4166 significantly stimulated insulin secretion as compared with basal levels at glucose concentrations of 8.0 and 11.0 mmol (p < 0.01 and p < 0.05, respectively). In contrast, glucagon secretion was not affected by administration of A-4166 up to 30 mumol/l at these glucose concentrations. At a glucose concentration of 5.6 mmol/l, neither 0.3 nor 3.0 mumol/l A-4166 produced significant changes in insulin and glucagon secretion. However, A-4166 at 30 mumol/l significantly stimulated insulin secretion and inhibited glucagon secretion as compared with basal levels (p < 0.01 and p < 0.01, respectively). We conclude that A-4166 at 3.0 and 30 mumol/l directly stimulates insulin secretion but has little effect on glucagon secretion in isolated perfused rat pancreas at glucose concentrations of 8.0 and 11.0 mmol/l. these results, taken together with previously published data, suggest that oral administration of A-4166 could be a useful strategy for stimulating endogenous insulin secretion in non-insulin-dependent diabetic patients.

Animals↗
PubMed1994

Anti-inflammatory action of orally active 5-lipoxygenase inhibitor TMK688.

A topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) to mouse ear surface induces nonallergic inflammation, i.e. ear edema. Oral administration of 3-30 mg/kg of 1-([5'-(3"-methoxy-4"-ethoxycarbonyloxyphenyl)-2',4'-pentadieno yl]-aminoethyl)-4-diphenylmethoxypiperidine (TMK 688), a potent 5-lipoxygenase inhibitor with antihistamine activity, inhibited TPA-induced ear edema in a dose-dependent manner. TMK688 inhibited not only 5-lipoxygenase activity but also epidermal cyclooxygenase activity. 1-([5'-(3"-methoxy-4"-hydroxyphenyl)-2',4'-pentadienoyl]-aminoe thy l)- 4-diphenylmethoxypiperidine (TMK777), an active metabolite of TMK688, had more potent 5-lipoxygenase inhibitory activity but less potent cyclooxygenase inhibitory activity than TMK688. Oral administration of TMK688 (30 mg/kg) markedly inhibited TPA-stimulated LTB4 formation in mouse skin but TPA-stimulated PGE2 formation only slightly. Our experimental results suggest that both cyclooxygenase inhibitory activity and antihistamine activity of TMK688 are not essential to its anti-inflammatory action. The anti-inflammatory effect of orally administered TMK688 is due most probably to the anti-5-lipoxygenase activity of TMK688 and its active metabolite TMK777.

Administration, Oral↗
PubMed1994

Elevated levels of interleukin-8 and leukotriene B4 in pulmonary edema fluid of a patient with reexpansion pulmonary edema.

We experienced a case of reexpansion pulmonary edema (RPE) after surgical treatment of pneumothorax. In this case, protein leakage and polymorphonuclear leukocyte (PMN) accumulation were observed in the reexpanded lung. Interleukin-8 and leukotriene B4 in edema fluid were increased at the onset of RPE. PMN elastase was also increased, though its peak was delayed. The plasma level of P-selectin, which mediates adhesion between PMN and endothelium, was elevated. We speculate that some of these fluid mediators may play important roles in chemotaxis and activation of PMN in the development of RPE.

Adult↗
PubMed1994

Pressure promotes DNA synthesis in rat cultured vascular smooth muscle cells.

High blood pressure is one of the major risk factors for atherosclerosis. In this study, we examined the effects of pressure on cell proliferation and DNA synthesis in cultured rat vascular smooth muscle cells. Pressure without shear stress and stretch promotes cell proliferation and DNA synthesis in a pressure-dependent manner. Pressure-induced DNA synthesis was inhibited significantly by the phospholipase C (PLC) inhibitor 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate, the protein kinase C inhibitor H-7, 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine, staurosporine, and the tyrosine kinase inhibitor ([3,4,5-trihydroxyphenyl]methylene)propanedinitrile. To clarify whether activation of PLC and calcium mobilization are involved in pressure-induced DNA synthesis, production of 1,4,5-inositol trisphosphate (IP3) and intracellular Ca2+ was measured. Pure pressure increased IP3 and intracellular Ca2+ in a pressure-dependent manner. The increases in both IP3 and intracellular Ca2+ were inhibited significantly by 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate. This study demonstrates a novel cellular mechanism whereby pressure regulates DNA synthesis in vascular smooth muscle cells, possibly via activation of PLC and protein kinase C.

Animals↗