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H Kase

Publications and source records attributed to H Kase.

At least 91 records · Page 5Linked to original sources
PubMed1990

KT5926, a potent and selective inhibitor of myosin light chain kinase.

KT5926, (8R*,9S*,11S*)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-14-n-propoxy-2,3 ,9, 10-tetrahydro-8,11-epoxy, 1H,8H, 11H-2,7b,11a-triazadibenzo[a,g]cycloocta[cde] trinden-1-one, was found to be a potent and selective inhibitor of myosin light chain kinase. The compound inhibited both Ca2+/calmodulin-dependent and -independent smooth muscle myosin light chain kinases to a similar extent. The inhibition was not affected by the concentration of calmodulin. Kinetic analyses showed that the mode of inhibition was of the competitive type with respect to ATP (Ki, 18 nM) and of the noncompetitive type with respect to myosin light chain (Ki, 12 nM). These results indicated that KT5926 directly interacted with the enzyme at the catalytic site. KT5926 also inhibited other protein kinases, but with relatively high Ki values; the values for protein kinase C, cAMP-dependent protein kinase, and cGMP-dependent protein kinase were 723, 1200, and 158 nM, respectively. Ca2(+)-ATPase, Na+/K(+)-ATPase, hexokinase, and 5'-nucleotidase were not inhibited by KT5926 at less than 10 microM. The effect of KT5926 on serotonin secretion and protein phosphorylation induced by platelet-activating factor or phorbol ester was examined in rabbit platelets. KT5926 inhibited the phosphorylation of a 20-kDa protein but had no effect on the phosphorylation of a 40-kDa protein, thereby indicating that the compound exerts its selective inhibition of myosin light chain kinase in intact cells. The compound inhibited serotonin secretion induced by platelet-activating factor, but its potency was significantly less than that of K-252a, (8R*,9S*,11S*)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9, 10-tetrahydro-8,11-epoxy-1H,8H,11H-2,7b, 11a-triazadibenzo[a,g]cycloocta [cde]trinden-1-one, which inhibited the phosphorylation of both the 20-kDa protein and the 40-kDa protein. Phorbol ester-induced secretion was not suppressed by KT5926. These results provide the evidence that both the 20-kDa protein phosphorylation by myosin light chain kinase and the 40-kDa protein phosphorylation by protein kinase C substantially contribute to the secretion response in platelets.

Alkaloids↗
PubMed1989

KS-501 and KS-502, new inhibitors of Ca2+ and calmodulin-dependent cyclic-nucleotide phosphodiesterase from Sporothrix sp.

New inhibitors of Ca2+ and calmodulin-dependent cyclic-nucleotide phosphodiesterase, KS-501 and KS-502 were isolated from a fungus, Sporothrix sp. KAC-1985. Inhibitory concentration causing 50% inhibition (IC50) values of KS-501 and KS-502 for bovine brain enzyme were 1.8 and 4.3 microM, respectively. The compounds exhibited no or weak inhibition for calmodulin-independent cyclic-nucleotide phosphodiesterases and protein kinase C.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1989

KS-504 compounds, novel inhibitors of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase from Mollisia ventosa.

Novel inhibitors of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase were isolated from the culture broth of a fungus, Mollisia ventosa KAC-1148. They were designated as KS-504a, KS-504b and KS-504d. A degradative product of KS-504a, called KS-504e, was also isolated and found to inhibit the enzyme. The 50% inhibitory concentration (IC50) values of KS-504a, KS-504b, KS-504d and KS-504e for bovine brain enzyme were 122, 109, greater than 500 and 139 microM, respectively.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

The effect of K-252a, a potent microbial inhibitor of protein kinase, on activated cyclic nucleotide phosphodiesterase.

K-252a, an indole carbazol compound of microbial origin, inhibited activation of bovine brain phosphodiesterase induced by calmodulin (CaM), sodium oleate, or limited proteolysis with almost equal potency. Kinetic analysis revealed that the CaM-activated phosphodiesterase (CaM-PDE) was competitively inhibited by K-252a with respect to CaM. On the other hand, inhibition of the trypsin-activated phosphodiesterase was competitive with respect to cyclic AMP. Addition of a lower amount of phosphatidylserine or sodium oleate to the reaction medium was efficacious in attenuating the inhibition of the CaM-PDE by W-7, compound 48/80, or calmidazolium but, in contrast, had no effect on the inhibition by K-252a. Furthermore, CaM-independent systems such as [3H]nitrendipine receptor binding or Na+ + K+-ATPase were influenced less by K-252a compared with W-7, compound 48/80 and calmidazolium. In conclusion, K-252a is an inhibitor of CaM-dependent cyclic nucleotide phosphodiesterase and it appears that it inhibits the enzyme not only via CaM antagonism but possibly also by interfering with the enzyme.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1988

Inhibitors of calmodulin and protein kinase C block different phases of hippocampal long-term potentiation.

The effects of a calmodulin (CaM) inhibitor, which does not influence Ca2+ fluxes (calmidazolium, RO-24571), and a new potent inhibitor of protein kinase C (K-252b) on long-term potentiation (LTP) were compared in hippocampal slices. Tetanic stimulation of the stratum radiatum during perfusion of calmidazolium (50 nM) failed to induce the characteristic post-tetanic and long-term increase in the magnitude of CA1-evoked responses. During perfusion with K-252b (50 nM) post-tetanic potentiation and initial LTP is expressed normally, but thereafter declines back to baseline with a 60 min delay. By themselves, the inhibitors had no significant effect on synaptic transmission in a non-tetanized control input. Our data are in line with current evidence from several laboratories that CaM- and protein kinase C (PKC)-dependent processes are involved in LTP and support the hypothesis that CaM mediates initiation and that PKC mediates mechanisms underlying the maintenance of LTP.

Action Potentials↗
PubMed1988

K-252a, a novel microbial product, inhibits smooth muscle myosin light chain kinase.

Effects of K-252a, (8R*, 9S*, 11S*)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9,10-tetrahydro-8, 11-epoxy-1H,8H,11H-2,7b,11a-triazadibenzo[a,g]cycloocta [cde]trinden-1-one, purified from the culture broth of Nocardiopsis sp., on the activity of myosin light chain kinase were investigated. 1) K-252a (1 x 10(-5) M) affected three characteristic properties of chicken gizzard myosin-B, natural actomyosin, to a similar degree: the Ca2+-dependent activity of ATPase, superprecipitation, and the phosphorylation of the myosin light chain. 2) K-252a inhibited the activities of the purified myosin light chain kinase and a Ca2+-independent form of the enzyme which was constructed by cross-linking of myosin light chain kinase and calmodulin using glutaraldehyde. The degrees of inhibition by 3 x 10(-6) M K-252a were 69 and 48% of the control activities with the purified enzyme and the cross-linked complex, respectively. Chlorpromazine (3 x 10(-4) M), a calmodulin antagonist, inhibited the native enzyme, but not the cross-linked one. These results suggested that K-252a inhibited myosin light chain kinase by direct interaction with the enzyme, whereas chlorpromazine suppressed the enzyme activation by interacting with calmodulin. 3) The inhibition by K-252a of the cross-linked kinase was affected by the concentration of ATP, a phosphate donor. The concentration causing 50% inhibition was two orders magnitude lower in the presence of 100 microM ATP than in the presence of 2 mM ATP. 4) Kinetic analyses using [gama-32P]ATP indicated that the inhibitory mode of K-252a was competitive with respect to ATP (Ki = 20 nM). These results suggest that K-252a interacts at the ATP-binding domain of myosin light chain kinase. The direct action of the compound on the enzyme would explain the multivarious inhibition of myosin ATPase, of superprecipitation, and of the contractile response of smooth muscle.

Animals↗
PubMed1988

Parallel inhibition of platelet-activating factor-induced protein phosphorylation and serotonin release by K-252a, a new inhibitor of protein kinases, in rabbit platelets.

K-252a, (8R*,9S*,11S*)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9,10-tetr ahy dro-8,11-epoxy-1H,8H,11H-2,7b,11a-triazadi benzo[a,g]cycloocta[c,d,e]triden-1-one, an indole carbazol compound isolated from microbial origin, potently inhibits protein kinase C in partially purified enzyme and intact platelets. We examined the effects of this compound on platelet-activating factor [1-O-alkyl-alpha-acetyl-sn-glycero-phosphocholine (AGEPC)] induced protein phosphorylation, serotonin release and a rise in intracellular free calcium using washed rabbit platelets. In Ca2+-containing medium (1 mM CaCl2), AGEPC at 10(-10) and 10(-9) M markedly phosphorylated two proteins having molecular weights of 40,000 daltons (40 K protein) and 20,000 daltons (20 K protein) and evoked a marked rise in cytosolic free calcium. K-252a at 3 and 10 microM caused a concentration-dependent inhibition in the 20 K protein phosphorylation but caused only slight inhibition in the 40 K protein phosphorylation. K-252a inhibited the basal phosphorylation of 20 K protein obtained in non-stimulated platelets, and caused no significant alteration in the rise of intracellular free calcium evoked by AGEPC. It can be considered, from this evidence, that K-252a may act directly on myosin light chain kinase, resulting in the inhibition of 20 K protein phosphorylation. In Ca2+-free medium [1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)], AGEPC at 10(-8) M predominantly phosphorylated 40K protein, although phosphorylation of 20K protein and cytosolic free calcium were increased slightly. K-252a at 1-10 microM caused a concentration-dependent inhibition in the 40K protein phosphorylation. These results indicate that K-252a functions as an inhibitor of both protein kinase C and myosin light chain kinase in rabbit platelets. In AGEPC-stimulated platelets, the inhibition of 20K protein phosphorylation in Ca2+-containing medium and of 40K protein phosphorylation in Ca2+-free medium was closely correlated with the inhibition of serotonin release by K-252a. These results strongly suggest that the phosphorylation of these two proteins may be a prerequisite for serotonin release in AGEPC-stimulated platelets.

Animals↗
PubMed1988

Phorbol ester-induced hippocampal long-term potentiation is counteracted by inhibitors of protein kinase C.

As was shown previously (Reymann et al. 1988), the protein kinase C (PKC)-inhibitor polymyxin B prevents the maintenance of electrically induced long-term potentiation (LTP) of synaptic transmission to CA1 neurons, indicating that posttranslational phosphorylation processes mediated by PKC are involved in mechanisms underlying this form of synaptic plasticity. To make sure that 1.) the polymyxin B actually acts against PKC activation and 2.) the long-lasting potentiation elicited by phorbol esters (Malenka et al. 1986) is mediated by PKC-activation, we have tested polymyxin B as well as the potent PKC-inhibitor K-252b during phorbol ester-induced LTP. 4-beta-phorbol-12,13-dibutyrate (PDBu) - a known activator of protein kinase C, induces a remarkable potentiation at concentrations as low as 0.5 microM. When 20 microM polymyxin B or 40 nM K-252b was administered to rat hippocampal slices prior to such a weak phorbol ester treatment, this potentiation did not develop with the exception of a small increase in the population spike in spite of polymyxin B-treatment (42% instead of 120% increase at 2 h after PDBu). In contrast, spike potentiation induced by high concentrations of PDBu (10 microM) could not be counteracted by 100 microM polymyxin B. It is concluded that at low concentrations the phorbol ester-induced potentiation is mainly mediated by a selective activation of protein kinase C and that the prevented maintenance of electrically induced LTP by polymyxin B is in fact due to inhibition of this kinase. The spike potentiation developed faster than that of the EPSP raising the possibility that PDBu activates two separate PKC-dependent processes.

Action Potentials↗
PubMed1988

Antiinflammatory and antiallergic effects of a novel metabolite of Nocardiopsis sp. as a potent protein kinase C inhibitor from microbial origin.

The antiallergic and antiinflammatory effects of the new protein kinase C and calmodulin inhibitor K-252a (8R, 9S, 11S)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9,10-tetrahydro-8,11- epoxy-1H,8H,11H-2,7b,11a-triazadibenzo [a,g]cycl oocta [cde] trinden-1-one) were investigated in animal models, and the following results were obtained: 1. Oral administration of K-252a, ketotifen or oxatomide showed a dose-dependent inhibition on 48 h homologous passive cutaneous anaphylaxis in rats and anaphylactic bronchoconstriction in passively sensitized guinea pigs. 2. K-252a (1-100 mg/kg p.o.) exerted a dose-dependent protection against platelet-activating factor (PAF)-induced mortality in mice. This protective effect of K-252a was sustained for 7 h. 3. K-252a (1-100 mg/kg p.o.), as well as dexamethasone (1 mg/kg s.c.), showed remarkable inhibitory effects on rat paw edema induced by carrageenin, zymosan, PAF, and antigen-antibody reaction (passive Arthus reaction) and on the croton oil-induced rat ear edema. On the other hand, indomethacin (10 mg/kg p.o.) significantly inhibited carrageenin-induced edema, but did not inhibit edema induced by other phlogistic agents. Based on these results it is suggested that K-252a, by oral administration, has antiallergic and antiinflammatory effects.

Anaphylaxis↗
PubMed1987

K252a, a new inhibitor of protein kinase C, concomitantly inhibits 40K protein phosphorylation and serotonin secretion in a phorbol ester-stimulated platelets.

K252a isolated from microbial origin was found to potently inhibit protein kinase C in vitro (1). This agent inhibits phosphorylation of 40,000 dalton protein (40K protein) induced by 12-0-tetradecanoylphorbol-13-acetate(TPA) in intact rabbit platelets. This indicates that K252a exhibits the inhibition of protein kinase C in intact cells. The serotonin secretion induced by TPA was inhibited by K252a at nearly equal concentrations required to inhibit the phosphorylation of 40K protein. This provides the evidence to support the cause-effect relationship between the protein phosphorylation and the secretion in TPA-stimulated platelets.

Adenosine Triphosphate↗
PubMed1987

K-252 compounds, novel and potent inhibitors of protein kinase C and cyclic nucleotide-dependent protein kinases.

K-252 compounds (K-252a and b isolated from Nocardiopsis sp. (1) and their synthetic derivatives) were found to inhibit cyclic nucleotide-dependent protein kinases and protein kinase C to various extents. The inhibitions were of the competitive type with respect to ATP. K-252a was a non-selective inhibitor for these three protein kinases with Ki values 18-25 nM. K-252b showed a comparable potency for protein kinase C (Ki, 20nM), whereas inhibitory potencies for cyclic nucleotide-dependent protein kinases were reduced. KT5720 and KT5822 selectively inhibited cAMP-dependent (Ki, 60nM) and cGMP-dependent (Ki, 2.4nM) protein kinases, respectively.

Adenosine Triphosphate↗
PubMed1987

K-259-2, a new inhibitor of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase from Micromonospora olivasterospora.

K-259-2, a new inhibitor of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase, was isolated from the cultured broth of Micromonospora olivasterospora K-259. K-259-2 has an anthraquinone moiety in its structure. IC50 values for the effect of K-259-2 against Ca2+ and calmodulin-stimulated activity of the enzyme preparations from bovine brain and heart were 6.6 and 2.9 microM, respectively. On the other hand, basal activity (the activity in the presence of ethylene bis(oxyethylenenitrilo)tetraacetic acid (EGTA) instead of Ca2+/calmodulin) of the bovine brain enzyme, calmodulin-independent cyclic nucleotide phosphodiesterase from bovine heart, and protein kinase C from rat brain were inhibited by K-259-2 to a lesser extent with IC50 values of 27.4, 40.7 and 45.8 microM, respectively.

Anthraquinones↗
PubMed1987

KS-619-1, a new inhibitor of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase from Streptomyces californicus.

KS-619-1, a new inhibitor of Ca2+ and calmodulin-dependent cyclic nucleotide phosphodiesterase, was isolated from the cultured broth of Streptomyces californicus. KS-619-1 has an anthraquinone moiety. IC50 values for the effect of KS-619-1 on Ca2+ and calmodulin-stimulated activity of bovine brain and heart enzymes were 2.0 and 1.5 microM, respectively. On the other hand, basal activity (the activity in the presence of ethylene bis(oxyethylenenitrilo)tetraacetic acid (EGTA) instead of Ca2+/calmodulin) of the bovine brain enzyme, calmodulin-independent cyclic nucleotide phosphodiesterase from bovine heart, and protein kinase C from rat brain were inhibited by KS-619-1 to a lesser extent with IC50 values; 12.3, 25.9 and 151 microM, respectively.

Anthraquinones↗
PubMed1987

K-13, a novel inhibitor of angiotensin I converting enzyme produced by Micromonospora halophytica subsp. exilisia. I. Fermentation, isolation and biological properties.

A novel inhibitor of angiotensin I converting enzyme (ACE), designated K-13, was isolated from the culture broth of Micromonospora halophytica subsp. exilisia K-13. K-13 inhibited ACE non-competitively when hippuryl-L-histidyl-L-leucine was used as a substrate. The inhibition constant (Ki) was 0.349 microM. K-13 hardly inhibited carboxypeptidase A, trypsin, alpha-chymotrypsin, leucine aminopeptidase, and aminopeptidase B even at a level of 61 microM. When K-13 was administered intravenously to rats, it inhibited the pressor response to angiotensin I.

Angiotensin-Converting Enzyme Inhibitors↗