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T Chijiwa

Publications and source records attributed to T Chijiwa.

27 records · Page 2Linked to original sources
PubMed1990

Inhibition of forskolin-induced neurite outgrowth and protein phosphorylation by a newly synthesized selective inhibitor of cyclic AMP-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), of PC12D pheochromocytoma cells.

A newly synthesized isoquinolinesulfonamide, H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline-sulfonamide), was shown to have a potent and selective inhibitory action against cyclic AMP-dependent protein kinase (protein kinase A), with an inhibition constant of 0.048 +/- 0.008 microM. H-89 exhibited weak inhibitory action against other kinases and Ki values of the compound for these kinases, including cGMP-dependent protein kinase (protein kinase G), Ca2+/phospholipid-dependent protein kinase (protein kinase C), casein kinase I and II, myosin light chain kinase, and Ca2+/calmodulin-dependent protein kinase II were 0.48 +/- 0.13, 31.7 +/- 15.9, 38.3 +/- 6.0, 136.7 +/- 17.0, 28.3 +/- 17.5, and 29.7 +/- 8.1 microM, respectively. Kinetic analysis indicated that H-89 inhibits protein kinase A, in competitive fashion against ATP. To examine the role of protein kinase A in neurite outgrowth of PC12 cells, H-89 was applied along with nerve growth factor (NGF), forskolin, or dibutyryl cAMP. Pretreatment with H-89 led to a dose-dependent inhibition of the forskolin-induced protein phosphorylation, with no decrease in intracellular cyclic AMP levels in PC12D cells, and the NGF-induced protein phosphorylation was not not inhibited. H-89 also significantly inhibited the forskolin-induced neurite outgrowth from PC12D cells. This inhibition also occurred when H-89 was added before the addition of dibutyryl cAMP. Pretreatment of PC12D cells with H-89 (30 microM) inhibited significantly cAMP-dependent histone IIb phosphorylation activity in cell lysates but did not affect other protein phosphorylation activity such as cGMP-dependent histone IIb phosphorylation activity, Ca2+/phospholipid-dependent histone IIIs phosphorylation activity, Ca2+/calmodulin-dependent myosin light chain phosphorylation activity, and alpha-casein phosphorylation activity. However, this protein kinase A inhibitor did not inhibit the NGF-induced neurite outgrowth from PC12D cells. Thus, the forskolin- and dibutyryl cAMP-induced neurite outgrowth is apparently mediated by protein kinase A while the NGF-induced neurite outgrowth is mediated by a protein kinase A-independent pathway.

Adrenal Gland Neoplasms↗
PubMed1990

KN-62, 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazi ne, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II.

1-[N,O-Bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpipera zine (KN-62), a selective inhibitor of rat brain Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM kinase II) was synthesized and its inhibitory properties in vitro and in vivo were investigated. KN-62 inhibited phosphorylation of exogenous substrate (chicken gizzard myosin 20-kDa light chain) by Ca2+/CaM kinase II with Ki value of 0.9 microM, but no significant effect up to 100 microM on activities of chicken gizzard myosin light chain kinase, rabbit brain protein kinase C, and bovine heart cAMP-dependent protein kinase type II. KN-62 also inhibited the Ca2+/calmodulin-dependent autophosphorylation of both alpha (50 kDa) and beta (60 kDa) subunits of Ca2+/CaM kinase II dose dependently in the presence or absence of exogenous substrate. Kinetic analysis indicated that this inhibitory effect of KN-62 was competitive with respect to calmodulin. However, KN-62 did not inhibit the activity of autophosphorylated Ca2+/CaM kinase II. Moreover, Ca2+/CaM kinase II bound to a KN-62-coupled Sepharose 4B column, but calmodulin did not. These results suggest that KN-62 affects the interaction between calmodulin and Ca2+/CaM kinase II following inhibition of this kinase activity by directly binding to the calmodulin binding site of the enzyme but does not affect the calmodulin-independent activity of already autophosphorylated (activated) enzyme. We examined the effect of KN-62 on cultured PC12 D pheochromocytoma cells. KN-62 suppressed the A23187 (0.5 microM)-induced autophosphorylation of the 53-kDa subunit of Ca2+/CaM kinase in PC12 D cells, which was immunoprecipitated with anti-rat forebrain Ca2+/CaM kinase II polypeptides antibodies coupled to Sepharose 4B, thereby suggesting that KN-62 could inhibit the Ca2+/CaM kinase II activity in vivo.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Potentiation of anti-platelet aggregating activity of cilostazol with vascular endothelial cells.

We developed the new system in which the platelet aggregation was detected turbidimetrically using glass cuvettes which were coated cultured vascular endothelial cells. Using this system, we evaluated the effect of cilostazol, having a selective inhibitory effect on cAMP-PDE, on the ADP-induced platelet aggregation in the presence of endothelial cells. Cilostazol inhibited the platelet aggregation dose-dependently in the presence or absence of endothelial cells. The inhibitory effect of cilostazol on platelet aggregation was potentiated by the presence of endothelial cells, and the slope of the dose-response curves were identified to be as the same between both experiments in the presence and the absence of endothelial cells. The pretreatment of endothelial cells with aspirin reversed the potentiated inhibitory effect of cilostazol on the platelet aggregation with endothelial cells. The amount of 6-keto-prostaglandin F1 alpha accumulated in the cuvette was reduced in this condition. On the other hand, the inhibitory effect of prostaglandin E1 on the platelet aggregation was not potentiated by the presence of endothelial cells. These results suggest that the endothelium-derived prostacyclin plays a role on the potentiation of anti-platelet aggregatory effect of cilostazol.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1989

A newly synthesized selective casein kinase I inhibitor, N-(2-aminoethyl)-5-chloroisoquinoline-8-sulfonamide, and affinity purification of casein kinase I from bovine testis.

When screening various isoquinolinesulfonamide compounds which we synthesized, CKI-7, N-(2-amino-ethyl)-5-chloroisoquinoline-8-sulfonamide, was found to have a potent inhibitory action against casein kinase I and a much weaker effect on casein kinase II and other protein kinases. Kinetic analysis indicated that CKI-7 inhibited casein kinase I competitively with respect to ATP and that the Ki values were 8.5 microM for casein kinase I and 70 microM for casein kinase II. An affinity chromatography absorbent was synthesized by coupling CKI-8 (1-(5-chloroisoquinoline-8-sulfonyl], a derivative of CKI-7, to cyanogen bromide-activated Sepharose 4B. Partially purified casein kinase I from bovine testis was subjected to affinity chromatography. Analysis of the purified casein kinase I by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed a single band with molecular weight 37,000. These newly synthesized compounds, CKI-7 and CKI-8, should serve as useful tools for elucidating the biological significance of casein kinase I-mediated reactions.

Animals↗
PubMed1989

Degeneration of zonular fibrils in a case of exfoliation glaucoma.

We examined ultrastructurally zonules of the lens obtained from a patient with exfoliation glaucoma and lens dislocation. There was a great accumulation of exfoliation materials adjacent to and within degenerated zonules, and a gradual transition between zonular fibrils and exfoliation materials was observed. The initial change in the zonular fibrils was a loss of their regularity, next we could see fine granules deposited on degenerated zonular fibrils. A sparse and irregular deposition was found on the surface of the fibrils. Subsequently, the deposition became increased, and densely stained exfoliation materials, which were composed of a single degenerated zonular fibril and fine granules, were formed. Several fibrils accompanied by fine granules clustered together and became exfoliation materials of larger diameter. These observations suggest that degenerated zonular fibrils may develop into exfoliation materials.

Aged↗
PubMed1989

Thyroid hormones directly interact with vascular smooth muscle strips.

The thyroid hormones have direct effects on vascular smooth muscle and are potent vasorelaxants. In the present study, the effects of d- and l-thyroxine (d-T4 and l-T4), 3,5,3'-triiodo-d-thyronine (d-T3), and 3,5,3'-triiodo-l-thyronine (l-T3) on the isolated mesenteric artery of the rabbit and superprecipitation of actomyosin from bovine aorta were examined. These thyroid hormones dose dependently relaxed vascular strips previously contracted with 50 mM KCl in the presence of phentolamine (1 microM), propranolol (1 microM), and atropine (0.3 microM), and the order of the inhibitory potency was l-T4 greater than d-T4 greater than l-T3 greater than d-T3 for the contraction. Pretreatment with l-T4 (10 and 30 microM) inhibited the contractile response concomitant with the inhibition of the 20,000-Da myosin light chain phosphorylation, without significant suppression of the increase in La3+-resistant 45Ca influx and uptake (5 and 30 min) induced by 50 mM KCl, suggesting that the inhibitory effect of l-T4 may not be primarily related to Ca2+ entry through the voltage-dependent Ca2+ channel. The l-T4 (10 and 30 microM) showed noncompetitive antagonism against the Ca2+-induced contraction in the high K+-depolarized vascular strips. Superprecipitation of actomyosin was inhibited by the addition of l-T4, in a dose-dependent manner, and calmodulin (1 microgram/ml) partly reversed the inhibitory effect of l-T4. Thyroid hormones were found to inhibit Ca2+/calmodulin-dependent smooth muscle myosin light chain kinase, and the Ki value for l-T4 was 2.5 microM. Although the concentrations of l-T4 used in this study are high, relative to circulating physiological levels, thyroid hormones act directly at the blood vessel wall to cause inhibition of the contractile process in vascular smooth muscle in vitro. Modulation of the 20,000-Da myosin light chain phosphorylation via the inhibition of myosin light chain kinase activity may at least in part contribute to the inhibitory effect of l-T4.

Animals↗
PubMed1988

ML-9 inhibits the vascular contraction via the inhibition of myosin light chain phosphorylation.

We investigated the effects of a newly synthesized compound, 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9), a myosin light chain kinase (MLCK) inhibitor of superprecipitation of actomyosin, isometric tension development, and phosphorylation of the 20,000-Da myosin light chain (LC20) in vascular smooth muscle. Superprecipitation of actomyosin from bovine aorta was inhibited by the addition of ML-9 in a dose-dependent manner. In chemically skinned smooth muscles of the rabbit mesenteric artery, ML-9 inhibited the Ca2+-independent contraction provoked by application of trypsin-treated MLCK. In the intact rabbit mesenteric artery, increases in LC20 phosphorylation reached a maximal value of 0.49 mol of Pi/mol of LC20 within 10 sec from a resting value of 0.15 mol of Pi/mol of LC20 and then declined to near the basal level during the maintained isometric force developed in response to 50 mM KCl. Preincubation with 10-30 microM ML-9 for 30 min significantly inhibited both the maximal rate and extent of KCl-induced contraction and the phosphorylation of LC20, in a dose-dependent manner. There was a linear relationship between the initial rate of tension development and the extent of LC20 phosphorylation at 10 sec after stimulation. ML-9 nonspecifically antagonized the contraction induced by various contractile agonists, such as CaCl2, norepinephrine, serotonin, histamine, and angiotensin II. ML-9 dose dependently produced a shift to the right and down, in the dose-response curves, to all the agonists tested. These results suggest that ML-9 inhibits the actin-myosin interaction through the modulation of LC20 phosphorylation via the inhibition of MLCK activity. Thus, ML-9 may be a useful compound for investigating the physiologic role of myosin light chain phosphorylation by MLCK in living cells and tissues as well as in vitro.

Animals↗
PubMed1987

Gastric mucosal protection by OPC-12759, a novel antiulcer compound, in the rat.

OPC-12759, 2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinon-4-yl]-propionic acid, was studied for its efficacy to prevent the gastric mucosal damage induced by several necrotizing agents. Experiments were also performed to elucidate the mechanism of this mucosal protective activity. OPC-12759 dose dependently prevented the formation of mucosal necrosis induced by absolute ethanol, 0.2 N NaOH or 0.6 N HCl. PGE2 was also shown to prevent the gastric mucosal erosion induced by necrotizing agents. The mucosal protective effect of OPC-12759 was completely counteracted by pretreatment with indomethacin while that of PGE2 was not. In addition, OPC-12759 given alone increased the generation of gastric mucosal PGE2-like activity. OPC-12759 dose dependently reduced the volume, acid output and pepsin output of the gastric juice in pylorus-ligated rats. The inhibitory effect of OPC-12759 but not of cimetidine or atropine on gastric secretion was also abolished by concurrent administration of indomethacin. These findings suggest that the mucosal protective effect and antisecretory effect of OPC-12759 presumably result from enhancement of the generation of endogenous PGs.

Alanine↗