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Biomedical subjects

S Nishibe

Publications and source records attributed to S Nishibe.

At least 19 recordsLinked to original sources
PubMed1995

Phenylethanoids in the herb of Plantago lanceolata and inhibitory effect on arachidonic acid-induced mouse ear edema.

The five phenylethanoids, acteoside (1), cistanoside F (2), lavandulifolioside (3), plantamajoside (4) and isoacteoside (5) were isolated from the herb of Plantago lanceolata L. (Plantaginaceae). Compounds 1, the major phenylethanoid in the herb of P. lanceolata L., and 4, the major phenylethanoid in the herb of P. asiatica L., showed inhibitory effects on arachidonic acid-induced mouse ear edema.

Animals↗
PubMed1995

Search for naturally occurring substances to prevent the complications of diabetes. II. Inhibitory effect of coumarin and flavonoid derivatives on bovine lens aldose reductase and rabbit platelet aggregation.

An EtOAc extract of Artemisiae Capillari Spica inhibited both bovine lens aldose reductase (bovine-LAR) and rabbit platelet aggregation. Two simple coumarins, scoparone (1) and scopoletin (2), and three flavonoids, capillarisin (21), cirsimaritin (22) and rhamnocitrin (23), were isolated from this extract. Scoparone (1) and scopoletin (2) exhibit a potent inhibitory effect on rabbit platelet aggregation induced by four types of agent, ADP, PAF, sodium arachidonate and/or collagen. Capillarisin (21) exhibits a potent inhibitory effect on bovine-LAR. In addition, thirteen simple coumarins, five coumarin glycosides and two flavonoids were tested for their inhibitory effect against bovine-LAR and rabbit platelet aggregation.

Aldehyde Reductase↗
PubMed1992

Growth factor stimulation of phospholipase C-gamma 1 activity. Comparative properties of control and activated enzymes.

We demonstrated previously tyrosine phosphorylation-dependent modulation of phospholipase C-gamma 1 (PLC-gamma 1) catalytic activity (Nishibe, S., Wahl, M. I., Hernandez-Sotomayor, S. M. T., Tonks, N. K., Rhee, S. G., and Carpenter, G. (1990) Science 250, 1253-1256). The increase in PLC-gamma 1 catalytic activity in A-431 cells occurs rapidly, with maximal activation 5 min after epidermal growth factor (EGF) stimulation. Certain other growth factors (fibroblast growth factor, platelet-derived growth factor) also stimulate PLC-gamma 1 catalytic activity, whereas insulin does not. A similar increase in PLC-gamma 1 specific activity (2-3-fold) was observed in both soluble (cytosol) and particulate (membrane) preparations from EGF-treated cells. Tyrosine-phosphorylated PLC-gamma 1 was detected in both cytosol and membrane fractions in lysates from EGF-treated A-431 cells, but the proportion of tyrosine-phosphorylated PLC-gamma 1 was higher in the cytosol (approximately 50%) than in the membrane (approximately 20%). Because a micellar concentration of the non-ionic detergent Triton X-100 allows detection of the tyrosine phosphorylation-dependent increase in PLC-gamma 1 catalytic activity in this assay, we evaluated the kinetic properties of PLC-gamma 1, immunoprecipitated from cytosol of control or EGF-treated cells, using substrate, phosphatidylinositol 4,5-bisphosphate (PtdIns 4,5-P2), solubilized in Triton X-100 at various molar ratios. The behavior of the control enzyme differed from the EGF-activated enzyme with respect to both Ks and Km. The control enzyme has a 7.5-fold higher Ks value than the activated enzyme (1.5 mM as compared with 0.22 mM). Activation by EGF is also a positive allosteric modifier of PLC-gamma 1-catalyzed PtdIns 4,5-P2 hydrolysis, i.e. the activated enzyme displayed apparent Michalis-Menton kinetics, with a Km of 0.6 mol fraction PtdIns 4,5-P2, whereas the control enzyme displayed sigmoidal kinetics with respect to PtdIns 4,5-P2 hydrolysis. At low substrate mol fractions (e.g. 0.07), the reaction velocity of the control enzyme was 4-fold lower than the activated enzyme. However, at a high substrate mol fraction (e.g. 0.33), the estimated maximal reaction velocities (Vmax) for both forms of PLC-gamma 1 were equivalent. PLC-gamma 1 activity from both control and EGF-treated cells was stimulated by increasing nanomolar Ca2+ concentrations. Although the catalytic activity of PLC-gamma 1 from EGF-treated cells was greater than control PLC-gamma 1 at every Ca2+ concentration tested, the relative stimulation of activity was markedly greater at Ca2+ concentrations above approximately 300 nM.

3T3 Cells↗
PubMed1992

Structural transformation of lignan compounds in rat gastrointestinal tract.

Structural transformation of arctiin and tracheloside, major components of seeds of Arctium lappa and Carthamus tinctorius, were investigated using rat gastric juice (pH 1.2-1.5) and rat large intestinal flora in vitro. Quantitative analysis of lignans and their metabolites was carried out by high performance liquid chromatography. Both lignans were stable in rat gastric juice and arctiin was rapidly transformed to arctigenin in rat large intestinal flora, followed by conversion to the major metabolite, 2-(3",4"-dihydroxybenzyl)-3-(3',4'-dimethoxybenzyl)-butyrolactone. On the other hand, tracheloside also decreased dependently with time and was converted to trachelogenin and its major metabolite, 2-(3",4"-dihydroxybenzyl)-3-(3',4'-dimethoxybenzyl)-2-hydroxybutyrola ctone. These experiments suggest that in the course of metabolism of lignans, firstly a cleavage of the glycosidic bond occurred and then demethylation of the phenolic methoxy group in the alimentary tract followed.

4-Butyrolactone↗
PubMed1992

Growth factor phosphorylation of PLC-gamma 1.

The hydrolysis of phosphatidylinositol 4,5-bisphosphate has a central role in many signalling pathways. One of the phospholipase C (PLC) isozymes that mediates this reaction is a direct substrate for the tyrosine kinase activity of several growth factor receptors. Growth factors elicit increases in both the phosphoserine and the phosphotyrosine content of the PLC-gamma 1 isozyme. PLC-gamma 1 contains three tyrosine phosphorylation sites, which have been identified as residues 771, 783 and 1254. Phosphorylation of tyrosine residues is sufficient to increase the catalytic activity of PLC-gamma 1, though other proteins may modulate this activation. However, the role of growth factor-enhanced phosphorylation of serine residues on PLC-gamma 1 remains obscure. In vitro studies of PLC-gamma 1, recovered from growth factor-treated cells, indicate that activation by tyrosine phosphorylation is not due to increased sensitivity to Ca2+, a required co-factor, but is reflected in altered kinetic constants, i.e. V(max) and, to a lesser extent, Km.

Enzyme Activation↗
PubMed1990

Increase of the catalytic activity of phospholipase C-gamma 1 by tyrosine phosphorylation.

Phospholipase C-gamma 1 (PLC-gamma 1), an isozyme of the phosphoinositide-specific phospholipase C family, which occupies a central role in hormonal signal transduction pathways, is an excellent substrate for the epidermal growth factor (EGF) receptor tyrosine kinase. Epidermal growth factor elicits tyrosine phosphorylation of PLC-gamma 1 and phosphatidylinositol 4,5-bisphosphate hydrolysis in various cell lines. The ability of tyrosine phosphorylation to activate the catalytic activity of PLC-gamma 1 was tested. Tyrosine phosphorylation in intact cells or in vitro increased the catalytic activity of PLC-gamma 1. Also, treatment of EGF-activated PLC-gamma 1 with a tyrosine-specific phosphatase substantially decreased the catalytic activity of PLC-gamma 1. These results suggest that the EGF-stimulated formation of inositol 1,4,5-trisphosphate and diacylglycerol in intact cells results, at least in part, from catalytic activation of PLC-gamma 1 through tyrosine phosphorylation.

Catalysis↗
PubMed1990

Tyrosine residues in bovine phospholipase C-gamma phosphorylated by the epidermal growth factor receptor in vitro.

We have identified the sites phosphorylated in vitro by epidermal growth factor (EGF) receptor kinase in bovine brain phospholipase C-gamma (PLC-gamma). They are tyrosine residues 472, 771, 783, and 1254. The rate of phosphorylation was fastest with the sites at 771 and 783, then at 1254, and slowest at 472. PLC-gamma isolated from cells treated with EGF is known to contain at least four tyrosine phosphate-containing peptides and two of them are identified to be residues 771 and 1254 in the accompanying paper (Wahl, M. I., Nishibe, S., Kim, J. W., Kim, H., Rhee, S. G., and Carpenter, G. (1990) J. Biol. Chem. 265, 3944-3948). The 3 residues 472, 771, and 783 are located closely to the regions of PLC-gamma which exhibit a high sequence similarity to the regulatory domain of the src family tyrosine kinases. Nevertheless, the tyrosine phosphorylation did not affect the catalytic activity of PLC-gamma in vitro. We propose, therefore, that the phosphorylation of PLC-gamma by EGF receptor kinase alters its interaction with putative inhibitory proteins and leads to its activation.

Amino Acid Sequence↗
PubMed1990

Identification of two epidermal growth factor-sensitive tyrosine phosphorylation sites of phospholipase C-gamma in intact HSC-1 cells.

The 145-kDa phospholipase C isozyme, PLC-gamma, is an excellent substrate for the epidermal growth factor (EGF) receptor both in vivo and in vitro. We now demonstrate that EGF treatment of HSC-1 cells, a human squamous cell carcinoma-derived cell line that expresses high levels of the EGF receptor, rapidly induces tyrosine phosphorylation of two-thirds of the total cellular PLC-gamma pool. A two-step immunoaffinity protocol was used for large-scale isolation of phosphorylated PLC-gamma from the cytosol of EGF-treated HSC-1 cells. Phosphorylated PLC-gamma was digested with trypsin, then phosphotyrosine-containing peptides were purified by phosphotyrosine affinity chromatography and reverse-phase high performance liquid chromatography. The two major phosphotyrosine-containing tryptic peptides were sequenced. Comparison of the sequence data with the bovine brain PLC-gamma amino acid sequence indicated that the major, EGF-sensitive tyrosine phosphorylation sites of human PLC-gamma correspond to the bovine brain PLC-gamma tyrosine residues 771 and 1254. The former residue is adjacent to regions of PLC-gamma that contain high homology to the non-catalytic, amino-terminal region of the src tyrosine kinase. The latter residue lies near the carboxyl terminus of the PLC-gamma molecule. The accompanying manuscript (Kim J.W., Sim, S.S., Kim, U-H., Nishibe, S., Wahl, M. I., Carpenter, G., and Rhe, S. G. (1990) J. Biol. Chem. 265, 3940-3943) identifies these same 2 residues plus 2 additional tyrosine phosphorylation sites through large-scale in vitro phosphorylation of purified bovine brain PLC-gamma by the EGF receptor.

Amino Acid Sequence↗
PubMed1990

Selectivity of phospholipase C phosphorylation by the epidermal growth factor receptor, the insulin receptor, and their cytoplasmic domains.

Phosphatidylinositol-specific phospholipase C isozyme gamma (PLC-gamma, Mr 145,000) is an excellent substrate for the epidermal growth factor (EGF) receptor both in vivo and in vitro. PLC-beta-1, another PLC isozyme, is a poor substrate for the EGF receptor. We examined the relative phosphorylation of PLC-gamma and PLC-beta-1 by the 170-kDa native EGF receptor molecule, the 66-kDa cytoplasmic kinase domain of the EGF receptor (Arg647-Ala1186), the alpha 2 beta 2 native insulin receptor, and the 48-kDa cytoplasmic kinase domain of the insulin receptor beta subunit (Gly947-Ser1343). Similar to the intact EGF receptor, the cytoplasmic kinase domain of the EGF receptor preferentially phosphorylated PLC-gamma. High-performance liquid chromatographic comparison of tryptic phosphopeptides from PLC-gamma phosphorylated by both forms of the EGF receptor kinase indicated similar patterns of multiple tyrosine phosphorylations. These results imply that substrate selectivity, at least in terms of PLC isozymes, is independent of the extracellular ligand-binding and membrane anchor domains of the EGF receptor. In comparison, neither the intact insulin receptor nor the beta-chain kinase domain was able to phosphorylate PLC-gamma to a significant extent. Also, insulin failed to stimulate the phosphorylation of PLC-gamma in NIH 3T3/HIR cells, which overexpress the human insulin receptor. Thus PLC-gamma is not a phosphorylation substrate for the insulin receptor in vitro or in the intact cell.

Animals↗
PubMed1990

Phenolic compounds from stem bark of Acanthopanax senticosus and their pharmacological effect in chronic swimming stressed rats.

Ten phenolic compounds, isofraxidin (1), (+)-syringaresinol-di-O-beta-D-glucoside (2), syringin (3), chlorogenic acid (4), isofraxidin-7-O-beta-D-glucoside (5), 2,6-dimethoxy-p-benzoquinone (6), (+)-pinoresinol-O-beta-D-glucoside (7), (7), (+)-syringaresinol-O-beta-D-glucoside (8), (+)-pinoresinol-di-O-beta-D-glucoside (9) and (+)-medioresinol-di-O-beta-D-glucoside (10), were isolated from the stem bark of Acanthopanax senticosus Harms and identified, respectively. The aqueous extract of the stem bark exhibited a prolonging effect on the exercise time to exhaustion in chronic swimming stressed rats. The effect on the exercise time in the chronic swimming stressed rats was respectively tested for compounds 2 and 4, which are major constituents of the stem bark. As a result, it was indicated that compound 2 is the compound responsible for part of the pharmacological effect which the aqueous extract of the stem bark showed.

Animals↗
PubMed1990

Tyrosine phosphorylation and the regulation of cell growth: growth factor-stimulated tyrosine phosphorylation of phospholipase C.

The significance of tyrosine phosphorylation in cell growth and transformation has been addressed. While the details of how tyrosine kinases actually function in mitogenic signal transduction is not fully understood, recent evidence suggests that phosphoinositide metabolism may have a significant role in growth factor signal transduction. Interestingly, one of phosphatidylinositol-specific phospholipase C isozymes is an excellent substrate for growth factor receptor tyrosine kinases. In this review, the current understanding of growth factor-mediated phosphoinositide metabolism and tyrosine phosphorylation of phospholipase C, is discussed.

Animals↗
PubMed1989

Tyrosine phosphorylation of phospholipase C-II in vitro by the epidermal growth factor receptor.

In a number of cell lines, epidermal growth factor (EGF) rapidly stimulates the breakdown of inositol phospholipids. Phosphatidylinositol-specific phospholipase C (PLC), therefore, plays an important role in this biological response to EGF, but the mechanism by which EGF-receptor complexes modulate the activation of PLC is not understood. We have previously suggested that tyrosine phosphorylation of PLC or an unknown PLC-associated protein by the EGF receptor is involved in the activation process (Wahl, M. I., Daniel, T. O., and Carpenter, G. (1988) Science 241, 968-970) and have recently shown by immunoprecipitation that the addition of EGF to 32P-labeled cells increases tyrosine and serine phosphorylation of PLC-II (Wahl, M. I., Nishibe, S., Suh, P.-G., Rhee, S. G., and Carpenter, G. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 1568-1572). In this communication we demonstrate that PLC-II (Mr = 145,000) purified from bovine brain can be phosphorylated in vitro in an EGF-dependent manner by the tyrosine kinase activity of the purified EGF receptor. While PLC-II is an efficient phosphorylation substrate for the purified EGF receptor, PLC-I is a poor substrate and PLC-III is not phosphorylated to any detectable extent. Though all three PLC isozymes possess typical tyrosine phosphorylation sequences, the EGF receptor is surprisingly selective in vitro for the phosphorylation of PLC-II. High performance liquid chromatography comparison of tryptic phosphotyrosyl peptides from PLC-II phosphorylated in vivo and in vitro indicated a similar pattern of multiple tyrosine phosphorylation sites. These findings show that the EGF receptor can directly phosphorylate PLC-II in an efficient and selective manner.

Adenosine Triphosphate↗
PubMed1989

Epidermal growth factor stimulates tyrosine phosphorylation of phospholipase C-II independently of receptor internalization and extracellular calcium.

Epidermal growth factor (EGF) rapidly stimulates the formation of inositol 1,4,5-trisphosphate in a variety of cell types. Previously we have found that in intact cells stimulation of phospholipase C (PLC) activity by EGF is correlated with the retention of increased amounts of PLC activity by a phosphotyrosine immunoaffinity matrix, suggesting that the EGF-receptor tyrosine kinase phosphorylates PLC. We now define parameters of the mechanism by which EGF addition to A-431 cells stimulates phosphotyrosine immunoisolation of PLC activity and demonstrate that EGF addition to A-431 cells increases tyrosine phosphorylation of PLC. EGF rapidly and reversibly stimulated the anti-phosphotyrosine recovery of increased PLC activity when cells were treated with growth factor at 3 degrees C, indicating that receptor internalization is not required and that the phosphorylation event occurs prior to formation of inositol 1,4,5-trisphosphate. Also, the EGF stimulation of anti-phosphotyrosine recovery of PLC activity occurred in the absence of extracellular Ca2+. Stimulation of PLC activity in intact cells by other agonists, such as bradykinin or ATP, did not result in increased anti-phosphotyrosine recovery of PLC activity, suggesting two separate mechanisms exist in A-431 cells for hormone-stimulated formation of inositol phosphates. Finally, using monoclonal antibodies that specifically recognize three distinct PLC isozymes, we show that an approximately 145-kDa PLC isozyme (PLC-II) is present in A-431 cells and that EGF treatment of A-431 cells stimulates phosphorylation of PLC-II on both tyrosine and serine residues.

Adenosine Triphosphate↗
PubMed1989

Platelet-derived growth factor induces rapid and sustained tyrosine phosphorylation of phospholipase C-gamma in quiescent BALB/c 3T3 cells.

Platelet-derived growth factor (PDGF) stimulates the proliferation of quiescent fibroblasts through a series of events initiated by activation of tyrosine kinase activity of the PDGF receptor at the cell surface. Physiologically significant substrates for this or other growth factor receptor or oncogene tyrosine kinases have been difficult to identify. Phospholipase C (PLC), a key enzyme of the phosphoinositide pathway, is believed to be an important site for hormonal regulation of the hydrolysis of phosphatidylinositol 4,5-bisphosphate, which produces the intracellular second-messenger molecules inositol 1,4,5-trisphosphate and 1,2-diacylglycerol. Treatment of BALB/c 3T3 cells with PDGF led to a rapid (within 1 min) and significant (greater than 50-fold) increase in PLC activity, as detected in eluates of proteins from a phosphotyrosine immunoaffinity matrix. This PDGF-stimulated increase in phosphotyrosine-immunopurified PLC activity occurred for up to 12 h after addition of growth factor to quiescent cells. Interestingly, the PDGF stimulation occurred at 3 as well as 37 degrees C and in the absence or presence of extracellular Ca2+. Immunoprecipitation of cellular proteins with monoclonal antibodies specific for three distinct cytosolic PLC isozymes demonstrated the presence of a 145-kilodalton isozyme, PLC-gamma (formerly PLC-II), in BALB/c 3T3 cells. Furthermore, these immunoprecipitation studies showed that PLC-gamma is rapidly phosphorylated on tyrosine residues after PDGF stimulation. The results suggest that mitogenic signaling by PDGF is coincident with tyrosine phosphorylation of PLC-gamma.

Aluminum↗
PubMed1989

Growth factor signaling pathways: phosphoinositide metabolism and phosphorylation of phospholipase C.

Recent demonstrations of growth factor-stimulated increases in cellular phosphoinositide metabolism suggest that regulatory enzymes of this important signaling pathway may be substrates for growth factor receptor tyrosine kinases. Studies employing phosphotyrosine antibodies, specific phospholipase C antibodies, and purified phospholipase C proteins support the conclusion that the 145-kD phospholipase C-gamma 1 isoenzyme is rapidly and selectively phosphorylated by the activated epidermal growth factor and platelet-derived growth factor receptors. The selective interaction of these receptors with phospholipase C-gamma 1 suggests a novel, direct mechanism for agonist stimulation of phosphoinositide metabolism.

Growth Substances↗