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M Kasuga

Publications and source records attributed to M Kasuga.

At least 307 records · Page 17Linked to original sources
PubMed1989

Tyrosine phosphorylation of pp185 by insulin receptor kinase in a cell-free system.

Insulin treatment of rat H-35 hepatoma cells causes rapid tyrosine phosphorylation of a high molecular weight protein termed pp185 besides autophosphorylation of the beta-subunit of the insulin receptor (IR) in an intact cell system. To elucidate the molecular basis for tyrosine phosphorylation of pp185, cell-free phosphorylation of pp185 was performed using phosphotyrosine-containing proteins (PYPs) purified from detergent-solubilized cell lysates by immunoprecipitation with anti-phosphotyrosine antibody. After insulin treatment of cells, marked increases of tyrosine phosphorylation of pp185 and IR were observed compared to noninsulin-treated cells. Site-specific antibodies that specifically inactivate IR kinase inhibited tyrosine phosphorylation of pp185 as well as the beta-subunit of IR. PYPs purified from detergent-free cell extracts contained pp185 but little IR; tyrosine phosphorylation of pp185 did not occur. Addition of IR kinase purified from human placenta to these PYPs restored insulin-dependent tyrosine phosphorylation of pp185. These results suggest that tyrosine phosphorylation of pp185 is catalyzed directly by IR kinase in this cell-free system.

Animals↗
PubMed1989

Rabbit brain glucose transporter responds to insulin when expressed in insulin-sensitive Chinese hamster ovary cells.

Transfection of Chinese hamster ovary cells with the expression vector containing rabbit brain HepG2-type glucose transporter cDNA resulted in a dramatic over-expression (approximately 10-fold) of glucose transporter as assessed by either immunoblotting with antipeptide antibody against rabbit brain glucose transporter or photoaffinity labeling with [3H]cytochalasin B. 2-Deoxyglucose uptake was also increased 4-fold in the transfected cells, while no increase in transport activity or transporter amount was observed in cells that were transfected with the expression vector alone without glucose transporter cDNA. Significantly, insulin (10(-7) M) increased 2-deoxyglucose uptake in both control and transfected cells, but the increased amount of the transported 2-deoxyglucose by insulin in the transfected cells was 4.2-fold greater than that in control cells, indicating that the expressed rabbit brain HepG2-type glucose transporter responded to insulin. In addition, we have recently demonstrated that the HepG2-type glucose transporter exists in rat adipocytes and responds to insulin in a fashion similar to a majority of other types of glucose transporters (Oka, Y., Asano, T., Shibasaki, Y., Kasuga, M., Kanazawa, Y., and Takaku, F. (1988) J. Biol. Chem. 263, 13432-13439). In contrast, insulin did not stimulate glucose transport activity in HepG2 cells or IM-9 lymphocytes that have a significant amount of the HepG2-type glucose transporter. Thus, the results in this study further support the notion that insulin regulation of glucose transport activity depends on a tissue-specific signaling mechanism.

Affinity Labels↗
PubMed1989

Heterogeneity in the breakpoints of chromosome 19 among acute leukemic patients with the t(11;19)(q23;p13) translocation.

Gene probes for insulin receptor (INSR) and c-ets-1 were hybridized to metaphase cells from three leukemic patients with the t(11;19)(q23;p13) translocation. Patients 1 and 2 were diagnosed as acute lymphocytic leukemia (ALL) (L2), and patient 3, as acute myelogenous leukemia (AML) (M4). The c-ets-1 gene was demonstrated to have translocated from chromosome 11 to the short arm of the rearranged chromosome 19 (19p+) in all three patients. On the other hand, the INSR gene translocated from chromosome 19 to the rearranged chromosome 11 (11q-) in the AML case, but remained on the rearranged chromosome 19 in the two ALL cases. Thus, the breakpoints of chromosome 19 are different among the patients studied, proximal to the INSR gene locus in the AML case and distal in the two ALL cases. Consequently, the c-ets-1 gene and the INSR gene remain separated in the AML case, whereas they become close to each other in the two ALL cases. Rearrangement of these two genes was studied in the two ALL patients, with no positive data being obtained. The results suggest that there may be heterogeneity in the breakpoints of chromosome 19 among the t(11;19)-associated acute leukemias.

Chromosomes, Human, Pair 11↗
PubMed1989

Autoantibodies to the insulin receptor (B-10) can stimulate tyrosine phosphorylation of the beta-subunit of the insulin receptor and a 185,000 molecular weight protein in rat hepatoma cells.

The immunoglobulin G (IgG) fraction obtained from the serum of a patient (B-10) with type B insulin resistance and acanthosis nigricans stimulated both glucose oxidation in rat adipocytes and autophosphorylation of tyrosine residues in the beta-subunit of insulin receptors in H-35 hepatoma cells. Partially purified insulin receptor from H-35 cells, when incubated with B-10 IgG, had increased tyrosine kinase activity for a synthetic peptide sequentially similar to the site of tyrosine phosphorylation in pp60v-arc (the gene product responsible for cellular transformation by the Rous sarcoma virus). In H-35 cells, both B-10 IgG and insulin stimulated tyrosine phosphorylation in an endogenous 185,000 mol wt protein. This phosphoprotein may be similar to the cellular substrate for insulin in hepatoma and other cultured cell lines demonstrated by others. These results suggest that antiinsulin receptor antibodies (B-10) may initiate their insulin-like effects via tyrosine phosphorylation of the insulin receptor, activation of its tyrosine kinase activity, and phosphorylation of a cellular protein substrate of 185,000 mol wt.

Adipose Tissue↗
PubMed1988

Insulin-induced tyrosine-phosphorylation in intact rat adipocytes.

Insulin-induced tyrosine-phosphorylation in intact isolated rat adipocytes was studied using immunoblotting method with antiphosphotyrosine antibodies. Insulin-stimulated adipocytes were solubilized with Triton X-100. The lysate was incubated with wheat germ agglutinin, then with hydroxylapatite. Insulin stimulated tyrosine-phosphorylation of a 95 KDa protein which adsorbs to wheat germ agglutinin and appears to be the beta-subunit of the insulin receptor. Among the proteins adsorbed to hydroxylapatite, tyrosine-phosphorylation of 170 KDa and 60 KDa proteins was stimulated. 170 KDa was also stimulated by polyclonal anti-insulin receptor antibodies B-10 Ig G, IGF-I and H2O2. The detection of these proteins in rat adipocytes may lead to the elucidation of a common signal transduction pathway in insulin-responsive cells.

Adipose Tissue↗
PubMed1988

Studies with antipeptide antibody suggest the presence of at least two types of glucose transporter in rat brain and adipocyte.

Three antipeptide antibodies were prepared by immunizing rabbits with synthesized short peptides corresponding to residues 215-226, 466-479, and 478-492 predicted from the cDNA of both the human hepatoma HepG2 and rat brain glucose transporters. All three antibodies were found to precipitate quantitatively the [3H]cytochalasin B photoaffinity-labeled human erythrocyte glucose transporter. Each antibody also recognized the rat brain protein of Mr 45,000 on immunoblots, and a similar molecular weight protein was labeled with [3H]cytochalasin B in a D-glucose-inhibitable manner, suggesting that this protein is glucose transporter. However, only up to 30% of the labeled rat brain glucose transporters were precipitated, even by repeated rounds of immunoprecipitation. In addition, these antibodies were observed to be unable to immunoprecipitate significantly the [3H]cytochalasin B-labeled rat adipocyte glucose transporter. Further, one-dimensional peptide maps of [3H]cytochalasin B-labeled human erythrocyte and adipocyte glucose transporters generated distinct tryptic fragments. Although Mr 45,000 protein in rat adipocyte low density microsomes was detected on immunoblots and its amount was decreased in insulin-treated cells, the rat adipocyte low density microsomes were much less reactive on immunoblots than the rat brain membranes in spite of the fact that the rat adipocyte low density microsomes contained more [3H]cytochalasin B-labeled glucose transporters. In addition, the ratio of cytochalasin B-labeled glucose transporter per unit HepG2-type glucose transporter mRNA was more than 10-fold higher in rat adipocyte than in rat brain. These results indicate that virtually all the human erythrocyte glucose transporters are of the HepG2 type, whereas this type of glucose transporter constitutes only approximately 30 and 3% of all the glucose transporters present in rat brain and rat adipocyte, respectively; and the rest, of similar molecular weight, is expressed by a different gene.

Adipose Tissue↗
PubMed1988

Cloning of a rabbit brain glucose transporter cDNA and alteration of glucose transporter mRNA during tissue development.

A full-length cDNA clone that codes for glucose transporter protein was isolated from a rabbit brain cDNA library by using synthetic oligonucleotide probe derived from the sequence of human glucose transporter cDNA. The coding region shared 93.2% nucleotide and 97.0% amino-acid similarities with those of human glucose transporter and 89.4% nucleotide and 97.4% amino-acid similarities with those of rat transporter. Northern blot analysis revealed that glucose transporter mRNA is most abundant in the placenta and that it is also abundant in the brain. The fat tissue, heart, liver, and skeletal muscle of adult rats contained a very small amount of mRNA, while heart, liver, skeletal muscle and kidney of fetal rats contained a very high amount of glucose transporter mRNA. These results suggest that this type of glucose transporter might be closely related with cell proliferation and tissue development.

Aging↗
PubMed1988

Requirement for receptor-intrinsic tyrosine kinase activities during ligand-induced membrane ruffling of KB cells. Essential sites of src-related growth factor receptor kinases.

We have prepared site-specific antibodies toward human insulin, insulin-like growth factor-I, and epidermal growth factor receptors with chemically synthesized peptides derived from the cDNA-predicted amino acid sequences of these receptors. Two classes of antibodies were produced toward each receptor: one toward the carboxyl termini and the other against the kinase domains containing sequences homologous to the tyrosyl phosphorylation site of the product of src gene (pp60v-src). Both classes of antibodies specifically immunoprecipitated the appropriate 125I-ligand-receptor complexes and [35S]methionine-labeled receptors with almost equal potencies. Antibodies toward the kinase domains inhibited both autophosphorylation and tyrosine kinase activity of the corresponding receptors in a cell-free system, whereas antibodies toward the carboxyl termini did not. Microinjection of the kinase-inhibitory antibodies into the cytoplasm of human epidermoid carcinoma KB cells blocked the ability of the corresponding ligand to induce membrane ruffling. In contrast, these inhibitory antibodies did not block the ability of noncorresponding ligands to induce the same response. Furthermore, control immunoglobulin and antibodies toward the carboxyl termini did not block this biological response. These results support a role for the tyrosine-specific protein kinase activities of these growth factor receptors in mediating their biological effects and suggest that the regions homologous to the tyrosyl phosphorylation site of pp60v-src are important for these kinase activities both in cell-free and intact cell systems.

Amino Acid Sequence↗
PubMed1988

Long-term comparison of oral hypoglycemic agents in diabetic retinopathy. Gliclazide vs. other sulfonylureas.

Gliclazide has been reported to possess the properties of preventing the progression of diabetic retinopathy and of controlling blood glucose levels. This report describes a long-term comparative clinical trial of this agent to assess its efficacy against diabetic retinopathy. One hundred and fifty-nine NIDDM patients with no retinopathy or with simple retinopathy entered this trial. One hundred and nineteen patients receiving other sulfonylurea agents were randomly allocated to two groups (G: gliclazide, SU: other sulfonylureas). Forty patients continued to be treated with diet alone (D group). Finally a total of 60 patients, that is, 21 patients in the G group, 19 patients in the SU group, and 20 patients in the D group, were followed with funduscopic examinations for more than 4 years. The results are summarized as follows. (1) Distribution of background factors between the two drug therapy groups was balanced, but in the D group more male patients and relatively milder cases were involved than in the drug therapy groups. (2) Fasting blood glucose control in the three groups was not significantly different. (3) Funduscopic deterioration was observed less frequently, though not significantly, in the G group than in the other groups. (4) Progression to preproliferative retinopathy was significantly less frequent in the G group than in the SU group. Thus, gliclazide seems to have additional properties compared with other sulfonylurea drugs in preventing deterioration of diabetic retinopathy, and particularly in preventing progression to proliferative retinopathy.

Diabetes Mellitus, Type 2↗
PubMed1988

Induction of the receptor for erythropoietin in murine erythroleukemia cells after dimethyl sulfoxide treatment.

Biologically active 125I-labeled human recombinant erythropoietin (EPO) was used to demonstrate specific receptors for this erythroid-specific hemopoietic growth factor on the cell surface of murine erythroleukemia cell clone B8. The binding of radioiodinated EPO to these cells was time and temperature dependent, specific, saturable, and reversible. During erythroid differentiation by dimethyl sulfoxide, B8 cells displayed a rapid and marked increase in the amount of specific 125I-EPO binding before the appearance of hemoglobin-containing cells. Scatchard analysis of the saturation binding data revealed that B8 cells had a single class and low number (350 to 650) of EPO receptors per cell with an apparent Kd of 1.2 to 1.4 nM. In addition, the number of EPO receptors on B8 cells was increased twice by induction with DMSO for 1 day, but the binding affinity of EPO toward its receptors did not change significantly. Affinity cross-linking experiments with disuccinimidyl suberate demonstrated two radiolabeled components with apparent molecular weights of 145,000 and 130,000 under both reducing and nonreducing conditions. Labeling of the two components was inhibited by incubation of cells with unlabeled EPO. These results suggest that some murine erythroleukemia cells potentially express EPO receptors as a differentiation marker of erythroid lineage, which contain two polypeptides with molecular weights of 109,000 and 94,000.

Affinity Labels↗
PubMed1988

Multiple endocrine neoplasia type I with Cushing's disease, primary hyperparathyroidism, and insulin-glucagonoma.

A case of multiple endocrine neoplasia type I (MEN I) consisting of Cushing's disease, primary hyperparathyroidism, and insulin-glucagonoma is described. This condition was treated successfully by transsphenoidal pituitary adenomectomy, subtotal parathyroidectomy, and enucleation of pancreatic tumors. Histologic features showed a basophilic adenoma in the pituitary, chief cell hyperplasia in the parathyroid, and islet cell adenomas in the pancreas. The rarity of multiple endocrine hyperfunctioning states and the pathophysiology created by the combination of these three diseases in this patient are of interest.

Adenoma, Islet Cell↗
PubMed1988

Hydrogen peroxide stimulates tyrosine phosphorylation of the insulin receptor and its tyrosine kinase activity in intact cells.

H-35 rat hepatoma cells were labelled with [32P]orthophosphate and their insulin receptors isolated on wheat germ agglutinin (WGA)-agarose and anti-(insulin receptor) serum. The incubation of these cells with 10 mM-H2O2 for 10 min increased the phosphorylation of both the serine and tyrosine residues of the beta subunit of the insulin receptor. Next, insulin receptors were purified on WGA-agarose from control and H2O2-treated H-35 cells and the purified fractions incubated with [gamma-32P]ATP and Mn2+. Phosphorylation of the beta subunit of insulin receptors obtained from H2O2-treated cells was 150% of that of control cells. The kinase activity of the WGA-purified receptor preparation obtained from H2O2-treated cells, as measured by phosphorylation of src-related synthetic peptide, was increased about 4-fold over control cells. These data suggest that in intact cell systems, H2O2 may increase the insulin receptor kinase activity by inducing phosphorylation of the beta subunit of insulin receptor.

Amino Acids↗
PubMed1988

Glucocorticoids increase insulin binding and the amount of insulin-receptor mRNA in human cultured lymphocytes.

The effect of steroid hormones on insulin binding and the amount of insulin-receptor mRNA was examined in IM-9 lymphocytes. Cortisol and cortexolone, but not oestrogen, increased both the binding of insulin and the amount of insulin-receptor mRNA in a time- and dose-dependent manner. Cortisol was most potent, and induced a 2-fold increase in insulin binding and a 4-fold increase in mRNA. The elevation in binding was due to an increased number of insulin receptors at the cell surface. The increase in mRNA involved all four of the insulin-receptor mRNAs and could not be inhibited by cycloheximide. The cortisol-induced increase in mRNA was associated with a 3-4-fold increase in the synthesis of pro-receptor. The relative potency of the three steroids indicated that these effects were mediated by an interaction with the glucocorticoid receptor. The results of this study suggest that cortisol can increase the number of insulin receptors at the cell surface by increasing the amounts of insulin-receptor mRNA and the synthesis de novo of insulin receptors.

17-Hydroxycorticosteroids↗
PubMed1988

Alteration in growth, cell morphology, and cytoskeletal structures of KB cells induced by epidermal growth factor and transforming growth factor-beta.

Long-term biological effects of epidermal growth factor (EGF), insulin, insulin-like growth factor-I (IGF-I), and transforming growth factor-beta (TGF-beta) were examined with human epidermoid carcinoma KB cells. EGF inhibited the growth of KB cells in both serum-containing and serum-free synthetic media by reducing the growth rate and by lowering the saturation density. The cells cultured with EGF showed relatively high motility and grew dispersely as single cells, whereas the cells cultured in the absence of EGF grew in clusters. Although TGF-beta itself did not inhibit the growth of KB cells, it augmented the growth inhibition by EGF. TGF-beta also affected the cell morphology. In the presence of TGF-beta, the cells became flattened and actin stress fibers were well developed compared to those cultured in its absence. The effects of EGF on growth, cell motility, and cell morphology were reversible. Tyrosine phosphorylation of EGF receptors was continuously observed for at least 50 h in the presence of EGF. TGF-beta did not increase the phosphorylation induced by EGF. These results suggested that signals continuously transmitted through EGF receptors caused the changes in cell growth and morphology and that TGF-beta did not act on the cells by modulating binding of EGF to its receptors or activation of the receptor kinase. In contrast to EGF and TGF-beta, neither insulin nor IGF-I affected cell morphology or growth, although KB cells express their receptors and the receptor kinases were also continuously activated during exposure of the cells to insulin or IGF-I.

Actin Cytoskeleton↗
PubMed1988

Rapid stimulation of fluid-phase endocytosis and exocytosis by insulin, insulin-like growth factor-I, and epidermal growth factor in KB cells.

Effects of growth factors on fluid-phase endocytosis and exocytosis in human epidermoid carcinoma KB cells were examined by measuring horseradish peroxidase (HRP) as a marker. Insulin, insulin-like growth factor-I (IGF-I), and epidermal growth factor (EGF) promoted HRP accumulation. They also stimulated the efflux of the preloaded HRP from the cells. From these results it follows that these growth factors stimulate the influx as well as the efflux of HRP, because the accumulation rate is the sum of the influx rate and the efflux rate. The stimulation of both HRP accumulation and HRP efflux was rapidly induced within 2-4 min of the addition of growth factors and persisted for at least 60 min. The concentrations eliciting half-maximal stimulatory effects of insulin, IGF-I, and EGF were about 5 X 10(-7), 1 X 10(-9), and 5 X 10(-10) M, respectively. aIR-3 (anti-type I IGF receptor antibody) completely blocked the stimulation of HRP accumulation by IGF-I but very slightly inhibited the stimulation by insulin. The 528 IgG (anti-EGF receptor antibody) inhibited the stimulation of HRP accumulation by EGF. These results indicated that each of these growth factors stimulates the HRP accumulation mediated by the corresponding (homologous) growth factor receptors. The rapid stimulation of fluid-phase influx and efflux may constitute one of the common early cellular responses to growth factors.

Antibodies↗
PubMed1988

Stimulation of the phosphorylation of cytoskeletal 350-kDa and 300-kDa proteins by insulin-like growth factor-I, platelet-derived growth factor and phorbol ester in rat 3Y1 cells.

Insulin-like growth factor-I (IGF-I) stimulated the phosphorylation of cytoskeletal 350-kDa and 300-kDa proteins which were immunoprecipitated with antibodies against brain high molecular weight microtubule-associated proteins in quiescent rat 3Y1 cells. The data on the effective concentrations of IGF-I and 125I-labeled IGF-I binding indicated that type I IGF receptors mediate this IGF-I effect. Platelet-derived growth factor (PDGF) as well as phorbol ester (TPA) also stimulated the phosphorylation of these proteins. These proteins, whether immunoprecipitated from cells stimulated by insulin, IGF-I, TPA, PDGF, or epidermal growth factor, produced very similar phosphopeptide mapping patterns irrespective of the stimulant. The results suggest the possibility that these growth factors and phorbol esters may activate a common protein kinase which is responsible for the phosphorylation of the 350-kDa and 300-kDa proteins in cells.

Animals↗