Mechanisms of cell adhesion and migration]

In order to understand the molecular mechanisms underlying cancer metastasis, it is important to clarify the mechanisms of cell adhesion and cell migration. When epithelial cells start to migrate, cell-cell junctions are first disrupted. During migration, membrane protrusions, such as lamellipodia and filopodia, are observed externally at the cell front, and retraction at the cell rear. In addition, dynamic reorganization of the actin cytoskeleton, such as disassembly and reassembly of stress fibers at cell-cell and cell-matrix junctions and membrane protrusions, is observed internally. Our experiments have demonstrated that the Rho and Rab family small G proteins coordinately regulate cell adhesion and migration of cultured MDCK cells. The Rho family consists of the Rho, Rac, and Cdc 42 subfamilies. The Rho subfamily regulates stress fiber formation, and integrin-based cell matrix adhesion. Furthermore, the Rac and Cdc 42 subfamilies regulate lamellipodia and filopodia formation, respectively, as well as cadherin-based cell-cell adhesion. The detailed modes of action of these small G proteins remain to be clarified; however, it is known that these proteins regulate cell adhesion and migration through reorganization of the actin cytoskeleton. The Rab family has over thirty members. We have found that some Rab family members are involved in HGF- or phorbol ester-induced endocytosis and exocytosis (recycling) of adhesion molecules such as integrin and cadherin. Endocytosis and exocytosis of these adhesion molecules are accompanied by disassembly and reassembly of the actin cytoskeleton, respectively, in a well coordinated manner. Thus, we propose the cooperative roles of the Rho and Rab families in cell adhesion and migration.     

An FH domain-containing Bnr1p is a multifunctional protein interacting with a variety of cytoskeletal proteins in Saccharomyces cerevisiae

Proteins containing formin homology domains, FH1 and FH2, are involved in cytokinesis or establishment of cell polarity in a variety of organisms. Bni1p and Bnr1p are FH proteins and potential targets of the Rho family small GTP-binding proteins in S. cerevisiae. We have shown that Bnr1p is localized at the bud neck to interact with Hof1p, involved in cytokinesis. We report here that the overexpression of BNR1 causes a cytokinesis deficiency which is similar to the phenotypes of the septin mutants, including cdc3, cdc10, cdc11, and cdc12. The region required for the septin mutant phenotypes was mapped to Bnr1p (35-500), which coincided with the region required for the bud-neck localization. To further isolate a gene interacting with BNI1 or BNR1, a multicopy suppressor of the bni1 bnr1 mutant was isolated. This gene encoded Smy1p, a kinesin-related protein. Bnr1p, but not Bni1p, directly interacted with the C-terminal region of Smy1p. The Smy1p-interacting region of Bnr1p was mapped to a region containing the FH2 domain. Bnr1p also directly interacted with Bud6p, a novel actin-binding protein. Bnr1p is thus a multifunctional protein which interacts with the septin system, a microtubule-dependent motor protein, and the actin system, to regulate cytoskeletal functions in S. cerevisiae.     

Involvement of ATP-sensitive K(+) channels in the anti-tussive effect of moguisteine

The effect of glibenclamide, an ATP-sensitive K(+) channel blocker, on the anti-tussive effect of moguisteine and of pinacidil, an ATP-sensitive K(+) channel opener in guinea pigs was studied. Pinacidil (1 and 5 mg/kg, subcutaneous (s.c.)) dose-dependently reduced the number of coughs. The anti-tussive effect of pinacidil was significantly and dose-dependently antagonized by pre-treatment with glibenclamide (3 and 10 mg/kg, i.p.). Moguisteine (1 and 5 mg/kg, s.c.) dose-dependently reduced the number of coughs. The anti-tussive effect of moguisteine was also reduced by pre-treatment with glibenclamide, in a dose-dependent manner. However, pre-treatment with glibenclamide had no effect on the anti-tussive effects of dihydrocodeine and dextromethorphan. Glibenclamide (10 mg/kg, i.p.), by itself, had no significant effect on the number of coughs. These results suggest that pinacidil and moguisteine may exert their anti-tussive effects through the activation of ATP-sensitive K(+) channels. Furthermore, it is possible that ATP-sensitive K(+) channels may be involved in the anti-tussive effect of peripherally acting non-narcotic anti-tussive drugs.     

Tumor cell growth suppression by tannic acid

Tannic acid was cultured together with tumor cells that had originated from human malignant tumors (HCT-15 & AGS). Significant suppression of tumor growth was observed. The 50% suppression was observed at the concentration between 50 micrograms/ml and 12.5 micrograms/ml. When tannic acid was injected into HCT-15 cells by electroporation at 1180 mu p and 200 ohm, the suppression rate was 34.3% at the concentration of 50 micrograms/ml in HBS solution. The suppression rate of cells only in contact with tannic acid solution for one hour under the same conditions as used for electroporation, was 26.1%. Histographic findings suggested that tannic acid almost completely blocked the S phase of the cell cycle.     

Hemolytic pattern of erythrocytes in the newborn measured by the coil planet centrifuge system and its relationship to neonatal jaundice

Dynamic osmotic fragility of erythrocytes in cord blood and its changes during the neonatal period were studied by means of a coil planet centrifuge system. The starting-point for hemolysis in the newborn become similar to that of adult blood after approximately a week, while the shift of the end-point to the adult range required one month or more.The percentage of fragile cord blood cells with a hemolysis starting-point above 110 m osmol and the maximum bilirubin level during neonatal period were examined. A high percentage of fragile cells was associated with high bilirubin levels, and when fragile cells comprised more than 7.0% of the total cord blood erythrocytes, the bilirubin level tended to rise above 15 mg/dl.This study was aided by a grant from the Ministry of Health and Wellfare of Japan for research on handicapped children, 1976     

A new model of allergic rhinitis in rats by topical sensitization and evaluation of H(1)-receptor antagonists

An animal model of chronic allergic rhinitis was developed by repeated local booster sensitization into the nasal cavity in sensitized rats. The severity of allergic rhinitis was assessed by determining the extent of two markers of nasal allergic symptoms (sneezing and nasal rubbing) after antigen challenge. The number of incidents of sneezing and nasal rubbing was markedly increased during intranasal instillation of antigen in sensitized rats. The PCA titers were also markedly elevated by intranasal sensitization. Some histamine H(1)-receptor antagonists such as chlorpheniramine, ketotifen, astemizole and epinastine inhibited the increase in antigen-induced nasal symptoms in a dose-related manner. Nasal rubbing was more potently inhibited by H(1)-receptor antagonists than sneezing.In conclusion, we developed a chronic allergic rhinitis model showing nasal symptoms in rats, and this model may be useful for evaluating the effects of drugs on allergic rhinitis.     

Regional and species differences in glyburide-sensitive K+ channels in airway smooth muscles as estimated from actions of KC 128 and levcromakalim.

1. The purpose of the present experiments was to elucidate the differences in actions of two K+ channel openers, KC 128 and levcromakalim, on the carbachol-induced contraction, membrane potential and 86Rb+ efflux of the dog tracheal and bronchial smooth muscles. Furthermore, we compared the effects of these agents on guinea-pig and human airway smooth muscles. 2. In the dog tracheal and bronchial smooth muscle tissues, levcromakalim induced a concentration-dependent relaxation of the carbachol-induced contraction. The IC50 values were 0.35 microM (pIC50: 6.46 +/- 0.10, n = 9) and 0.55 microM (pIC50: 6.26 +/- 0.07, n = 5), respectively. KC 128 relaxed bronchial smooth muscles precontracted by carbachol with an IC50 value of 0.19 microM (pIC50: 6.73 +/- 0.10, n = 7). However, KC 128 had almost no effect on the contraction evoked by carbachol in the trachea (IC50 > 10 microM). The relaxations induced by levcromakalim and KC 128 were antagonized by glyburide (0.03-1 microM) but not by charybdotoxin (100 nM). 3. Levcromakalim (1 microM) hyperpolarized the membrane of both dog tracheal and bronchial smooth muscle cells, whereas KC 128 (1 microM) hyperpolarized the membrane of bronchial but not of tracheal smooth muscle cells. 4. Levcromakalim (10 microM) increased 86Rb+ efflux rate from both tracheal and bronchial smooth muscle tissues but KC 128 (10 microM) increased 86Rb+ efflux rate only from bronchial and not tracheal smooth muscle tissues. Glyburide (1 microM) prevented the hyperpolarization and the 86Rb+ efflux induced by these agents at the same concentration as observed for mechanical responses.(ABSTRACT TRUNCATED AT 250 WORDS)