[Human cDNA project: functional analysis of novel genes].
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Amino Acid Sequence↗
Biomedical subjects
M Horie
Publications and source records attributed to M Horie.
Does tyrosine kinase modulate delayed-rectifier K channels in guinea pig ventricular cells?
Phosphorylation by tyrosine kinases has been shown to promote cellular growth and hypertrophy and to play a key role in modulating ion channels. We have examined possible effects of genistein, a protein tyrosine kinase (PTK) inhibitor, on cardiac delayed-rectifier K currents (IK). Guinea pig ventricular myocytes were voltage-clamped by conventional whole-cell mode (5.4 mM [K]out/150 mM [K]in; pCa = 8; 36 degrees C). Amplitudes of tail and steady-state (2-s pulse) currents were measured as IK. Micromolar concentrations of genistein (10-100 microM) reversibly inhibited basal, swelling-enhanced (by 70% hypotonic solution), and intrapipette Cyclic adenosine monophosphate (cAMP) (1 mM)-enhanced IK concentration-dependently, while intrapipette cAMP-enhanced IK were also affected by daidzein, an inactive analog of genistein. In contrast, lavendustin A (10 microM) and tyrphostin 51 (100 microM), other types of PTK inhibitors, had no effect on IK. These results suggest that genistein may inhibit IK and that this inhibition is not mediated by an inhibition of tyrosine kinase activity.
Animals↗
Alterations in basal and glucose-stimulated voltage-dependent Ca2+ channel activities in pancreatic beta cells of non-insulin-dependent diabetes mellitus GK rats.
In genetically occurring non-insulin-dependent diabetes mellitus (NIDDM) model rats (GK rats), the activities of L- and T-type Ca2+ channels in pancreatic beta cells are found to be augmented, by measuring the Ba2+ currents via these channels using whole-cell patch-clamp technique, while the patterns of the current-voltage curves are indistinguishable. The hyper-responsiveness of insulin secretion to nonglucose depolarizing stimuli observed in NIDDM beta cells could be the result, therefore, of increased voltage-dependent Ca2+ channel activity. Perforated patch-clamp recordings reveal that the augmentation of L-type Ca2+ channel activity by glucose is markedly less pronounced in GK beta cells than in control beta cells, while glucose-induced augmentation of T-type Ca2+ channel activity is observed neither in the control nor in the GK beta cells. This lack of glucose-induced augmentation of L-type Ca2+ channel activity in GK beta cells might be causatively related to the selective impairment of glucose-induced insulin secretion in NIDDM beta cells, in conjunction with an insufficient plasma membrane depolarization due to impaired closure of the ATP-sensitive K+ channels caused by the disturbed intracellular glucose metabolism in NIDDM beta cells.
Animals↗
Endothelin-1 inhibits L-type Ca currents enhanced by isoproterenol in guinea-pig ventricular myocytes.
To investigate the action of endothelin-1 (ET-1) on L-type Ca currents (ICa,L) in guinea-pig ventricular cells, whole-cell currents were recorded at approximately 36-37 degrees C in enzymatically isolated myocytes. ET-1 (> or =10 nM) suppressed the basal ICa,L to 79+/-8% of control at 20 nM. Bath application of isoproterenol (ISO; 10 nM) enhanced ICa,L to 192+/-28% with about a -10-mV shift of its relationship with membrane potential. ET-1 concentration dependently inhibited this ISO-enhanced ICa,L with a half-maximally inhibitory concentration (IC50) of 168 pM. The inhibitory actions of ET-1 were antagonised by BQ-123 (300 nM), cyclo(D-Asp-L-Pro-D-Val-L-Leu-D-Trp), a specific ETA receptor antagonist. Histamine-enhanced ICa,L was also suppressed by ET-1, but ICa, L potentiated by internal adenosine 3',5'-cyclic monophosphate (cAMP) was unaffected. Preincubation of myocytes with pertussis toxin (PTX, at 5 microgram/ml for >60 min at 36 degrees C) completely occluded the ET-1 action. Thus, stimulation of ETA receptors by subnanomolar ET-1 inhibits ICa,L via PTX-sensitive G-proteins.
Animals↗
Regulation of egr-1 gene expression by retinoic acid in a human growth factor-dependent cell line.
Retinoic acid (RA) has profound suppressive effects on growth and survival of human growth factor-dependent cell line, M07e. Treatment of M07e cells by RA reduced expression of egr-1 gene, while the levels of c-myc gene expression remained similar. Suppression of egr-1 gene expression by RA was dosage-dependent and reached maximum at 4 h after RA addition. The decay of egr-1 mRNA was similar in M07e cells treated with or without RA. The transcriptional activity of the promoter region up to -600 or -480 bp upstream of the egr-1 gene was greatly reduced by RA treatment. These data suggest that biological effects of RA on hematopoietic cells may, in part, be mediated by transcriptional suppression of egr-1 gene through its promoter region within -480 bp.
DNA-Binding Proteins↗
Block of pancreatic ATP-sensitive K+ channels and insulinotrophic action by the antiarrhythmic agent, cibenzoline.
1. We investigated the effect of cibenzoline (a class Ia antiarrhythmic drug) on basal insulin secretory activity of rat pancreatic islets and ATP-sensitive K+ channels (KATP) in single pancreatic beta cells of the same species, using radioimmunoassay and patch clamp techniques. 2. Micromolar cibenzoline had a dose-dependent insulinotrophic action with an EC50 of 94.2 +/- 46.4 microM. The compound inhibited the activity of the KATP channel recorded from a single beta-cell in a concentration-dependent manner. The IC50 was 0.4 microM in the inside-out mode and 5.2 microM in the cell-attached mode, at pH 7.4. 3. In the cell-attached mode, alkalinization of extracellular solution increased the inhibitory action of cibenzoline and the IC50 was reduced from 26.8 microM at pH 6.2 to 0.9 microM at pH 8.4. On the other hand, the action of cibenzoline in the excised inside-out mode was acute in onset with a small IC50, indicating that the drug attains its binding site from the cytoplasmic side of the cell membrane. 4. In the inside-out mode, micromolar ADP reactivated the cibenzoline-blocked KATP channels in a manner similar to that by which ADP restored ATP-dependent block of the channel. 5. The binding of [3H]-glibenclamide to pancreatic islets was inhibited by glibenclamide but not by cibenzoline. In contrast, the [3H]-cibenzoline binding was displaced by unlabelled cibenzoline but not by glibenclamide. It is concluded that cibenzoline blocks pancreatic KATP channels via a binding site distinct from the sulphonylurea receptor.
Animals↗
Hormonal regulation of cardiac cystic fibrosis transmembrane conductance regulator chloride channels.
The chloride conductance that arises from the stimulation of beta-adrenoceptors has been shown to be carried by a cardiac isoform of cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels. This brief review will focus first upon the cellular signal transduction system for the activation of this type of Cl- channels and then its regulation by catecholamines, muscarinic agonists, endothelin-1 and angiotensin-II. Both in physiological and pathological conditions, the complex interaction of these agonists modulates the Cl- conductance, which is potentially arrhythmogenic by shortening the action potential duration and inducing the depolarization.
Action Potentials↗
[Changes in serum lipoprotein (a) levels related to hyperlipidemia during pregnancy--comparing normal pregnancy and toxemia of pregnancy].
In this study, we investigated fluctuations in serum lipoprotein (a) (Lp(a)) levels in normal and toxemic pregnancy. We measured serum total cholesterol (TC), triglyceride (TG), phospholipid (PL), high-density lipoprotein (HDL), apolipoprotein and Lp(a) levels in 33 normal pregnant and 11 toxemic pregnant women at delivery and in 47 normal pregnant women throughout gestation. Lp(a) and apolipoproteins were detected by turbidimetric immunoassay. The levels of serum lipids, HDL and apolipoproteins were all increased in pregnancy. In toxemia of pregnancy, serum TC and PL levels were lower (p < 0.05) and the apolipoprotein C-III level was higher (p < 0.005) than in normal pregnancy. Serum Lp(a) levels increased until the 20th week and reached a value which was 1.5 times higher than at the 10th week. Thereafter Lp(a) levels were constant until the late stage of pregnancy. In contrast, serum TC and TG levels increased steadily throughout gestation. The serum Lp(a) level was 18.1 +/- 27.5mg/dl in normal pregnancy and 17.8 +/- 17.9mg/dl in toxemia of pregnancy. These results revealed changes in serum Lp(a) levels during pregnancy. Further studies will be required to clarify the metabolic control of Lp(a) in pregnancy and the matabolic disorders of lipids and lipoproteins in toxemia of pregnancy.
Adult↗
[Vaughan Williams class IV antiarrhythmic drugs].
Vaughan Williams class IV antiarrhythmic drugs have Ca-channel blocking actions. Since L-type Ca-channels play key roles in regulating pulse conduction in atrioventricular node as well as in pathologically-depolarized myocardium, Ca-channel blockers known to modulate this type of Ca-channel (ICa,L) are used as antiarrhythmic agents. ICa,L channels have relatively high threshold potential (-40 mV) to activate and long-opening properties, and are enhanced by beta-adrenergic stimulation. Among three major ICa,L blockers, dihydropyridines such as nifedipine were found to bind to the channel from extracellular side. In contrast, verapamil and diltiazem interact with the channel from the cytoplasmic side, thereby causing rate-dependent block of ICa,L channels. This sideness of pharmacological action of the Ca-channel blockers determines an important therapeutic modality and their indication for tachyarrhythmias.
Animals↗
Transcriptional induction of pim-1 protein kinase gene expression by interferon gamma and posttranscriptional effects on costimulation with steel factor.
Steel factor (SLF) synergizes with interferon gamma (IFN gamma) to stimulate proliferation of the human factor-dependent cell line MO7e. We examined the effects of IFN gamma and SLF treatment, alone or in combination, on the expression of a 33-kD cytoplasmic protein serine/threonine kinase designated pim-1 whose expression has been closely associated with proliferation induced by related myeloid cytokines. IFN gamma alone, but not SLF, stimulated expression of pim-1 RNA and protein in MO7e cells; compared with IFN gamma alone, costimulation with IFN gamma and SLF resulted in a twofold to threefold increase in pim-1 message and protein expression, correlating with synergistic effects on cell proliferation. Both IFN gamma and IFN gamma/SLF induced pim-1 mRNA in the absence of de novo protein synthesis. Nuclear run-on assays showed that, although IFN gamma alone increased the rate of pim-1 gene transcription, costimulation with IFN gamma and SLF did not further potentiate this effect; however, the stability of pim-1 message was significantly enhanced in the presence of both cytokines. An IFN gamma-responsive element within the 5' flanking region of the pim-1 gene that could confer IFN gamma responsiveness on a heterologous promoter was identified. This sequence, designated PMGAS, formed a specific complex with Stat (signal transducers and activators of transcription) 1 alpha (the p91 subunit of the transcription factor ISGF3 [interferon-stimulated gene factor 3]) in IFN gamma-treated cell extracts, suggesting that the transcriptional effects of IFN gamma on pim-1 expression may be mediated by Stat 1 alpha.
Base Sequence↗
Cloning and functional characterization of a novel ATP-sensitive potassium channel ubiquitously expressed in rat tissues, including pancreatic islets, pituitary, skeletal muscle, and heart.
ATP-sensitive K+ (KATP) channels play a crucial role in coupling metabolic energy to the membrane potential of cells. We have isolated a cDNA encoding a novel member (uKATP-1) of the inward rectifier K+ channel family from a rat pancreatic islet cDNA library. Rat uKATP-1 is a 424-amino acid residue protein (M(r) = 47,960). Electrophysiological studies of uKATP-1 expressed in Xenopus laevis oocytes show that uKATP-1 is a weak rectifier and is blocked with Ba2+ ions. Single-channel patch clamp study of clonal human kidney epithelial cells (HEK293) transfected with uKATP-1 cDNA reveals that uKATP-1 closes in response to 1 mM ATP and has a single channel conductance of 70 +/- 2 picosiemens (n = 6), indicating that uKATP-1 is an ATP-sensitive inward rectifier K+ channel. In addition, uKATP-1 is activated by the KATP channel opener, diazoxide. RNA blot analysis shows that uKATP-1 mRNA is expressed ubiquitously in rat tissues, including pancreatic islets, pituitary, skeletal muscle, and heart, suggesting that uKATP-1 may play a physiological role as a link between the metabolic state and membrane K+ permeability of cells in almost every normal tissue. Since uKATP-1 shares only 43-46% amino acid identity with members of previously reported inward rectifier K+ channel subfamilies, including ROMK1, IRK1, GIRK1, and cKATP-1, uKATP-1 is not an isoform of these subfamilies and, therefore, represents a new subfamily of the inward rectifier K+ channel family having two transmembrane segments.
ATP-Binding Cassette Transporters↗
Alloantigen priming induces a state of unresponsiveness in human umbilical cord blood T cells.
Induction of alloreactivity in human adult and umbilical cord blood T cells was evaluated in mixed leukocyte culture by exposure to an allogeneic lymphoblastoid line that expresses known costimulatory molecules. Initial exposure to alloantigen-presenting cells (allo-APC) induced strong proliferative responses in both adult and cord blood T cells. However, in contrast to adult T cells, cord blood T cells exhibited little proliferation after restimulation with donor APC. Primed cord blood T cells could respond to interleukin 2 (IL-2), but unresponsiveness to alloantigen was not overcome by addition of exogenous IL-2. Unresponsiveness was long-lasting and appeared to be maintained by a combination of induction of anergy and activity of CD8+ suppressor cells. This information may contribute to use of human cord blood as an allogeneic source of transplantable stem cells.
Adult↗
A fast transient outward current in cultured cells from human pulmonary artery smooth muscle.
A voltage-dependent transient outward current (I(to)) was observed in cells cultured from human pulmonary artery smooth muscle when K+, but not Cs+, was the dominant cation in the pipette solution. In 30% of cells investigated using the Cs+ pipette solution, a tetrodotoxin-sensitive inward current (I(in)) dependent on extracellular Na+ was evoked from depolarizations positive to -30 mV.Iin showed voltage-dependent inactivation with a membrane potential at 50% of the evoked current (V50%) of -75.53 +/- 0.81 mV and slope factor potential (Vs) of -10.73 +/- 0.01 mV. In the presence of 1 microM tetrodotoxin, I(to) was rapidly evoked by depolarizations positive to -40 mV and decayed with a single exponential time course (tau = 9.9 +/- 1.1 ms, pulse potential = +50 mV). I(to) also showed voltage-dependent inactivation with a V50% of -70.9 +/- 2.63 mV and Vs of -7.7 +/- 0.03 mV. I(to) was inhibited concentration dependently by the K+ channel blocker, 4-aminopyridine (4-AP), with a concentration of 4-AP at which I(to) was reduced to 50% of control of 36.5 +/- 2.8 microM. These cells possess voltage-dependent currents characteristic of the K(+)-selective fast transient outward and Na(+)-selective inward currents of smooth muscle cells.
4-Aminopyridine↗
Glibenclamide, an ATP-sensitive K+ channel blocker, inhibits cardiac cAMP-activated Cl- conductance.
Stimulation of the beta-adrenoceptor activates a time-independent Cl- conductance that is known to be regulated via phosphorylation by cAMP-dependent protein kinase in guinea pig ventricular myocytes. Since epithelial cystic fibrosis transmembrane conductance regulator Cl- channels are known to be sensitive to an antidiabetic sulfonylurea, glibenclamide, we tested whether the drug modulates cardiac cAMP-activated Cl- conductance. Bath application of isoproterenol (1 mumol/L, n = 11) or forskolin (1 mumol/L, n = 17) or the intracellular application of cAMP (1 mmol/L, n = 9) activated whole-cell Cl- currents recorded from single myocytes at 36 degrees C. External glibenclamide (> or = 10 mumol/L, n = 26) inhibited the Cl- current induced by either of the stimulants in a concentration-dependent manner. The half-maximal inhibition concentration (IC50) of glibenclamide and the Hill coefficient were 24.5 to 37.9 mumol/L and 1.6 to 2.2, respectively. During current-clamp experiments, forskolin was found to shorten the action potential significantly (250 +/- 45 to 201 +/- 52 milliseconds, P < .05) in 7 of 11 cells tested. Glibenclamide antagonized the forskolin-induced shortening (to 243 +/- 54 milliseconds, n = 7, P < .05). Intracellular administration of sodium orthovanadate (0.5 to approximately 1 mmol/L, n = 6) brought about persistent activation of Cl- current after brief bath application of forskolin. This Cl- current was not affected by H-89 (100 mumol/L, n = 3), a specific inhibitor of cAMP-dependent protein kinase, and was suppressed by glibenclamide similarly, with an IC50 of 29.7 mumol/L.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Lungworm, Filaroides osleri, infection in a dog in Japan.
A 7-month-old male Pomeranian had severe dyspnea for 2 weeks. The lateral bronchogram showed a stenosis of the trachea. Inspite of supportive therapy including supplemental oxygen, the dog died 5 days later. Six pedunculated nodules were recognized in the mucosal surface of the trachea at necropsy. The tracheal nodules were histopathologically granuloma characterized by many coiled parasites containing a little collagen fibers, lymphocytes, plasma cells and macrophages. Female parasites had a lot of embryonated eggs in the uterus. Immature worms were observed in the dilated lymph vessels of bronchial and bronchiolar wall in the lungs. The worms were identified as Filaroides osleri based on the parasitological examinations.
Animals↗
The combination of Steel factor and GM-CSF blocks apoptosis induced by retinoic acid and upregulates AP-1 in a human growth factor-dependent cell line.
The effects of hematopoietic growth factors were examined on the cellular action of retinoic acid (RA) using the human factor-dependent cell line, MO7e. Treatment of cells with Steel factor (SLF) plus granulocyte-macrophage colony-stimulating factor (GM-CSF) synergistically stimulated cell proliferation compared to that with each factor alone. This synergism was even greater in the presence of RA than in its absence. Treatment of cells with RA resulted in apoptotic cell death associated with internucleosomal DNA fragmentation in the presence of either SLF or GM-CSF. RA-induced apoptosis and DNA fragmentation were completely blocked by treating cells with SLF plus GM-CSF. Northern analysis showed that the inhibition of RA effects on MO7e cells by SLF plus GM-CSF treatment occurred without modulation of expression of RA receptor-alpha (RAR-alpha) gene. Furthermore, a higher amount of AP-1 complex was detected by electrophoretic mobility shift assays in a nuclear extract prepared from cells treated with SLF plus GM-CSF compared to those treated with each factor alone, while the level of RAR-complex remained similar in cells treated with SLF and/or GM-CSF. These data suggest an interaction in signaling pathways among different types of receptors that might be associated with the AP-1 complex.
Apoptosis↗
[Intracellular perfusion and giant excised-patch method].
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Animals↗
Regional medical information network using optical memory cards and integrated services for digital network.
Since 1986, we have been developing a regional health and welfare system using optical memory cards. We have expanded the system and performed model experiments and evaluations this time. There are approximately 3000 card-holders and 23 card-reader terminals in use. They cover 50 percent of the medical facilities in the city of Isehara. Two medical clinics within neighboring cities have joined our project. Standard Deviation Index (SDI) has been introduced to standardize the numeric results of examinations. The terminals are connected with Integrated Services for Digital Network (ISDN) allowing remote access to the optical memory cards. This enhanced connectivity has allowed greater cooperation in delivering quality medical services.
Aged↗