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M Hashii

Publications and source records attributed to M Hashii.

At least 19 recordsLinked to original sources
PubMed2001

Cyclic ADP-ribose as a potential second messenger for neuronal Ca2+ signaling.

Cyclic ADP-ribose (cADPR), a known endogenous modulator of ryanodine receptor Ca2+ releasing channels, is found in the nervous system. Injection of cADPR into neuronal cells primarily induces a transient elevation of intracellular Ca2+ concentration ([Ca2+]i), and/or secondarily potentiates [Ca2+]i increases that are the result of depolarization-induced Ca2+ influx. Acetylcholine release from cholinergic neurons is facilitated by cADPR. cADPR modifies K+ currents or elicits Ca2+-dependent inward currents. cADPR is synthesized by both membrane-bound and cytosolic forms of ADP-ribosyl cyclase in neuronal cells. cADPR hydrolase activity is weak in the membrane fraction, but high in the cytoplasm. Cytosolic ADP-ribosyl cyclase activity is upregulated by nitric oxide/cyclic GMP-dependent phosphorylation. Stimulation of muscarinic and beta-adrenergic receptors activates membrane-bound ADP-ribosyl cyclase via G proteins within membranes of neuronal tumor cells and cortical astrocytes. These findings strongly suggest that cADPR is a second messenger in Ca2+ signaling in the nervous system, although many intriguing issues remain to be addressed before this identity is confirmed.

ADP-ribosyl Cyclase↗
PubMed2001

Signal transduction from bradykinin, angiotensin, adrenergic and muscarinic receptors to effector enzymes, including ADP-ribosyl cyclase.

Muscarinic acetylcholine receptors in NG108-15 neuroblastoma x glioma cells, and beta-adrenergic or angiotensin II receptors in cortical astrocytes and/or ventricular myocytes, utilize the direct signaling pathway to ADP-ribosyl cyclase within cell membranes to produce cyclic ADP-ribose (cADPR) from beta-NAD+. This signal cascade is analogous to the previously established transduction pathways from bradykinin receptors to phospholipase Cbeta and beta-adrenoceptors to adenylyl cyclase via G proteins. Upon receptor stimulation, the newly-formed cADPR may coordinately function to upregulate the release of Ca2+ from the type II ryanodine receptors as well as to facilitate Ca2+ influx through voltage-dependent Ca2+ channels. cADPR interacts with FK506, an immunosuppressant, at FKBP12.6, FK506-binding-protein, and calcineurin, or ryanodine receptors. cADPR also functions through activating calcineurin released from A-kinase anchoring protein (AKAP79). Thus, some G(q/11)-coupled receptors can control cADPR-dependent modulation in Ca2+ signaling.

ADP-ribosyl Cyclase↗
PubMed2000

Angiotensin II stimulates cyclic ADP-ribose formation in neonatal rat cardiac myocytes.

To examine the role of cyclic ADP-ribose (cADP-ribose) as a second messenger downstream of angiotensin II (Ang II) receptor activation in the heart, ADP-ribosyl cyclase activity was measured in a crude membrane fraction of ventricular myocytes. Ang II at 10-100 nM increased ADP-ribosyl cyclase activity by 40-90% in the ventricular muscle of neonatal (2-4-day-old) rats, but not in fetal or adult hearts. This increase was inhibited by the Ang II antipeptide. Stimulation of ADP-ribosyl cyclase was reproduced by GTP and guanosine 5'-[gamma-thio]triphosphate, and prevented by guanosine 5'-[beta-thio]diphosphate. Prior treatment of the rats with cholera toxin A and B subunits also blocked the Ang II-induced activation. The density of Ang II receptors detected as [(3)H]Ang II binding was higher in neonatal than adult rats. These results demonstrate the existence of a signalling pathway from Ang II receptors to membrane-bound ADP-ribosyl cyclase in the ventricular muscle cell and suggest that the Ang II-induced increase in cADP-ribose synthesis is involved in the regulation of cardiac function and development.

Adenosine Diphosphate Ribose↗
PubMed2000

cADP-ribose potentiates cytosolic Ca2+ elevation and Ca2+ entry via L-type voltage-activated Ca2+ channels in NG108-15 neuronal cells.

The effects of cADP-ribose (cADPR), a metabolite of beta-NAD(+), on the elevation of cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) and Ca(2+) influx through voltage-activated Ca(2+) channels (VACCs) were studied in NG108-15 neuroblastomaxglioma hybrid cells. NG108-15 cells were pre-loaded with fura-2 and whole-cell patch-clamped. Application of cADPR through patch pipettes did not by itself trigger any [Ca(2+)](i) rise at the resting membrane potential. A rise in [Ca(2+)](i) was evoked upon sustained membrane depolarization, and was significantly larger in cADPR-infused cells than in non-infused cells. This potentiation in the [Ca(2+)](i) elevation was reproduced by infusion of beta-NAD(+), and was blocked by 8-bromo-cADPR and antagonized by external application of ryanodine or by pretreatment of cells with FK506. Nicotinamide inhibited beta-NAD(+)-induced, but not cADPR-elicited, potentiation. [Ca(2+)](i) increases or Ca(2+) influx, measured by Mn(2+) quenching, elicited by the same protocol of depolarization was blocked completely by nifedipine but not by omega-conotoxin. Ca(2+) influx in cADPR- or beta-NAD(+)-infused cells was steeper and greater than that in control cells, and was inhibited partly by ryanodine. In contrast, ryanodine accelerated Ca(2+) influx in non-infused cells. These results show that cADPR amplifies both depolarization-induced [Ca(2+)](i) increase and Ca(2+) influx through L-type VACCs. These results suggest that cADPR functions on ryanodine receptors as a direct agonist and also interacts with L-type VACCs as an indirect agonist, i.e. via a retrograde signal.

Adenosine Diphosphate Ribose↗
PubMed1999

Potential mechanism for bradykinin-activated and inositol tetrakisphosphate-dependent Ca2+ influx by Ras and GAP1 in fibroblast cells.

Here we propose a molecular model for bradykinin receptor-operated and second messenger (inositol-1,3,4,5-tetrakisphosphate)-evoked Ca2+ influx and its potentiation by oncogenic Ras, which is not store-depletion-induced, so-called capacitative, Ca2+ influx. The principal idea for this hypothesis stems from observation that two bradykinin B2 receptor-activated signal pathways, protein tyrosine phosphorylation and formation of inositol tetrakisphosphate, merge during the Ca2+ influx process and that GTPase activating-protein 1 (GAP 1) is inositol tetrakisphosphate binding protein.

3T3 Cells↗
PubMed1998

Differential interactions of the C terminus and the cytoplasmic I-II loop of neuronal Ca2+ channels with G-protein alpha and beta gamma subunits. II. Evidence for direct binding.

The present study was designed to obtain evidence for direct interactions of G-protein alpha (Galpha) and beta gamma subunits (Gbeta gamma) with N- (alpha1B) and P/Q-type (alpha1A) Ca2+ channels, using synthetic peptides and fusion proteins derived from loop 1 (cytoplasmic loop between repeat I and II) and the C terminus of these channels. For N-type, prepulse facilitation as mediated by Gbeta gamma was impaired when a synthetic loop 1 peptide was applied intracellularly. Receptor agonist-induced inhibition of N-type as mediated by Galpha was also impaired by the loop 1 peptide but only when applied in combination with a C-terminal peptide. For P/Q-type channels, by contrast, the Galpha-mediated inhibition was diminished by application of a C-terminal peptide alone. Moreover, in vitro binding analysis for N- and P/Q-type channels revealed direct interaction of Galpha with C-terminal fusion proteins as well as direct interaction of Gbeta gamma with loop 1 fusion proteins. These findings define loop 1 of N- and P/Q-type Ca2+ channels as an interaction site for Gbeta gamma and the C termini for Galpha.

Amino Acid Sequence↗
PubMed1997

Muscarinic receptor-mediated dual regulation of ADP-ribosyl cyclase in NG108-15 neuronal cell membranes.

Cyclic ADP-ribose (cADP-ribose) is an endogenous modulator of ryanodine-sensitive Ca2+ release channels. An unsolved question is whether or not cADP-ribose mediates intracellular signals from hormone or neurotransmitter receptors. The first step in this study was to develop a TLC method to measure ADP-ribosyl cyclase, by which conversion of [3H]NAD+ to [3H]cADP-ribose was confirmed in COS-7 cells overexpressing human CD38. A membrane fraction of NG108-15 neuroblastoma x glioma hybrid cells possessed ADP-ribosyl cyclase activity measured by TLC. Carbamylcholine increased this activity by 2.6-fold in NG108-15 cells overexpressing m1 or m3 muscarinic acetylcholine receptors (mAChRs), but inhibited it by 30-52% in cells expressing m2 and/or m4 mAChRs. Both of these effects were mimicked by GTP. Pretreatment of cells with cholera toxin blocked the activation, whereas pertussis toxin blocked the inhibition. Application of carbamylcholine caused significant decreases in NAD+ concentrations in untreated m1-transformed NG108-15 cells, but an increase in cholera toxin-treated cells. These results suggest that mAChRs couple to ADP-ribosyl cyclase within cell membranes via trimeric G proteins and can thereby control cellular function by regulating cADP-ribose formation.

ADP-ribosyl Cyclase↗
PubMed1997

Sulfhydryl modification inhibits K+ (M) current with kinetics close to acetylcholine in rodent NG108-15 cells.

The effects of sulfhydryl reagents on M-type voltage-dependent potassium currents (IK(M)) were examined in NG108-15 cells transformed to express ml muscarinic acetylcholine receptors (mAChRs), a NGPM1-27 clone. Focal application of glutathione at millimolar concentrations dissolved in acidic solutions caused a transient inward current in NGPM1-27 cells at holding potentials of -30mV, associated with an inhibition of IK(M). The glutathione-induced response was mimicked by cysteine. These effects were also reproduced by superfusion with micromolar concentrations of HgCl2, AgNO3, N-methylmaleimide and p-chloromercuribenzoic acid (pCMB), agents which target protein thiols. Glutathione, HgCl2, AgNO3 and pCMB inhibited the peak conductance of IK(M) without shifting the half activating voltage (V1/2), which was comparable to the acetylcholine (ACh)-induced response. The voltage dependence of time constants for IK(M) deactivation in sulfhydryl reagent-, ACh- and non-treated cells resembled, but differed from that in Ba(2+)-treated cells. These results reveal that there is an accessible cysteine moiety, but not a disulfide bond, either on the M channel protein itself or on a protein directly involved in agonist-M channel coupling.

Acetylcholine↗
PubMed1997

[Measurement of receptor-operated Ca2+ influx by microspectrofluometry combined with the whole-cell patch clamp technique].

Signal transduction from mouse bradykinin B2-receptors to Ca2+ influx was studied in single control or v-Ki-ras-transformed NIH/3T3 (DT) fibroblasts. Microspectrofluometry (fura-2) was combined with the whole-cell patch-clamp technique to study bradykinin-activated Ca2+ influx. Cytosolic Ca2+ oscillations observed at holding potentials of -20 to -80 mV were terminated by holding at -10 mV or more depolarized potentials. Bradykinin significantly enhanced the hyperpolarization-induced increases in the intracellular free Ca2+ concentration upon membrane hyperpolarization only in DT cells but not in control cells. Internal application of 10 microM inositol 1,3,4,5-tetrakisphosphate (InsP4) mimicked membrane potential-dependent Ca2+ entry. Activation of B2-receptors resulted in a decrease of cellular fluorescence at the excitation wavelength of 340 or 360 nm after MnCl2 application in DT cells. This Mn2+ entry through the Ca2+ influx pathway increased with membrane hyperpolarization below -20 mV. The results suggest that bradykinin-induced cytosolic Ca2+ oscillations in ras-transformed NIH/3T3 cells are maintained by bradykinin-activated continuous Ca2+ influx, which may use Ins(1,3,4,5)P4 as an intracellular messenger.

Animals↗
PubMed1996

Bradykinin B2 receptor-induced and inositol tetrakisphosphate-evoked Ca2+ entry is sensitive to a protein tyrosine phosphorylation inhibitor in ras-transformed NIH/3T3 fibroblasts.

Signal transduction from mouse bradykinin B2 receptors to calcium influx was studied in ras-transformed NIH/3T3 (DT) fibroblasts. DT cells were preloaded with fura-2 and whole-cell voltage-clamped. Activation of B2 receptors resulted in a decrease of cellular fluorescence at the excitation wavelength of 340, or 360 nm after MnCl2 application, in both the presence and absence of external Ca2+ in DT cells, at a holding potential of -40 mV. This Mn2+ entry through the Ca2+ influx pathway increased with membrane hyperpolarization. Internal application of inositol 1,3,4,5-tetrakisphosphate (InsP4), but not of inositol 1,4,5-trisphosphate, mimicked membrane potential-dependent Mn2+ entry. Bradykinin- and InsP4-induced Ca2+ influx was blocked by 10-100 microM genistein, a tyrosine kinase inhibitor. B2 receptor activation induced time-dependent tyrosine phosphorylation of mitogen-activated protein kinase and 120 kDa protein, which was dose-dependently inhibited by genistein. Bradykinin was unable to induce Ca2+ oscillations in genistein-treated DT cells. Our results show that bradykinin-induced Ca2+ influx and oscillations depend upon protein tyrosine phosphorylation. The results suggest that two bradykinin B2 receptor-activated signal pathways, protein tyrosine phosphorylation and formation of InsP4, merge at the Ca2+ influx process in ras-transformed NIH/3T3 fibroblasts.

3T3 Cells↗
PubMed1996

Anti- and proconvulsive actions of levcromakalim, an opener of ATP-sensitive K+ channel, in the model of hippocampus-generating partial seizures in rats.

We assessed the effect of an opener of ATP-sensitive K+ channel, levcromakalim (BRL 38227, (-)6-cyano-3,4-dihydro-2, 2-dimethyl-trans-4-(2-oxo-1-pyrrolidyl)-2H-1-benzopyran-3-ol) on seizure threshold and severity of the hippocampus-generating partial seizures in rats. For comparison, an ATP-sensitive K+ channel blocker, glibenclamide; K+ channel blocker, tetraethylammonium; Ca2+ channel antagonist, nimodipine and Ca2+ channel agonist, (+/-)-BAY K 8644 (1,4-dihydro-2, 6-dimethyl-5-nitro-4-[2-(trifluoromethyl)-phenyl]-3-pyridinecarboxyli c acid methyl ester) were also examined. Seizure threshold was determined using pulse number threshold and seizure severity was ascertained using afterdischarge duration. Levcromakalim decreased afterdischarge duration at 10 nmol i.c.v. and decreased pulse number threshold at 100 nmol i.c.v. Tetraethylammonium at 10 nmol i.c.v. increased afterdischarge duration selectively and at 100 nmol i.c.v. induced spontaneous seizures. Glibenclamide (1-100 nmol i.c.v.) failed to change pulse number threshold and afterdischarge duration. Nimodipine (40 mg/kg i.p.) decreased afterdischarge duration and pulse number threshold. BAY K 8644 (1 mg/kg i.p.) decreased pulse number threshold and increased afterdischarge duration. In addition, voltage-clamp recording from neuroblastoma x glioma hybrid cells indicates that levcromakalim inhibited the fast component of Ca(2+)-dependent K+ currents, in addition to the inhibition of T- and L-types of voltage-dependent Ca2+ currents reported (Ito et al., FEBS Lett. 262, 313, 1990). These results suggest that levcromakalim shows anti- and proconvulsive actions in the hippocampus-generating partial seizures in rats and these effects might be, at least partly, caused by inhibiting Ca2+ channel and Ca(2+)-dependent K+ channel, respectively.

Adenosine Triphosphate↗
PubMed1996

Inositol trisphosphate/Ca2+ as messengers of bradykinin B2 and muscarinic acetylcholine m1-m4 receptors in neuroblastoma-derived hybrid cells.

Neuroblastoma x glioma hybrid NG 108-15 and neuroblastoma x fibroblast hybrid NL308 cells possess endogenous bradykinin B2 receptors and m4 muscarinic acetylcholine receptors (mAChRs), which couple to phospholipase C and adenylate cyclase, respectively. Four genetic subtypes of mAChRs differed in their effects when stimulated in NG108-15 and NL308 cells overexpressing mAChRs. Broadly speaking, the principal effects fell into two categories: the odd-numbered receptors (m1 and m3) activated phospholipase C and increased inositol trisphosphate/Ca2+, as bradykinin did, whereas the even-numbered receptors (m2 and m4) inhibited adenylate cyclase via a pertussis toxin (PTx)-sensitive G-protein in NG108-15 cells. But all four types of NL308 cells overexpressing each m1, m2, m3 and m4 receptor activated phospholipase C, while keeping the PTx-sensitivity in m2/m4, but not in m1/m3 receptors. Coupling to ion channel effectors showed a comparable dichotomy in NG108-15 cells, while cross-activation occurred in NL308 cells.

Animals↗
PubMed1995

Inositol 1,4,5-trisphosphate formation and ryanodine-sensitive oscillations of cytosolic free Ca2+ concentrations in neuroblastoma x fibroblast hybrid NL308 cells expressing m2 and m4 muscarinic acetylcholine receptor subtypes.

Intracellular free Ca2+ concentrations ([Ca2+]i) were measured in subclones of NL308 neuroblastoma x fibroblast hybrid cells expressing each of the individual muscarinic acetylcholine receptor (mAChR) subtypes m1, m2, m3 and m4. Application of 100 microM acetylcholine (ACh) increased [Ca2+]i in all four subclones. The increased [Ca2+]i levels were significantly higher in m1- and m3-transformed cells than those in m2- and m4-transformed cells. In more than 95% of m2- and m4-transformed cells, [Ca2+]i showed sinusoidal oscillations. ACh-induced increases in [Ca2+]i were not observed in cells treated with an intracellular Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Removal of extracellular Ca2+ with ethylene-glycol-bis-(beta- aminoethyl)-N,N,N',N'-tetraacetate (EGTA) did not affect the initial [Ca2+]i increases, but reduced the late phases of delta [Ca2+]i in ml- and m3-transformed cells by 20-30%. Oscillations in m2- and m4-transformed cells persisted in EGTA solution (though sometimes slowed in frequency), suggesting that they were of intracellular origin. ACh-induced delta [Ca2+]i and inositol 1,4,5-trisphosphate formation was completely suppressed by pre-treatment with 50-100 ng ml-1 Pertussis toxin (PTX) for 12 h in m2- and m4-transformed cells, but not in m1- and m3-transformed cells. In all cells, extracellular application of caffeine and ryanodine, or intracellular application of cyclic adenosine diphosphate ribose (cAD-PR) produced a rise in [Ca2+]i. ACh-induced [Ca2+]i oscillations were not observed in ryanodine-treated m2-transformed cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

Ca2+ influx gated by inositol-3,4,5,6-tetrakisphosphate in NIH/3T3 fibroblasts.

The functional role of three inositol tetrakisphosphate isomers on Ca2+ influx was examined by intracellular application in NIH/3T3 mouse fibroblasts. Infusion of inositol-1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4), inositol-1,3,4,6- tetrakisphosphate, and inositol-3,4,5,6-tetrakisphosphate (Ins(3,4,5,6)P4) from the patch pipette into the cytoplasm produced a transient increase in cytoplasmic free Ca2+ concentration by fura-2 recording in extracellular Ca(2+)-dependent fashion. Stimulation of NIH/3T3 cells with bradykinin increased the levels of Ins(1,3,4,5)P4 and Ins(3,4,5,6)P4. These results suggest that mouse fibroblast cells possess a Ca2+ influx pathway gated with naturally occurring inositol tetrakisphosphates in response to stimulation with bradykinin.

3T3 Cells↗
PubMed1994

Ca2+ influx evoked by inositol-3,4,5,6-tetrakisphosphate in ras-transformed NIH/3T3 fibroblasts.

Infusion of inositol-3,4,5,6-tetrakisphosphate (Ins(3,4,5,6)P4) from the patch pipette into the cytoplasm, produced a biphasic intracellular free Ca2+ concentration ([Ca2+]i) increase in ras-transformed NIH/3T3 (DT) cells. The Ins(3,4,5,6)P4-induced increase in DT cells depended upon extracellular Ca2+, and was enhanced by membrane hyperpolarization. Identical [Ca2+]i increases were observed with intracellular application of inositol-1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) and inositol-1,3,4,6-tetrakisphosphate but not with inositol-1,2,4,5-tetrakisphosphate, inositol-1,4,5-trisphosphate or inositol-1,3,4,5,6-pentakisphosphate. Stimulation of DT cells with bradykinin increased the levels of Ins(3,4,5,6)P4 and Ins(1,3,4,5)P4. These results suggest that Ins(3,4,5,6)P4 may serve as a second messenger for continuous Ca2+ influx along with other tetrakisphosphates downstream from bradykinin receptors in DT cells.

3T3 Cells↗