A5002922679- Ion channel regulation and function
- Cardiac electrophysiology and arrhythmias
- Neuroscience and Neuropharmacology Research
- Calpain Protease Function and Regulation
- Cardiac Ischemia and Reperfusion
- Receptor Mechanisms and Signaling
- Neuroscience and Neural Engineering
- Signaling Pathways in Disease
- Venomous Animal Envenomation and Studies
- Healthcare and Venom Research
- Cardiac Arrhythmias and Treatments
- Enzyme Structure and Function
- Connexins and lens biology
- Parkinson's Disease Mechanisms and Treatments
- Mitochondrial Function and Pathology
- GABA and Rice Research
- Marine Toxins and Detection Methods
- Cellular transport and secretion
- Autophagy in Disease and Therapy
- Neurobiology and Insect Physiology Research
- Adenosine and Purinergic Signaling
- Cardiomyopathy and Myosin Studies
- Heat shock proteins research
- Cardiovascular Effects of Exercise
- Autism Spectrum Disorder Research
Kagoshima University
2013-2023
Kyoto Pharmaceutical University
2001
Abstract Both tetrodotoxin‐sensitive (TTX‐S) and TTX‐resistant (TTX‐R) voltage‐dependent Na + channels are expressed in the human neuroblastoma cell line NB‐1, but a gene encoding TTX‐R channel has not been identified. In this study, we have cloned cDNA α subunit of NB‐1 cells designated it hNbR1. The longest open reading frame hNbR1 (accession no. AB158469 ) encodes 2016 amino acid residues. Sequence analysis indicated that is highly homologous with cardiac Nav1.5/ SCN5A > 99% identity....
Although Cav1.2 Ca(2+) channels are modulated by reactive oxygen species (ROS), the underlying mechanisms not fully understood. In this study, we investigated effects of hydrogen peroxide (H2O2) on channel using a patch-clamp technique in guinea pig ventricular myocytes. Externally applied H2O2 (1 mM) increased activity cell-attached mode. A specific inhibitor Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) KN-93 (10 μM) partially attenuated H2O2-mediated facilitation channel,...
We have previously found that both CaMKII-mediated phosphorylation and calmodulin (CaM) binding to the channels are required for maintaining basal activity of Cav1.2 Ca(2+) channels. In this study, we investigated hypothetical CaMKII site on contributes channel regulation. phosphorylates Thr1603 residue (Thr1604 in rabbit) within preIQ region C-terminal tail guinea-pig channel. Mutation Asp (T1603D) slowed run-down inside-out patch mode abolished time-dependency CaM's effects reverse...
Activity of cardiac Cav1.2 channels is enhanced by cyclic AMP-PKA signaling. In this study, we studied the effects PKA phosphorylation on binding calmodulin to fragment peptide proximal C-terminal tail α1C subunit (CT1, a.a. 1509–1789 guinea-pig). pull-down assay, in vitro significantly decreased CT1 (61%) at high [Ca2+]. The phosphoresistant (CT1SA) and phosphomimetic (CT1SD) mutants, which three sites (Ser1574, 1626, 1699) were mutated Ala Asp, respectively, bound with 99% 65% amount,...
The present study examined the binding of individual N‐ and C‐lobes calmodulin (CaM) to Cav1.2 at different Ca 2+ concentration ([Ca ]) from ≈ free 2 mM, found that they may bind ‐dependently. In particular, using patch‐clamp technique, we confirmed or can rescue basal activity run‐down, demonstrating functional relevance lobes. data imply resting [Ca ], CaM tether channel with its single lobe, leading multiple molecule increase grade ‐dependent regulation Cav1.2.
To demonstrate the interaction of calpastatin (CS) domain L (CS ) with Cav1.2 channel, we investigated binding CS various C‐terminus‐derived peptides at ≈ free, 100 nM, 10 μM, and 1 mM Ca 2+ by using GST pull‐down assay method. Besides IQ motif, was also found to bind PreIQ motif. With increasing [Ca ], affinity –IQ gradually decreased, –PreIQ increased. The results suggest that may both motifs channel in different ‐dependent manners.
Cardiac L-type Ca(2+) channels are modulated by phosphorylation protein kinase A (PKA). To explore the PKA-targeted site(s), five potential sites in carboxyl (COOH) terminal region of α1C-subunit guinea pig Cav1.2 channel were mutated replacing serine (S) or threonine (T) residues with alanine (A): S1574A (C1 site), S1626A (C2), S1699A (C3), T1908A, (C4), S1927A (C5), and their various combinations. The wild-type activity was enhanced three- to fourfold adenylyl cyclase activator forskolin...
The present study is to investigate the mechanism by which ATP regulates Cav1.2 channel activity. Ventricular tissue was obtained from adult guinea pig hearts using collagenase. Ca 2+ activity monitored patch-clamp technique. Proteins were purified wheat germ agglutinin-Sepharose, and concentration determined Coomassie brilliant blue binding examined photoaffinity method. EDA-ATP-biotin maintains in inside-out membrane patches. directly bound a dose-dependent manner, at least two molecules...
Cardiac Cav1.2 channels, coupling membrane stimulation to intracellular Ca2+ signaling, are regulated by multiple cytoplasmic factors, such as calmodulin (CaM), phosphorylation, Ca2+, ATP and intramolecular fragments of the channel. The interaction between distal proximal C-terminal regulatory domains (DCRD PCRD) channel is suggested inhibit activity, while PKA-mediated phosphorylation facilitates releasing an interaction. Here, we report that C-terminus (CT3) (CT1) inhibited CaM in a...
This study examined the bindings of calmodulin (CaM) and its mutants with C- N-terminal tails voltage-gated Ca(2+) channel CaV1.2 at different CaM concentrations ([Ca(2+)]) by using pull-down assay method to obtain basic information on binding mode, including concentration- Ca(2+)-dependencies. Our data show that more than one molecule could bind C-terminal tail high [Ca(2+)]. Additionally, C-lobe is highly critical in sensing change [Ca(2+)] CaV1.2, between requires provide new details...
Calmodulin (CaM) + ATP can reprime voltage-gated L-type Ca 2+ channels (Ca V 1.2) in inside-out patches for activation, but this effect decreases time dependently. This suggests that the 1.2 channel activity is regulated by additional cytoplasmic factors. To test hypothesis, we examined role of cAMP-dependent protein kinase A (PKA) and phosphatases regulation mode guinea pig ventricular myocytes. quickly disappeared after patch was excised from cell recovered to only 9% cell-attached on...
This study aimed to investigate protein phosphatases involved in the run down of Cav1.2 Ca(2+) channels. Single ventricular myocytes obtained from adult guinea pig hearts were used record channel currents with patch-clamp technique. Calmodulin (CaM) and ATP restore activity inside-out patches. Inhibitors applied role phosphatases. The specific phosphatase type 1 (PP1) inhibitor (PP1 inhibitor-2) 2A (PP2A) (fostriecin) abolished slow channels, which was evident as time-dependent attenuation...
Calmodulin (CaM) is well known as an activator of calcium/calmodulin-dependent protein kinase II (CaMKII). Voltage-gated sodium channels (VGSCs) are basic signaling molecules in excitable cells and crucial molecular targets for nervous system agents. However, the way which Ca2+/CaM/CaMKII cascade modulates NaV1.1 IQ (isoleucine glutamine) domain VGSCs remains obscure. In this study, binding CaM, its mutants at calcium sites (CaM12, CaM34, CaM1234), truncated proteins (N-lobe C-lobe) to were...