Publications by authors named "Minoru Wakamori"

The peripheral sensory nerve must be maintained to perceive environmental changes. Daily physiological mechanical stimulations, like gravity, floor reaction force, and occlusal force, influence the nerve homeostasis directly or indirectly. Although the direct axonal membrane stretch enhances axon outgrowth via mechanosensitive channel activation, the indirect mechanisms remain to be elucidated.

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Myoepithelial cells (MECs) are responsible for receiving stimuli from the central nervous system and translating their responses into the form of secretion into glandular tissue, including salivary glands (SG), sweet glands, and mammary glands. SG MECs cause the secretion of serous saliva by contracting of acini/ductal cells with acetylcholine (Ach) from parasympathetic nerves via muscarinic receptors. To response the parasympathetic physiological stimulation, SG epithelial cell-derived MECs are supposed to be induced and placed adjacent to parasympathetic system nerve ends in SGs by forming a neuro-myoepithelial junction.

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Several large-scale whole-exome sequencing studies in patients with schizophrenia (SCZ) and autism spectrum disorder (ASD) have identified rare variants with modest or strong effect size as genetic risk factors. Dysregulation of cellular calcium homeostasis might be involved in SCZ/ASD pathogenesis, and genes encoding L-type voltage-gated calcium channel (VGCC) subunits Ca1.1 (CACNA1S), Ca1.

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Article Synopsis
  • The TRPV1 channel is a cation channel found in certain neurons that responds to stimuli like capsaicin, heat (over 43°C), mechanical stress, and acidic conditions.
  • Research explored how capsaicin and protons influence the opening of the TRPV1 channel at different voltages, revealing that the channel's behavior changes under varying pH levels.
  • Findings indicate that capsaicin and protons modulate the TRPV1 channel differently, with implications for understanding pain signaling mechanisms.
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The transient receptor potential vanilloid 1 (TRPV1) channel is a polymodal receptor in sensory nerves and involved in pain sensation. TRPV1 has at least three distinct activation modes that are selectively induced by different stimuli capsaicin, noxious heat, and protons. Although many mode-selective TRPV1 antagonists have been developed for their anticipated analgesic effects, there have been few successful reports because of adverse effects due to burn injuries and hyperthermia.

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Activation of transient receptor potential melastatin 2 (TRPM2), an oxidative stress-sensitive Ca-permeable channel, contributes to the aggravation of cerebral ischemia-reperfusion (CIR) injury. Recent studies indicated that treatment with the antidepressant duloxetine for 24 hours (long term) attenuates TRPM2 activation in response to oxidative stress in neuronal cells. To examine the direct effects of antidepressants on TRPM2 activation, we examined their short-term (0-30 minutes) treatment effects on HO-induced TRPM2 activation in TRPM2-expressing human embryonic kidney 293 cells using the Ca indicator fura-2.

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Background And Purpose: The development of subtype-selective ligands to inhibit voltage-sensitive sodium channels (VSSCs) has been attempted with the aim of developing therapeutic compounds. Tetrodotoxin (TTX) is a toxin from pufferfish that strongly inhibits VSSCs. Many TTX analogues have been identified from marine and terrestrial sources, although their specificity for particular VSSC subtypes has not been investigated.

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Alternative splicing (AS) that occurs at the final coding exon (exon 47) of the Cav2.1 voltage-gated calcium channel (VGCC) gene produces two major isoforms in the brain, MPI and MPc. These isoforms differ in their splice acceptor sites; human MPI is translated into a polyglutamine tract associated with spinocerebellar ataxia type 6 (SCA6), whereas MPc splices to an immediate stop codon, resulting in a shorter cytoplasmic tail.

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Crambescin B carboxylic acid, a synthetic analog of crambescin B, was recently found to inhibit the voltage-sensitive sodium channels (VSSC) in a cell-based assay using neuroblastoma Neuro 2A cells. In the present study, whole-cell patch-clamp recordings were conducted with three heterologously expressed VSSC subtypes, Na1.2, Na1.

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T-type voltage-gated Ca channels (T-VGCCs) function in the pathophysiology of epilepsy, pain and sleep. However, their role in cognitive function remains unclear. We previously reported that the cognitive enhancer ST101, which stimulates T-VGCCs in rat cortical slices, was a potential Alzheimer's disease therapeutic.

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Lavender oil (LO) is a commonly used essential oil in aromatherapy as non-traditional medicine. With an aim to demonstrate LO effects on the body, we have recently established an animal model investigating the influence of orally administered LO in rat tissues, genome-wide. In this brief, we investigate the effect of LO ingestion in the blood of rat.

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Article Synopsis
  • TRPM2 is a calcium-permeable channel that responds to oxidative stress, and its activation is linked to the production of inflammatory substances through Janus kinase 2 (Jak2).
  • The study showed that AG490, a Jak2 inhibitor, significantly blocked the increase in intracellular calcium caused by hydrogen peroxide (H2O2) in human cells, suggesting its role in preventing TRPM2 activation.
  • AG490 appears to work by scavenging hydroxyl radicals rather than via Jak2 inhibition, highlighting its potential for exploring TRPM2's role in disease models, even though it has a minor effect on another channel, TRPA1.
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Cholinergically induced network activity is a useful analogue of theta rhythms involved in memory processing or epileptiform activity in the hippocampus, providing a powerful tool to elucidate the mechanisms of synchrony in neuronal networks. In absence epilepsy, although its association with cognitive impairments has been reported, the mechanisms underlying hippocampal synchrony remain poorly investigated. Here we simultaneously recorded electrical activities from 64 sites in hippocampal slices of CaV2.

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Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disease caused by the expansion of a polyglutamine tract in the Ca(v)2.1 voltage-gated calcium channel. To elucidate how the expanded polyglutamine tract in this plasma membrane protein causes the disease, we created a unique knockin mouse model that modestly overexpressed the mutant transcripts under the control of an endogenous promoter (MPI-118Q).

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Article Synopsis
  • Voltage-dependent Ca(2+) channels (VDCCs) interact with Rab3-interacting molecules (RIMs) to regulate neurotransmitter release by stabilizing vesicles and facilitating calcium influx.
  • RIM1alpha, a long alpha isoform, enhances this process by binding specifically with VDCC beta-subunits, while the shorter gamma isoforms, RIM3 and RIM4, also suppress VDCC inactivation but differ in vesicle anchoring abilities.
  • The study highlights that while both RIM types support sustained calcium influx in neurons, their competition for binding to VDCC beta-subunits affects the localization of neurotransmitter vesicles near the plasma membrane.
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Although febrile seizures (FSs) are the most common convulsive syndrome in infants and childhood, the etiology of FSs has remained unclarified. Several missense mutations of the Na(v)1.1 channel (SCN1A), which alter channel properties, have been reported in a familial syndrome of GEFS+ (generalized epilepsy with febrile seizures plus).

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The CACNA1A gene encodes the poreforming, voltage-sensitive subunit of the voltage-dependent Ca(v)2.1 calcium channel. Mutations in this gene have been linked to several human disorders, including familial hemiplegic migraine type 1, episodic ataxia type 2, and spinocerebellar ataxia type 6.

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Mutations in PKD2 gene result in autosomal dominant polycystic kidney disease (ADPKD). PKD2 encodes polycystin-2 (TRPP2), which is a homologue of transient receptor potential (TRP) cation channel proteins. Here we identify a novel PKD2 mutation that generates a C-terminal tail-truncated TRPP2 mutant 697fsX with a frameshift resulting in an aberrant 17-amino acid addition after glutamic acid residue 697 from a family showing mild ADPKD symptoms.

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Canonical transient receptor potential (TRPC) channels control influxes of Ca(2+) and other cations that induce diverse cellular processes upon stimulation of plasma membrane receptors coupled to phospholipase C (PLC). Invention of subtype-specific inhibitors for TRPCs is crucial for distinction of respective TRPC channels that play particular physiological roles in native systems. Here, we identify a pyrazole compound (Pyr3), which selectively inhibits TRPC3 channels.

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Genetic analyses have revealed an association between the gene encoding the Rab3A-interacting molecule (RIM1) and the autosomal dominant cone-rod dystrophy CORD7. However, the pathogenesis of CORD7 remains unclear. We recently revealed that RIM1 regulates voltage-dependent Ca(2+) channel (VDCC) currents and anchors neurotransmitter-containing vesicles to VDCCs, thereby controlling neurotransmitter release.

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Agelenin, isolated from the Agelenidae spider Agelena opulenta, is a peptide composed of 35 amino acids. We determined the three-dimensional structure of agelenin using two-dimensional NMR spectroscopy. The structure is composed of a short antiparallel beta-sheet and four beta-turns, which are stabilized by three disulfide bonds.

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The molecular organization of presynaptic active zones is important for the neurotransmitter release that is triggered by depolarization-induced Ca2+ influx. Here, we demonstrate a previously unknown interaction between two components of the presynaptic active zone, RIM1 and voltage-dependent Ca2+ channels (VDCCs), that controls neurotransmitter release in mammalian neurons. RIM1 associated with VDCC beta-subunits via its C terminus to markedly suppress voltage-dependent inactivation among different neuronal VDCCs.

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Spinocerebellar ataxia type 6 (SCA6) is caused by polyglutamine expansion in P/Q-type Ca2+ channels (Ca(v)2.1) and is characterized by predominant degeneration of cerebellar Purkinje cells. To characterize the Ca(v)2.

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The rocker mice are hereditary ataxic mutants that carry a point mutation in the gene encoding the CaV2.1 (P/Q-type) Ca2+ channel alpha1 subunit, and show the mildest symptoms among the reported CaV2.1 mutant mice.

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