Okazaki Institute for Integrative Bioscience National Institute for Physiological science

Okazaki, Japan

Okazaki Institute for Integrative Bioscience National Institute for Physiological science

Okazaki, Japan
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Mihara H.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Mihara H.,University of Toyama | Boudaka A.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Sugiyama T.,University of Toyama | And 3 more authors.
Journal of Physiology | Year: 2011

In the oesophagus the ion channel TRPV4 senses multiple stimuli, including heat and mechanical stimulation. TRPV4 activation causes ATP release from oesophageal cells, which could be important in oesophageal disease mechanisms. Abstract Gastro-oesophageal reflux disease (GERD) is a multi-factorial disease that may involve oesophageal hypersensitivity to mechanical or heat stimulus as well as acids. Intraganglionic laminar endings (IGLEs) are the most prominent terminal structures of oesophageal vagal mechanosensitive afferents and may modulate mechanotransduction via purinergic receptors. Transient receptor potential channel vanilloid 4 (TRPV4) can detect various stimuli such as warm temperature, stretch and some chemicals, including 4α-phorbol 12,13-didecanoate (4α-PDD) and GSK1016790A. TRPV4 is expressed in many tissues, including renal epithelium, skin keratinocytes and urinary bladder epithelium, but its expression and function in the oesophagus is poorly understood. Here, we show anatomical and functional TRPV4 expression in mouse oesophagus and its involvement in ATP release. TRPV4 mRNA and protein were detected in oesophageal keratinocytes. Several known TRPV4 activators (chemicals, heat and stretch stimulus) increased cytosolic Ca 2+ concentrations in cultured WT keratinocytes but not in TRPV4 knockout (KO) cells. Moreover, the TRPV4 agonist GSK1016790A and heat stimulus evoked TRPV4-like current responses in isolated WT keratinocytes, but not in TRPV4KO cells. GSK1016790A and heat stimulus also significantly increased ATP release from WT oesophageal keratinocytes compared to TRPV4KO cells. The vesicle-trafficking inhibitor brefeldin A (BFA) inhibited the ATP release. This ATP release could be mediated by the newly identified vesicle ATP transporter, VNUT, which is expressed by oesophageal keratinocytes at the mRNA and protein levels. In conclusion, in response to heat, chemical and possibly mechanical stimuli, TRPV4 contributes to ATP release in the oesophagus. Thus, TRPV4 could be involved in oesophageal mechano- and heat hypersensitivity. © 2011 The Authors. Journal compilation © 2011 The Physiological Society.


Saito S.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Saito S.,Graduate University for Advanced Studies | Banzawa N.,Tottori University | Fukuta N.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | And 6 more authors.
Molecular Biology and Evolution | Year: 2014

Nociceptive receptors enable animals to sense tissue-damaging stimuli, thus playing crucial roles in survival. Due to evolutionary diversification, responses of nociceptive receptors to specific stimuli can vary among species. Multispecies functional comparisons of nociceptive receptors help elucidate their evolutionary process and molecular basis for activation. The transient receptor potential ankyrin 1 (TRPA1) ion channel serves as a nociceptive receptor for chemical and thermal stimuli that is heat-activated in reptiles and frogs while potentially cold-activated in rodents. Here, we characterized channel properties of avian TRPA1 in chicken. Chicken TRPA1 was activated by noxious chemicals that also activate TRPA1 in other vertebrates. Regarding thermal sensitivity, chicken TRPA1 was activated by heat stimulation, but not cold, thus thermal sensitivity of avian TRPA1 does not coincide with rodent TRPA1, although both are homeotherms. Furthermore, in chicken sensory neurons, TRPA1 was highly coexpressed with TRPV1, another nociceptive heat and chemical receptor, similar to mammals and frogs. These results suggest that TRPA1 acted as a noxious chemical and heat receptor, and was coexpressed with TRPV1 in the ancestral terrestrial vertebrate. The acquisition of TRPV1 as a novel heat receptor in the ancestral terrestrial vertebrate is likely to have affected the functional evolution of TRPA1 regarding thermal sensitivity and led to the diversification among diverse vertebrate species. Additionally, we found for the first time that chicken TRPA1 is activated by methyl anthranilate (MA) and its structurally related chemicals used as nonlethal bird repellents. MA-induced responses were abolished by a TRPA1 antagonist in somatosensory neurons, indicating that TRPA1 acts as a MA receptor in chicken. Furthermore, TRPA1 responses to MA varied among five diverse vertebrate species. Utilizing species diversity and mutagenesis experiments, three amino acids were identified as critical residues for MA-induced activation of chicken TRPA1. © 2014 The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved.


Zhou Y.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Suzuki Y.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Suzuki Y.,Graduate University for Advanced Studies | Uchida K.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | And 2 more authors.
Nature Communications | Year: 2013

Transient receptor potential ankyrin 1 (TRPA1) protein is a nonselective cation channel. Although many studies suggest that TRPA1 is involved in inflammatory and neuropathic pain, its mechanism remains unclear. Here we identify an alternative splice variant of the mouse Trpa1 gene. TRPA1a (full-length) and TRPA1b (splice variant) physically interact with each other and TRPA1b increases the expression of TRPA1a in the plasma membrane. TRPA1a and TRPA1b co-expression significantly increases current density in response to different agonists without affecting their single-channel conductance. Exogenous overexpression of Trpa1b gene in wild-type and TRPA1KO DRG neurons also increases TRPA1a-mediated AITC responses. Moreover, expression levels of Trpa1a and Trpa1b mRNAs change dynamically in two pain models (complete Freund's adjuvant-induced inflammatory pain and partial sciatic nerve ligation-induced neuropathic pain models). These results suggest that TRPA1 may be regulated through alternative splicing under these pathological conditions. © 2013 Macmillan Publishers Limited. All rights reserved.


Saito S.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Fukuta N.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Shingai R.,Iwate University | Tominaga M.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Tominaga M.,Graduate University for Advanced Studies
PLoS Genetics | Year: 2011

Transient Receptor Potential (TRP) channels serve as temperature receptors in a wide variety of animals and must have played crucial roles in thermal adaptation. The TRP vanilloid (TRPV) subfamily contains several temperature receptors with different temperature sensitivities. The TRPV3 channel is known to be highly expressed in skin, where it is activated by warm temperatures and serves as a sensor to detect ambient temperatures near the body temperature of homeothermic animals such as mammals. Here we performed comprehensive comparative analyses of the TRPV subfamily in order to understand the evolutionary process; we identified novel TRPV genes and also characterized the evolutionary flexibility of TRPV3 during vertebrate evolution. We cloned the TRPV3 channel from the western clawed frog Xenopus tropicalis to understand the functional evolution of the TRPV3 channel. The amino acid sequences of the N- and C-terminal regions of the TRPV3 channel were highly diversified from those of other terrestrial vertebrate TRPV3 channels, although central portions were well conserved. In a heterologous expression system, several mammalian TRPV3 agonists did not activate the TRPV3 channel of the western clawed frog. Moreover, the frog TRPV3 channel did not respond to heat stimuli, instead it was activated by cold temperatures. Temperature thresholds for activation were about 16 °C, slightly below the lower temperature limit for the western clawed frog. Given that the TRPV3 channel is expressed in skin, its likely role is to detect noxious cold temperatures. Thus, the western clawed frog and mammals acquired opposite temperature sensitivity of the TRPV3 channel in order to detect environmental temperatures suitable for their respective species, indicating that temperature receptors can dynamically change properties to adapt to different thermal environments during evolution. © 2011 Saito et al.


Saito S.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Saito S.,Graduate University for Advanced Studies | Tominaga M.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Tominaga M.,Graduate University for Advanced Studies | Tominaga M.,Okazaki Institute for Integrative Bioscience
Cell Calcium | Year: 2015

Animals have evolved sophisticated physiological systems for sensing ambient temperature since changes in environmental temperatures affect various biological processes. Thermosensitive transient receptor potential (thermoTRP) channels serve as thermal sensors in diverse animal species. They are multimodal receptors that are activated by temperature as well as other physical and chemical stimuli. Since thermoTRP channels are calcium permeable non-selective cation channels, their activation leads to an influx of calcium and sodium ions into the cell and triggers downstream signal transduction. ThermoTRP channels have been characterized in diverse animal species over the past several years, illuminating the diversification of thermoTRP channels in the course of evolution. The gene repertoires of thermoTRP channels differ among animal species. Additionally, in some cases, the temperature and chemical sensitivities among orthologous thermoTRP channels vary among species. The evolutionary flexibility of thermoTRP channels enabled them to contribute to unique physiological systems such as infrared sensation in snakes and bats and seasonal adaptation in silk moth. On the other hand, the functional differences of thermoTRP channels among species have been utilized for understanding the molecular basis for their activation (or inhibition) mechanisms, and amino acid residues (or domains) responsible for the respective channel properties have been identified in various thermoTRP channels. Here we summarize the current understanding of the functional diversity and evolutionary dynamics of thermoTRP channels. © 2014 Elsevier Ltd.


Kohno K.,Nagoya University | Sokabe T.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Sokabe T.,Johns Hopkins University | Tominaga M.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | And 2 more authors.
Journal of Neuroscience | Year: 2010

Insects are relatively small heterothermic animals, thus they are highly susceptible to changes in ambient temperature. However, a group of honey bees is able to maintain the brood nest temperature between 32°C and 36°C by either cooling or heating the nest. Nevertheless, how honey bees sense the ambient temperature is not known. We identified a honey bee Hymenoptera-specific transient receptor potential A (HsTRPA) channel (AmHsTRPA), which is activated by heat with an apparent threshold temperature of 34°C and insect antifeedants such as camphor in vitro. AmHsTRPA is expressed in the antennal flagellum, and ablation of the antennal flagella and injection of AmHsTRPA inhibitors impair warmth avoidance of honey bees. Gustatory responses of honey bees to sucrose are suppressed by noxious heat and insect antifeedants, but are relieved in the presence of AmHsTRPA inhibitors. These results suggest that AmHsTRPA may function as a thermal/chemical sensor in vivo. As shown previously, Hymenoptera has lost the ancient chemical sensor TRPA1; however, AmHsTRPA is able to complement the function of Drosophila melanogaster TRPA1. These results demonstrate that HsTRPA, originally arisen by the duplication of Water witch, has acquired thermal- and chemical-responsive properties, which has resulted in the loss of ancient TRPA1. Thus, this is an example of neofunctionalization of the duplicated ion channel gene followed by the loss of the functionally equivalent ancient gene. Copyright © 2010 the authors.


Nishida M.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Nishida M.,Japan Science and Technology Agency | Nishida M.,Kyushu University | Toyama T.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | And 2 more authors.
Journal of Molecular and Cellular Cardiology | Year: 2014

Structural and morphological changes of the cardiovascular systems (cardiovascular remodeling) are a major clinical outcome of cardiovascular diseases. Many lines of evidences have implied that transfiguration of reduction/oxidation (redox) homeostasis due to excess production of reactive oxygen species (ROS) and/or ROS-derived electrophilic metabolites (electrophiles) is the main cause of cardiovascular remodeling. Gasotransmitters, such as nitric oxide (NO) and endogenous electrophiles, are considered major bioactive species and have been extensively studied in the context of physiological and pathological cardiovascular events. We have recently found that hydrogen sulfide-related reactive species function as potent nucleophiles to eliminate electrophilic modification of signaling proteins induced by NO-derived electrophilic byproducts (e.g., 8-nitroguanosine 3',5'-cyclic monophosphate and nitro-oleic acid). In this review, we discuss the current understanding of redox control of cardiovascular pathophysiology by electrophiles and nucleophiles. We propose that modulation of electrophile-mediated post-translational modification of protein cysteine thiols may be a new therapeutic strategy of cardiovascular diseases. This article is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System". © 2014 Elsevier Ltd.


Uchida K.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Tominaga M.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Tominaga M.,Aichi University
Endocrine Journal | Year: 2011

Insulin secretion from pancreatic β-cells is the only efficient means to decrease blood glucose concentrations. Glucose is the principal stimulator of insulin secretion with the ATP-sensitive K + channel-voltage-gated Ca 2+ channelmediated pathway being the primary one involved in glucose-stimulated insulin secretion. Recently, several reports demonstrated that some transient receptor potential (TRP) channels are expressed in pancreatic β-cells and contribute to pancreatic β-cell functions. Interestingly, six of them (TRPM2, TRPM4, TRPM5, TRPV1, TRPV2 and TRPV4) are thermosensitive TRP channels. Thermosensitive TRP channels in pancreatic β-cells can function as multimodal receptors and cause Ca 2+ influx and membrane depolarization at physiological body temperature. TRPM channels (TRPM2, TRPM4 and TRPM5) control insulin secretion levels by sensing intracellular Ca 2+ increase, NAD metabolites, or hormone receptor activation. TRPV2 is involved not only in insulin secretion but also cell proliferation, and is regulated by the autocrine effects of insulin. TRPV1 expressed in sensory neurons is involved in β-cell stress and islet inflammation by controlling neuropeptide release levels. It is thus clear that thermosensitive TRP channels play important roles in pancreatic β-cell functions, and future analyses of TRP channel function will lead to better understanding of the complicated mechanisms involved in insulin secretion and diabetes pathogenesis. © The Japan Endocrine Society.


Uchida K.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Uchida K.,Aichi University | Tominaga M.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Tominaga M.,Aichi University
Cell Calcium | Year: 2014

TRPM2 is a Ca2+-permeable non-selective cation channel that can be activated by adenosine dinucleotides, hydrogen peroxide, or intracellular Ca2+. The protein is expressed in a wide variety of cells, including neurons in the brain, immune cells, endocrine cells, and endothelial cells. This channel is also well expressed in β-cells in the pancreas. Insulin secretion from pancreatic β-cells is the primary mechanism by which the concentration of blood glucose is reduced. Thus, impairment of insulin secretion leads to hyperglycemia and eventually causes diabetes. Glucose is the principal stimulator of insulin secretion. The primary pathway involved in glucose-stimulated insulin secretion is the ATP-sensitive K+ (KATP) channel to voltage-gated Ca2+ channel (VGCC)-mediated pathway. Increases in the intracellular Ca2+ concentration are necessary for insulin secretion, but VGCC is not sufficient to explain [Ca2+]i increases in pancreatic β-cells and the resultant secretion of insulin. In this review, we focus on TRPM2 as a candidate for a [Ca2+]i modulator in pancreatic β-cells and its involvement in insulin secretion and development of diabetes. Although further analyses are needed to clarify the mechanism underlying TRPM2-mediated insulin secretion, TRPM2 could be a key player in the regulation of insulin secretion and could represent a new target for diabetes therapy. © 2014 Elsevier Ltd.


Kurganov E.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Zhou Y.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Saito S.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science | Tominaga M.,Okazaki Institute for Integrative Bioscience National Institute for Physiological science
Pflügers Archiv : European journal of physiology | Year: 2014

Transient receptor potential ankyrin 1 (TRPA1) is a member of the large TRP super family of ion channels and functions as a Ca(2+)-permeable nonselective cation channel that is activated by various noxious stimuli. TRPA1 was initially identified as a potential mediator of noxious cold stimuli in mammalian nociceptive sensory neurons, while TRPA1s from nonmammalian vertebrates (snakes, green anole lizards, and frogs) were recently reported to be activated by heat, but not cold stimulus. In this study, we examined detailed properties of the green anole TRPA1 channel (gaTRPA1) related to thermal and chemical stimulation in whole-cell and single-channel recordings. Heat activates gaTRPA1 with a temperature threshold for activation of 35.8 °C, while heat together with allyl isothiocyanate (AITC), a chemical agonist, had synergistic effects on gaTRPA1 channel activation in that either the temperature threshold or activating AITC concentration was reduced in the presence of the other stimulus. Significant heat-evoked gaTRPA1 activation was observed in the presence but not absence of extracellular Ca(2+). gaTRPA1 channels were also activated by heat and AITC in excised membrane patches with an inside-out configuration. By comparing the kinetics of heat- and AITC-evoked single-channel currents, we defined similarities and differences of gaTRPA1 channel responses to heat and AITC. We observed similar current-voltage relationship and unitary amplitudes for heat- and AITC-evoked currents and found that heat-activated currents showed shorter durations of both open and closed times. Our results suggest that the gaTRPA1 channel is directly activated by heat and chemical stimuli.

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