The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Hiroshi Ezura - One of the best experts on this subject based on the ideXlab platform.

  • single step purification of native miraculin using immobilized metal affinity chromatography
    Journal of Agricultural and Food Chemistry, 2009
    Co-Authors: Narendra Duhita, Kyoko Hiwasatanase, Shigeki Yoshida, Hiroshi Ezura
    Abstract:

    Miraculin is a Taste-modifying protein that can be isolated from miracle fruit (Richadella dulcifica), a shrub native to West Africa. It is able to turn a Sour Taste into a sweet Taste. The commercial exploitation of this sweetness-modifying protein is underway, and a fast and efficient purification method to extract the protein is needed. We succeeded in purifying miraculin from miracle fruit in a single-step purification using immobilized metal-affinity chromatography (IMAC). The purified miraculin exhibited high purity (>95%) in reverse-phase high-performance liquid chromatography. We also demonstrated the necessity of its structure for binding to the nickel-IMAC column.

  • Genetically stable expression of functional miraculin, a new type of alternative sweetener, in transgenic tomato plants
    Plant biotechnology journal, 2007
    Co-Authors: Hyeon-jin Sun, Megumu Yano, Hiroshi Kataoka, Hiroshi Ezura
    Abstract:

    Miraculin is a Taste-modifying protein isolated from the red berries of Richadella dulcifica, a shrub native to West Africa. Miraculin by itself is not sweet, but it is able to turn a Sour Taste into a sweet Taste. This unique property has led to increasing interest in this protein. In this article, we report the high-yield production of miraculin in transgenic tomato plants. High and genetically stable expression of miraculin was confirmed by Western blot analysis and enzyme-linked immunosorbent assay. Recombinant miraculin accumulated to high levels in leaves and fruits, up to 102.5 and 90.7 microg/g fresh weight, respectively. Purified recombinant miraculin expressed in transgenic tomato plants showed strong sweetness-inducing activity, similar to that of native miraculin. These results demonstrate that recombinant miraculin was correctly processed in transgenic tomato plants, and that this production system could be a good alternative to production from the native plant.

  • functional expression of the Taste modifying protein miraculin in transgenic lettuce
    FEBS Letters, 2006
    Co-Authors: Hyeon-jin Sun, Minlong Cui, Hiroshi Ezura
    Abstract:

    Taste-modifying proteins are a natural alternative to artificial sweeteners and flavor enhancers and have been used in some cultures for centuries. The Taste-modifying protein, miraculin, has the unusual property of being able to modify a Sour Taste into a sweet Taste. Here, we report the use of a plant expression system for the production of miraculin. A synthetic gene encoding miraculin was placed under the control of constitutive promoters and transferred to lettuce. Expression of this gene in transgenic lettuce resulted in the accumulation of significant amounts of miraculin protein in the leaves. The miraculin expressed in transgenic lettuce possessed sweetness-inducing activity. These results demonstrate that the production of miraculin in edible plants can be a good alternative strategy to enhance the availability of this protein.

Yoshiro Ishimaru - One of the best experts on this subject based on the ideXlab platform.

  • a large increase of Sour Taste receptor cells in skn 1 deficient mice does not alter the number of their Sour Taste signal transmitting gustatory neurons
    Neuroscience Letters, 2017
    Co-Authors: Naohiro Maeda, Masataka Narukawa, Yoshiro Ishimaru, Takumi Misaka, Kurumi Yamamoto, Keiko Abe
    Abstract:

    The connections between Taste receptor cells (TRCs) and innervating gustatory neurons are formed in a mutually dependent manner during development. To investigate whether a change in the ratio of cell types that compose Taste buds influences the number of innervating gustatory neurons, we analyzed the proportion of gustatory neurons that transmit Sour Taste signals in adult Skn-1a-/- mice in which the number of Sour TRCs is greatly increased. We generated polycystic kidney disease 1 like 3-wheat germ agglutinin (pkd1l3-WGA)/Skn-1a+/+ and pkd1l3-WGA/Skn-1a-/- mice by crossing Skn-1a-/- mice and pkd1l3-WGA transgenic mice, in which neural pathways of Sour Taste signals can be visualized. The number of WGA-positive cells in the circumvallate papillae is 3-fold higher in Taste buds of pkd1l3-WGA/Skn-1a-/- mice relative to pkd1l3-WGA/Skn-1a+/+ mice. Intriguingly, the ratio of WGA-positive neurons to P2X2-expressing gustatory neurons in nodose/petrosal ganglia was similar between pkd1l3-WGA/Skn-1a+/+ and pkd1l3-WGA/Skn-1a-/- mice. In conclusion, an alteration in the ratio of cell types that compose Taste buds does not influence the number of gustatory neurons that transmit Sour Taste signals.

  • molecular mechanisms underlying the reception and transmission of Sour Taste information
    Bioscience Biotechnology and Biochemistry, 2015
    Co-Authors: Yoshiro Ishimaru
    Abstract:

    Taste enables organisms to determine the properties of ingested substances by conveying information regarding the five basic Taste modalities: sweet, salty, Sour, bitter, and umami. The sweet, salty, and umami Taste modalities convey the carbohydrate, electrolyte, and glutamate content of food, indicating its desirability and stimulating appetitive responses. The Sour and bitter modalities convey the acidity of food and the presence of potential toxins, respectively, stimulating aversive responses to such Tastes. In recent years, the receptors mediating sweet, bitter, and umami Tastes have been identified as members of the T1R and T2R G-protein-coupled receptor families; however, the molecular mechanisms underlying Sour Taste detection have yet to be clearly elucidated. This review covers the molecular mechanisms proposed to mediate the detection and transmission of Sour stimuli, focusing on polycystic kidney disease 1-like 3 (Pkd1l3), Pkd2l1, and carbonic anhydrase 4 (Car4).

  • Sour Taste responses in mice lacking pkd channels
    PLOS ONE, 2011
    Co-Authors: Nao Horio, Yoshiro Ishimaru, Hiroaki Matsunami, Ryusuke Yoshida, Keiko Yasumatsu, Yuchio Yanagawa, Yuzo Ninomiya
    Abstract:

    Background The polycystic kidney disease-like ion channel PKD2L1 and its associated partner PKD1L3 are potential candidates for Sour Taste receptors. PKD2L1 is expressed in type III Taste cells that respond to Sour stimuli and genetic elimination of cells expressing PKD2L1 substantially reduces chorda tympani nerve responses to Sour Taste stimuli. However, the contribution of PKD2L1 and PKD1L3 to Sour Taste responses remains unclear.

  • acetic acid activates pkd1l3 pkd2l1 channel a candidate Sour Taste receptor
    Biochemical and Biophysical Research Communications, 2009
    Co-Authors: Sho Ishii, Yoshiro Ishimaru, Takumi Misaka, Mikiya Kishi, Takayuki Kaga, Keiko Abe
    Abstract:

    Abstract The polycystic kidney disease (PKD) 1L3–PKD2L1 channel is a candidate Sour Taste receptor expressed in mammalian Taste receptor cells. Various acids are reported to activate PKD channels after the removal of the acid stimuli, but little information is available on the activation of these channels by acetic acid. It was difficult to analyze the PKD channel activation by acetic acid using Ca2+ imaging experiments because this acid induces a transient and nonspecific response in cultured cells. Here, we developed a novel method to evaluate PKD channel activation by acetic acid. Nonspecific responses were observed only over a short period after the application of acetic acid. In contrast, PKD channel activation evoked by acetic acid as well as citric acid was detected even at a later time point. This method revealed that PKD1L3–PKD2L1 channel activation by acetic acid was pH-dependent and occurred when the ambient pH was

  • off response property of an acid activated cation channel complex pkd1l3 pkd2l1
    EMBO Reports, 2008
    Co-Authors: Hitoshi Inada, Yoshiro Ishimaru, Hiroaki Matsunami, Fuminori Kawabata, Tohru Fushiki, Makoto Tominaga
    Abstract:

    Ligand-gated ion channels are important in sensory and synaptic transduction. The PKD1L3–PKD2L1 channel complex is a Sour Taste receptor candidate that is activated by acids. Here, we report that the proton-activated PKD1L3–PKD2L1 ion channels have the unique ability to be activated after the removal of an acid stimulus. We refer to this property as the off-response (previously described as a delayed response). Electrophysiological analyses show that acid-induced responses are observed only after the removal of an acid solution at less than pH 3.0. A small increase in pH is sufficient for PKD1L3–PKD2L1 channel activation, after exposure to an acid at pH 2.5. These results indicate that this channel is a new type of ion channel—designated as an ‘off-channel'—which is activated during stimulus application but not gated open until the removal of the stimulus. The off-response property of PKD1L3–PKD2L1 channels might explain the physiological phenomena occurring during Sour Taste sensation.

Keiko Abe - One of the best experts on this subject based on the ideXlab platform.

  • a large increase of Sour Taste receptor cells in skn 1 deficient mice does not alter the number of their Sour Taste signal transmitting gustatory neurons
    Neuroscience Letters, 2017
    Co-Authors: Naohiro Maeda, Masataka Narukawa, Yoshiro Ishimaru, Takumi Misaka, Kurumi Yamamoto, Keiko Abe
    Abstract:

    The connections between Taste receptor cells (TRCs) and innervating gustatory neurons are formed in a mutually dependent manner during development. To investigate whether a change in the ratio of cell types that compose Taste buds influences the number of innervating gustatory neurons, we analyzed the proportion of gustatory neurons that transmit Sour Taste signals in adult Skn-1a-/- mice in which the number of Sour TRCs is greatly increased. We generated polycystic kidney disease 1 like 3-wheat germ agglutinin (pkd1l3-WGA)/Skn-1a+/+ and pkd1l3-WGA/Skn-1a-/- mice by crossing Skn-1a-/- mice and pkd1l3-WGA transgenic mice, in which neural pathways of Sour Taste signals can be visualized. The number of WGA-positive cells in the circumvallate papillae is 3-fold higher in Taste buds of pkd1l3-WGA/Skn-1a-/- mice relative to pkd1l3-WGA/Skn-1a+/+ mice. Intriguingly, the ratio of WGA-positive neurons to P2X2-expressing gustatory neurons in nodose/petrosal ganglia was similar between pkd1l3-WGA/Skn-1a+/+ and pkd1l3-WGA/Skn-1a-/- mice. In conclusion, an alteration in the ratio of cell types that compose Taste buds does not influence the number of gustatory neurons that transmit Sour Taste signals.

  • skn 1a pou2f3 specifies Taste receptor cell lineage
    Nature Neuroscience, 2011
    Co-Authors: Makoto Ohmoto, Ichiro Matsumoto, Yoshihiro Yoshihara, Masataka Narukawa, Keiko Abe
    Abstract:

    This paper describes the homeodomain transcription factor Skn-1a as a specification factor for a subset of Taste receptor cells (TRCs). Mice lacking functional Skn-1a did not have TRCs or behavioral response to sweet, umami and bitter Tastes, but instead had more TRCs that detect Sour Taste.

  • acetic acid activates pkd1l3 pkd2l1 channel a candidate Sour Taste receptor
    Biochemical and Biophysical Research Communications, 2009
    Co-Authors: Sho Ishii, Yoshiro Ishimaru, Takumi Misaka, Mikiya Kishi, Takayuki Kaga, Keiko Abe
    Abstract:

    Abstract The polycystic kidney disease (PKD) 1L3–PKD2L1 channel is a candidate Sour Taste receptor expressed in mammalian Taste receptor cells. Various acids are reported to activate PKD channels after the removal of the acid stimuli, but little information is available on the activation of these channels by acetic acid. It was difficult to analyze the PKD channel activation by acetic acid using Ca2+ imaging experiments because this acid induces a transient and nonspecific response in cultured cells. Here, we developed a novel method to evaluate PKD channel activation by acetic acid. Nonspecific responses were observed only over a short period after the application of acetic acid. In contrast, PKD channel activation evoked by acetic acid as well as citric acid was detected even at a later time point. This method revealed that PKD1L3–PKD2L1 channel activation by acetic acid was pH-dependent and occurred when the ambient pH was

Hyeon-jin Sun - One of the best experts on this subject based on the ideXlab platform.

  • Genetically stable expression of functional miraculin, a new type of alternative sweetener, in transgenic tomato plants
    Plant biotechnology journal, 2007
    Co-Authors: Hyeon-jin Sun, Megumu Yano, Hiroshi Kataoka, Hiroshi Ezura
    Abstract:

    Miraculin is a Taste-modifying protein isolated from the red berries of Richadella dulcifica, a shrub native to West Africa. Miraculin by itself is not sweet, but it is able to turn a Sour Taste into a sweet Taste. This unique property has led to increasing interest in this protein. In this article, we report the high-yield production of miraculin in transgenic tomato plants. High and genetically stable expression of miraculin was confirmed by Western blot analysis and enzyme-linked immunosorbent assay. Recombinant miraculin accumulated to high levels in leaves and fruits, up to 102.5 and 90.7 microg/g fresh weight, respectively. Purified recombinant miraculin expressed in transgenic tomato plants showed strong sweetness-inducing activity, similar to that of native miraculin. These results demonstrate that recombinant miraculin was correctly processed in transgenic tomato plants, and that this production system could be a good alternative to production from the native plant.

  • functional expression of the Taste modifying protein miraculin in transgenic lettuce
    FEBS Letters, 2006
    Co-Authors: Hyeon-jin Sun, Minlong Cui, Hiroshi Ezura
    Abstract:

    Taste-modifying proteins are a natural alternative to artificial sweeteners and flavor enhancers and have been used in some cultures for centuries. The Taste-modifying protein, miraculin, has the unusual property of being able to modify a Sour Taste into a sweet Taste. Here, we report the use of a plant expression system for the production of miraculin. A synthetic gene encoding miraculin was placed under the control of constitutive promoters and transferred to lettuce. Expression of this gene in transgenic lettuce resulted in the accumulation of significant amounts of miraculin protein in the leaves. The miraculin expressed in transgenic lettuce possessed sweetness-inducing activity. These results demonstrate that the production of miraculin in edible plants can be a good alternative strategy to enhance the availability of this protein.

Hiroaki Matsunami - One of the best experts on this subject based on the ideXlab platform.

  • Sour Taste responses in mice lacking pkd channels
    PLOS ONE, 2011
    Co-Authors: Nao Horio, Yoshiro Ishimaru, Hiroaki Matsunami, Ryusuke Yoshida, Keiko Yasumatsu, Yuchio Yanagawa, Yuzo Ninomiya
    Abstract:

    Background The polycystic kidney disease-like ion channel PKD2L1 and its associated partner PKD1L3 are potential candidates for Sour Taste receptors. PKD2L1 is expressed in type III Taste cells that respond to Sour stimuli and genetic elimination of cells expressing PKD2L1 substantially reduces chorda tympani nerve responses to Sour Taste stimuli. However, the contribution of PKD2L1 and PKD1L3 to Sour Taste responses remains unclear.

  • off response property of an acid activated cation channel complex pkd1l3 pkd2l1
    EMBO Reports, 2008
    Co-Authors: Hitoshi Inada, Yoshiro Ishimaru, Hiroaki Matsunami, Fuminori Kawabata, Tohru Fushiki, Makoto Tominaga
    Abstract:

    Ligand-gated ion channels are important in sensory and synaptic transduction. The PKD1L3–PKD2L1 channel complex is a Sour Taste receptor candidate that is activated by acids. Here, we report that the proton-activated PKD1L3–PKD2L1 ion channels have the unique ability to be activated after the removal of an acid stimulus. We refer to this property as the off-response (previously described as a delayed response). Electrophysiological analyses show that acid-induced responses are observed only after the removal of an acid solution at less than pH 3.0. A small increase in pH is sufficient for PKD1L3–PKD2L1 channel activation, after exposure to an acid at pH 2.5. These results indicate that this channel is a new type of ion channel—designated as an ‘off-channel'—which is activated during stimulus application but not gated open until the removal of the stimulus. The off-response property of PKD1L3–PKD2L1 channels might explain the physiological phenomena occurring during Sour Taste sensation.

  • the candidate Sour Taste receptor pkd2l1 is expressed by type iii Taste cells in the mouse
    Chemical Senses, 2008
    Co-Authors: Shinji Kataoka, Yoshiro Ishimaru, Ruibiao Yang, Hiroaki Matsunami, Jean Sevigny, John C Kinnamon, Thomas E. Finger
    Abstract:

    The transient receptor potential (TRP) channel, PKD2L1, is reported to be a candidate receptor for Sour Taste based on molecular biological and functional studies. Here, we investigated the expression pattern of PKD2L1-immunoreactivity (IR) in Taste buds of the mouse. PKD2L1-IR is present in a few elongate cells in each Taste bud as reported previously. The PKD2L1-expressing cells are different from those expressing PLCβ2, a marker of Type II cells. Likewise PKD2L1-immunoreactive Taste cells do not express ecto-ATPase which marks Type I cells. The PKD2L1 positive cells are immunoreactive for NCAM, serotonin, PGP-9.5 (ubiquitin carboxy terminal transferase) and chromogranin A, all of which are present in Type III Taste cells. At the ultrastructural level, PKD2L1-immunoreactive cells form synapses onto afferent nerve fibers, another feature of Type III Taste cells. These results are consistent with the idea that different Taste cells in each Taste bud perform distinct functions. We suggest that Type III cells are necessary for transduction and/or transmission of information about “Sour”, but have little or no role in transmission of Taste information of other Taste qualities.

  • transient receptor potential family members pkd1l3 and pkd2l1 form a candidate Sour Taste receptor
    Proceedings of the National Academy of Sciences of the United States of America, 2006
    Co-Authors: Yoshiro Ishimaru, Makoto Tominaga, Hitoshi Inada, Momoka Kubota, Hanyi Zhuang, Hiroaki Matsunami
    Abstract:

    Animals use their gustatory systems to evaluate the nutritious value, toxicity, sodium content, and acidity of food. Although characterization of molecular identities that receive Taste chemicals is essential, molecular receptors underlying Sour Taste sensation remain unclear. Here, we show that two transient receptor potential (TRP) channel members, PKD1L3 and PKD2L1, are coexpressed in a subset of Taste receptor cells in specific Taste areas. Cells expressing these molecules are distinct from Taste cells having receptors for bitter, sweet, or umami tastants. The PKD2L1 proteins are accumulated at the Taste pore region, where Taste chemicals are detected. PKD1L3 and PKD2L1 proteins can interact with each other, and coexpression of the PKD1L3 and PKD2L1 is necessary for their functional cell surface expression. Finally, PKD1L3 and PKD2L1 are activated by various acids when coexpressed in heterologous cells but not by other classes of tastants. These results suggest that PKD1L3 and PKD2L1 heteromers may function as Sour Taste receptors.