Researcher basic information

• Ph.D (Veterinary Medicine), Hokkaido University, Mar. 2009

• https://researchmap.jp/read0154023?lang=en

• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201101008731937823

• 50596864

• 201101008731937823

• 消化管生理学
• 酸塩基平衡
• ion channel
• transporter

• Life Science, Physiology, ion channel
• Life Science, Veterinary medical science

• Bachelor's degree program, School of Veterinary Medicine
• Doctoral (PhD) degree program, Graduate School of Veterinary Medicine

Research activity information

• Sep. 2011, 日本獣医学会 生理学・生化学分科会, 生理学・生化学分科会奨励賞
  山口 聡一郎

• Transient changes in body weight and behavior during the placentation period in non-human primates and rodents
  Saori Yano-Nashimoto; Kazutaka Shinozuka; Takuma Kurachi; Katsura Kagawa; Kentaro Q. Sakamoto; Yuko Shigeno; Kimie Niimi; Kumi O. Kuroda; Soichiro Yamaguchi
  Scientific Reports, 16, 1, 8162, Springer Science and Business Media LLC, 25 Mar. 2026, [Peer-reviewed], [Last author], [International Magazine]
  Scientific journal, Abstract
  
  During early pregnancy, many women experience physical changes, including nausea and vomiting of pregnancy (NVP), which negatively impact their quality of life. However, the absence of model animals has limited our understanding of such pregnancy-associated physiological changes. Here, we examined pregnancy-associated metabolic and behavioral changes in common marmosets and mice. Marmosets exhibited a transient weight decrease during the period of placental development in approximately 22% of pregnancies. Some marmosets repeatedly showed transient weight loss across multiple pregnancies, suggesting individual variations in the likelihood of pregnancy-associated weight loss. Although mice did not show apparent alteration in body weight, they exhibited a slowdown in food intake and alterations in locomotor activity during the corresponding phase. The observed transient changes in pregnant marmosets and mice may provide a basis for generating hypotheses regarding physiological changes associated with placentation.
• Human chorionic gonadotropin inhibits locomotion but not food intake independently of the area postrema and the nucleus tractus solitarius in female mice
  Masami Anan; Katsura Kagawa; Yuko Okamatsu-Ogura; Soichiro Yamaguchi; Saori Yano-Nashimoto
  Physiology & Behavior, 303, 115151, 115151, Elsevier BV, Jan. 2026, [Peer-reviewed]
  Scientific journal
• Functional expression of the proton channel OTOP1 in brown adipocytes
  MD Mominul Islam; Omi Sasaki; Saori Yano-Nashimoto; Yuko Okamatsu-Ogura; Soichiro Yamaguchi
  Biochemical and Biophysical Research Communications, Nov. 2025, [Peer-reviewed], [Last author, Corresponding author]
  Scientific journal
• Transmembrane channel-like 4 (TMC4) could act as a negative regulator of KCNQ1 (Kv7.1) potassium channel.
  Hirota Aoyagi; Koya Kawaguchi; Saori Yano-Nashimoto; Soichiro Yamaguchi
  Biochimica et biophysica acta. Biomembranes, 184460, 184460, 02 Oct. 2025, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
  English, Scientific journal, TMC4 is a member of the transmembrane channel-like (TMC) protein family. In this family, TMC1 and TMC2 are thought to form the mechano-electrical transduction (MET) channel in the inner ear. On the other hand, the intrinsic functions of the other TMC family members (TMC3-8) are largely unknown. KCNQ1 (Kv7.1) channel is a voltage-gated potassium channel and plays crucial physiological roles with its auxiliary subunits, KCNE proteins (e.g. KCNQ1/KCNE1 complex contributes to cardiac repolarization, and KCNQ1/KCNE3 complex participates in epithelial ion transport). Recently, it was reported that TMC1 and TMC2 interacted with KCNQ1 and suppressed its K+ currents. However, the relationships between KCNQ1 and the other TMC proteins have not been examined. Here, we show a novel interaction and a functional association between overexpressed TMC4 and KCNQ1. The Bead Halo assay and FRET analysis revealed the physical interaction between these two proteins. Whole-cell patch clamp recording demonstrated that co-expression of TMC4 reduced KCNQ1 current densities without altering their voltage dependence and activation kinetics. This effect was also observed in the KCNQ1/KCNE1 and KCNQ1/KCNE3 channel complexes. A structural prediction using AlphaFold-Multimer suggested possible interaction sites between TMC4 and KCNQ1. Mutageneses, followed by patch clamp recording, suggested that specific amino acid residues at these sites contribute to the inhibitory effect of TMC4. These results indicate that TMC4 could function as a negative regulator of the KCNQ1 channel. Our findings could enhance the understanding of KCNQ1 channel regulation and propose potential research directions on the function of TMC4 under various physiological and pathological conditions.
• Epidermal growth factor increases cystathionine β-synthase expression in cultured embryonic spinal cord cells.
  Ryota Eguchi; Yuya Higashida; Mizuki Oouchi; Soichiro Yamaguchi; Ken-Ichi Otsuguro
  In vitro cellular & developmental biology. Animal, 61, 4, 416, 424, Apr. 2025, [Peer-reviewed], [International Magazine]
  English, Scientific journal, In the central nervous system (CNS), cystathionine β-synthase (CBS) is localized in astrocytes. CBS degrades cytotoxic homocysteine and produces cytoprotective hydrogen sulfide; thus the proper expression of CBS is required to maintain CNS functions. CBS expression is very low at the late embryonic stage and increases after birth. This study examined CBS expression in cultured spinal cord cells derived from fetal rats. Treatment of spinal cord cells with epidermal growth factor (EGF) promoted the proliferation and maturation of astrocytes during development. EGF (30 ng/ml, 4 days) increased CBS protein expression and the number of CBS-expressing astrocytes in the culture. A high cell density also increased CBS expression, and EGF was able to increase CBS expression when cellular proliferation was inhibited. The EGF receptor was predominately expressed in neural stem cells rather than astrocytes. These results suggest that EGF acts on neural stem cells, leading to increase in CBS-expressing astrocytes. This effect may reflect the maturation process of astrocytes during embryonic development.
• A proton channel, Otopetrin 1 (OTOP1) is N-glycosylated at two asparagine residues in third extracellular loop.
  Omi Sasaki; Saori Yano-Nashimoto; Soichiro Yamaguchi
  Journal of cellular physiology, 239, 9, e31403, Sep. 2024, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
  English, Scientific journal, A proton (H+) channel, Otopetrin 1 (OTOP1) is an acid sensor in the sour taste receptor cells. Although OTOP1 is known to be activated by extracellular acid, no posttranslational modification of OTOP1 has been reported. As one of the posttranslational modifications, glycosylation is known to modulate many ion channels. In this study, we investigated whether OTOP1 is glycosylated and how the glycosylation affects OTOP1 function. Pharmacological and enzymatic examinations (using an N-glycosylation inhibitor, tunicamycin and peptide: N-glycanase F [PNGase F]) revealed that overexpressed mouse OTOP1 was N-glycosylated. As the N-glycans were Endoglycosidase H (Endo H)-sensitive, they were most likely high-mannose type. A site-directed mutagenesis approach revealed that both two asparagine residues (N238 and N251) in the third extracellular loop between the fifth transmembrane region and the sixth transmembrane region (L5-6) were the glycosylation sites. Prevention of the glycosylations by the mutations of the asparagine residues or by tunicamycin treatment diminished the whole-cell OTOP1 current densities. The results of cell surface biotinylation assay showed that the prevention of the glycosylations reduced the surface expression of OTOP1 at the plasma membrane. These results indicate that mouse OTOP1 is N-glycosylated at N238 and N251, and that the glycosylations are necessary for OTOP1 to show the maximum degree of H+ current densities at the plasma membrane through promoting its targeting to the plasma membrane. These findings on glycosylations of OTOP1 will be a part of a comprehensive understanding on the regulations of OTOP1 function., 40246914
• Cibacron blue 3G-A is a novel inhibitor of Otopetrin 1 (OTOP1), a proton channel.
  Md Mominul Islam; Omi Sasaki; Saori Yano-Nashimoto; Yuko Okamatsu-Ogura; Soichiro Yamaguchi
  Biochemical and biophysical research communications, 665, 64, 70, 12 Jul. 2023, [Last author, Corresponding author], [International Magazine]
  English, Scientific journal, Otopetrin 1 (OTOP1) is a proton (H+) channel which detects acidic stimuli in sour taste receptor cells and plays some sort of role in the formation of otoconia in the inner ear. Although it is known that zinc ion (Zn2+) inhibits OTOP1, Zn2+ requires high concentrations (mM order) to inhibit OTOP1 sufficiently, and no other inhibitors have been found. Therefore, to identify a novel inhibitor, we screened a chemical library (LOPAC1280) by whole-cell patch clamp recordings, measuring proton currents of heterologously-expressed mouse OTOP1. From the screening, we found that reactive blue 2 inhibited OTOP1 currents. Further evaluations of three analogues of reactive blue 2 revealed that cibacron blue 3G-A potently inhibited OTOP1 currents. Cibacron blue 3G-A inhibited OTOP1 currents in a concentration-dependent manner, and its 50% inhibitory concentration (IC50) and the Hill coefficient were 5.0 μM and 1.1, respectively. The inhibition of OTOP1 currents by cibacron blue 3G-A was less affected by extracellular anion compositions, membrane potentials, and low pH than the inhibition by Zn2+. These results suggest that the inhibition of OTOP1 by cibacron blue 3G-A is neither likely to be a pore-blocking inhibition nor a competitive inhibition. Furthermore, our findings revealed that cibacron blue 3G-A can be used as a novel inhibitor of OTOP1 especially under the conditions in which OTOP1 activity is evaluated such as low pH.
• The cytosolic N-terminal region of heterologously-expressed transmembrane channel-like protein 1 (TMC1) can be cleaved in HEK293 cells.
  Soichiro Yamaguchi; Maho Kamino; Maho Hamamura; Ken-Ichi Otsuguro
  PloS one, 18, 6, e0287249, 2023, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Transmembrane channel-like protein 1 (TMC1) is a transmembrane protein forming mechano-electrical transduction (MET) channel, which transduces mechanical stimuli into electrical signals at the top of stereocilia of hair cells in the inner ear. As an unexpected phenomenon, we found that the cytosolic N-terminal (Nt) region of heterologously-expressed mouse TMC1 (mTMC1) was localized in nuclei of a small population of the transfected HEK293 cells. This raised the possibility that the Nt region of heterologously-expressed mTMC1 was cleaved and transported into the nucleus. To confirm the cleavage, we performed western blot analyses. The results revealed that at least a fragment of the Nt region was produced from heterologously-expressed mTMC1. Site-directed mutagenesis experiments identified amino acid residues which were required to produce the fragment. The accumulation of the heterologously-expressed Nt fragment into the nuclei depended on nuclear localization signals within the Nt region. Furthermore, a structural comparison showed a similarity between the Nt region of mTMC1 and basic region leucine zipper (bZIP) transcription factors. However, transcriptome analyses using a next-generation sequencer showed that the heterologously-expression of the Nt fragment of mTMC1 hardly altered expression levels of genes. Although it is still unknown what is the precise mechanism and the physiological significance of this cleavage, these results showed that the cytosolic Nt region of heterologously-expressed mTMC1 could be cleaved in HEK293 cells. Therefore, it should be taken into account that the cleavage of Nt region might influence the functional analysis of TMC1 by the heterologous-expression system using HEK293 cells.
• Opposing functions of α- and β-adrenoceptors in the formation of processes by cultured astrocytes.
  Taisuke Kitano; Ryota Eguchi; Yuko Okamatsu-Ogura; Soichiro Yamaguchi; Ken-Ichi Otsuguro
  Journal of pharmacological sciences, 145, 3, 228, 240, (公社)日本薬理学会, Mar. 2021, [Peer-reviewed], [Domestic magazines]
  English, Astrocytes are glial cells with numerous fine processes which are important for the functions of the central nervous system. The activation of β-adrenoceptors induces process formation of astrocytes via cyclic AMP (cAMP) signaling. However, the role of α-adrenoceptors in the astrocyte morphology has not been elucidated. Here, we examined it by using cultured astrocytes from neonatal rat spinal cords and cortices. Exposure of these cells to noradrenaline and the β-adrenoceptor agonist isoproterenol increased intracellular cAMP levels and induced the formation of processes. Noradrenaline-induced process formation was enhanced with the α1-adrenoceptor antagonist prazosin and α2-adrenoceptor antagonist atipamezole. Atipamezole also enhanced noradrenaline-induced cAMP elevation. Isoproterenol-induced process formation was not inhibited by the α1-adrenoceptor agonist phenylephrine but was inhibited by the α2-adrenoceptor agonist dexmedetomidine. Dexmedetomidine also inhibited process formation induced by the adenylate cyclase activator forskolin and the membrane-permeable cAMP analog dibutyryl-cAMP. Moreover, dexmedetomidine inhibited cAMP-independent process formation induced by adenosine or the Rho-associated kinase inhibitor Y27632. In the presence of propranolol, noradrenaline inhibited Y27632-induced process formation, which was abolished by prazosin or atipamezole. These results demonstrate that α-adrenoceptors inhibit both cAMP-dependent and -independent astrocytic process formation.
• Hydrogen sulfide induces Ca2+ release from the endoplasmic reticulum and suppresses ATP-induced Ca2+ signaling in rat spinal cord astrocytes.
  Takeshi Nii; Ryota Eguchi; Soichiro Yamaguchi; Ken-Ichi Otsuguro
  European journal of pharmacology, 891, 173684, 173684, 15 Jan. 2021, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Hydrogen sulfide (H2S) has a variety of physiological functions. H2S reportedly increases intracellular Ca2+ concentration ([Ca2+]i) in astrocytes. However, the precise mechanism and functional role of this increase are not known. Here, we examined the effects of H2S on [Ca2+]i in astrocytes from the rat spinal cord and whether H2S affects ATP-induced Ca2+ signaling, which is known to be involved in synaptic function. Na2S (150 μM), an H2S donor, produced a nontoxic increase in [Ca2+]i. The [Ca2+]i increase by Na2S was inhibited by Ca2+ depletion in the endoplasmic reticulum (ER) but not by removal of extracellular Ca2+, indicating that H2S releases Ca2+ from the ER. On the other hand, Na2S inhibited ATP-induced [Ca2+]i increase when Na2S clearly increased [Ca2+]i in the astrocytes, which was not suppressed by a reducing agent. In addition, Na2S had no effect on intracellular cyclic AMP (cAMP) level. These results indicate that oxidative post-translational modification of proteins and cAMP are not involved in the inhibitory effect of H2S on ATP-induced Ca2+ signaling. We conclude that H2S indirectly inhibits ATP-induced Ca2+ signaling by decreasing Ca2+ content in the ER in astrocytes. In this way, H2S may influence intercellular communication between astrocytes and neurons, thereby contributing to neuronal signaling in the nervous system.
• A Mechanosensitive Channel, Mouse Transmembrane Channel-Like Protein 1 (Mtmc1) Is Translated from a Splice Variant mTmc1ex1 but Not from the Other Variant mTmc1ex2.
  Soichiro Yamaguchi; Maho Hamamura; Ken-Ichi Otsuguro
  International journal of molecular sciences, 21, 18, 04 Sep. 2020, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Mechanical stimuli caused by sound waves are detected by hair cells in the cochlea through the opening of mechanoelectrical transduction (MET) channels. Transmembrane channel-like protein 1 (TMC1) has been revealed to be the pore-forming component of the MET channel. The two splice variants for mouse Tmc1 (mTmc1ex1 and mTmc1ex2) were reported to be expressed in the cochlea of infant mice, though only the sequence of mTmc1ex2 had been deposited in GenBank. However, due to the presence of an upstream open reading frame (uORF) and the absence of a typical Kozak sequence in mTmc1ex2, we questioned whether mTMC1 was translated from mTmc1ex2. Therefore, in this study, we evaluated which splice variant was protein-coding mRNA. Firstly, the results of RT-PCR and cDNA cloning of mTmc1 using mRNA isolated from the cochlea of five-week-old mice suggested that more Tmc1ex1 were expressed than mTmc1ex2. Secondly, mTMC1 was translated from mTmc1ex1 but not from mTmc1ex2 in a heterologous expression system. Finally, analyses using site-directed mutagenesis revealed that the uORF and the weak Kozak sequence in mTmc1ex2 prevented the translation of mTMC1 from mTmc1ex2. These results suggest that mTmc1ex1 plays a main role in the expression of mTMC1 in the mouse cochlea, and therefore, mTmc1ex1 should be the mRNA for mTMC1 hereafter.
• TRPM4 and TRPM5 Channels Share Crucial Amino Acid Residues for Ca2+ Sensitivity but Not Significance of PI(4,5)P2.
  Soichiro Yamaguchi; Akira Tanimoto; Shinsuke Iwasa; Ken-Ichi Otsuguro
  International journal of molecular sciences, 20, 8, 24 Apr. 2019, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Transient receptor potential melastatin member 4 (TRPM4) and 5 (TRPM5) channels are Ca2+-activated nonselective cation channels. Intracellular Ca2+ is the most important regulator for them to open, though PI(4,5)P2, a membrane phosphoinositide, has been reported to regulate their Ca2+-sensitivities. We previously reported that negatively-charged amino acid residues near and in the TRP domain are necessary for the normal Ca2+ sensitivity of TRPM4. More recently, a cryo-electron microscopy structure of Ca2+-bound (but closed) TRPM4 was reported, proposing a Ca2+-binding site within an intracellular cavity formed by S2 and S3. Here, we examined the functional effects of mutations of the amino acid residues related to the proposed Ca2+-binding site on TRPM4 and also TRPM5 using mutagenesis and patch clamp techniques. The mutations of the amino acid residues of TRPM4 and TRPM5 reduced their Ca2+-sensitivities in a similar way. On the other hand, intracellular applications of PI(4,5)P2 recovered Ca2+-sensitivity of desensitized TRPM4, but its effect on TRPM5 was negligible. From these results, the Ca2+-binding sites of TRPM4 and TRPM5 were shown to be formed by the same amino acid residues by functional analyses, but the impact of PI(4,5)P2 on the regulation of TRPM5 seemed to be smaller than that on the regulation of TRPM4.
• The α_2A -adrenoceptor subtype plays a key role in the analgesic and sedative effects of xylazine.
  Kitano T; Kobayashi T; Yamaguchi S; Otsuguro KI
  Journal of veterinary pharmacology and therapeutics, 42, 2, 243, 247, Wiley, Mar. 2019, [Peer-reviewed]
  Scientific journal
• Fibroblast growth factor 2 modulates extracellular purine metabolism by upregulating ecto-5'-nucleotidase and adenosine deaminase in cultured rat spinal cord astrocytes.
  Eguchi R; Yamaguchi S; Otsuguro KI
  Journal of pharmacological sciences, 139, 2, 98, 104, Feb. 2019, [Peer-reviewed]
• IL-1β augments H2S-induced increase in intracellular Ca2+ through polysulfides generated from H2S/NO interaction
  Ayako Ujike; Tomoki Kuraishi; Soichiro Yamaguchi; Ryota Eguchi; Taisuke Kitano; Jumpei Kamise; Shigeo Ito; Ken-ichi Otsuguro
  European Journal of Pharmacology, 821, 88, 96, Elsevier B.V., 15 Feb. 2018, [Peer-reviewed]
  English, Scientific journal
• A mechanically activated ion channel is functionally expressed in the MrgprB4 positive sensory neurons, which detect stroking of hairy skin in mice
  Soichiro Yamaguchi; Ken-ichi Otsuguro
  NEUROSCIENCE LETTERS, 653, 139, 145, Jul. 2017, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Hydrogen sulfide activates TRPA1 and releases 5-HT from epithelioid cells of the chicken thoracic aorta
  Dugar Delgermurun; Soichiro Yamaguchi; Osamu Ichii; Yasuhiro Kon; Shigeo Ito; Ken-ichi Otsuguro
  COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY, 187, 43, 49, Sep. 2016, [Peer-reviewed]
  English, Scientific journal
• Endogenous 5-HT outflow from chicken aorta by 5-HT uptake inhibitors and amphetamine derivatives
  Dugar Delgermurun; Shigeo Ito; Toshio Ohta; Soichiro Yamaguchi; Ken-ichi Otsuguro
  JOURNAL OF VETERINARY MEDICAL SCIENCE, 78, 1, 71, 76, Jan. 2016, [Peer-reviewed]
  English
• An adenosine kinase inhibitor, ABT-702, inhibits spinal nociceptive transmission by adenosine release via equilibrative nucleoside transporters in rat
  Ken-ichi Otsuguro; Yuki Tomonari; Saori Otsuka; Soichiro Yamaguchi; Yasuhiro Kon; Shigeo Ito
  NEUROPHARMACOLOGY, 97, 160, 170, Oct. 2015, [Peer-reviewed]
  English, Scientific journal
• Bidirectional effects of hydrogen sulfide via ATP-sensitive K+ channels and transient receptor potential A1 channels in RIN14B cells
  Ayako Ujike; Ken-ichi Otsuguro; Ryo Miyamoto; Soichiro Yamaguchi; Shigeo Ito
  EUROPEAN JOURNAL OF PHARMACOLOGY, 764, 463, 470, Oct. 2015, [Peer-reviewed]
  English, Scientific journal
• Contribution of alpha(2A)-adrenoceptor subtype to effect of dexmedetomidine and xylazine on spinal synaptic transmission of mice
  Takeshi Kobayashi; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito
  EUROPEAN JOURNAL OF PHARMACOLOGY, 761, 321, 329, Aug. 2015, [Peer-reviewed]
  English, Scientific journal
• Neuronal regulation of expression of hydrogen sulfide-producing enzyme cystathionine beta-synthase in rat spinal cord astrocytes
  Ryo Miyamoto; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito
  NEUROSCIENCE RESEARCH, 97, 52, 59, Aug. 2015, [Peer-reviewed]
  English, Scientific journal
• Different mechanisms of extracellular adenosine accumulation by reduction of the external Ca2+ concentration and inhibition of adenosine metabolism in spinal astrocytes
  Ryota Eguchi; Sanae Akao; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito
  JOURNAL OF PHARMACOLOGICAL SCIENCES, 128, 1, 47, 53, May 2015, [Peer-reviewed]
  English, Scientific journal
• Negatively Charged Amino Acids Near and in Transient Receptor Potential (TRP) Domain of TRPM4 Channel Are One Determinant of Its Ca2+ Sensitivity
  Soichiro Yamaguchi; Akira Tanimoto; Ken-ichi Otsuguro; Hiroshi Hibino; Shigeo Ito
  JOURNAL OF BIOLOGICAL CHEMISTRY, 289, 51, 35265, 35282, Dec. 2014, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Contribution of cysteine aminotransferase and mercaptopyruvate sulfurtransferase to hydrogen sulfide production in peripheral neurons
  Ryo Miyamoto; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito
  JOURNAL OF NEUROCHEMISTRY, 130, 1, 29, 40, Jul. 2014, [Peer-reviewed]
  English, Scientific journal
• AHCYL2 (long-IRBIT) as a potential regulator of the electrogenic Na+-HCO3- cotransporter NBCe1-B
  Soichiro Yamaguchi; Toru Ishikawa
  FEBS LETTERS, 588, 5, 672, 677, Mar. 2014, [Peer-reviewed], [Lead author]
  English, Scientific journal
• The mechanism underlying maintenance of the endocochlear potential by the K+ transport system in fibrocytes of the inner ear
  Naoko Adachi; Takamasa Yoshida; Fumiaki Nin; Genki Ogata; Soichiro Yamaguchi; Toshihiro Suzuki; Sizuo Komune; Yasuo Hisa; Hiroshi Hibino; Yoshihisa Kurachi
  JOURNAL OF PHYSIOLOGY-LONDON, 591, 18, 4459, 4472, Sep. 2013, [Peer-reviewed]
  English, Scientific journal
• IRBIT reduces the apparent affinity for intracellular Mg2+ in inhibition of the electrogenic Na+-HCO3- cotransporter NBCe1-B
  Soichiro Yamaguchi; Toru Ishikawa
  BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 424, 3, 433, 438, Aug. 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Transient Receptor Potential Mucolipin 1 (TRPML1) and Two-pore Channels Are Functionally Independent Organellar Ion Channels
  Soichiro Yamaguchi; Archana Jha; Qin Li; Abigail A. Soyombo; George D. Dickinson; Dev Churamani; Eugen Brailoiu; Sandip Patel; Shmuel Muallem
  JOURNAL OF BIOLOGICAL CHEMISTRY, 286, 26, 22934, 22942, Jul. 2011, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Properties of the TRPML3 Channel Pore and Its Stable Expansion by the Varitint-Waddler-causing Mutation
  Hyun Jin Kim; Soichiro Yamaguchi; Qin Li; Insuk So; Shmuel Muallem
  JOURNAL OF BIOLOGICAL CHEMISTRY, 285, 22, 16513, 16520, May 2010, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Functional Characterization of a ClC-2-Like Cl- Conductance in Surface Epithelial Cells of Rat Rectal Colon
  Akihiro Inagaki; Soichiro Yamaguchi; Hiromi Takahashi-Iwanaga; Toshihiko Iwanaga; Toru Ishikawa
  JOURNAL OF MEMBRANE BIOLOGY, 235, 1, 27, 41, May 2010, [Peer-reviewed]
  English, Scientific journal
• Opening the TRPML Gates
  Soichiro Yamaguchi; Shmuel Muallem
  CHEMISTRY & BIOLOGY, 17, 3, 209, 210, Mar. 2010, [Peer-reviewed]
  English
• Aberrant Ca2+ handling in lysosomal storage disorders
  Kirill Kiselyov; Soichiro Yamaguchi; Christopher W. Lyons; Shmuel Muallem
  CELL CALCIUM, 47, 2, 103, 111, Feb. 2010, [Peer-reviewed]
  English
• The electrogenic Na+-HCO3- cotransporter NBCe1-B is regulated by intracellular Mg2+
  Soichiro Yamaguchi; Toru Ishikawa
  BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 376, 1, 100, 104, Nov. 2008, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Electrophysiological characterization of native Na+-HCO3- cotransporter current in bovine parotid acinar cells
  S Yamaguchi; T Ishikawa
  JOURNAL OF PHYSIOLOGY-LONDON, 568, 1, 181, 197, Oct. 2005, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Amiloride-sensitive epithelial Na+ channel currents in surface cells of rat rectal colon
  A Inagaki; S Yamaguchi; T Ishikawa
  AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY, 286, 2, C380, C390, Feb. 2004, [Peer-reviewed]
  English, Scientific journal

• 牛耳下腺腺房細胞の管腔側膜にCI-/HCO3-交換輸送体であるSLC26A6が機能発現する
  井上 龍生; 山口 聡一郎; 矢野 沙織[梨本], 日本獣医学会学術集会講演要旨集, 164回, [IO, 27], Sep. 2021
  (公社)日本獣医学会, Japanese
• 強制発現系におけるtransmembrane channel-like protein 1(TMC1)の細胞内N端領域の核移行と転写調節(A cytosolic N-terminal region of Transmembrane Channel-like protein 1 (TMC1) is cleaved and imported into the nucleus in an overexpression system)
  Yamaguchi Soichiro; Kamino Maho; Hamamura Maho; Otsuguro Ken-ichi, The Journal of Physiological Sciences, 70, Suppl.1, S107, S107, Mar. 2020
  (一社)日本生理学会, English
• TMC1の細胞内N端領域における核移行機序および切断部位の同定
  神野 真帆; 濱村 眞帆; 山口 聡一郎; 乙黒 兼一, 日本獣医学会学術集会講演要旨集, 162回, 497, 497, Aug. 2019
  (公社)日本獣医学会, Japanese
• アストロサイトの突起形成におけるα2アドレナリン受容体の役割
  北野 泰佑; 江口 遼太; 山口 聡一郎; 乙黒 兼一, 日本獣医学会学術集会講演要旨集, 162回, 499, 499, Aug. 2019
  (公社)日本獣医学会, Japanese
• ラット脊髄アストロサイトにおけるH2S誘発性Ca2+上昇機構
  新居 剛; 江口 遼太; 山口 聡一郎; 乙黒 兼一, 日本獣医学会学術集会講演要旨集, 162回, 499, 499, Aug. 2019
  (公社)日本獣医学会, Japanese
• TRPM4およびTRPM5チャネルのCa2+結合部位に関する機能分析(Functional analyses for a Ca2+ binding site of TRPM4 and TRPM5 channels)
  Yamaguchi Soichiro; Tanimoto Akira; Iwasa Shinsuke; Otsuguro Ken-ichi, The Journal of Physiological Sciences, 69, Suppl.1, S166, S166, Jun. 2019
  (一社)日本生理学会, English
• FGF2によるアストロサイトの細胞外アデノシンデアミナーゼ発現および活性の増強作用
  江口 遼太; 山口 聡一郎; 乙黒 兼一, 日本獣医学会学術集会講演要旨集, 161回, 465, 465, Aug. 2018
  (公社)日本獣医学会, Japanese
• 低Ca2+によるアストロサイトの細胞外アデノシン蓄積に対するFGF2の影響
  江口 遼太; 山口 聡一郎; 乙黒 兼一, 日本獣医学会学術集会講演要旨集, 160回, 503, 503, Aug. 2017
  (公社)日本獣医学会, Japanese
• キシラジンによるブタα2Aアドレナリン受容体活性化作用
  北野 泰佑; 小林 武志; 山口 聡一郎; 乙黒 兼一, 日本獣医学会学術集会講演要旨集, 160回, 503, 503, Aug. 2017
  (公社)日本獣医学会, Japanese
• 鶏胸大動脈におけるグロムス細胞からの5-HT放出に対するH2Sの作用(Effect of H2S on 5-HT release from glomus cells in the chicken thoracic aorta)
  Delgermurun Dugar; 山口 聡一郎; 市居 修; 昆 泰寛; 伊藤 茂男; 乙黒 兼一, 日本獣医学会学術集会講演要旨集, 159回, 495, 495, Aug. 2016
  (公社)日本獣医学会, English
• 5-HT取り込み阻害剤とamphetamine誘導体がトリ大動脈体の5-HT流出に与える影響(Effects of 5-HT uptake inhibitors and amphetamine derivatives on 5-HT outflow from chicken aortic body)
  Dugar Delgermurun; Ito Shigeo; Yamaguchi Soichiro; Ohta Toshio; Otsuguro Ken-ichi, Journal of Pharmacological Sciences, 130, 3Suppl., S190, S190, Mar. 2016
  (公社)日本薬理学会, English
• ラット脊髄アストロサイトでの虚血刺激によるadenosineの細胞外蓄積(Extracellular accumulation of adenosine by ischemic stimulations in rat spinal astrocytes)
  Eguchi Ryota; Yamaguchi Soichiro; Otsuguro Ken-ichi, Journal of Pharmacological Sciences, 130, 3Suppl., S227, S227, Mar. 2016
  (公社)日本薬理学会, English
• 炎症性サイトカインがRIN14B細胞におけるH2S誘発性のCa2+反応に及ぼす影響(Effect of pro-inflammatory cytokine on H2S-induced Ca2+ responses in RIN14B cells)
  Ujike Ayako; Yamaguchi Soichiro; Ito Shigeo; Otsuguro Ken-ichi, Journal of Pharmacological Sciences, 130, 3Suppl., S251, S251, Mar. 2016
  (公社)日本薬理学会, English
• MrgprB4陽性後根神経節神経における細胞膨張によるCa2+流入経路(A swelling-induced Ca2+ entry pathway in MrgprB4+ dorsal root ganglion neurons)
  Yamaguchi Soichiro; Otsuguro Ken-ichi, The Journal of Physiological Sciences, 66, Suppl.1, S159, S159, Mar. 2016
  (一社)日本生理学会, English
• ラット脊髄における硫化水素産生酵素CBSの発現はニューロンにより維持される
  宮本 亮; 乙黒 兼一; 山口 聡一郎; 伊藤 茂男, 日本生化学会大会・日本分子生物学会年会合同大会講演要旨集, 88回・38回, [1P0515], [1P0515], Dec. 2015
  (公社)日本生化学会, Japanese
• ニューロンによるラット脊髄アストロサイトの硫化水素産生酵素の発現調節
  宮本 亮; 乙黒 兼一; 山口 聡一郎; 伊藤 茂男, 日本獣医学会学術集会講演要旨集, 158回, 436, 436, Aug. 2015
  (公社)日本獣医学会, Japanese
• 5-HT取り込み阻害剤とアンフェタミン誘導体による鶏大動脈からの5-HT流出(5-HT outflow from chicken aorta by 5-HT uptake inhibitors and amphetamine derivatives)
  Dugar Delgermurun; 山口 聡一郎; 太田 利男; 乙黒 兼一; 伊藤 茂男, 日本獣医学会学術集会講演要旨集, 158回, 436, 436, Aug. 2015
  (公社)日本獣医学会, English
• ラット脊髄アストロサイトにおける細胞外Ca2+低下によるアデノシンの細胞外蓄積に対するギャップ結合ヘミチャネルの関与(Gap junction hemichannels contribute to extracellular accumulation of adenosine by external Ca2+ reduction in rat spinal astrocytes)
  Eguchi Ryota; Akao Sanae; Otsuguro Ken-ichi; Yamaguchi Soichiro; Ito Shigeo, Journal of Pharmacological Sciences, 128, 3Suppl., S157, S157, Jul. 2015
  (公社)日本薬理学会, English
• ラット脊髄アストロサイトにおける硫化水素産生は神経シグナルにより制御される(Hydrogen sulfide production is controled by neuronal signals in rat spinal cord astrrocytes)
  Miyamoto Ryo; Otsuguro Ken-ichi; Yamaguchi Soichiro; Ito Shigeo, Journal of Pharmacological Sciences, 128, 3Suppl., S158, S158, Jul. 2015
  (公社)日本薬理学会, English
• TRPM4チャネルの一過性受容器電位(TRP)ドメイン内及び近辺の酸性アミノ酸はその正常なCa2+感受性の維持に必要である(Acidic amino acids near and in Transient Receptor Potential (TRP) domain of TRPM4 channel are required for maintaining its normal Ca2+ sensitivity)
  Yamaguchi Soichiro; Tanimoto Akira; Otsuguro Ken-ichi; Hibino Hiroshi; Ito Shigeo, The Journal of Physiological Sciences, 65, Suppl.1, S113, S113, Mar. 2015
  (一社)日本生理学会, English
• 脊髄アストロサイトのCa2+除去下で見られる細胞外アデノシン増加におけるギャップジャンクションヘミチャネルの関与
  江口 遼太; 増本 早苗; 乙黒 兼一; 山口 聡一郎; 伊藤 茂男, 日本獣医学会学術集会講演要旨集, 157回, 521, 521, Aug. 2014
  (公社)日本獣医学会, Japanese
• 細胞内Ca2+によって活性化されるTRPM4チャネルの二価陽イオン結合部位の解析
  山口 聡一郎; 谷本 章; 乙黒 兼一; 伊藤 茂男, 日本獣医学会学術集会講演要旨集, 157回, 521, 521, Aug. 2014
  (公社)日本獣医学会, Japanese
• CYSTEINE AMINOTRANSFERASE AND MERCAPTOPYRUVATE SULFURTRANSFERASE CONTRIBUTE TO HYDROGEN SULFIDE PRODUCTION IN THE PERIPHERAL NERVOUS SYSTEM
  R. Miyamoto; K. Otsuguro; S. Yamaguchi; S. Ito, BASIC & CLINICAL PHARMACOLOGY & TOXICOLOGY, 115, 258, 259, Jul. 2014
  English, Summary international conference
• HYDROGEN SULFIDE BIDIRECTIONALLY MODULATES CA2+SIGNALS IN RIN14B CELLS
  A. Ujike; K. Otsuguro; R. Miyamoto; S. Yamaguchi; S. Ito, BASIC & CLINICAL PHARMACOLOGY & TOXICOLOGY, 115, 264, 264, Jul. 2014
  English, Summary international conference
• H2S production in peripheral neurons is mediated by cysteine aminotransferase and mercaptopyruvate sulfurtransferase
  Ryo Miyamoto; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito, NITRIC OXIDE-BIOLOGY AND CHEMISTRY, 39, S34, S34, May 2014
  English, Summary international conference
• The bidirectional effect of hydrogen sulfide on Ca2+ signals via opening K-ATP and TRPA1 channels in RIN14B cells
  Ayako Ujike; Ken-ichi Otsuguro; Ryo Miyamoto; Soichiro Yamaguchi; Shigeo Ito, NITRIC OXIDE-BIOLOGY AND CHEMISTRY, 39, S37, S38, May 2014
  English, Summary international conference
• Inhibitory and excitatory effects of hydrogen sulfide on RIN14B cells
  Ayako Ujike; Ken-ichi Otsuguro; Ryo Miyamoto; Soichiro Yamaguchi; Shigeo Ito, JOURNAL OF PHARMACOLOGICAL SCIENCES, 124, Suppl.1, 165P, 165P, 2014
  English, Summary international conference
• Contribution of CAT/MPST to H2S production in peripheral neurons
  Ryo Miyamoto; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito, JOURNAL OF PHARMACOLOGICAL SCIENCES, 124, 191P, 191P, 2014
  English, Summary international conference
• デクスメデトミジンとキシラジンの脊髄シナプス伝達抑制作用におけるα2A-アドレナリン受容体の関与の違い
  小林 武志; 乙黒 兼一; 山口 聡一郎; 伊藤 茂男, 日本獣医学会学術集会講演要旨集, 156回, 378, 378, Aug. 2013
  (公社)日本獣医学会, Japanese
• ウシ耳下腺腺房細胞を用いた起電性Na+-HCO3-共輸送体の細胞内Mg2+感受性を調節する相互作用タンパク質の探索
  山口 聡一郎; 石川 透, 日本獣医学会学術集会講演要旨集, 156回, 379, 379, Aug. 2013
  (公社)日本獣医学会, Japanese
• 内耳機能に重要な蝸牛外側壁の電気化学的特性(Electrochemical property of the cochlear lateral wall crucial for inner ear function)
  Yoshida Takamasa; Nin Fumiaki; Adachi Naoko; Yamaguchi Soichiro; Kurachi Yoshihisa; Hibino Hiroshi, Journal of Pharmacological Sciences, 121, Suppl.1, 172P, 172P, Mar. 2013
  (公社)日本薬理学会, English
• アデノシン代謝阻害薬と細胞外Ca2+除去によるラット脊髄アストロサイトでの細胞外アデノシン蓄積について
  増本 早苗; 乙黒 兼一; 山口 聡一郎; 伊藤 茂男, 日本獣医学会学術集会講演要旨集, 155回, 263, 263, Mar. 2013
  (公社)日本獣医学会, Japanese
• Increase in extracellular adenosine level by adenosine metabolic enzyme inhibitors and removal of extracellular Ca2+ in rat spinal astrocytes
  Sanae Masumoto; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito, JOURNAL OF PHARMACOLOGICAL SCIENCES, 121, Suppl.1, 215P, 215P, 2013
  English, Summary international conference
• Electrochemical analysis of the cochlear lateral wall crucial for inner ear function
  Takamasa Yoshida; Fumiaki Nin; Naoko Adachi; Soichiro Yamaguchi; Yoshihisa Kurachi; Hiroshi Hibino, JOURNAL OF PHYSIOLOGICAL SCIENCES, 63, S142, S142, 2013
  English, Summary international conference
• IRBIT relieves the inhibition of NBCe1-B by intracellular Mg2+
  Soichiro Yamaguchi; Toru Ishikawa, JOURNAL OF PHYSIOLOGICAL SCIENCES, 63, S136, S136, 2013
  English, Summary international conference
• Contribution of alpha(2A) adrenoceptor to effect of alpha(2) agonists on spinal reflex potential
  Takeshi Kobayashi; Ken-ichi Otsuguro; Soichiro Yamaguchi; Shigeo Ito, JOURNAL OF PHARMACOLOGICAL SCIENCES, 121, Suppl.1, 213P, 213P, 2013
  English, Summary international conference
• 【聴覚-分子機構から先端治療まで】内耳の神経科学 内リンパ液の電位・イオン環境と聴覚
  日比野 浩; 任 書晃; 山口 聡一郎; 倉智 嘉久, Clinical Neuroscience, 29, 12, 1344, 1347, Dec. 2011
  (株)中外医学社, Japanese
• 酸性細胞内小器官におけるNAADP受容体Ca2+チャネルの二つの候補(TRPML1とTPCチャネル)からの分子基盤の決着
  山口 聡一郎; Jha Archana; Li Qin; Soyombo Abigail; Dickinson George; Churamani Dev; Brailoiu Eugen; Patel Sandip; Muallem Shumel, 日本獣医学会学術集会講演要旨集, 152回, 314, 314, Aug. 2011
  (公社)日本獣医学会, Japanese
• 細胞内Mg2+は起電性Na+-HCO3-共輸送体活性を制御する(Intraceilular Mg2+ can regulate the electrogenic Na+-HCO3- cotransporter activity)
  Yamaguchi Soichiro; Ishikawa Toru, The Journal of Physiological Sciences, 58, Suppl., S210, S210, Apr. 2008
  (一社)日本生理学会, English
• Intracellular Mg²⁺ can regulate the electrogenic Na⁺-HCO₃⁻ cotransporter activity
  Yamaguchi Soichiro; Ishikawa Toru, Proceedings of Annual Meeting of the Physiological Society of Japan, 2008, 210, 210, 2008
  The electrogenic Na⁺-HCO₃⁻ cotransporter (NBCe) plays a critical role in secretion and absorption of HCO₃⁻ and regulation of intracellular pH in various tissues, and thus its activity is necessary to be regulated tightly. Despite intensive studies, the regulatory mechanisms of NBCe activity have not been fully understood. It has been shown that intracellular Mg²⁺ (Mg²⁺_i) regulates various ion channels and transporters in several ways. In this presentation, we show using the standard whole-cell patch clamp technique that Mg²⁺_i can control natively and heterologously expressed NBCe currents. Mg²⁺_i concentration was varied by pipette solutions having different calculated free Mg²⁺. Native NBCe currents recorded from freshly dissociated bovine parotid acinar cells were inhibited by increasing Mg²⁺_i in a dose-dependent manner (K_i =–1 mM). The native currents were also inhibited by intracellular polyvalent cationic compounds such as neomycin and spermine. Mg²⁺_i and neomycin inhibited heterologous NBCe currents in mammalian cultured cells transiently transfected with the cloned bovine parotid NBCe1-B. These results suggest that Mg²⁺_i might regulate the NBCe1-B activity under physiological conditions, and the underlying mechanism will be discussed. [J Physiol Sci. 2008;58 Suppl:S210], PHYSIOLOGICAL SOCIETY OF JAPAN
• 起電性Na^+-HCO_3^-共輸送体のパッチクランプ法を用いた機能解析
  山口 聡一郎, 日本生理学雜誌 = JOURNAL OF THE PHYSIOLOGICAL SOCIETY OF JAPAN, 68, 6, 197, 197, 01 Jun. 2006
  Japanese
• Electrophysiological analysis of electrogenic Na⁺-HCO₃⁻ cotransporter activity in bovine parotid acinar cells
  Yamaguchi Souichirou; Ishikawa Toru, Proceedings of Annual Meeting of the Physiological Society of Japan, 2006, 112, 112, 2006
  Electrogenic Na⁺-HCO₃⁻ cotransporter (NBCe) plays an important role in mediating HCO₃⁻ efflux and influx across the basolateral membrane in various HCO₃⁻-transporting epithelia, including kidney proximal tubules and pancreatic ducts. Its activity has been generally assessed by monitoring intracellular pH, Na⁺ concentration, or membrane potential, but electrophysiological properties of the cotransporter at the native state still remain largely unknown. Using the whole-cell patch clamp technique, we have recently, for the first time, identified and characterized membrane currents attributable to the activity of a NBCe expressed in acutely dissociated acinar cells (BPA cells) from bovine parotid that secretes large volumes of a HCO₃⁻-rich fluid. Under voltage-clamp conditions, the currents were dependent upon extracellular Na⁺ and HCO₃⁻ and DIDS-sensitive. Further analysis of the currents indicated that the stoichiometry of the native cotransporter is most likely to be 2 HCO₃⁻ : 1 Na⁺. We could also demonstrate that BPA cells express transcripts of NBCe1-B (bNBCe1-B) and that recombinant bNBCe1-B currents in HEK293 cells shares common electrophysiological and pharmacological properties with those of the native currents. This study represents an initial attempt to provide electrophysiological characterization of a NBCe expressed in a native HCO₃⁻-secreting exocrine gland. [J Physiol Sci. 2006;56 Suppl:S112], PHYSIOLOGICAL SOCIETY OF JAPAN
• Functional expression of ENaC and ClC-2-like channel in surface cells of rat rectal colon
  Inagaki Akihiro; Yamaguchi Souichirou; Ishikawa Toru, Proceedings of Annual Meeting of the Physiological Society of Japan, 2004, S58, S58, 2004
  The epithelial Na⁺ channel (ENaC), composed of three homologous subunits (α, β, and γ), is shown to be molecularly expressed in the apical membrane of surface cells of the distal colon. We have recently demonstrated that electrophysiological properties of an amiloride-sensitive macroscopic Na⁺ current in surface cells, which are freshly isolated from rectal colon of rats fed a normal Na⁺ diet resemble those reported for heterologously expressed αβγ-ENaC and that the currents are most likely responsible for electrogenic Na⁺ transport in rat rectum (Inagaki et al., Am.J.Physiol. Cell Physiol. 286 (2): C380-C390, 2004). Using the standard whole-cell patch-clamp technique, we have found that the surface cells also exhibit an inwardly rectifying anion current, which is activated by membrane hyperpolarization, has an anion selectivity sequence of Cl⁻ > I⁻, and is blocked by external Zn²⁺. RT-PCR analysis showed the presence of transcripts of rClC-2 in rat rectal mucosa. Electrophysiological properties of the native currents were similar to those of whole-cell currents recorded from HEK-293 cells heterologously expressing rClC-2 cloned from rat rectal mucosa. We also demonstrated that both ENaC and ClC-2-like currents were recorded in the same surface cells. Collectively, these results provide the electrophysiological evidence for functional coexpression of ENaC and ClC-2-like channel in rat rectal surface cells. Possible role of ClC-2-like channel in electrogenic Na⁺ transport in the distal colon is also discussed. [Jpn J Physiol 54 Suppl:S58 (2004)], PHYSIOLOGICAL SOCIETY OF JAPAN

• 獣医科学特別研究, 2024年, 博士後期課程, 獣医学院
• ケミカルハザード対策専門特論, 2024年, 博士後期課程, 獣医学院
• 獣医科学特論演習, 2024年, 博士後期課程, 獣医学院
• 生命科学特論, 2024年, 博士後期課程, 獣医学院
• 汎動物科学特論, 2024年, 博士後期課程, 獣医学院
• 先端生命科学特論Ⅱ：細胞生理学, 2024年, 博士後期課程, 獣医学院
• 生理学Ⅰ, 2024年, 学士課程, 獣医学部
• 生理学Ⅱ, 2024年, 学士課程, 獣医学部
• 生理学実習, 2024年, 学士課程, 獣医学部
• アドバンスト演習, 2024年, 学士課程, 獣医学部

• PHYSIOLOGICAL SOCIETY OF JAPAN
• JAPANESE SOCIETY OF VETERINARY SCIENCE
• 日本薬理学会

• 熱産生する褐色脂肪細胞に新規H+チャネルが高発現する生理的意義の解明
  科学研究費助成事業 基盤研究(C)
  01 Apr. 2022 - 31 Mar. 2026
  山口 聡一郎; 岡松 優子
  日本学術振興会, 基盤研究(C), 北海道大学, 22K06825
• Research on a possible novel transcriptional regulation by a membrane protein
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
  01 Apr. 2016 - 31 Mar. 2020
  Yamaguchi Soichiro
  Transmembrane channel like protein 1 (TMC1) is the mechanoelectrical transduction (MET) channel in hair cells of the inner ear. I found a phenomenon that the cytosolic N-terminal region of overexpressed mouse TMC1 (mTMC1) is localized in nuclei of a small population of HEK293 cells. This suggests that in some cells the N-terminal region of mTMC1 is cleaved and transported into nuclei. In this study, I revealed the positions of the cleavage of overexpressed mTMC1 and the involvement of Importin α in the mechanism of accumulation of the N-terminal region into nuclei. Moreover, overexpression of the N-terminal fragment of mTMC1 changed the expression levels of several genes. These findings suggest the possibility that TMC1 is cleaved and the produced N-terminal fragment regulates transcription in hair cells of the inner ear. However, further investigation is required in order to prove that the transcriptional regulation by mTMC1 happens in vivo.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 16K08066
• Gliotransmitter release and its protective effects in spinal astrocytes
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
  01 Apr. 2014 - 31 Mar. 2017
  Otsuguro Ken-ichi; YAMAGUCHI Soichiro
  Production and release mechanisms of adenosine and hydrogen sulfide (H2S), which are known to be neuroprotective agents, were examined in the cultured spinal astrocytes. Under the low Ca2+ conditions, ATP released by astrocytes was extracellularly degraded to adenosine, resulting in the increase in extracellular adenosine level. The astrocytic CBS (H2S synthase) expression was suggested to be controlled/maintained by the neurons. Adenosine and H2S affect cellular functions via the activation of receptors and ion channels. Under the ischemic conditions, it is suggested that the change in adenosine and H2S production and releases by the low Ca2+ and/or neuronal death is involved in disease onset and progression.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 26450440
• Molecular mechanisms of pleasant tactile sensation.
  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
  2014 - 2015
  YAMAGUCHI Soichiro
  The aim of this research is to reveal how MrgprB4 positive DRG neurons detect a massage-like pleasant tactile sensation in mice. The neurons were mechanically stimulated by application of hypotonic solutions during intracellular Ca2+ concentration ([Ca2+]i) measurement. [Ca2+]i was increased by the application of hypotonic solutions. The increase of [Ca2+]i was inhibited by Piezo channel inhibitors. Immunocytochemistry showed that MrgprB4 positive neurons express Piezo2 channel. In conclusion, it was suggested that Piezo2 may be functionally expressed in the isolated MrgprB4 positive neurons.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, Principal investigator, Competitive research funding, 26850204
• Research on the system of pH regulation in endocochlear epithelium
  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
  2011 - 2011
  YAMAGUCHI Soichiro; HIBINO Hiroshi; YAMAGUCHI Kenichi
  The aim of this research is to clarify the system of pH regulation in stria vascularis in endocochlea. Using RT-PCR technique, transcripts of NBCe1-B, an electrogenic Na^+-HCO_3^- cotransporter, was shown to be expressed in stria vascularis. Results of immunostaining suggested that basal cells in stria vascularis expressed NBCe1-B. Application of DIDS, a NBCe1-B inhibitor, to perilymph reduced endocochlear potential measured from anesthetized guinea pigs. These results suggest that NBCe1-B plays an important role in pH regulation in stria vascularis.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), 新潟大学, Principal investigator, Competitive research funding, 23790244
• ウシ耳下腺でのナトリウム重炭酸イオン共輸送体の分子基盤の解明:複合体形成の可能性
  科学研究費助成事業 特別研究員奨励費
  2006 - 2008
  山口 聡一郎
  Yeast two-hybrid法を用いたウシ耳下腺cDNAライブラリーの探索によりNBCe1-BのN端領域との結合タンパク質候補として浮上した2種類のタンパク質(以下、タンパク質Aとタンパク質B)について、以下の実験を行った。共焦点顕微鏡を用いたimmunocytochemistryの実験により、分離したウシ耳下腺腺房細胞において、NBCe1-B、タンパク質A、およびタンパク質Bが発現し、形質膜上にそれらが集積し共局在している傾向が見られた。導管細胞と思われる細胞からはいずれのシグナルも検出されなかった。また、タンパク質AあるいはBをNBCe1-Bと共発現させたHEK293細胞を用いた実験でも、タンパク質AあるいはBとNBCe1-Bの共局在を示唆する結果が得られた。さらに、関連する実験テーマとしてNBCe1-Bの輸送活性が細胞内Mg^<2+>によって抑制され、その抑制作用にNBCe1-Bの特異的N端領域が関与することを明らかにしたことから、N端領域に結合するタンパク質AあるいはBの共発現によるNBCe1-Bに対する細胞内Mg^<2+>の抑制作用への影響を調べた。HEK293細胞にタンパク質AあるいはBとNBCe1-Bを共発現させ、パッチクランプ法によりNBCe1-B電流を測定したところ、条件によっては共発現により細胞内Mg^<2+>による抑制作用が減弱することが明らかとなった。これはタンパク質AあるいはBの結合によるNBCe1-Bの活性化のメカニズムに細胞内Mg^<2+>による抑制作用が関与する可能性を示唆する結果である。以上、本研究によりNBCe1-Bに対する新たな相互作用タンパク質が明らかとなり、それらによる機能的修飾のメカニズムの一つの可能性を提唱することができた。現在、これらの成果を論文としてまとめているところである。
  日本学術振興会, 特別研究員奨励費, 北海道大学, 06J04516