TY - JOUR AB - Mitochondrial transhydrogenase has been reported previously to be inhibited by high, rather non-physiological concentrations (in the range of 2-20 mM) of divalent cations. We show that the enzyme could be activated by low (from about 1 μM to 1 mM) concentrations of Ca2+ and Mg2+, which are within physiological range. These results bring in line the effects observed with mitochondrial enzyme to the findings with bacterial transhydrogenases. The activation of transhydrogenase by divalent cations is interpreted as an increase in affinity of the NADP(H)-binding site of the enzyme-NAD(H) complex. Reported effects of the metal ions could be important for the enzyme function in vivo. AU - Sazanov, Leonid A AU - Jackson, Julie ID - 1947 IS - 2 JF - Biochimica et Biophysica Acta - Bioenergetics SN - 0005-2728 TI - Activation and inhibition of mitochondrial transhydrogenase by metal ions VL - 1144 ER - TY - JOUR AU - Sazanov, Leonid A AU - Jackson, Julie ID - 1948 IS - 3 JF - Biochemical Society Transactions SN - 0300-5127 TI - Possible functions of the NADP-linked isocitrate dehydrogenase and H+ -transhydrogenase in heart mitochondria VL - 21 ER - TY - JOUR AU - Jackson, Julie AU - Cotton, N P J AU - Williams, Ross AU - Bizouarn, Tania AU - Hutton, Mike AU - Sazanov, Leonid A AU - Thomas, Christopher ID - 1950 IS - 4 JF - Biochemical Society Transactions SN - 0300-5127 TI - Proton-translocating transhydrogenase in bacteria VL - 21 ER - TY - JOUR AB - Distribution of the mRNA for a metabotropic glutamate receptor, mGluR3, which is coupled to the inhibitory cAMP cascade, was examined in the central nervous system of the adult albino rat by in situ hybridization. The hybridization signals of mGluR3 were detected not only on neuronal cells but also on many glial cells throughout the brain and spinal cord. In the neuronal cells, prominent expression of mGluR3 mRNA was seen in the thalamic reticular nucleus. Moderately labeled neurons were seen in the anterior olfactory nucleus, cerebral neo- and mesocortical regions, lateral amygdaloid nucleus, ventral part of the basolateral amygdaloid nucleus, dorsal endopiriform nucleus, supraoptic nucleus, superficial layers of the superior colliculus, inferior colliculus, interpeduncular nucleus, superior olivary nuclei, and Golgi cells in the cerebellar cortex. Weakly labeled neurons were observed in the striatum, nucleus accumbens, ventral pallidum, globus pallidus, entopeduncular nucleus, lateral hypothalamic area, hypothalamic paraventricular nucleus, medial habenular nucleus, anterior pretectal nucleus, Barrington's nucleus, Nucleus O, paragenual nucleus, trigeminal sensory complex, cochlear nuclei, dorsal motor nucleus of the trigeminal nerve, dorsal cap of the inferior olive, spinal dorsal horn, and lamina X of the spinal cord. The stellate cells in the cerebellar cortex, and neurons in the deep cerebellar nuclei were also labeled weakly. The granule cell layer of the dentate gyrus, as a whole, appeared to be labeled intensely, but each of the granule cells was labeled only weakly. No significant labeling was detected in the mitral and tufted cells in the olfactory bulb, hippocampal pyramidal cells, Purkinje and granule cells in the cerebellar cortex, or somatic motoneurons. The distribution of mGluR3 mRNA in particular neurons and glial cells indicates specific roles of mGluR3 in the glutamatergic system of the central nervous system. AU - Ohishi, Hitoshi AU - Shigemoto, Ryuichi AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2487 IS - 2 JF - Journal of Comparative Neurology SN - 0021-9967 TI - Distribution of the mRNA for a metabotropic glutamate receptor (mGluR3) in the rat brain: An in situ hybridization study VL - 335 ER - TY - JOUR AB - A cDNA clone for a new metabotropic glutamate receptor, termed mGluR6, was isolated from a rat retinal cDNA library by cross-hybridization with the previously isolated cDNA clone for a metabotropic glutamate receptor. The cloned mGluR6 subtype consists of 871 amino acid residues and exhibits a structural architecture common to the metabotropic receptor family, possessing a large extracellular domain preceding the seven putative membrane-spanning domains. mGluR6 shows the highest sequence similarity to mGluR4 among the metabotropic receptor subtypes and inhibits the forskolin- stimulated cyclic AMP accumulation in Chinese hamster ovary cells transfected with the cloned cDNA. mGluR6 potently reacts with L-2-amino-4- phosphonobutyrate (L-AP4) and L-serine-O-phosphate, and the potencies of these compounds are one order of magnitude greater than that of L-glutamate. Blot and in situ hybridization analyses indicated that mGluR6 mRNA is restrictedly expressed in the inner nuclear layer of the retina where ON- bipolar cells are distributed. The metabotropic receptor that responds strongly to L-AP4 and L-serine-O-phosphate in ON-bipolar cells is known to mediate glutamate synaptic transmission between photoreceptor cells and ON- bipolar cells. On the basis of the agonist selectivity of mGluR6 and its specific expression in retinal cells, the physiological role of this receptor subtype in the visual system is discussed. AU - Nakajima, Yoshiaki AU - Iwakabe, Hideki AU - Akazawa, Chihiro AU - Nawa, Hiroyuki AU - Shigemoto, Ryuichi AU - Mizuno, Noboru AU - Nakanishi, Shigetada ID - 2536 IS - 16 JF - Journal of Biological Chemistry SN - 0021-9258 TI - Molecular characterization of a novel retinal metabotropic glutamate receptor mGluR6 with a high agonist selectivity for L-2-amino-4- phosphonobutyrate VL - 268 ER - TY - JOUR AB - The metabotropic glutamate receptors are coupled to intracellular signal transduction via G-proteins and consist of a family of at least five different subtypes, termed mGluR1-mGluR5. We studied the signal transduction mechanism and pharmacological characteristics of the rat mGluR3 and mGluR4 subtypes in Chinese hamster ovary cells permanently expressing the cloned receptors. Both mGluR3 and mGluR4 inhibit the forskolin-stimulated accumulation of intracellular cAMP formation in response to agonist interaction. Consistent with the high degree of sequence similarity to mGluR2, mGluR3 closely resembles mGluR2 in its agonist selectivity; the potency rank order of agonists is L-glutamate > trans-1-aminocyclopentane- 1,3-dicarboxylate > ibotenate > quisqualate. mGluR4 is totally different in its agonist specificity from any other member of the metabotropic receptors. This receptor potently reacts with L-2-amino-4-phosphonobutyrate(L-AP4) in a stereo-selective manner and moderately responds to L-serine-O-phosphate. mGluR4 thus corresponds well to the putative L-AP4 receptor characterized from brain preparations. Blot and in situ hybridization analyses indicated that both mRNAs are widely distributed in the rat brain. mGluR3 mRNA is highly expressed in neuronal cells of the cerebral cortex and the caudate- putamen, and in granule cells of the hippocampal dentate gyrus. The expression pattern of mGluR4 mRNA is more restricted, and this expression is prominent in the cerebellum, olfactory bulb, and thalamus. Furthermore, the mGluR3 mRNA, unlike the other mRNAs for the metabotropic receptors, is highly expressed in glial cells throughout the brain regions. The metabotropic glutamate receptor subtypes can thus be classified into three subgroups according to the similarity in their amino acid sequences, signal transduction, and agonist selectivity: mGluR1/mGluR5, mGluR2/mGluR3, and mGluR4. The mRNAs for the individual receptor subtypes, however, show overlapping but distinct patterns of expression in the rat CNS. AU - Tanabe, Yasuto AU - Nomura, Akinori AU - Masu, Masayuki AU - Shigemoto, Ryuichi AU - Mizuno, Noboru AU - Nakanishi, Shigetada ID - 2537 IS - 4 JF - Journal of Neuroscience SN - 0270-6474 TI - Signal transduction, pharmacological properties, and expression patterns of two rat metabotropic glutamate receptors, mGluR3 and mGluR4 VL - 13 ER - TY - JOUR AB - cDNA clones for four different N-methyl-D-aspartate (NMDA) receptor subunits (NMDAR2A-NMDAR2D) were isolated through polymerase chain reactions followed by molecular screening of a rat brain cDNA library. These subunits are only about 15% identical with the key subunit of the NMDA receptor (NMDAR1) but are highly homologous (~50% homology) with one another. They also commonly possess large hydrophilic domains at both amino- and carboxyl- terminal sides of the four putative transmembrane segments. NMDAR2A and NMDAR2C expressed individually in Xenopus oocytes showed no electrophysiological response to agonists. However, these subunits in combined expression with NMDAR1 markedly potentiated the NMDAR1 activity and produced functional variability in the affinity of agonists, the effectiveness of antagonists, and the sensitivity to Mg2+ blockade. Thus, NMDAR1 is essential for the function of the NMDA receptor, and multiple NMDAR2 subunits potentiate and differentiate the function of the NMDA receptor by forming different heteromeric configurations with NMDAR1. Northern blotting and in situ hybridization analyses revealed that the expressions of individual mRNAs for the NMDAR2 subunits overlap in some brain regions but are also specialized in many other regions. This investigation demonstrates the anatomical and functional differences of the NMDAR2 subunits, which provide the molecular basis for the functional diversity of the NMDA receptor. AU - Ishii, Takahiro AU - Moriyoshi, Koki AU - Sugihara, Hidemitsu AU - Sakurada, Kazuhir AU - Kadotani, Hiroshi AU - Yokoi, Mineto AU - Akazawa, Chihiro AU - Shigemoto, Ryuichi AU - Mizuno, Noboru AU - Masu, Masayuki AU - Nakanishi, Shigetada ID - 2539 IS - 4 JF - Journal of Biological Chemistry SN - 0021-9258 TI - Molecular characterization of the family of the N-methyl-D-aspartate receptor subunits VL - 268 ER - TY - JOUR AB - Distribution of the messenger RNA for a metabotropic glutamate receptor, mGluR2, which is coupled to the inhibitory cyclic AMP cascade, was investigated in the central nervous system of the adult rat by in situ hybridization. Transcripts of mGluR2 were specifically localized to neuronal cells of the brain. Although the hybridization signals were widely distributed in the brain, the most prominent expression of mGluR2 messenger RNA was seen in Golgi cells of the cerebellum. Marked expression of mGluR2 messenger RNA was further observed in the mitral cells of the accessory olfactory bulb, neurons in the external part of the anterior olfactory nucleus, and pyramidal neurons in the entorhinal and parasubicular cortical regions. The granule cells of the accessory olfactory bulb, and many pyramidal and non-pyramidal neurons in the neocortical, cingulate, retrosplenial and subicular cortices, were moderately labeled. All of the granule cells in the dentate gyrus were also labeled moderately, whereas no significant hybridization signals were detected in Ammon's horn. In the basal forebrain regions, moderately labeled neurons were distributed in the triangular septal nucleus, in the lateral, basolateral and basomedial amygdaloid nuclei, and in the medial mammillary nucleus. Weakly labeled neurons were sparsely scattered in the striatum, globus pallidus, ventral pallidum and claustrum. The subthalamic nucleus was also labeled weakly. No significant labeling was found in the entopeduncular nucleus and substantia nigra. In the thalamus, moderately labeled neurons were distributed in the anterodorsal, anteromedial, ventromedial, intralaminar and midline nuclei; the ventrolateral part of the anteroventral nucleus and the rostral pole of the ventrolateral nucleus also contained moderately labeled neurons. No significant labeling was found in the thalamic reticular, submedius, ventroposterior, lateral geniculate and medial geniculate nuclei. In the lower brainstem, labeling was generally weak. No significant hybridization signals were found in the spinal cord. Some neurons in the inner part of the inner nuclear layer of the retina and some retinal ganglion cells were labeled moderately. The pattern of distribution of mGluR2 messenger RNA revealed in the present study indicates specific roles of mGluR2 in the glutamatergic system in the brain. AU - Ohishi, Hitoshi AU - Shigemoto, Ryuichi AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2540 IS - 4 JF - Neuroscience SN - 0306-4522 TI - Distribution of the messenger RNA for a metabotropic glutamate receptor, mGluR2, in the central nervous system of the rat VL - 53 ER - TY - JOUR AB - Rat mRNAs encoding two subtypes of the endothelin (ET) receptor (ET(A) and ET(B)) were studied in the rat ovary and fallopian tube by means of Northern blotting and in situ hybridization. The mRNA transcripts for the endothelin- 1-specific type receptor (ET(A)) in pooled RNA from the ovary and fallopian tube were 4.2 and 5.2 kilonucleotides, and that for the nonselective type receptor (ET(B)) was 4.7 kilonucleotides; these were similar to transcripts for endothelin receptors from other tissues. ET(A) mRNA expression was abundant in the muscle cell layer of the fallopian tube, but low in the ovary. On the other hand, ET(B) mRNA was abundant in the granulosa cells in the developing follicles, but low in atretic follicles and absent in the fallopian tube. These results demonstrated that the mRNAs for the two subtypes of the rat endothelin receptor have different expression profiles in the ovary and fallopian tube. ETs may mainly affect the granulosa cells in the dominant follicles as well as the muscle cells of the fallopian tube through ET(B) and ET(A), respectively. AU - Iwai, Masazumi AU - Hori, Seiji AU - Shigemoto, Ryuichi AU - Kanzaki, Hideharu AU - Mori, Takahide AU - Nakanishi, Shigetada ID - 2538 IS - 4 JF - Biology of Reproduction SN - 0006-3363 TI - Localization of endothelin receptor messenger ribonucleic acid in the rat ovary and fallopian tube by in situ hybridization VL - 49 ER - TY - JOUR AB - VARIOUS functions of glutamate transmission are mediated by both ionotropic and metabotropic glutamate receptors1. The metabotropic glutamate receptors (mGluRs) consist of at least six different subtypes that are classified into three subgroups, mGluR1/mGluR5, mGluR2/mGluR3, and mGluR4/mGluR6 (refs 1-5), but their physiological roles are largely unknown. Here we report the identification of a very potent agonist for mGluR2/mGluR3, DCG-IV, and the specific localization of mGluR2 in granule cell dendrites that form dendrodendritic synapses with mitral cells in the accessory olfactory bulb. Using the DCG-IV agonist for mGluR2 in combination with slice patchrecording, we demonstrate that the granule cell mGluR2 presynaptically suppresses inhibitory GABA (γ-aminobutyrate) transmission to the mitral cell. Our results indicate that mGluR2 in granule cells plays an important role in the persistent excitation of olfactory sensory transmission in the accessory olfactory bulb by relieving mitral cells from the GABA inhibition. AU - Hayashi, Yasunori AU - Momiyama, Akiko AU - Takahashi, Tomoyuki AU - Ohishi, Hitoshi AU - Ogawa Meguro, Reiko AU - Shigemoto, Ryuichi AU - Mizuno, Noboru AU - Nakanishi, Shigetada ID - 2544 IS - 6456 JF - Nature SN - 0028-0836 TI - Role of a metabotropic glutamate receptor in synaptic modulation in the accessory olfactory bulb VL - 366 ER -