Alpha-CaMKII deficiency causes immature dentate gyrus, a novel candidate endophenotype of psychiatric disorders

Yamasaki Nobuyuki, Maekawa Motoko, Kobayashi Katsunori, Kajii Yasushi, Maeda Jun, Soma Miho, Takao Keizo, Tanda Koichi, Ohira Koji, Toyama Keiko, Kanzaki Kouji, Fukunaga Kohji, Sudo Yusuke, Ichinose Hiroshi, Ikeda Masashi, Iwata Nakao, Ozaki Norio, Suzuki Hidenori, Higuchi Makoto, Suhara Tetsuya, Yuasa Shigeki, Miyakawa Tsuyoshi

Description

Elucidating the neural and genetic factors underlying psychiatric illness is hampered by current methods of clinical diagnosis. The identification and investigation of clinical endophenotypes may be one solution, but represents a considerable challenge in human subjects. Here we report that mice heterozygous for a null mutation of the alpha-isoform of calcium/calmodulin-dependent protein kinase II (alpha-CaMKII+/-) have profoundly dysregulated behaviours and impaired neuronal development in the dentate gyrus (DG). The behavioral abnormalities include a severe working memory deficit and an exaggerated infradian rhythm, which are similar to symptoms seen in schizophrenia, bipolar mood disorder and other psychiatric disorders. Transcriptome analysis of the hippocampus of these mutants revealed that the expression levels of more than 2000 genes were significantly changed. Strikingly, among the 20 most downregulated genes, 5 had highly selective expression in the DG. Whereas BrdU incorporated cells in the mutant mouse DG was increased by more than 50 percent, the number of mature neurons in the DG was dramatically decreased. Morphological and physiological features of the DG neurons in the mutants were strikingly similar to those of immature DG neurons in normal rodents. Moreover, c-Fos expression in the DG after electric footshock was almost completely and selectively abolished in the mutants. Statistical clustering of human post-mortem brains using 10 genes differentially-expressed in the mutant mice were used to classify individuals into two clusters, one of which contained 16 of 18 schizophrenic patients. Nearly half of the differentially-expressed probes in the schizophrenia-enriched cluster encoded genes that are involved in neurogenesis or in neuronal migration/maturation, including calbindin, a marker for mature DG neurons. Based on these results, we propose that an "immature DG" in adulthood might induce alterations in behavior and serve as a promising candidate endophenotype of schizophrenia and other human psychiatric disorders.

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• Publié par: biomed
• Publié le: 01 janvier 2008
• Nombre de lectures: 17
• Poids de l'ouvrage: 1 Mo

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Molecular Brain

BioMedCentral

Open Access Research Alpha-CaMKII deficiency causes immature dentate gyrus, a novel candidate endophenotype of psychiatric disorders †1,2,3,4 †3,5†3,6 Nobuyuki Yamasaki, Motoko Maekawa, Katsunori Kobayashi, †7 †8†5 †1,3,4,9 Yasushi Kajii, Jun Maeda, Miho Soma, Keizo Takao, 1,3,4 3,4,91,3,4,9 7 Koichi Tanda, Koji Ohira, Keiko Toyama, Kouji Kanzaki, 10 113,11 3,12,13 Kohji Fukunaga, Yusuke Sudo, Hiroshi Ichinose, Masashi Ikeda, 3,12 3,136 8 Nakao Iwata, Norio Ozaki, Hidenori Suzuki, Makoto Higuchi, 8 3,51,3,4,9,14 Tetsuya Suhara, Shigeki Yuasaand Tsuyoshi Miyakawa*

1 Address: GeneticEngineering and Functional Genomics Group, Frontier Technology Center, Kyoto University Graduate School of Medicine, 2 YoshidaKonoecho, Sakyoku, Kyoto, Japan,Department of Psychiatry, Kyoto University Graduate School of Medicine, 54 ShogoinKawahara 3 4 cho, Sakyoku, Kyoto, Japan,Japan Science and Technology Agency, CREST, Saitama, Japan,Japan Science and Technology Agency, BIRD, 5 Saitama, Japan,Department of Ultrastructural Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 411 6 Ogawahigashi, Kodaira, Tokyo, Japan,Department of Pharmacology, Nippon Medical School, 115 Sendagi, Bunkyoku, Tokyo, Japan, 7 8 Mitsubishi Tanabe Pharma Corporation, 1000 Kamoshidacho, Aobaku, Yokohama, Japan,Department of Molecular Neuroimaging, Molecular 9 Imaging Center, National Institute of Radiological Sciences, 491 Anagawa, Inageku, Chiba, Japan,Division of Systems Medicine, Institute for 10 Comprehensive Medical Science, Fujita Health University, 198 Dengakugakubo, Kutsukakecho, Toyoake, Japan,Graduate School of 11 Pharmaceutical Sciences, Tohoku University, Aramaki, Aobaku, Sendai, Japan,Graduate School of Bioscience and Biotechnology, Tokyo 12 Institute of Technology, 4259 Nagatsutacho, Midoriku, Yokohama, Japan,Graduate School of Medicine, Fujita Health University, 198 13 Dengakugakubo, Kutsukakecho, Toyoake, Japan,Graduate School of Medicine, Nagoya University, 65 Tsurumacho, Showaku, Nagoya, Japan 14 and Centerfor Genetic Analysis of Behavior, National Institute for Physiological Sciences, Myodaiji, Okazaki, Japan

Email: Nobuyuki Yamasaki  [e-mail]u.ac.jp; Motoko Maekawa  [e-mail]; Katsunori Kobayashi  kkatsu [e-mail]; Yasushi Kajii  [e-mail]pharma.co.jp; Jun Maeda  [e-mail]; Miho Soma  [e-mail]; Keizo Takao  keizo@fujitahu.ac.jp; Koichi Tanda  [e-mail]u.ac.jp; Koji Ohira  ohira@fujitahu.ac.jp; Keiko Toyama  ktoyama@fujitahu.ac.jp; Kouji Kanzaki  [e-mail]pharma.co.jp; Kohji Fukunaga  [e-mail]; Yusuke Sudo  [e-mail]; Hiroshi Ichinose  [e-mail]; Masashi Ikeda  ikedama@fujitahu.ac.jp; Nakao Iwata  nakao@fujitahu.ac.jp; Norio Ozaki  ozaki[e-mail]u.ac.jp; Hidenori Suzuki  [e-mail]; Makoto Higuchi  [e-mail]; Tetsuya Suhara  [e-mail]; Shigeki Yuasa  yuasa[e-mail]; Tsuyoshi Miyakawa*  miyakawa@fujitahu.ac.jp * Corresponding author†Equal contributors

Published: 10 September 2008Received: 12 August 2008 Accepted: 10 September 2008 Molecular Brain2008,1:6 doi:10.1186/1756-6606-1-6 This article is available from: http://www.molecularbrain.com/content/1/1/6 © 2008 Yamasaki et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract Elucidating the neural and genetic factors underlying psychiatric illness is hampered by current methods of clinical diagnosis. The identification and investigation of clinical endophenotypes may be one solution, but represents a considerable challenge in human subjects. Here we report that mice heterozygous for a null mutation of the alpha-isoform of calcium/calmodulin-dependent protein kinase II (alpha-CaMKII+/-) have profoundly dysregulated behaviours and impaired neuronal development in the dentate gyrus (DG). The behavioral abnormalities include a severe working memory deficit and an exaggerated infradian rhythm, which are similar to symptoms seen in schizophrenia, bipolar mood disorder and other psychiatric disorders. Transcriptome analysis of the hippocampus of these mutants revealed that the expression levels of more than 2000 genes

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Molecular Brain2008,1:6

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were significantly changed. Strikingly, among the 20 most downregulated genes, 5 had highly selective expression in the DG. Whereas BrdU incorporated cells in the mutant mouse DG was increased by more than 50 percent, the number of mature neurons in the DG was dramatically decreased. Morphological and physiological features of the DG neurons in the mutants were strikingly similar to those of immature DG neurons in normal rodents. Moreover, c-Fos expression in the DG after electric footshock was almost completely and selectively abolished in the mutants. Statistical clustering of human post-mortem brains using 10 genes differentially-expressed in the mutant mice were used to classify individuals into two clusters, one of which contained 16 of 18 schizophrenic patients. Nearly half of the differentially-expressed probes in the schizophrenia- enriched cluster encoded genes that are involved in neurogenesis or in neuronal migration/ maturation, including calbindin, a marker for mature DG neurons. Based on these results, we propose that an "immature DG" in adulthood might induce alterations in behavior and serve as a promising candidate endophenotype of schizophrenia and other human psychiatric disorders.

Background Elucidating the neural and genetic factors underlying psy chiatric illness is hampered by the current methods of clinical diagnosis [1]. The identification and investigation of clinical endophenotypes might be one solution [2], but represents a considerable challenge in human subjects. Therefore, establishing animal models of psychiatric dis orders is essential for understanding the pathogenesis/ pathophysiology of the disorders [36]. Previously, we reported that forebrainspecific calcineurin (CN) knock out mice have severe working/episodiclike memory defi cits [7], and exhibit multiple abnormal behaviors related to schizophrenia [8]. Schizophrenia is significantly associ ated with a variation in the 8p21.3 gene,PPP3CC, which encodes the CNA gamma subunit of calcineurin [911]. Based on these findings, we speculated that we could effi ciently obtain a mouse model of psychiatric disorders by applying a comprehensive behavioral test battery [12] to various strains of mice bearing mutations of the genes encoding the molecules involved in CN signaling path ways or CN related neural mechanisms [13]. We assessed seven different strains of mutant mice: mice lacking type 3 isoform ryanodine receptor, neuronal nitric oxide syn thase, adenomatous polyposis coli, calcium/calmodulin dependent protein kinase IV, pituitary adenylate cyclase activated polypeptide, nuclear factor of activated T cells c2/c3/c4 [14] or alphaisoform of calcium/calmodulin dependent protein kinase II (alphaCaMKII). Four strains exhibited increased locomotor activity, and three strains exhibited abnormal social behavior (Miyakawa, unpub lished observations). Among them, the only mutant mouse strain that exhibited a significant working memory deficit, a proposed functional endophenotype of schizo phrenia and other psychiatric disorders [15], was hetero zygous for a null mutation of the alphaisoform of CaMKII (alphaCaMKII+/) (Figure 1A and 1B). CaMKII is a ubiquitous serine/threonine protein kinase that is abun dant in the brain (up to 2% of the total protein); a holoen zyme that consists of four isozymes (α,β,γ,δ); phosphorylates protein substrates, such as AMPA recep

2+ tors, synapsin I, tyrosine hydroxylase, Ltype Cachan nels, and MAP2, and itself by autophosphorylation; and is important for longterm potentiation, synaptic plastic ity, and memory formation [1618]. CaMKII is situated downstream of CN in a model [19].

Here we report that alphaCaMKII+/ mice have pro foundly dysregulated behaviors and impaired neuronal development in the DG. The behavioral abnormalities include a severe working memory deficit and an exagger ated infradian rhythm, which are similar to symptoms seen in schizophrenia and other psychiatric disorders. Transcriptome analysis of the hippocampus of these mutants revealed that the expression levels of more than 2000 genes were significantly changed. Strikingly, among the 20 most downregulated genes, 5 had highly selective expression in the DG. Whereas BrdU incorporated cells in the mutant mouse DG was increased by more than 50 per cent, the number of mature neurons in the DG was dra matically decreased. Morphological and physiological features of the DG neurons in the mutants were strikingly similar to those of immature DG neurons in normal rodents. Statistical clustering of human postmortem brains using 10 genes differentiallyexpressed in the mutant mice were used to classify individuals into two clusters, one of which contained 16 of 18 schizophrenic patients. Nearly half of the differentiallyexpressed probes in the schizophreniaenriched cluster encoded genes that are involved in neurogenesis or in neuronal migration/ maturation. Based on these results, we propose that an "immature DG" in adulthood might induce alterations in behavior and serve as a promising candidate endopheno type of human psychiatric disorders.

Results Severe working memory deficits and exaggerated infradian rhythm in alpha-CaMKII+/- mice AlphaCaMKII+/ mice have decreased anxietylike behav ior, increased aggressive behavior [20], and deficits in longterm memory and the establishment of permanent

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