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Synaptic Development in Diverse Olfactory Neuron Classes Uses Distinct Temporal and Activity-Related Programs. J Neurosci 2023; 43:28-55. [PMID: 36446587 PMCID: PMC9838713 DOI: 10.1523/jneurosci.0884-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 10/18/2022] [Accepted: 11/02/2022] [Indexed: 12/03/2022] Open
Abstract
Developing neurons must meet core molecular, cellular, and temporal requirements to ensure the correct formation of synapses, resulting in functional circuits. However, because of the vast diversity in neuronal class and function, it is unclear whether or not all neurons use the same organizational mechanisms to form synaptic connections and achieve functional and morphologic maturation. Moreover, it remains unknown whether neurons united in a common goal and comprising the same sensory circuit develop on similar timescales and use identical molecular approaches to ensure the formation of the correct number of synapses. To begin to answer these questions, we took advantage of the Drosophila antennal lobe (AL), a model olfactory circuit with remarkable genetic access and synapse-level resolution. Using tissue-specific genetic labeling of active zones, we performed a quantitative analysis of synapse formation in multiple classes of neurons of both sexes throughout development and adulthood. We found that olfactory receptor neurons (ORNs), projection neurons (PNs), and local interneurons (LNs) each have unique time courses of synaptic development, addition, and refinement, demonstrating that each class follows a distinct developmental program. This raised the possibility that these classes may also have distinct molecular requirements for synapse formation. We genetically altered neuronal activity in each neuronal subtype and observed differing effects on synapse number based on the neuronal class examined. Silencing neuronal activity in ORNs, PNs, and LNs impaired synaptic development but only in ORNs did enhancing neuronal activity influence synapse formation. ORNs and LNs demonstrated similar impairment of synaptic development with enhanced activity of a master kinase, GSK-3β, suggesting that neuronal activity and GSK-3β kinase activity function in a common pathway. ORNs also, however, demonstrated impaired synaptic development with GSK-3β loss-of-function, suggesting additional activity-independent roles in development. Ultimately, our results suggest that the requirements for synaptic development are not uniform across all neuronal classes with considerable diversity existing in both their developmental time frames and molecular requirements. These findings provide novel insights into the mechanisms of synaptic development and lay the foundation for future work determining their underlying etiologies.SIGNIFICANCE STATEMENT Distinct olfactory neuron classes in Drosophila develop a mature synaptic complement over unique timelines and using distinct activity-dependent and molecular programs, despite having the same generalized goal of olfactory sensation.
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Kamemura K, Moriya H, Ukita Y, Okumura M, Miura M, Chihara T. Endoplasmic reticulum proteins Meigo and Gp93 govern dendrite targeting by regulating Toll-6 localization. Dev Biol 2022; 484:30-39. [DOI: 10.1016/j.ydbio.2022.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/29/2021] [Accepted: 02/02/2022] [Indexed: 12/15/2022]
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Kamemura K, Chen CA, Okumura M, Miura M, Chihara T. Amyotrophic lateral sclerosis-associated Vap33 is required for maintaining neuronal dendrite morphology and organelle distribution in Drosophila. Genes Cells 2021; 26:230-239. [PMID: 33548103 DOI: 10.1111/gtc.12835] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 01/23/2021] [Accepted: 02/03/2021] [Indexed: 12/19/2022]
Abstract
VAMP-associated protein (VAP) is an endoplasmic reticulum (ER) membrane protein that functions as a tethering protein at the membrane contact sites between the ER and various intracellular organelles. Mutations such as P56S in human VAPB cause neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). However, VAP functions in neurons are poorly understood. Here, we utilized Drosophila olfactory projection neurons with a mosaic analysis with a repressible cell marker (MARCM) to analyze the neuronal function of Vap33, a Drosophila ortholog of human VAPB. In vap33 null mutant clones, the dendrites of projection neurons exhibited defects in the maintenance of their morphology. The subcellular localization of the Golgi apparatus and mitochondria were also abnormal. These results indicate that Vap33 is required for neuronal morphology and organelle distribution. Additionally, to examine the impact of ALS-associated mutations in neurons, we overexpressed human VAPB-P56S in vap33 null mutant clones (mosaic rescue experiments) and found that, in aged flies, human VAPB-P56S expression caused mislocalization of Bruchpilot, a presynaptic protein. These results implied that synaptic protein localization and ER quality control may be affected by disease mutations. We provide insights into the physiological and pathological functions of VAP in neurons.
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Affiliation(s)
- Kosuke Kamemura
- Program of Biomedical Science and Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Chun-An Chen
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Misako Okumura
- Program of Biomedical Science and Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Masayuki Miura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Takahiro Chihara
- Program of Biomedical Science and Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
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Anzo M, Sekine S, Makihara S, Chao K, Miura M, Chihara T. Dendritic Eph organizes dendrodendritic segregation in discrete olfactory map formation in Drosophila. Genes Dev 2017. [PMID: 28637694 PMCID: PMC5495121 DOI: 10.1101/gad.297424.117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Proper function of the neural network results from the precise connections between axons and dendrites of presynaptic and postsynaptic neurons, respectively. In the Drosophila olfactory system, the dendrites of projection neurons (PNs) stereotypically target one of ∼50 glomeruli in the antennal lobe (AL), the primary olfactory center in the brain, and form synapses with the axons of olfactory receptor neurons (ORNs). Here, we show that Eph and Ephrin, the well-known axon guidance molecules, instruct the dendrodendritic segregation during the discrete olfactory map formation. The Eph receptor tyrosine kinase is highly expressed and localized in the glomeruli related to reproductive behavior in the developing AL. In one of the pheromone-sensing glomeruli (DA1), the Eph cell-autonomously regulates its dendrites to reside in a single glomerulus by interacting with Ephrins expressed in adjacent PN dendrites. Our data demonstrate that the trans interaction between dendritic Eph and Ephrin is essential for the PN dendritic boundary formation in the DA1 olfactory circuit, potentially enabling strict segregation of odor detection between pheromones and the other odors.
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Affiliation(s)
- Marie Anzo
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Sayaka Sekine
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shirin Makihara
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kinhong Chao
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masayuki Miura
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Japan Agency for Medical Research and Development (AMED)-CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan
| | - Takahiro Chihara
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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Immunolocalization of the vesicular acetylcholine transporter in larval and adult Drosophila neurons. Neurosci Lett 2017; 643:76-83. [PMID: 28188850 DOI: 10.1016/j.neulet.2017.02.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/20/2017] [Accepted: 02/06/2017] [Indexed: 11/21/2022]
Abstract
Vesicular acetylcholine transporter (VAChT) function is essential for organismal survival, mediating the packaging of acetylcholine (ACh) for exocytotic release. However, its expression pattern in the Drosophila brain has not been fully elucidated. To investigate the localization of VAChT, we developed an antibody against the C terminal region of the protein and we show that this antibody recognizes a 65KDa protein corresponding to VAChT on an immunoblot in both Drosophila head homogenates and in Schneider 2 cells. Further, we report for the first time the expression of VAChT in the antennal lobe and ventral nerve cord of Drosophila larva; and we independently confirm the expression of the protein in mushroom bodies and optic lobes of adult Drosophila. Importantly, we show that VAChT co-localizes with a synaptic vesicle marker in vivo, confirming previous reports of the localization of VAChT to synaptic terminals. Together, these findings help establish the vesicular localization of VAChT in cholinergic neurons in Drosophila and present an important molecular tool with which to dissect the function of the transporter in vivo.
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Sizemore TR, Dacks AM. Serotonergic Modulation Differentially Targets Distinct Network Elements within the Antennal Lobe of Drosophila melanogaster. Sci Rep 2016; 6:37119. [PMID: 27845422 PMCID: PMC5109230 DOI: 10.1038/srep37119] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/25/2016] [Indexed: 01/10/2023] Open
Abstract
Neuromodulation confers flexibility to anatomically-restricted neural networks so that animals are able to properly respond to complex internal and external demands. However, determining the mechanisms underlying neuromodulation is challenging without knowledge of the functional class and spatial organization of neurons that express individual neuromodulatory receptors. Here, we describe the number and functional identities of neurons in the antennal lobe of Drosophila melanogaster that express each of the receptors for one such neuromodulator, serotonin (5-HT). Although 5-HT enhances odor-evoked responses of antennal lobe projection neurons (PNs) and local interneurons (LNs), the receptor basis for this enhancement is unknown. We used endogenous reporters of transcription and translation for each of the five 5-HT receptors (5-HTRs) to identify neurons, based on cell class and transmitter content, that express each receptor. We find that specific receptor types are expressed by distinct combinations of functional neuronal classes. For instance, the excitatory PNs express the excitatory 5-HTRs, while distinct classes of LNs each express different 5-HTRs. This study therefore provides a detailed atlas of 5-HT receptor expression within a well-characterized neural network, and enables future dissection of the role of serotonergic modulation of olfactory processing.
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Affiliation(s)
- Tyler R Sizemore
- Department of Biology, West Virginia University, Morgantown, WV, 26505, United States of America
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, WV, 26505, United States of America
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Miyake N, Fukai R, Ohba C, Chihara T, Miura M, Shimizu H, Kakita A, Imagawa E, Shiina M, Ogata K, Okuno-Yuguchi J, Fueki N, Ogiso Y, Suzumura H, Watabe Y, Imataka G, Leong HY, Fattal-Valevski A, Kramer U, Miyatake S, Kato M, Okamoto N, Sato Y, Mitsuhashi S, Nishino I, Kaneko N, Nishiyama A, Tamura T, Mizuguchi T, Nakashima M, Tanaka F, Saitsu H, Matsumoto N. Biallelic TBCD Mutations Cause Early-Onset Neurodegenerative Encephalopathy. Am J Hum Genet 2016; 99:950-961. [PMID: 27666374 DOI: 10.1016/j.ajhg.2016.08.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/09/2016] [Indexed: 01/01/2023] Open
Abstract
We describe four families with affected siblings showing unique clinical features: early-onset (before 1 year of age) progressive diffuse brain atrophy with regression, postnatal microcephaly, postnatal growth retardation, muscle weakness/atrophy, and respiratory failure. By whole-exome sequencing, we identified biallelic TBCD mutations in eight affected individuals from the four families. TBCD encodes TBCD (tubulin folding co-factor D), which is one of five tubulin-specific chaperones playing a pivotal role in microtubule assembly in all cells. A total of seven mutations were found: five missense mutations, one nonsense, and one splice site mutation resulting in a frameshift. In vitro cell experiments revealed the impaired binding between most mutant TBCD proteins and ARL2, TBCE, and β-tubulin. The in vivo experiments using olfactory projection neurons in Drosophila melanogaster indicated that the TBCD mutations caused loss of function. The wide range of clinical severity seen in this neurodegenerative encephalopathy may result from the residual function of mutant TBCD proteins. Furthermore, the autopsied brain from one deceased individual showed characteristic neurodegenerative findings: cactus and somatic sprout formations in the residual Purkinje cells in the cerebellum, which are also seen in some diseases associated with mitochondrial impairment. Defects of microtubule formation caused by TBCD mutations may underlie the pathomechanism of this neurodegenerative encephalopathy.
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Lee SG, Poole K, Linn CE, Vickers NJ. Transplant Antennae and Host Brain Interact to Shape Odor Perceptual Space in Male Moths. PLoS One 2016; 11:e0147906. [PMID: 26816291 PMCID: PMC4729490 DOI: 10.1371/journal.pone.0147906] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/07/2016] [Indexed: 11/30/2022] Open
Abstract
Behavioral responses to odors rely first upon their accurate detection by peripheral sensory organs followed by subsequent processing within the brain’s olfactory system and higher centers. These processes allow the animal to form a unified impression of the odor environment and recognize combinations of odorants as single entities. To investigate how interactions between peripheral and central olfactory pathways shape odor perception, we transplanted antennal imaginal discs between larval males of two species of moth Heliothis virescens and Heliothis subflexa that utilize distinct pheromone blends. During metamorphic development olfactory receptor neurons originating from transplanted discs formed connections with host brain neurons within olfactory glomeruli of the adult antennal lobe. The normal antennal receptor repertoire exhibited by males of each species reflects the differences in the pheromone blends that these species employ. Behavioral assays of adult transplant males revealed high response levels to two odor blends that were dissimilar from those that attract normal males of either species. Neurophysiological analyses of peripheral receptor neurons and central olfactory neurons revealed that these behavioral responses were a result of: 1. the specificity of H. virescens donor olfactory receptor neurons for odorants unique to the donor pheromone blend and, 2. central odor recognition by the H. subflexa host brain, which typically requires peripheral receptor input across 3 distinct odor channels in order to elicit behavioral responses.
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Affiliation(s)
- Seong-Gyu Lee
- Dept. of Biology, University of Utah, Salt Lake City, UT 84112, United States of America
| | - Kathy Poole
- Dept. of Entomology, Cornell University, Geneva, NY 14456, United States of America
| | - Charles E. Linn
- Dept. of Entomology, Cornell University, Geneva, NY 14456, United States of America
| | - Neil J. Vickers
- Dept. of Biology, University of Utah, Salt Lake City, UT 84112, United States of America
- * E-mail:
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A STRIPAK component Strip regulates neuronal morphogenesis by affecting microtubule stability. Sci Rep 2015; 5:17769. [PMID: 26644129 PMCID: PMC4672346 DOI: 10.1038/srep17769] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 11/05/2015] [Indexed: 11/08/2022] Open
Abstract
During neural development, regulation of microtubule stability is essential for proper morphogenesis of neurons. Recently, the striatin-interacting phosphatase and kinase (STRIPAK) complex was revealed to be involved in diverse cellular processes. However, there is little evidence that STRIPAK components regulate microtubule dynamics, especially in vivo. Here, we show that one of the core STRIPAK components, Strip, is required for microtubule organization during neuronal morphogenesis. Knockdown of Strip causes a decrease in the level of acetylated α-tubulin in Drosophila S2 cells, suggesting that Strip influences the stability of microtubules. We also found that Strip physically and genetically interacts with tubulin folding cofactor D (TBCD), an essential regulator of α- and β-tubulin heterodimers. Furthermore, we demonstrate the genetic interaction between strip and Down syndrome cell adhesion molecule (Dscam), a cell surface molecule that is known to work with TBCD. Thus, we propose that Strip regulates neuronal morphogenesis by affecting microtubule stability.
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Linking cell surface receptors to microtubules: tubulin folding cofactor D mediates Dscam functions during neuronal morphogenesis. J Neurosci 2015; 35:1979-90. [PMID: 25653356 DOI: 10.1523/jneurosci.0973-14.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Formation of functional neural networks requires the coordination of cell surface receptors and downstream signaling cascades, which eventually leads to dynamic remodeling of the cytoskeleton. Although a number of guidance receptors affecting actin cytoskeleton remodeling have been identified, it is relatively unknown how microtubule dynamics are regulated by guidance receptors. We used Drosophila olfactory projection neurons to study the molecular mechanisms of neuronal morphogenesis. Dendrites of each projection neuron target a single glomerulus of ∼50 glomeruli in the antennal lobe, and the axons show stereotypical pattern of terminal arborization. In the course of genetic analysis of the dachsous mutant allele (ds(UAO71)), we identified a mutation in the tubulin folding cofactor D gene (TBCD) as a background mutation. TBCD is one of five tubulin-folding cofactors required for the formation of α- and β-tubulin heterodimers. Single-cell clones of projection neurons homozygous for the TBCD mutation displayed disruption of microtubules, resulting in ectopic arborization of dendrites, and axon degeneration. Interestingly, overexpression of TBCD also resulted in microtubule disruption and ectopic dendrite arborization, suggesting that an optimum level of TBCD is crucial for in vivo neuronal morphogenesis. We further found that TBCD physically interacts with the intracellular domain of Down syndrome cell adhesion molecule (Dscam), which is important for neural development and has been implicated in Down syndrome. Genetic analyses revealed that TBCD cooperates with Dscam in vivo. Our study may offer new insights into the molecular mechanism underlying the altered neural networks in cognitive disabilities of Down syndrome.
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Sakuma C, Kawauchi T, Haraguchi S, Shikanai M, Yamaguchi Y, Gelfand VI, Luo L, Miura M, Chihara T. Drosophila Strip serves as a platform for early endosome organization during axon elongation. Nat Commun 2014; 5:5180. [PMID: 25312435 PMCID: PMC4197811 DOI: 10.1038/ncomms6180] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/05/2014] [Indexed: 12/19/2022] Open
Abstract
Early endosomes are essential for regulating cell signalling and controlling the amount of cell surface molecules during neuronal morphogenesis. Early endosomes undergo retrograde transport (clustering) before their homotypic fusion. Small GTPase Rab5 is known to promote early endosomal fusion, but the mechanism linking the transport/clustering with Rab5 activity is unclear. Here we show that Drosophila Strip is a key regulator for neuronal morphogenesis. strip knockdown disturbs the early endosome clustering and Rab5-positive early endosomes become smaller and scattered. Strip genetically and biochemically interacts with both Glued (the regulator of dynein-dependent transport) and Sprint (the guanine nucleotide exchange factor for Rab5), suggesting that Strip is a molecular linker between retrograde transport and Rab5 activation. Overexpression of an active form of Rab5 in strip mutant neurons suppresses the axon elongation defects. Thus, Strip acts as a molecular platform for the early endosome organization that plays important roles in neuronal morphogenesis.
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Affiliation(s)
- Chisako Sakuma
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takeshi Kawauchi
- 1] Department of Physiology, Keio University School of Medicine, Tokyo 160-8582, Japan [2] PRESTO, Japan Science and Technology Agency (JST), 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan
| | - Shuka Haraguchi
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Mima Shikanai
- Department of Physiology, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Yoshifumi Yamaguchi
- 1] Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan [2] PRESTO, Japan Science and Technology Agency (JST), 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, USA
| | - Masayuki Miura
- 1] Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan [2] CREST, Japan Science and Technology Agency (JST), 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan
| | - Takahiro Chihara
- 1] Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan [2] PRESTO, Japan Science and Technology Agency (JST), 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan [3] CREST, Japan Science and Technology Agency (JST), 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan
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