Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jbc.2021.100409

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Authorship：Last author,　Corresponding author  

DOI： 10.1371/journal.pone.0231450

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Authorship：Last author,　Corresponding author  

DOI： 10.3390/ijms20051010

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT  

Cell type-specific transcriptomes are enabled by the action of multiple regulators, which are frequently expressed within restricted tissue regions. In the present study, we identify one such regulator, Quaking 5 (Qki5), as an RNA-binding protein (RNABP) that is expressed in early embryonic neural stem cells and subsequently down-regulated during neurogenesis. mRNA sequencing analysis in neural stem cell culture indicates that Qki proteins play supporting roles in the neural stem cell transcriptome and various forms of mRNA processing that may result from regionally restricted expression and subcellular localization. Also, our in utero electroporation gain-of-function study suggests that the nuclear-type Qki isoform Qki5 supports the neural stem cell state. We next performed in vivo transcriptome-wide protein-RNA interaction mapping to search for direct targets of Qki5 and elucidate how Qki5 regulates neural stem cell function. Combined with our transcriptome analysis, this mapping analysis yielded a bona fide map of Qki5-RNA interaction at single-nucleotide resolution, the identification of 892 Qki5 direct target genes, and an accurate Qki5-dependent alternative splicing rule in the developing brain. Last, our target gene list provides the first compelling evidence that Qki5 is associated with specific biological events; namely, cell-cell adhesion. This prediction was confirmed by histological analysis of mice in which Qki proteins were genetically ablated, which revealed disruption of the apical surface of the lateral wall in the developing brain. These data collectively indicate that Qki5 regulates communication between neural stem cells by mediating numerous RNA processing events and suggest new links between splicing regulation and neural stem cell states.

DOI： 10.1101/gad.300822.117

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Authorship：Lead author,　Corresponding author   Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

RNA regulation participates in many aspects of brain development. There is substantial evidence that RNA dysregulation is critical in the pathogenesis of neurodevelopmental disorders, neurological diseases, and cancer. Several gene families encode RNA-binding proteins (RNABPs) that bind directly to RNA and orchestrate the post-transcriptional regulation of gene expression, including pre-mRNA splicing, stability, and poly(A) site usage. Among neural RNABPs, the Elavl and Msi families are the focus of neuronal development research owing to their hierarchical expression pattern: Msi1 is expressed in neural progenitor/stem cells, Elavl2 is expressed in early neuronal progenitors to mature neurons, and Elavl3/4 expression begins slightly later, during cortical neuron development. Traditional biochemical analyses provide mechanistic insight into RNA regulation by these RNABPs, and Drosophila and mouse genetic studies support a relationship between these RNABPs and several neurodevelopmental disorders. In addition, a recent cohort analysis of the human genome shows that genetic mutations and SNPs in these RNABPs are associated with various neurological disorders. Newly emerged technologies assess transcriptome-wide RNA-protein interactions in vivo. These technologies, combined with classical genetics methods, provide new insight into Elavl and Msi, not only with respect to their neurodevelopmental functions, but also their roles in several diseases. We review recent discoveries related to the two RNABP families in brain development and disease. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijdevneu.2016.01.002

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Adaptation to hypoxia depends on a conserved alpha/beta heterodimeric transcription factor called Hypoxia Inducible Factor (HIF), whose alpha-subunit is regulated by oxygen through different concurrent mechanisms. In this study, we have identified the RNA binding protein dMusashi, as a negative regulator of the fly HIF homologue Sima. Genetic interaction assays suggested that dMusashi participates of the HIF pathway, and molecular studies carried out in Drosophila cell cultures showed that dMusashi recognizes a Musashi Binding Element in the 3' UTR of the HIF alpha transcript, thereby mediating its translational repression in normoxia. In hypoxic conditions dMusashi is downregulated, lifting HIF alpha repression and contributing to trigger HIF-dependent gene expression. Analysis performed in mouse brains revealed that murine Msi1 protein physically interacts with HIF-1 alpha transcript, suggesting that the regulation of HIF by Msi might be conserved in mammalian systems. Thus, Musashi is a novel regulator of HIF that inhibits responses to hypoxia specifically when oxygen is available.

DOI： 10.1093/nar/gkw372

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Pancreatic intraepithelial neoplasia is a pre-malignant lesion that can progress to pancreatic ductal adenocarcinoma, a highly lethal malignancy marked by its late stage at clinical presentation and profound drug resistance1. The genomic alterations that commonly occur in pancreatic cancer include activation of KRAS2 and inactivation of p53 and SMAD4 (refs 2-4). So far, however, it has been challenging to target these pathways therapeutically; thus the search for other key mediators of pancreatic cancer growth remains an important endeavour. Here we show that the stem cell determinant Musashi (Msi) is a critical element of pancreatic cancer progression both in genetic models and in patient-derived xenografts. Specifically, we developed Msi reporter mice that allowed image-based tracking of stem cell signals within cancers, revealing that Msi expression rises as pancreatic intraepithelial neoplasia progresses to adenocarcinoma, and that Msi-expressing cells are key drivers of pancreatic cancer: they preferentially harbour the capacity to propagate adenocarcinoma, are enriched in circulating tumour cells, and are markedly drug resistant. This population could be effectively targeted by deletion of either Msi1 or Msi2, which led to a striking defect in the progression of pancreatic intraepithelial neoplasia to adenocarcinoma and an improvement in overall survival. Msi inhibition also blocked the growth of primary patient-derived tumours, suggesting that this signal is required for human disease. To define the translational potential of this work we developed antisense oligonucleotides against Msi; these showed reliable tumour penetration, uptake and target inhibition, and effectively blocked pancreatic cancer growth. Collectively, these studies highlight Msi reporters as a unique tool to identify therapy resistance, and define Msi signalling as a central regulator of pancreatic cancer.

DOI： 10.1038/nature17988

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Amyotrophic lateral sclerosis (ALS) is a late-onset motor neuron disorder. Although its neuropathology is well understood, the cellular and molecular mechanisms are yet to be elucidated due to limitations in the currently available human genetic data. In this study, we generated induced pluripotent stem cells (iPSC) from two familial ALS (FALS) patients with a missense mutation in the fused-in sarcoma (FUS) gene carrying the heterozygous FUS H517D mutation, and isogenic iPSCs with the homozygous FUS H517D mutation by genome editing technology. These cell-derived motor neurons mimicked several neurodegenerative phenotypes including mis-localization of FUS into cytosolic and stress granules under stress conditions, and cellular vulnerability. Moreover, exon array analysis using motor neuron precursor cells (MPCs) combined with CLIP-seq datasets revealed aberrant gene expression and/or splicing pattern in FALS MPCs. These results suggest that iPSC-derived motor neurons are a useful tool for analyzing the pathogenesis of human motor neuron disorders.

DOI： 10.1016/j.stemcr.2016.02.011

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Activity-dependent gene regulation in neurons has been hypothesized to be under transcriptional control and to include dramatic increases in immediate early genes (IEGs) after neuronal activity. In addition, several reports have focused on post-transcriptional regulation, which could be mediated by neuronal post-transcriptional regulators, including RNA binding proteins (RNABPs). One such protein family is the neuronal Elavls (nElavls; Elavl2, Elavl3, and Elavl4), whose members are widely expressed in peripheral and central nervous system. Previous reports showed that Elavl3 and 4 are up-regulated following repeated stimulation such as during cocaine administration, a seizure, or a spatial discrimination task. In this study, we focused on Elavl2, a candidate gene for schizophrenia and studied its role in neuronal activity. First we found that Elavl2 has a cell-type specific expression pattern that is highly expressed in hippocampal CA3 pyramidal neurons and hilar interneurons using Elavl2 specific antibody. Second, unexpectedly, we discovered that the Elavl2 protein level in the hippocampus was acutely downregulated for 3 h after a kainic acid (KA)-induced seizure in the hippocampal CA3 region. In addition, level of Gap43 mRNA, a target mRNA of Elavl2 is decreased 12 h after KA treatment, thus suggesting the involvement of Elavl2 in activity-dependent RNA regulation. (C) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2015.08.103

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Authorship：Corresponding author   Language：English   Publisher：SPRINGER  

An increasing number of studies have demonstrated that neural RNA-binding proteins (nRNABPs) participate in several steps of neural development through post-transcriptional regulation of their RNA targets (Grabowski Curr Opin Genet Dev 21:388-394, 2011). Classical genetics and in vitro biochemical approaches have identified several important RNA targets of nRNABPs linked to cell-fate decision and neuronal functions. In recent years, new technologies, such as unbiased in vivo protein-RNA interaction approaches, high-throughput sequencing-cross-linked immunoprecipitation (HITS-CLIP), microarrays, RNAseq and others, have been developed. The use of these with genetics has succeeded in defining a dynamic range of RNA targets of RNABPs at the transcriptome-wide level. This new platform also provides the mechanistic insights into a specific biological function of nRNABPs. This review highlights the discoveries and challenges of the interplay between the nRNABPs and their biological functions in neural development.

DOI： 10.1007/s00441-014-1923-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT  

Two polypyrimidine tract RNA-binding proteins (PTBs), one near-ubiquitously expressed (Ptbp1) and another highly tissue-restricted (Ptbp2), regulate RNA in interrelated but incompletely understood ways. Ptbp1, a splicing regulator, is replaced in the brain and differentiated neuronal cell lines by Ptbp2. To define the roles of Ptbp2 in the nervous system, we generated two independent Ptbp2-null strains, unexpectedly revealing that Ptbp2 is expressed in neuronal progenitors and is essential for postnatal survival. A HITS-CLIP (high-throughput sequencing cross-linking immunoprecipitation)-generated map of reproducible Ptbp2-RNA interactions in the developing mouse neocortex, combined with results from splicing-sensitive microarrays, demonstrated that the major action of Ptbp2 is to inhibit adult-specific alternative exons by binding pyrimidine-rich sequences upstream of and/or within them. These regulated exons are present in mRNAs encoding proteins associated with control of cell fate, proliferation, and the actin cytoskeleton, suggesting a role for Ptbp2 in neurogenesis. Indeed, neuronal progenitors in the Ptbp2-null brain exhibited an aberrant polarity and were associated with regions of premature neurogenesis and reduced progenitor pools. Thus, Ptbp2 inhibition of a discrete set of adult neuronal exons underlies early brain development prior to neuronal differentiation and is essential for postnatal survival.

DOI： 10.1101/gad.191338.112

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CELL PRESS  

Neuronal migration leads to a highly organized laminar structure in the mammalian brain, and its misregulation causes lissencephaly and behavioral and cognitive defects. Reelin signaling, which is mediated in part by a key adaptor, disabled-1 (Dab1), plays a critical but incompletely understood role in this process. We found that the neuron-specific RNA-binding protein Nova2 regulates neuronal migration in late-generated cortical and Purkinje neurons. An unbiased HITS-CLIP and exon junction array search for Nova-dependent reelin-pathway RNAs at E14.5 revealed only one candidate-an alternatively spliced isoform of Dab1 (Dab1.7bc). In utero electroporation demonstrated that Dab1.7bc was sufficient to induce neuronal migration defects in wild-type mice and exacerbate defects when Dab1 levels were reduced, whereas Dab1 overexpression mitigates defects in Nova2 null mice. Thus, Nova2 regulates an RNA switch controlling the ability of Dab1 to mediate neuronal responsiveness to reelin signaling and neuronal migration, suggesting new links between splicing regulation, brain disease, and development.

DOI： 10.1016/j.neuron.2010.05.007

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

The Hu family is a group of neuronal RNA-binding proteins required for neuronal differentiation in the developing nervous system. Previously, Hu proteins have been shown to enhance the stabilization and/or translation of target mRNAs, such as p21 ( CIP1), by binding to AU-rich elements in untranslated regions ( UTRs). In this study, we show that Hu induces p21 expression, cell cycle arrest, and neuronal differentiation in mouse neuroblastoma N1E-115 cells. p21 expression is also up-regulated during Me2SO- induced differentiation in N1E-115 cells and is controlled by post-transcriptional mechanisms through its 3'-UTR. To investigate the molecular mechanisms of Hu functions, we used a proteomics strategy to isolate Hu-interacting proteins and identified heterogeneous nuclear ribonucleoprotein (hnRNP) K. hnRNP K also specifically binds to CU-rich sequences in p21 mRNA 3'-UTR and represses its translation in both nonneuronal and neuronal cells. Further, using RNA interference experiments, we show that the Hu-p21 pathway contributes to the regulation of neurite outgrowth and proliferation in N1E-115 cells, and this pathway is antagonized by hnRNP K. Our results suggest a model in which the mutually antagonistic action of two RNA-binding proteins, Hu and hnRNP K, control the timing of the switch from proliferation to neuronal differentiation through the post-transcriptional regulation of p21 mRNA.

DOI： 10.1074/jbc.M411119200

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATL ACAD SCIENCES  

Neural Hu proteins (HuB/C/D) are RNA-binding proteins that have been shown to induce neuronal differentiation activity when overexpressed in immature neural progenitor cells or undifferentiated neuronal tumors. Newly generated HuD-deficient mice exhibited a transient impaired-cranial-nerve-development phenotype at an early embryonic stage. Adult HuD-deficient mice exhibited an abnormal hind-limb reflex and poor rotarod performance. Analysis of neurosphere formation revealed that the number and self-renewal capacity of the neural stem/progenitor cells were increased in HuD-deficient mice. HuD-deficient primary neurospheres also generated a smaller number of neurons. Cohort analysis of the cellular proliferative activity by using BrdUrd and iododeoxuridine labeling revealed that the number of differentiating quiescent cells in the embryonic cerebral wall was decreased. Long-term administration of BrdUrd revealed that the number of slowly dividing stem cells in the adult subventricular zone was increased in the HuD-deficient mice. Taken together, the results suggest that HuD is required at multiple points during neuronal development, including negative regulation of proliferative activity and neuronal cell-fate acquisition of neural stem/progenitor cells.

DOI： 10.1073/pnas.0407523102

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Phosphoinositides (PIPs) act as intracellular signaling molecules that regulate various cellular processes. Abnormalities in PIP metabolism cause various pathological conditions, including neurodegenerative diseases, cancer, and immune disorders. Several neurological diseases with diverse phenotypes, such as ataxia with cerebellar atrophy or intellectual disability without brain malformation, are caused by mutations in INPP4A, which encodes a phosphoinositide phosphatase. This study examined two strains of Inpp4a mutant mice with distinct cerebellar phenotypes: the first Inpp4aΔEx1,2 mutant exhibited striatal degeneration without cerebellar atrophy, and the other Inpp4aΔEx23 mutant exhibited a severe striatal phenotype with cerebellar atrophy. Both strains exhibited reduced expressions of Inpp4a mutant proteins in the cerebellum. N-terminal truncated Inpp4a proteins were expressed from Inpp4aΔEx1,2 allele by alternative translation initiation and had phosphatase activity for PI(3,4)P2, whereas the Inpp4a mutant protein encoded by Inpp4aΔEx23 completely lacked phosphatase activity. The diverse phenotypes observed in Inpp4a-related neurological diseases could be due to the varying protein expression levels and retained phosphatase activity in different Inpp4a variants. These findings provide insights into the role of Inpp4a mutations in disease pathogenesis and may help to develop personalized therapy.

DOI： 10.1242/dmm.050169

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Loss-of-function mutations in dystonin (DST) can cause hereditary sensory and autonomic neuropathy type 6 (HSAN-VI) or epidermolysis bullosa simplex (EBS). Recently, DST-related diseases were recognized to be more complex than previously thought because a patient exhibited both neurological and skin manifestations, whereas others display only one or the other. A single DST locus produces at least three major DST isoforms: DST-a (neuronal isoform), DST-b (muscular isoform) and DST-e (epithelial isoform). Dystonia musculorum (dt) mice, which have mutations in Dst, were originally identified as spontaneous mutants displaying neurological phenotypes. To reveal the mechanisms underlying the phenotypic heterogeneity of DST-related diseases, we investigated two mutant strains with different mutations: a spontaneous Dst mutant (Dstdt-23Rbrc mice) and a gene-trap mutant (DstGt mice). The Dstdt-23Rbrc allele possesses a nonsense mutation in an exon shared by all Dst isoforms. The DstGt allele is predicted to inactivate Dst-a and Dst-b isoforms but not Dst-e There was a decrease in the levels of Dst-a mRNA in the neural tissue of both Dstdt-23Rbrc and DstGt homozygotes. Loss of sensory and autonomic nerve ends in the skin was observed in both Dstdt-23Rbrc and DstGt mice at postnatal stages. In contrast, Dst-e mRNA expression was reduced in the skin of Dstdt-23Rbrc mice but not in DstGt mice. Expression levels of Dst proteins in neural and cutaneous tissues correlated with Dst mRNAs. Because Dst-e encodes a structural protein in hemidesmosomes (HDs), we performed transmission electron microscopy. Lack of inner plaques and loss of keratin filament invasions underneath the HDs were observed in the basal keratinocytes of Dstdt-23Rbrc mice but not in those of DstGt mice; thus, the distinct phenotype of the skin of Dstdt-23Rbrc mice could be because of failure of Dst-e expression. These results indicate that distinct mutations within the Dst locus can cause different loss-of-function patterns among Dst isoforms, which accounts for the heterogeneous neural and skin phenotypes in dt mice and DST-related diseases.

DOI： 10.1242/dmm.041608

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Spinal bulbar muscular atrophy (SBMA) is an adult-onset, slowly progressive motor neuron disease caused by abnormal CAG repeat expansion in the androgen receptor (AR) gene. Although ligand (testosterone)-dependent mutant AR aggregation has been shown to play important roles in motor neuronal degeneration by the analyses of transgenic mice models and in vitro cell culture models, the underlying disease mechanisms remain to be fully elucidated because of the discrepancy between model mice and SBMA patients. Thus, novel human disease models that recapitulate SBMA patients' pathology more accurately are required for more precise pathophysiological analysis and the development of novel therapeutics. Here, we established disease specific iPSCs from four SBMA patients, and differentiated them into spinal motor neurons. To investigate motor neuron specific pathology, we purified iPSC-derived motor neurons using flow cytometry and cell sorting based on the motor neuron specific reporter, HB9e438::Venus, and proceeded to the genome-wide transcriptome analysis by RNA sequences. The results revealed the involvement of the pathology associated with synapses, epigenetics, and endoplasmic reticulum (ER) in SBMA. Notably, we demonstrated the involvement of the neuromuscular synapse via significant upregulation of Synaptotagmin, R-Spondin2 (RSPO2), and WNT ligands in motor neurons derived from SBMA patients, which are known to be associated with neuromuscular junction (NMJ) formation and acetylcholine receptor (AChR) clustering. These aberrant gene expression in neuromuscular synapses might represent a novel therapeutic target for SBMA.

DOI： 10.1186/s13041-020-0561-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ireland Ltd  

Alternative splicing of RNAs diversifies the functionalities of proteins, and it is optimized for each cell type and each developmental stage. nElavl (composed of Elavl2, Elavl3, and Elavl4) proteins are the RNA-binding proteins that is specifically expressed in neurons, regulate the alternative splicing of target RNAs, and promote neuronal differentiation and maturation. Recent studies revealed that Elavl3 knockout (Elavl3−/−) mice completely lost the expression of nElavl proteins in the Purkinje cells and exhibited cerebellar dysfunction. Here, we found that the alternative splicing of AnkyrinG exon 34 was misregulated in the cerebella of Elavl3−/− mice. AnkyrinG is an essential factor for the formation of neuronal polarity and is required for normal neuronal functions. We revealed that exon 34 of AnkyrinG was normally included in immature neurons and was mostly excluded in mature neurons
however, it was included in the cerebella of Elavl3−/− mice even in adulthood. In the Purkinje cells of adult Elavl3−/− mice, the length of the AnkyrinG-positive region shortened and somatic organelles leaked into the axons. These results suggested that exon 34 of AnkyrinG is an embryonic-stage-preferential exon that should be excluded from mature neurons and that Elavl3 regulates neuronal polarity through alternative splicing of this exon.

DOI： 10.1016/j.neures.2018.03.008

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Given the complexity and heterogeneity of the genomic architecture underlying schizophrenia, molecular analyses of these patients with defined and large effect-size genomic defects could provide valuable clues. We established human-induced pluripotent stem cells from two schizophrenia patients with the 22q11.2 deletion (two cell lines from each subject, total of four cell lines) and three controls (total of four cell lines). Neurosphere size, neural differentiation efficiency, neurite outgrowth, cellular migration and the neurogenic-to-gliogenic competence ratio were significantly reduced in patient-derived cells. As an underlying mechanism, we focused on the role of DGCR8, a key gene for microRNA (miRNA) processing and mapped in the deleted region. In mice, Dgcr8 hetero-knockout is known to show a similar phenotype of reduced neurosphere size (Ouchi et al., 2013). The miRNA profiling detected reduced expression levels of miRNAs belonging to miR-17/92 cluster and miR-106a/b in the patient-derived neurospheres. Those miRNAs are reported to target p38α, and conformingly the levels of p38α were upregulated in the patient-derived cells. p38α is known to drive gliogenic differentiation. The inhibition of p38 activity by SB203580 in patient-derived neurospheres partially restored neurogenic competence. Furthermore, we detected elevated expression of GFAP, a gliogenic (astrocyte) marker, in postmortem brains from schizophrenia patients without the 22q11.2 deletion, whereas inflammation markers (IL1B and IL6) remained unchanged. In contrast, a neuronal marker, MAP2 expressions were decreased in schizophrenia brains. These results suggest that a dysregulated balance of neurogenic-to-gliogenic competence may underlie neurodevelopmental disorders such as schizophrenia.

DOI： 10.1038/tp.2016.206

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

HuD is a neuronal RNA-binding protein that plays an important role in neuronal differentiation of the nervous system. HuD has been reported to have three RNA recognition motifs (RRMs) and three splice variants (SVs) that differ in their amino acid sequences between RRM2 and RRM3. This study investigates whether these SVs have specific roles in neuronal differentiation. In primary neural epithelial cells under differentiating conditions, HuD splice variant 1 (HuD-sv1), which is a general form, and HuD-sv2 were expressed at all tested times, whereas HuD-sv4 was transiently expressed at the beginning of differentiation, indicating that HuD-sv4 might play a role compared different from that of HuD-sv1. Indeed, HuD-sv4 did not promote neuronal differentiation in epithelial cells, whereas HuD-sv1 did promote neuronal differentiation. HuD-sv4 overexpression showed less neurite-inducing activity than HuD-sv1 in mouse neuroblastoma N1E-115 cells; however, HuD-sv4 showed stronger growth-arresting activity. HuD-sv1 was localized only in the cytoplasm, whereas HuD-sv4 was localized in both the cytoplasm and the nuclei. The Hu protein has been reported to be involved in translation and alternative splicing in the cytoplasm and nuclei, respectively. Consistent with this observation, HuD-sv1 showed translational activity on p21, which plays a role in growth arrest and neuronal differentiation, whereas HuD-sv4 did not. By contrast, HuD-sv4 showed stronger pre-mRNA splicing activity than did HuD-sv1 on Clasp2, which participates in cell division. Therefore, HuD SVs might play a role in controlling the timing of proliferation/differentiation switching by controlling the translation and alternative splicing of target genes. (c) 2014 Wiley Periodicals, Inc.

DOI： 10.1002/jnr.23496

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Musashi (Msi) is an evolutionarily conserved gene family of RNA-binding proteins (RBPs) that is preferentially expressed in the nervous system. The first member of the Msi family was identified in Drosophila. Drosophila Msi plays an important role in regulating asymmetric cell division of the sensory organ precursor cells. The mammalian orthologs, including human and mouse Musashi1 (Msi1), are neural RBPs that are strongly expressed in fetal and adult neural stem/progenitor cells (NS/PCs). Mammalian Msi1 contributes to self renewal of NS/PCs through translational regulation of several target mRNAs. In this study, the zebrafish Msi ortholog zMsi1 was identified and characterized. The normal spatial and temporal expression profiles for both protein and mRNA were determined. A series of splice variants were detected. Overall, zMsi1 was strongly expressed in neural tissue in early stages of development and exhibited similarity to mammalian Msi1 expression patterns. To reveal the in vivo function of zMsi1, morpholinos against Msi1 were introduced into one-cell stage zebrafish embryos. Knock down of zmsi1 frequently resulted in aberrant formation of the Central Nervous System (CNS). These results suggest that Msi1 plays roles in CNS development in vertebrates.
This article is part of a Special Issue entitled "RNA-Binding Proteins". (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.brainres.2012.01.068

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Sox21, a high-mobility group box transcription factor, is expressed throughout the immature neural stem/progenitor population in ventricular zone but not in the cortical plate in embryonic mouse brain and its expression is restricted to the subventricular zone in the adult brain. In undifferentiated PC 12 cells, endogenous Sox21 expression is detected but its expression ceases during the nerve growth factor (NGF)-induced neuronal differentiation. Overexpression of Sox21 results in a substantial repression of NGF-induced neurite outgrowth in PC12 cells. Further, we biochemically identified a Sox21-associating protein, Y-box binding protein I which not only binds to Sox21 but also partially restores NGF-induced neurite outgrowth of PC12 cells inhibited by Sox21. These results suggest that Sox21 is a repressor of neuronal differentiation in the developing nervous system. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.neulet.2004.01.026

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We have found that a 12-lipoxygenase metabolite of arachidonic acid, 12(S)-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-HETE), induces CAMP production in human normal fibroblast TIG-1 cells. This phenomenon was not observed in other cells tested including human embryonic kidney HEK293 cells. We have speculated that this specific response might be influenced by the kinds of isoform of adenylyl cyclase (AC) present in cells. We found that TIG-1 cells specifically expressed type VIII AC. As type VIII AC is known to be activated by an increase of calcium concentration, we determined the change of intracellular Ca2+ concentration after the addition of 12-HETE. It was elevated not only in TIG-1 cells, but also HEK293 cells, which did not respond to 12-HETE to produce CAMP. The addition of a calcium ionophore elevated the concentration of intracellular CAMP in TIG-1 cells, but it was without effect in HEK293 cells. To show that the expression of this particular isoform of AC is responsible for the positive response to 12-HETE, we transfected this AC isoform into HEK293 cells. The type VIII AC-transfected cells, in contrast to the mock-transfected ones, became very responsive to 12HETE to produce CAMP. Taken all together the data would strongly suggest that 12-HETE specifically activates type VIII AC via increasing intracellular Ca2+ concentration. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/S0014-5793(03)01128-1

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DOI： 10.11477/mf.1542102724

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DOI： 10.1016/j.neures.2009.09.368

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：SPRINGER TOKYO  

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