Honors & Awards


  • Training Program in Aging Research (TPAR; T32), Stanford University (2021)
  • Fellowship, Takeda Science Foundation (2020)

Boards, Advisory Committees, Professional Organizations


  • Board Certified Fellow, Japanese Society of Neurology (2019 - Present)
  • Board Certified Fellow, Japanese Society of Internal Medicine (2019 - Present)

Professional Education


  • M.D., Tohoku University (2010)
  • Ph.D, Tohoku University Graduate School of Medicine (2017)

Stanford Advisors


All Publications


  • Cracking the cryptic code in amyotrophic lateral sclerosis and frontotemporal dementia: Towards therapeutic targets and biomarkers. Clinical and translational medicine Akiyama, T., Koike, Y., Petrucelli, L., Gitler, A. D. 2022; 12 (5): e818

    Abstract

    Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two devastating human neurodegenerative diseases. A hallmark pathological feature of both diseases is the depletion of the RNA-binding protein TDP-43 from the nucleus in the brain and spinal cord of patients. A major function of TDP-43 is to repress the inclusion of cryptic exons during RNA splicing. When it becomes depleted from the nucleus in disease, this function is lost, and recently, several key cryptic splicing targets of TDP-43 have emerged, including STMN2, UNC13A, and others. UNC13A is a major ALS/FTD risk gene, and the genetic variations that increase the risk for disease seem to do so by making the gene more susceptible to cryptic exon inclusion when TDP-43 function is impaired. Here, we discuss the prospects and challenges of harnessing these cryptic splicing events as novel therapeutic targets and biomarkers. Deciphering this new cryptic code may be a touchstone for ALS and FTD diagnosis and treatment.

    View details for DOI 10.1002/ctm2.818

    View details for PubMedID 35567447

  • TDP-43 represses cryptic exon inclusion in the FTD-ALS gene UNC13A. Nature Ma, X. R., Prudencio, M., Koike, Y., Vatsavayai, S. C., Kim, G., Harbinski, F., Briner, A., Rodriguez, C. M., Guo, C., Akiyama, T., Schmidt, H. B., Cummings, B. B., Wyatt, D. W., Kurylo, K., Miller, G., Mekhoubad, S., Sallee, N., Mekonnen, G., Ganser, L., Rubien, J. D., Jansen-West, K., Cook, C. N., Pickles, S., Oskarsson, B., Graff-Radford, N. R., Boeve, B. F., Knopman, D. S., Petersen, R. C., Dickson, D. W., Shorter, J., Myong, S., Green, E. M., Seeley, W. W., Petrucelli, L., Gitler, A. D. 2022

    Abstract

    A hallmark pathological feature of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is the depletion of RNA-binding protein TDP-43 from the nucleus of neurons in the brain and spinal cord1. A major function of TDP-43 is as a repressor of cryptic exon inclusion during RNA splicing2-4. Single nucleotide polymorphisms in UNC13A are among the strongest hits associated with FTD and ALS in human genome-wide association studies5,6, but how those variants increase risk for disease is unknown. Here we show that TDP-43 represses a cryptic exon-splicing event in UNC13A. Loss of TDP-43 from the nucleus in human brain, neuronal cell lines and motor neurons derived from induced pluripotent stem cells resulted in the inclusion of a cryptic exon in UNC13A mRNA and reduced UNC13A protein expression. The top variants associated with FTD or ALS risk in humans are located in the intron harbouring the cryptic exon, and we show that they increase UNC13A cryptic exon splicing in the face of TDP-43 dysfunction. Together, our data provide a direct functional link between one of the strongest genetic risk factors for FTD and ALS (UNC13A genetic variants), and loss of TDP-43 function.

    View details for DOI 10.1038/s41586-022-04424-7

    View details for PubMedID 35197626

  • Identification of hub molecules of FUS-ALS by Bayesian gene regulatory network analysis of iPSC model: iBRN NEUROBIOLOGY OF DISEASE Nogami, M., Ishikawa, M., Doi, A., Sano, O., Sone, T., Akiyama, T., Aoki, M., Nakanishi, A., Ogi, K., Yano, M., Okano, H. 2021; 155: 105364

    Abstract

    Fused in sarcoma/translated in liposarcoma (FUS) is a causative gene of amyotrophic lateral sclerosis (ALS). Mutated FUS causes accumulation of DNA damage and cytosolic stress granule (SG) formation, thereby motor neuron (MN) death. However, key molecular aetiology remains unclear. Here, we applied a novel platform technology, iBRN, "Non- biased" Bayesian gene regulatory network analysis based on induced pluripotent stem cell (iPSC)-derived cell model, to elucidate the molecular aetiology using transcriptome of iPSC-derived MNs harboring FUSH517D. iBRN revealed "hub molecules", which strongly influenced transcriptome network, such as miR-125b-5p-TIMELESS axis and PRKDC for the molecular aetiology. Next, we confirmed miR-125b-5p-TIMELESS axis in FUSH517D MNs such that miR-125b-5p regulated several DNA repair-related genes including TIMELESS. In addition, we validated both introduction of miR-125b-5p and knocking down of TIMELESS caused DNA damage in the cell culture model. Furthermore, PRKDC was strongly associated with FUS mis-localization into SGs by DNA damage under impaired DNA-PK activity. Collectively, our iBRN strategy provides the first compelling evidence to elucidate molecular aetiology in neurodegenerative diseases.

    View details for DOI 10.1016/j.nbd.2021.105364

    View details for Web of Science ID 000663807700001

    View details for PubMedID 33857636

  • Reduced PHOX2B stability causes axonal growth impairment in motor neurons with TARDBP mutations STEM CELL REPORTS Mitsuzawa, S., Suzuki, N., Akiyama, T., Ishikawa, M., Sone, T., Kawada, J., Funayama, R., Shirota, M., Mitsuhashi, H., Morimoto, S., Ikeda, K., Shijo, T., Ohno, A., Nakamura, N., Ono, H., Ono, R., Osana, S., Nakagawa, T., Nishiyama, A., Izumi, R., Kaneda, S., Ikeuchi, Y., Nakayama, K., Fujii, T., Warita, H., Okano, H., Aoki, M. 2021; 16 (6): 1527-1541

    Abstract

    Amyotrophic lateral sclerosis (ALS) is an adult-onset incurable motor neuron (MN) disease. The reasons for selective MN vulnerability in ALS are unknown. Axonal pathology is among the earliest signs of ALS. We searched for novel modulatory genes in human MN axon shortening affected by TARDBP mutations. In transcriptome analysis of RNA present in the axon compartment of human-derived induced pluripotent stem cell (iPSC)-derived MNs, PHOX2B (paired-like homeobox protein 2B) showed lower expression in TARDBP mutant axons, which was consistent with axon qPCR and in situ hybridization. PHOX2B mRNA stability was reduced in TARDBP mutant MNs. Furthermore, PHOX2B knockdown reduced neurite length in human MNs. Finally, phox2b knockdown in zebrafish induced short spinal axons and impaired escape response. PHOX2B is known to be highly express in other types of neurons maintained after ALS progression. Collectively, TARDBP mutations induced loss of axonal resilience, which is an important ALS-related phenotype mediated by PHOX2B downregulation.

    View details for DOI 10.1016/j.stemcr.2021.04.021

    View details for Web of Science ID 000659201500014

    View details for PubMedID 34048688

    View details for PubMedCentralID PMC8190591

  • An Amyotrophic Lateral Sclerosis-Associated Mutant of C21ORF2 Is Stabilized by NEK1-Mediated Hyperphosphorylation and the Inability to Bind FBXO3. iScience Watanabe, Y., Nakagawa, T., Akiyama, T., Nakagawa, M., Suzuki, N., Warita, H., Aoki, M., Nakayama, K. 2020; 23 (9): 101491

    Abstract

    C21ORF2 and NEK1 have been identified as amyotrophic lateral sclerosis (ALS)-associated genes. Both genes are also mutated in certain ciliopathies, suggesting that they might contribute to the same signaling pathways. Here we show that FBXO3, the substrate receptor of an SCF ubiquitin ligase complex, binds and ubiquitylates C21ORF2, thereby targeting it for proteasomal degradation. C21ORF2 stabilizes the kinase NEK1, with the result that loss of FBXO3 stabilizes not only C21ORF2 but also NEK1. Conversely, NEK1-mediated phosphorylation stabilizes C21ORF2 by attenuating its interaction with FBXO3. We found that the ALS-associated V58L mutant of C21ORF2 is more susceptible to phosphorylation by NEK1, with the result that it is not ubiquitylated by FBXO3 and therefore accumulates together with NEK1. Expression of C21ORF2(V58L) in motor neurons induced from mouse embryonic stem cells impaired neurite outgrowth. We suggest that inhibition of NEK1 activity is a potential therapeutic approach to ALS associated with C21ORF2 mutation.

    View details for DOI 10.1016/j.isci.2020.101491

    View details for PubMedID 32891887

    View details for PubMedCentralID PMC7481237

  • Generation of an ALS human iPSC line KEIOi001-A from peripheral blood of a Charcot disease-affected patient carrying TARDBP p.N345K heterozygous SNP mutation. Stem cell research Leventoux, N., Morimoto, S., Hara, K., Nakamura, S., Ozawa, F., Mitsuzawa, S., Akiyama, T., Nishiyama, A., Suzuki, N., Warita, H., Aoki, M., Okano, H. 2020; 47: 101896

    Abstract

    Amyotrophic Lateral Sclerosis is the most common motor neuron degenerative disease in adults, and TARDBP gene mutations have been reported to be involved in the pathogenesis. We present here how we generated the human induced pluripotent stem cell (hiPSC) line KEIOi001-A/SM4-4-5 from the peripheral blood of a 63-year-old male patient presenting the c.1035C > G heterozygous SNP mutation in the TARDBP gene locus. The established hiPSC line does not express the exogenous reprogramming factors oriP nor EBNA1 and shows no karyotypic abnormalities, while it expresses pluripotent stem cell markers, presents the SNP mutation and is capable of three-germ layers differentiation in vitro.

    View details for DOI 10.1016/j.scr.2020.101896

    View details for PubMedID 32659732

  • AMPK Complex Activation Promotes Sarcolemmal Repair in Dysferlinopathy. Molecular therapy : the journal of the American Society of Gene Therapy Ono, H., Suzuki, N., Kanno, S. I., Kawahara, G., Izumi, R., Takahashi, T., Kitajima, Y., Osana, S., Nakamura, N., Akiyama, T., Ikeda, K., Shijo, T., Mitsuzawa, S., Nagatomi, R., Araki, N., Yasui, A., Warita, H., Hayashi, Y. K., Miyake, K., Aoki, M. 2020; 28 (4): 1133-1153

    Abstract

    Mutations in dysferlin are responsible for a group of progressive, recessively inherited muscular dystrophies known as dysferlinopathies. Using recombinant proteins and affinity purification methods combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS), we found that AMP-activated protein kinase (AMPK)γ1 was bound to a region of dysferlin located between the third and fourth C2 domains. Using ex vivo laser injury experiments, we demonstrated that the AMPK complex was vital for the sarcolemmal damage repair of skeletal muscle fibers. Injury-induced AMPK complex accumulation was dependent on the presence of Ca2+, and the rate of accumulation was regulated by dysferlin. Furthermore, it was found that the phosphorylation of AMPKα was essential for plasma membrane repair, and treatment with an AMPK activator rescued the membrane-repair impairment observed in immortalized human myotubes with reduced expression of dysferlin and dysferlin-null mouse fibers. Finally, it was determined that treatment with the AMPK activator metformin improved the muscle phenotype in zebrafish and mouse models of dysferlin deficiency. These findings indicate that the AMPK complex is essential for plasma membrane repair and is a potential therapeutic target for dysferlinopathy.

    View details for DOI 10.1016/j.ymthe.2020.02.006

    View details for PubMedID 32087766

    View details for PubMedCentralID PMC7132631

  • Omics Approach to Axonal Dysfunction of Motor Neurons in Amyotrophic Lateral Sclerosis (ALS). Frontiers in neuroscience Suzuki, N., Akiyama, T., Warita, H., Aoki, M. 2020; 14: 194

    Abstract

    Amyotrophic lateral sclerosis (ALS) is an intractable adult-onset neurodegenerative disease that leads to the loss of upper and lower motor neurons (MNs). The long axons of MNs become damaged during the early stages of ALS. Genetic and pathological analyses of ALS patients have revealed dysfunction in the MN axon homeostasis. However, the molecular pathomechanism for the degeneration of axons in ALS has not been fully elucidated. This review provides an overview of the proposed axonal pathomechanisms in ALS, including those involving the neuronal cytoskeleton, cargo transport within axons, axonal energy supply, clearance of junk protein, neuromuscular junctions (NMJs), and aberrant axonal branching. To improve understanding of the global changes in axons, the review summarizes omics analyses of the axonal compartments of neurons in vitro and in vivo, including a motor nerve organoid approach that utilizes microfluidic devices developed by this research group. The review also discusses the relevance of intra-axonal transcription factors frequently identified in these omics analyses. Local axonal translation and the relationship among these pathomechanisms should be pursued further. The development of novel strategies to analyze axon fractions provides a new approach to establishing a detailed understanding of resilience of long MN and MN pathology in ALS.

    View details for DOI 10.3389/fnins.2020.00194

    View details for PubMedID 32269505

    View details for PubMedCentralID PMC7109447

  • Extracellular α-synuclein enters dopaminergic cells by modulating flotillin-1-assisted dopamine transporter endocytosis. FASEB journal : official publication of the Federation of American Societies for Experimental Biology Kobayashi, J., Hasegawa, T., Sugeno, N., Yoshida, S., Akiyama, T., Fujimori, K., Hatakeyama, H., Miki, Y., Tomiyama, A., Kawata, Y., Fukuda, M., Kawahata, I., Yamakuni, T., Ezura, M., Kikuchi, A., Baba, T., Takeda, A., Kanzaki, M., Wakabayashi, K., Okano, H., Aoki, M. 2019; 33 (9): 10240-10256

    Abstract

    The neuropathological hallmarks of Parkinson's disease (PD) include the appearance of α-synuclein (α-SYN)-positive Lewy bodies (LBs) and the loss of catecholaminergic neurons. Thus, a potential mechanism promoting the uptake of extracellular α-SYN may exist in susceptible neurons. Of the various differentially expressed proteins, we are interested in flotillin (FLOT)-1 because this protein is highly expressed in the brainstem catecholaminergic neurons and is strikingly up-regulated in PD brains. In this study, we found that extracellular monomeric and fibrillar α-SYN can potentiate FLOT1-dopamine transporter (DAT) binding and pre-endocytic clustering of DAT on the cell surface, thereby facilitating DAT endocytosis and down-regulating its transporter activity. Moreover, we demonstrated that α-SYN itself exploited the DAT endocytic process to enter dopaminergic neuron-like cells, and both FLOT1 and DAT were found to be the components of LBs. Altogether, these findings revealed a novel role of extracellular α-SYN on cellular trafficking of DAT and may provide a rationale for the cell type-specific, functional, and pathologic alterations in PD.-Kobayashi, J., Hasegawa, T., Sugeno, N., Yoshida, S., Akiyama, T., Fujimori, K., Hatakeyama, H., Miki, Y., Tomiyama, A., Kawata, Y., Fukuda, M., Kawahata, I., Yamakuni, T., Ezura, M., Kikuchi, A., Baba, T., Takeda, A., Kanzaki, M., Wakabayashi, K., Okano, H., Aoki, M. Extracellular α-synuclein enters dopaminergic cells by modulating flotillin-1-assisted dopamine transporter endocytosis.

    View details for DOI 10.1096/fj.201802051R

    View details for PubMedID 31211923

  • Aberrant axon branching via Fos-B dysregulation in FUS-ALS motor neurons. EBioMedicine Akiyama, T., Suzuki, N., Ishikawa, M., Fujimori, K., Sone, T., Kawada, J., Funayama, R., Fujishima, F., Mitsuzawa, S., Ikeda, K., Ono, H., Shijo, T., Osana, S., Shirota, M., Nakagawa, T., Kitajima, Y., Nishiyama, A., Izumi, R., Morimoto, S., Okada, Y., Kamei, T., Nishida, M., Nogami, M., Kaneda, S., Ikeuchi, Y., Mitsuhashi, H., Nakayama, K., Fujii, T., Warita, H., Okano, H., Aoki, M. 2019; 45: 362-378

    Abstract

    The characteristic structure of motor neurons (MNs), particularly of the long axons, becomes damaged in the early stages of amyotrophic lateral sclerosis (ALS). However, the molecular pathophysiology of axonal degeneration remains to be fully elucidated.Two sets of isogenic human-induced pluripotent stem cell (hiPSCs)-derived MNs possessing the single amino acid difference (p.H517D) in the fused in sarcoma (FUS) were constructed. By combining MN reporter lentivirus, MN specific phenotype was analyzed. Moreover, RNA profiling of isolated axons were conducted by applying the microfluidic devices that enable axon bundles to be produced for omics analysis. The relationship between the target gene, which was identified as a pathological candidate in ALS with RNA-sequencing, and the MN phenotype was confirmed by intervention with si-RNA or overexpression to hiPSCs-derived MNs and even in vivo. The commonality was further confirmed with other ALS-causative mutant hiPSCs-derived MNs and human pathology.We identified aberrant increasing of axon branchings in FUS-mutant hiPSCs-derived MN axons compared with isogenic controls as a novel phenotype. We identified increased level of Fos-B mRNA, the binding target of FUS, in FUS-mutant MNs. While Fos-B reduction using si-RNA or an inhibitor ameliorated the observed aberrant axon branching, Fos-B overexpression resulted in aberrant axon branching even in vivo. The commonality of those phenotypes was further confirmed with other ALS causative mutation than FUS.Analyzing the axonal fraction of hiPSC-derived MNs using microfluidic devices revealed that Fos-B is a key regulator of FUS-mutant axon branching. FUND: Japan Agency for Medical Research and development; Japanese Ministry of Education, Culture, Sports, Science and Technology Clinical Research, Innovation and Education Center, Tohoku University Hospital; Japan Intractable Diseases (Nanbyo) Research Foundation; the Kanae Foundation for the Promotion of Medical Science; and "Inochi-no-Iro" ALS research grant.

    View details for DOI 10.1016/j.ebiom.2019.06.013

    View details for PubMedID 31262712

    View details for PubMedCentralID PMC6642224

  • Modeling sporadic ALS in iPSC-derived motor neurons identifies a potential therapeutic agent. Nature medicine Fujimori, K., Ishikawa, M., Otomo, A., Atsuta, N., Nakamura, R., Akiyama, T., Hadano, S., Aoki, M., Saya, H., Sobue, G., Okano, H. 2018; 24 (10): 1579-1589

    Abstract

    Amyotrophic lateral sclerosis (ALS) is a heterogeneous motor neuron disease for which no effective treatment is available, despite decades of research into SOD1-mutant familial ALS (FALS). The majority of ALS patients have no familial history, making the modeling of sporadic ALS (SALS) essential to the development of ALS therapeutics. However, as mutations underlying ALS pathogenesis have not yet been identified, it remains difficult to establish useful models of SALS. Using induced pluripotent stem cell (iPSC) technology to generate stem and differentiated cells retaining the patients' full genetic information, we have established a large number of in vitro cellular models of SALS. These models showed phenotypic differences in their pattern of neuronal degeneration, types of abnormal protein aggregates, cell death mechanisms, and onset and progression of these phenotypes in vitro among cases. We therefore developed a system for case clustering capable of subdividing these heterogeneous SALS models by their in vitro characteristics. We further evaluated multiple-phenotype rescue of these subclassified SALS models using agents selected from non-SOD1 FALS models, and identified ropinirole as a potential therapeutic candidate. Integration of the datasets acquired in this study permitted the visualization of molecular pathologies shared across a wide range of SALS models.

    View details for DOI 10.1038/s41591-018-0140-5

    View details for PubMedID 30127392

  • Antagonizing bone morphogenetic protein 4 attenuates disease progression in a rat model of amyotrophic lateral sclerosis. Experimental neurology Shijo, T., Warita, H., Suzuki, N., Ikeda, K., Mitsuzawa, S., Akiyama, T., Ono, H., Nishiyama, A., Izumi, R., Kitajima, Y., Aoki, M. 2018; 307: 164-179

    Abstract

    Amyotrophic lateral sclerosis (ALS) is an adult-onset, fatal neurodegenerative syndrome characterized by the systemic loss of motor neurons with prominent astrocytosis and microgliosis in the spinal cord and brain. Astrocytes play an essential role in maintaining extracellular microenvironments that surround motor neurons, and are activated by various insults. Growing evidence points to a non-cell autonomous neurotoxicity caused by chronic and sustained astrocytic activation in patients with neurodegenerative diseases, including ALS. However, the mechanisms that underlie the harmful effects of astrocytosis in patients with ALS remain unresolved. We focused on bone morphogenetic proteins as a major soluble factor that promotes astrocytogenesis and its activation in the adult spinal cord. In a transgenic rat model with ALS-linked mutant Cu/Zn superoxide dismutase gene, BMP4 was progressively up-regulated in reactive astrocytes of the spinal ventral horns, whereas the BMP-antagonist noggin was decreased in association with neuronal degeneration. Continuous intrathecal noggin supplementation after disease onset significantly ameliorated motor dysfunction symptoms, neurogenic muscle atrophy, and extended survival of symptomatic ALS model rats, despite lack of deterrence against neuronal death itself. The exogenous noggin inhibited astrocytic hypertrophy, astrocytogenesis, and neuroinflammation by inactivating both Smad1/5/8 and p38 mitogen-activated protein kinase pathways. Moreover, intrathecal infusion of a Bmp4-targeted antisense oligonucleotides and provided selective Bmp4 knockdown in vivo, which suppressed astrocyte and microglia activation, reproducing the aforementioned results by noggin treatment. Collectively, we clarified the involvement of BMP4 in the processes of excessive gliosis that exacerbate the disease progression of the ALS model rats. Our study demonstrated that BMP4, with its downstream signaling, might be a novel therapeutic target for disease-modifying therapies in ALS.

    View details for DOI 10.1016/j.expneurol.2018.06.009

    View details for PubMedID 29932880

  • TARDBP p.G376D mutation, found in rapid progressive familial ALS, induces mislocalization of TDP-43. eNeurologicalSci Mitsuzawa, S., Akiyama, T., Nishiyama, A., Suzuki, N., Kato, M., Warita, H., Izumi, R., Osana, S., Koyama, S., Kato, T., Suzuki, Y., Aoki, M. 2018; 11: 20-22

    View details for DOI 10.1016/j.ensci.2018.04.001

    View details for PubMedID 29928714

    View details for PubMedCentralID PMC6006914

  • Aberrant astrocytic expression of chondroitin sulfate proteoglycan receptors in a rat model of amyotrophic lateral sclerosis. Journal of neuroscience research Shijo, T., Warita, H., Suzuki, N., Kitajima, Y., Ikeda, K., Akiyama, T., Ono, H., Mitsuzawa, S., Nishiyama, A., Izumi, R., Aoki, M. 2018; 96 (2): 222-233

    Abstract

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Progressive and systemic loss of motor neurons with gliosis in the central nervous system (CNS) is a neuropathological hallmark of ALS. Chondroitin sulfate proteoglycans (CSPGs) are the major components of the extracellular matrix of the mammalian CNS, and they inhibit axonal regeneration physically by participating to form the glial scar. Recently, protein tyrosine phosphatase sigma (PTPσ) and leukocyte common antigen-related protein were discovered as CSPG receptors that play roles in inhibiting regeneration. Here we examined the expression of CSPG receptors in transgenic female rats overexpressing an ALS-linked mutant cytosolic Cu/Zn superoxide dismutase gene (SOD1). In contrast to controls, multiple immunofluorescence analyses revealed aberrant expression of CSPG receptors dominantly in reactive astrocytes, while PTPσ expression in neurons decreased in the spinal ventral horns of ALS transgenic rats. The aberrant and progressive astrocytic expression of CSPG receptors and reactive astrocytes themselves may be therapeutic targets for reconstructing a regeneration-supportive microenvironment under neurodegenerative conditions such as ALS.

    View details for DOI 10.1002/jnr.24127

    View details for PubMedID 28752900

  • Comprehensive targeted next-generation sequencing in Japanese familial amyotrophic lateral sclerosis. Neurobiology of aging Nishiyama, A., Niihori, T., Warita, H., Izumi, R., Akiyama, T., Kato, M., Suzuki, N., Aoki, Y., Aoki, M. 2017; 53: 194.e1-194.e8

    Abstract

    Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterized by loss of motor neurons. We have recently identified SOD1 and FUS mutations as the most common causes in a consecutive series of 111 familial ALS pedigrees in Japan. To reveal possible genetic causes for the remaining 51 patients with familial ALS (45 pedigrees), we performed targeted next-generation sequencing of 35 known ALS/motor neuron diseases-related genes. Known variants in ANG, OPTN, SETX, and TARDBP were identified in 6 patients. A novel likely pathogenic homozygous variant in ALS2 was identified in 1 patient. In addition, 18 patients harbored 1-3 novel variants of uncertain significance, whereas hexanucleotide repeat expansions in C9ORF72 were not detected using repeat-primed polymerase chain reaction. Collectively, in our Japanese cohort, the frequencies of SOD1, FUS, SETX, TARDBP, ANG, and OPTN variants were 32%, 11%, 2%, 2%, 1%, and 1%, respectively. These findings indicate considerable differences in the genetic variations associated with familial ALS across populations. Further genetic analyses and functional studies of novel variants are warranted.

    View details for DOI 10.1016/j.neurobiolaging.2017.01.004

    View details for PubMedID 28160950

  • Prominent sensory involvement in a case of familial amyotrophic lateral sclerosis carrying the L8V SOD1 mutation CLINICAL NEUROLOGY AND NEUROSURGERY Nishiyama, A., Warita, H., Takahashi, T., Suzuki, N., Nishiyama, S., Tano, O., Akiyama, T., Watanabe, Y., Takahashi, K., Kuroda, H., Kato, M., Tateyama, M., Niihori, T., Aoki, Y., Aoki, M. 2016; 150: 194-196
  • Genotype-phenotype relationships in familial amyotrophic lateral sclerosis with FUS/TLS mutations in Japan. Muscle & nerve Akiyama, T., Warita, H., Kato, M., Nishiyama, A., Izumi, R., Ikeda, C., Kamada, M., Suzuki, N., Aoki, M. 2016; 54 (3): 398-404

    Abstract

    We investigated possible genotype-phenotype correlations in Japanese patients with familial amyotrophic lateral sclerosis (FALS) carrying fused in sarcoma/translated in liposarcoma (FUS/TLS) gene mutations.A consecutive series of 111 Japanese FALS pedigrees were screened for copper/zinc superoxide dismutase 1 (SOD1) and FUS/TLS gene mutations. Clinical data, including onset age, onset site, disease duration, and extramotor symptoms, were collected.Nine different FUS/TLS mutations were found in 12 pedigrees. Most of the patients with FUS/TLS-linked FALS demonstrated early onset in the brainstem/upper cervical region, and relatively short disease duration. A few mutations exhibited phenotypes that were distinct from typical cases. Frontotemporal dementia was present in 1 patient.This study revealed a characteristic phenotype in FUS/TLS-linked FALS patients in Japan. FUS/TLS screening is recommended in patients with FALS with this phenotype. Muscle Nerve 54: 398-404, 2016.

    View details for DOI 10.1002/mus.25061

    View details for PubMedID 26823199

  • Establishment of In Vitro FUS-Associated Familial Amyotrophic Lateral Sclerosis Model Using Human Induced Pluripotent Stem Cells. Stem cell reports Ichiyanagi, N., Fujimori, K., Yano, M., Ishihara-Fujisaki, C., Sone, T., Akiyama, T., Okada, Y., Akamatsu, W., Matsumoto, T., Ishikawa, M., Nishimoto, Y., Ishihara, Y., Sakuma, T., Yamamoto, T., Tsuiji, H., Suzuki, N., Warita, H., Aoki, M., Okano, H. 2016; 6 (4): 496-510

    Abstract

    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.

    View details for DOI 10.1016/j.stemcr.2016.02.011

    View details for PubMedID 26997647

    View details for PubMedCentralID PMC4834049

  • FALS with FUS mutation in Japan, with early onset, rapid progress and basophilic inclusion (vol 55, pg 252, 2010) JOURNAL OF HUMAN GENETICS Suzuki, N., Aoki, M., Warita, H., Kato, M., Mizuno, H., Shimakura, N., Akiyama, T., Furuya, H., Hokonohara, T., Iwaki, A., Togashi, S., Konno, H., Itoyama, Y. 2015; 60 (10): 653-654

    View details for DOI 10.1038/jhg.2015.93

    View details for Web of Science ID 000363797200016

    View details for PubMedID 26500017

  • Neuronal representation of task performance in the medial frontal cortex undergoes dynamic alterations dependent upon the demand for volitional control of action EXPERIMENTAL BRAIN RESEARCH Matsuzaka, Y., Akiyama, T., Mushiake, H. 2013; 229 (3): 395-405

    Abstract

    Neural network contributing to forelimb task performance in the frontal cortex is dynamically reorganized by the necessity for volitional control of action. Neurons in the posterior medial prefrontal cortex (pmPFC) exhibit clear activity modulation when monkeys volitionally select the correct response tactic from multiple choices, but such activity disappears if selection of a tactic is unnecessary. Prompted by these results, we studied how the requirement to select an appropriate tactic affects the neural representation of action in downstream cortical areas. Two monkeys performed a spatial arm-reaching task with either left or right targets. The task required the monkeys to reach either toward (concordant trials) or away from (discordant trials) an illuminated target. Under the dual-tactic condition, concordant and discordant trials were randomly intermixed, requiring the selection of a response tactic. Under the single-tactic condition, only concordant trials were presented, allowing the monkeys to use the same tactic. Neurons in the pmPFC exhibited clear activity related to task performance under the former condition, but such activity disappeared under the latter condition. In contrast, neurons related to task performance were present under both conditions in supplementary motor area (SMA) and presupplementary motor area (pre-SMA). However, the efficacy of action representation by SMA but not pre-SMA neurons dramatically improved under the single-tactic condition. These results suggest that selection of the appropriate response tactic reorganizes neural circuits in specific motor areas in the medial frontal cortex, in addition to the pmPFC.

    View details for DOI 10.1007/s00221-013-3454-z

    View details for Web of Science ID 000323287000011

    View details for PubMedID 23479139

  • Neuronal activity in the primate dorsomedial prefrontal cortex contributes to strategic selection of response tactics. Proceedings of the National Academy of Sciences of the United States of America Matsuzaka, Y., Akiyama, T., Tanji, J., Mushiake, H. 2012; 109 (12): 4633-8

    Abstract

    The functional roles of the primate posterior medial prefrontal cortex have remained largely unknown. Here, we show that this region participates in the regulation of actions in the presence of multiple response tactics. Monkeys performed a forelimb task in which a visual cue required prompt decision of reaching to a left or a right target. The location of the cue was either ipsilateral (concordant) or contralateral (discordant) to the target. As a result of extensive training, the reaction times for the concordant and discordant trials were indistinguishable, indicating that the monkeys developed tactics to overcome the cue-response conflict. Prefrontal neurons exhibited prominent activity when the concordant and discordant trials were randomly presented, requiring rapid selection of a response tactic (reach toward or away from the cue). The following findings indicate that these neurons are involved in the selection of tactics, rather than the selection of action or monitoring of response conflict: (i) The response period activity of neurons in this region disappeared when the monkeys performed the task under the behavioral condition that required a single tactic alone, whereas the action varied across trials. (ii) The neuronal activity was found in the dorsomedial prefrontal cortex but not in the anterior cingulate cortex that has been implicated for the response conflict monitoring. These results suggest that the medial prefrontal cortex participates in the selection of a response tactic that determines an appropriate action. Furthermore, the observation of dynamic, task-dependent neuronal activity necessitates reconsideration of the conventional concept of cortical motor representation.

    View details for DOI 10.1073/pnas.1119971109

    View details for PubMedID 22371582

    View details for PubMedCentralID PMC3311351

  • Continuous administration of poloxamer 188 reduces overload-induced muscular atrophy in dysferlin-deficient SJL mice NEUROSCIENCE RESEARCH Suzuki, N., Akiyama, T., Takahashi, T., Komuro, H., Warita, H., Tateyama, M., Itoyama, Y., Aoki, M. 2012; 72 (2): 181-186

    Abstract

    Dysferlin-deficient SJL mice are commonly used to study dysferlinopathy. We demonstrated that poloxamer 188 (P188), a membrane sealant, is effective in reducing the loss of muscle mass in SJL mice when administered using an osmotic pump for 6 weeks. We did not observe significant changes over a 2-week administration period, suggesting that longthier observation is necessary to determine the effectiveness of P188. We also examined exercise endurance in P188-administered SJL mice using a rolling cage. Phosphorylated p38 was found to be reduced in P188-administered SJL mice; additionally, using microarray analysis, we found diminished expression of atrogin-1, an E3 ubiquitin ligase, as the effector of muscular atrophy. Chronic infusion of P188 to dysferlin-deficient SJL mice reduced muscular atrophy, and administering p38 and atrogin-1 in the gastrocnemius muscle improved its motor function. These results provide a basis for potential treatments for dysferlin-deficient skeletal muscle fibers.

    View details for DOI 10.1016/j.neures.2011.10.005

    View details for Web of Science ID 000299853400009

    View details for PubMedID 22044584

  • FALS with FUS mutation in Japan, with early onset, rapid progress and basophilic inclusion. Journal of human genetics Suzuki, N., Aoki, M., Warita, H., Kato, M., Mizuno, H., Shimakura, N., Akiyama, T., Furuya, H., Hokonohara, T., Iwaki, A., Togashi, S., Konno, H., Itoyama, Y. 2010; 55 (4): 252-4

    Abstract

    Mutations in the fused in sarcoma (FUS, also known as translated in liposarcoma) gene have been recently discovered to be associated with familial amyotrophic lateral sclerosis (FALS) in African, European and American populations. In a Japanese family with FALS, we found the R521C FUS mutation, which has been reported to be found in various ethnic backgrounds. The family history revealed 23 patients with FALS among 46 family members, suggesting a 100% penetrance rate. They developed muscle weakness at an average age of 35.3 years, followed by dysarthria, dysphagia, spasticity and muscle atrophy. The average age of death was 37.2 years. Neuropathological examination of the index case revealed remarkable atrophy of the brainstem tegmentum characterized by cytoplasmic basophilic inclusion bodies in the neurons of the brainstem. We screened 40 FALS families in Japan and found 4 mutations (S513P, K510E, R514S, H517P) in exon 14 and 15 of FUS. Even in Asian races, FALS with FUS mutations may have the common characteristics of early onset, rapid progress and high penetrance rate, although in patients with the S513P mutation it was late-onset. Degeneration in multiple systems and cytoplasmic basophilic inclusion bodies were found in the autopsied cases.

    View details for DOI 10.1038/jhg.2010.16

    View details for PubMedID 20224596