TOP ＞ Symposium

Symposium 10 Modeling neurological and psychiatric disorders using iPS cell technologies and its application to drug development シンポジウム10 iPS細胞技術を用いた精神・神経疾患の病態解析とその創薬への応用 SY10-1 Pathophysiological consequences of retromer dysfunction in neurological disorder レトロマー複合体機能不全を伴う神経変性疾患の病態解析 Okano Hirotaka James（岡野 ジェームズ洋尚），坊野 恵子，原 央子，馬目 陽子，角 俊輔 Division of Regenerative Medicine, The Jikei University School of Medicine, Tokyo, Japan Retromer is a heteromeric protein complex that plays a critical role in endosome-to-Golgi retrieval of membrane proteins. Recent studies demonstrate that retromer dysfunction is pathogenically linked to several brain disorders including Parkinson's disease (PD). Mutations of the retromer component Vacuolar Protein Sorting-35 (VPS35) is linked to autosomal dominant forms of familial PD, PARK17. However, the precise biological mechanisms by which the mutation causes the neurological disorder is not clear. To understand pathophysiological consequences of the mutations, we analyzed two independent iPS cell lines from PD patients heterozygous for the VPS35 mutation. After induction to dopaminergic neurons (DN), the movement of the retromer and early endosomes are monitored by using newly generated retromer-reporters which enable fluorescent live imaging. We found that the fluorescent-labeled retromer rapidly moved around within the cytoplasm and dendrites together with early endosomes in control DN, however the movement of early endosome was slower in PD. Furthermore, the localization of the early endosomes including M6PRs, transmembrane glycoproteins that target lysosomal enzymes, was abnormal in PD, suggests VPS35 mutation affects the normal delivery of lysosomal enzymes to the endosomal-lysosomal system. Our result indicates that VPS35 mutation causes mistrafficking and mislocalization of endosomes in PARK17 iPSC-derived neural cells. Recent studies show that retromer dysfunction is also linked to Alzheimer disease, indicating a pathogenic role in two of the most common neurodegenerative diseases. Retromer is a potential target in drug discovery and strengthening its functional activity would be a strong therapeutic promise for these neurological disorders. SY10-2 Disease Modeling of Refractory Epilepsy using iPSCs iPS細胞技術を用いた小児難治性てんかんの病態解析 Hirose Shinichi（廣瀬 伸一）1,2 1Department of Pediatrics, School of Medicine, Fukuoka University 2Research Institute for the molecular pathomechanisms of epilepsy, Fukuoka University While induced pluripotent stem cells (iPSCs) are generally considered to be used in regenerative medicine, they can also be used to reproduce disease pathophysiology in vitro. This ability to replicate disease pathophysiology using iPSCs may be beneficial for intractable childhood disorders, specifically those involving the central nervous system, such as Dravet syndrome. Dravet syndrome, one of the intractable genetic epilepsies affecting children, is caused by mutations of SCN1A, the gene encoding the α1 subunit of Na+ channels in the brain. To understand the pathomechanisms of Dravet syndrome, we established iPSC lines from a patient harboring a pathological SCN1A mutation and differentiated the iPSCs into neuronal cells. We found, for the first time in humans, that the derived inhibitory GABAergic neurons had impaired action potentials compared to neurons derived from control iPSC lines. This finding is consistent with results from genetically engineered murine models with Scn1a mutations. Thus, the pathomechanisms of Dravet syndrome can be attributed to dysfunction of the inhibitory interneurons, termed interneuronopathy, due to SCN1A mutations. The discovery of these molecular pathomechanisms aligns with clinical observations that some anti-epileptic drugs that block Na+ channels precipitate seizures in patients with Dravet syndrome. This new understanding of the pathomechanisms of Dravet syndrome should open fresh avenues for novel drug development. Additionally, current technologies are able to readily introduce any mutation into iPSCs, which can facilitate high-throughput iPSC screening platforms for new potential drugs that target affected organs, even in rare genetic intractable childhood disorders. SY10-3 Neurological disease modeling and drug discovery using human iPSC platform iPS細胞を用いた神経疾患の病態・創薬研究 Inoue Haruhisa（井上 治久）1,2 1Dept. of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan 2RIKEN, Kyoto, Japan The iPSC technology was established a decade ago, and enormous progress in stem cell medicine has since been made. Human iPSC-derived cells, which had previously been inaccessible, exhibit the exciting promise of multiple purposes. iPSC-based disease modeling revealed pathomechanisms, and new drugs originating from iPSC screens are in the pipeline. Furthermore, recent developments of new technologies make iPSC-based platforms even more robust in each area of their application. In this symposium, I discuss the progress in applications of iPSC technology that are relevant to a neurological disease, and consider the remaining challenges and the emerging opportunities in the field. SY10-4 Elucidation of pathogenesis of schizophrenia using induced pluripotent stem cells (iPSC) established from patients with rare disease-associated variants 稀な疾患関連ゲノム変異を有する患者由来iPS細胞を用いた統合失調症の病因解明 Ozaki Norio（尾崎 紀夫） Nagoya University Graduate School of Medicine, Department of Psychiatry The recent progress of molecular genetic analysis enabled researchers to search for large effect, rare disease-susceptibility variants, such as copy number variants (CNVs) and single nucleotide variants (SNVs). Thus, using array comparative genomic hybridization, we performed a high-resolution genome-wide CNV analysis in about 2,000 schizophrenia (SCZ) and identified clinically significant CNVs that were more frequent in cases than controls. Furthermore, international collaborative autistic spectrum disorder (ASD) exome study identified 33 genes. Many of the implicated genes encode proteins for synaptic formation and chromatin-remodeling pathways and also have been implicated in other disorders including SCZ such as RELN. In order to develop the new psychotropic drug for mental disorders, the next generation of research in these disorders must address the neural circuitry underlying the psychiatric symptoms, the cell types playing pivotal roles in these circuits, and common intercellular signaling pathways that link diverse genes. Therefore, now we are trying to elucidate the molecular pathogenesis of these neurodevelopmental disorders using cell-based models (induced pluripotent stem cell (iPSC) established from patients with rare variants derived neurons), as well as animal models with high construct validity. In this symposium, I am going to introduce our recent progress using established from SCZ patients with rare disease associated variants including RELN or ARHGAP10 for modeling the genetic contribution to SCZ and yields access to patient-specific cells for drug discovery and personalized medicine. SY10-5 Disease Modeling and Drug Development for ALS using iPSCs-technlogies iPS細胞技術を用いたALSの病態解析と創薬研究 Okano Hideyuki（岡野 栄之） Department of Physiology, Keio University , Tokyo, Japan There is an increasing interest in disease modeling and drug development using induced pluripotent stem cells (iPSCs)-technologies. So far, we have established iPSCs from the patients of about 40 human psychiatric/psychiatric disorders and characterized their pathophysiology, including Alzheimer disease, Parkinson disease, ALS, Rett syndrome, Pelizaues-Merzbacher disease, lissencephaly, CHARGE syndrome, retinal pigmentosa, Pendred syndrome, and mental disorders such schizophrenia. In this talk, I will mention about our recent progress of disease modeling and drug development using iPSC-technologies, particularly drug development for ALS using a library of FDA-approved drugs. Using iPSCs-derived from two types of familial ALS, we have developed ALS-motor neurons model which recapitulated in vivo ALS phenotypes in a dish, including mislocalization (cytoplasmic leak) of the mutant proteins encoded by the causative genes, stress granule formation, neurite retraction and selective deaths of motor neurons. Using these ALS-related phenotypes in vitro, we have screened FDA-approved library to identify drugs that suppress those phenotypes. As a result, we have chosen the best candidate drug which is an approved drug for neurodegenerative disease other than ALS and is known to have BBB permeability. Furthermore, this drug was shown to suppress the mitochondria dysfunction and ROS-production that are related to motor neuron phenotypes of ALS. Notably, this drug had a superior therapeutic effects for ALS in vitro than the already-approved anti-ALS drugs. Furthermore, this drug also showed dosage-dependent therapeutic effects for sporadic form of ALS. Based on these findings, we are now proposing to start a clinical trial for sporadic or familial forms of ALS.