TOP ＞ Symposia

Symposia The discovery of pathological mechanisms in inherited neurodegenerative diseases／遺伝性神経疾患における病態解明の最前線～基礎から臨床へ～ 3S3-1 Elucidation of the pathology in inherited neurodegenerative diseases targeting G-quadruplex. Norifumi Shioda Depart Biofunctional Analysis Lab Mol Biol, Gifu Pharm Univ ATR-X syndrome is caused by mutations in ATRX, which encodes a chromatin-remodeling protein. ATRX predominantly binds to DNA G-quadruplexes, regulating transcription. Here, we report that Atrx mutation induces aberrant Xlr3b expression in brain, which is associated with neuronal pathogenesis displayed by ATR-X model mice. ATRX binds G-quadruplexes in CpG islands of the imprinted Xlr3b gene, regulating expression by DNA methylation. Xlr3b binds to dendritic mRNAs, and its overexpression inhibits dendritic transport of CaMKIIalpha mRNA, promoting synaptic dysfunction. Notably, treatment with 5-ALA that can be metabolized to porphyrins, protoporphyrin IX and hemin represses Xlr3b transcription by modifying G-quadruplex structure. 5-ALA treatment also antagonizes decreased synaptic plasticity and cognitive deficits seen in ATR-X model mice and rescues aberrant gene expression and synaptic dysfunction in human ATR-X iPSC-derived neurons. Our findings suggest a potential therapeutic strategy to target G-quadruplexes and decrease cognitive impairment associated with ATR-X syndrome. 3S3-2 Exosome-mediated transcellular transmission of molecular chaperones contributes to non-cell autonomous therapeutic effects on polyglutamine diseases Yoshitaka Nagai1,2 1Dept Neurotherapeutics, Osaka Univ Grad Sch Med，2Dept Degener Neurol Dis , NCNP The polyglutamine (polyQ) diseases are a group of inherited neurodegenerative diseases including Huntington's disease and various types of spinocerebellar ataxias, which are caused by an abnormal expansion of the polyQ stretch within disease-causing proteins. The expanded polyQ stretch triggers misfolding and aggregation of mutant proteins, resulting in their accumulation as inclusion bodies, and eventually leads to neurodegeneration. Molecular chaperones such as Hsp70 and Hsp40, have been shown to suppress polyQ protein aggregation and neurodegeneration in various polyQ disease in vivo models. We previously found that viral vector-mediated gene therapy of Hsp40 for polyQ disease mice unexpectedly suppressed polyQ inclusions even in virus non-infected surrounding neurons in the brain. To elucidate the mechanistic basis of this non-cell autonomous therapeutic effect, we employed a cell co-culture system and Drosophila models of polyQ diseases in which another transgene could be specifically expressed in different tissues. We found that Hsp40 as well as Hsp70 is physiologically secreted from cells via exosomes and taken up by surrounding cells. The J domain of Hsp40 is responsible for its exosome-mediated secretion. Addition of Hsp40/Hsp70-containing exosomes to the culture medium of the polyQ-expressing cells results in efficient suppression of polyQ inclusions. We further demonstrate that expression of Hsp40 or Hsp70 in the muscle or fat body significantly suppresses polyQ-induced eye degeneration in Drosophila. We therefore conclude that exosome-mediated intercellular transmission of molecular chaperones contributes to their non-cell autonomous therapeutic effects on polyQ disease models, and possibly, to maintenance of proteostasis at the organismal level. 3S3-3 The diagnosis and therapy of Fragile X syndrome and its related disorders. Eiji Nanba Divi Funct Genomics, Center Bioscience Technol, Tottori Univ Fragile X syndrome(FXS) is a famous well known genetic disease with intellectual disability and autistic behavior in human. FXS is caused by the large expansion (>200) of a cytosine–guanine–guanine (CGG) triplet repeat in the 5′ untranslated region of the fragile mental retardation 1(FMR1) gene on X chromosome and a loss of function of the gene. Recently, the mechanism of abnormal synapse in FXS has been elucidate and several strategies which rescue the synapse have been reported. FXS patient is usually born from the mother with the smaller expansion of triplet repeat. The normal expansion is less than 55 and the smaller expansions named permutation (55-200) can cause the different pathological changes with neurodegenerative disease named fragile X syndrome tremor / ataxia syndrome (FXTAS) or fragile X ovarian insufficiency (FPOI). The mechanisms of FXTAS and FPOI are not clear and no therapeutic approach has been found. The estimated prevalence of FXS in Japanese male was 1:5,000 by the examination of CGG repeats from normal population. However we have detected less than 100 patients and more than several thousand of the patients will be undiagnosed in Japan. We reported first Japanese case of FXTAS in 2010 and diagnosed further 13 patients. The prevalence of FMR1 premutation among Japanese POI patients was 1.56%. We should promote the genetic testing for the diagnosis in Japan. We have established a Japanese research group for FXS and its related disorders from 2010. I present here the overview and our study for FXS, FXTAS and FPOI. 3S3-4 Clinical application of gene therapy for genetic neurological diseases, present and future Takanori Yamagata Department of Pediatrics, Jichi Medical University According to the improvement of vector, gene therapy for neurological diseases have been developed and clinical application has started for some disease. Main vector in clinical use is the adeno-associated virus (AAV) vector, We performed a clinical study of gene therapy for aromatic L-amino acid decarboxylase (AADC) deficiency, which causes dopamine, catecholamine and serotonin depletion. Main symptoms were oculogyric crises, dystonia and impaired voluntary movement, and most patients are bedridden throughout their lives. Human AADC cDNA was ligated into a type 2 AAV vector (AAV-hAADC-2), that was injected into the bilateral putamen in a stereotaxic operation. Five patients have been treated; all showed an improved motor function. Among four severe patients, one could walk using a walker. Three patients started to eat again. One milder patient could walk long distances, and showed an improved mental status to make conversation. The only adverse event was transient choreic movement. And also, we are planning to develop a gene therapy for GLUT1 deficiency, which is caused by a defect of the glucose transporter gene, SLC2A1. The main clinical features include intractable seizure, ataxia, intellectual disability, from a low cerebrospinal fluid glucose level. We synthesized the treatment vector AAV9-SLC2A1, in which SLC2A1 was inserted in AAV9. AAV9-SLC2A1 improved the motor function and CSF glucose concentration in Slc2a1+/- mice after ventricular injection. Since gene therapy using the AAV vector has been shown to be safe and effective for treating AADC deficiency. There are many candidate childhood neurological diseases for gene therapy. Clinical application has started for several diseases, worldwide.