TGF-β signal disruption in polyglutamine disease

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Abstracts

ence was detected in the neuropathological phenotypes between CD−/− mice and double knockout mice lacking cathepsin D and p62. These data indicate that ubiquitin, but not necessarily p62, on the membrane of GRODs may serve as a signal of autophagy that contributes to the pathogenesis of NCLs. doi:10.1016/j.neures.2009.09.1405

P3-m10 Effects of MM-1 and molecular chaperones on formation of polyglutamine aggregation Erika Tashiro 1,2 , Hideki Muto 3 , Tamotsu Zako 4 , Makoto Kitaura 1 , Akira Kitamura 3 , Hiroshi Miyazawa 1,2 , Hirotake Kubota 5 , Mizuo Maeda 4 , Sanae M.M. Iguchi-Ariga 6 , Masataka Kinjo 3 , Hiroyoshi Ariga 1 1

Facul. of Pharm., Hokkaido Univ., Hokkaido; 2 Grad. Sch. of Lifesci., Hokkaido Univ., Hokkaido; 3 Facul. of Adv. Life Sci., Hokkaido Univ., Hokkaido; 4 Bioengineer Labo., RIKEN Institute, Saitama; 5 Facul. of Engineer and Resource Sci., Akita Univ., Akita; 6 Facul. of Agri., Hokkaido Univ., Hokkaido MM-1, a c-Myc-binding protein, is a tumor suppressor and suppresses activities of cell growth and transformation catalyzed by c-myc/ras. MM-1 is also known to be Prefoldin5, a subunit of Prefoldin. Prefoldin regulates the folding of nascent polypeptide chain in cooperation with Hsp70/Hsp40 and Tric/CCT. Since it has been reported that molecular chaperones, including Hsp70, Hsp40 and Tric/CCT, affect formation of polyglutamine aggregation, we investigated a role of MM-1 in process of polyQ formation. Aggregation of EGFP-polyQ72 were found to be increased in MM-1 knockdown Neuro2A cells by using siRNA and by Filter-trap assays and FCS (Fluorescence Correlation Spectroscopy) were used. These results indicate that Prefoldin affects the formation of polyQ aggregations. doi:10.1016/j.neures.2009.09.1406

P3-m11 The establishment and analysis of 26S proteasome conditional knockout mice for the mechanisms of neurodegenerative diseases Yoshitaka Tashiro 1 , Haruhisa Inoue 2 , Maya Yamazaki 3 , Manabu Abe 3 , Hidemi Misawa 4 , Kenji Sakimura 3 , Ryosuke Takahashi 1,5 1

Dept. Neurol., Kyoto Univ. Grad. Sch. Med., Japan; 2 Center for iPS Cell Research and Application, Institute for integrated Cell-Material Sciences, Kyoto University, Japan; 3 Basic Neuroscience Branch, Niigata University Brain Research, Japan; 4 Department of Pharmacology, School of Medicine, Keio University, Japan; 5 JST-CREST, Japan The accumulation of misfolded proteins is thought to be one of the main causes of neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease and amyotrophic lateral sclerosis. The degradation of misfolded proteins via the ubiquitin proteasome system (UPS) inhibits the accumulation of misfolded proteins, and inhibition of UPS exacerbates this accumulation, suggesting a vicious circle may be causative for neurodegeneration. In this study, we have established a conditional knockout mouse system of Rpt3, a 26S proteasome subunit by Cre loxP system. This floxed Rpt3 mice will provide a valuable tool for regulation of UPS in neurodegeneration. doi:10.1016/j.neures.2009.09.1407

P3-m12 TGF-␤ signal disruption in polyglutamine disease Masahisa Katsuno 1,2 , Hiroaki Adachi 2 , Makoto Minamiyama 2 , Masahiro Waza 2 , Keisuke Tokui 2 , Hideki Doi 2 , Fumiaki Tanaka 2 , Gen Sobue 2 1

Nagoya University, Japan; 2 Department of neurology, Nagoya Universuty Graduate School of Medicine, Nagoya, Japan Polyglutamine diseases are neurodegenerative disorders caused by the expansion of a trinucleotide CAG repeat. Here we demonstrate that TGF-␤ signaling is disrupted in a mouse model of spinal and bulbar muscular atrophy (SBMA), a polyglutaminemediated motor neuron disease, and in SBMA patients. The pathogenic androgen receptor, the causative protein of SBMA, inhibits the transcription of TGF-␤ receptor type II (T␤RII), via abnormal interactions with NF-Y and p300/CBP-associated factor. Similar findings were detected in a cellular model of spinocerebellar ataxia type3 (SCA3). Furthermore, overexpression of T␤RII dampens polyglutamine-induced cytotoxicity, whereas inhibition of TGF-␤ signaling increases motor dysfunction in SBMA mice. The present study thus indicates that disruption of TGF-␤ signaling mediates polyglutamine-induced neuron damage. doi:10.1016/j.neures.2009.09.1408

P3-m13 Inhibition of prostaglandin D synthase suppresses muscular necrosis Ikuko Mohri 1,2,3 , Kosuke Aritake 3 , Hidetoshi Taniguchi 2 , Kamauchi 3 , Nanae Nagata 3 , Toshihiko Yo Sato 3 , Shinya Maruyama 3 , Masako Taniike 1,2 , Yoshihiro Urade 3 1 Mol. Res. Cent. for Child Mental Develop., Osaka Univ. Grad. Schl. Med., Osaka, Japan; 2 Dept. of Pediatr., Osaka University Grad. Schl. Med., Osaka, Japan; 3 Dept. of Mol. Behavior. Biol., Osaka Biosci. Instit., Osaka, Japan

Previously we reported that hematopoietic prostaglandin D synthase (HPGDS) expressed in necrotic muscle fibers of Duchenne’s muscular dystrophy (DMD), a fatal musclar disease. HPGDS is responsible for the production of PGD2 , a strong inflammatory mediator. In this study, we investigated the role of HPGDS in the etiology of muscular necrosis using 2 different models, i.e., bupivacaine-induced muscle necrosis and the mdx mouse. We confirmed that HPGDS expression was induced in necrotic muscle fibers in both models. The necrotic muscle volume and CD11b and TGF␤1 mRNAs were significantly decreased in HQL-79-treated mdx mice than vehicle-treated ones. Furthermore, HQL-79 suppressed PGD2 production and improved muscle strength in mdx mouse. HPGDS augments the inflammation, and inhibition of HPGDS ameliorates the muscle necrosis even in genetic muscular dystrophy. doi:10.1016/j.neures.2009.09.1409

P3-m14 Effects of 405/532/808 nm low-power laser irradiation on the muscle contraction of frog gastrocnemius Shinichi Kogure, Kazuya Kozuka, Komei Tsuchiya, Masahiro Kakuno Soka University, Japan To identify the process which received the effect of low-power laser irradiation (LLI), we made waveform analysis on twich curves of the frog gastrocnemius. Thirty-eight frogs (Xenopus laevis) were used and their gastrocnemius muscle with sciatic nerve was prepared. Electrical stimulation with a supramaximal intensity to the sciatic nerve was delivered at 1/s for 10 min, and the gastgrocnemius was received three kinds of continuous LLI (405 nm: 20 mW; 532 nm: 60, 100 mW; 808 nm: 60, 100 mW) during the stimulation. Alterations of amplitude, latency, contraction period and relaxation period were analyzed. The LLIs (532 nm, 808 nm: 100 mW) influenced the amplitude to retard its decrement, and also latency and contraction period to retard their prolongations (p < 0.05: compared with the control), whereas another LLI (405 nm: 20 mW) promoted the amplitude decrement (p < 0.05). It is concluded that the LLI with an adequate wavelength as well as power has a potential to more activate the excitation-contraction coupling of the muscle. doi:10.1016/j.neures.2009.09.1410

P3-m15 Activation of complement is dispensable for myasthenia gravis caused by MuSK antibodies Shuuichi Mori, Sachiho Kubo, Takuyu Akiyoshi, Shigeru Yamada, Kazuhiro Shigemoto Dep. Geriatric. Med., Tokyo Metro Inst. of Gerontology, Japan The role of muscle-specific kinase (MuSK) antibodies (Ab) for the onset of myasthenia gravis (MG) has remained in dispute because the majority of MuSK Ab in the patients have shown to be incapable to activate complement, leading to the lysis of post-synaptic membrane at neuromuscular junction (NMJ). In order to reveal whether the activation of complement is indispensable for the pathogenicity of MG caused by MuSK Ab, complement (C5) -deficient mice were immunized with MuSK protein. The immunized mice developed the significant reductions of body weight and muscle strength with a high titer of MuSK Ab in the sera. Further, the electromyogram showed the decremental pattern, consistent with MG. In addition, histological studies revealed the scattering of AChR clustering and the simplification of post-synaptic structure at NMJ.We first demonstrated that the MG with MuSK Ab was caused by the direct inhibition of MuSK functions, which plays important role for the maintenance of the structure of mature NMJ, instead of the activation of complement. doi:10.1016/j.neures.2009.09.1411