* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Session 2. Synaptic Plasticity (Chair, H. Kamiguchi)
Environmental enrichment wikipedia , lookup
Endocannabinoid system wikipedia , lookup
Aging brain wikipedia , lookup
Cognitive neuroscience wikipedia , lookup
Electrophysiology wikipedia , lookup
Multielectrode array wikipedia , lookup
Neuroinformatics wikipedia , lookup
Signal transduction wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Subventricular zone wikipedia , lookup
Single-unit recording wikipedia , lookup
Neuroplasticity wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Amyotrophic lateral sclerosis wikipedia , lookup
Alzheimer's disease wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Haemodynamic response wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Nervous system network models wikipedia , lookup
Development of the nervous system wikipedia , lookup
Axon guidance wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Chemical synapse wikipedia , lookup
Synaptic gating wikipedia , lookup
Metastability in the brain wikipedia , lookup
Optogenetics wikipedia , lookup
Neuroanatomy wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Synaptogenesis wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Channelrhodopsin wikipedia , lookup
The 2nd Japan-Korea Neuroscience Symposium (A Satellite Symposium to Neuro2007) “Cutting Edge of Neuroscience” Date: September 13, 2007 Venue: Room 503, Pacifico Yokohama, Japan Organizer: Japan Neuroscience Society Korean Society of Brain and Neural Science RIKEN Brain Science Institute Organizing Committee: Tadaharu Tsumoto (RIKEN Brain Science Institute) Masao Ito (RIKEN Brain Science Institute) Yoo-Hun Suh (Seoul National University) 1 Program Session 1. Growth and Differentiation of Neurons (Chair, K. Yamaguchi) 9:30-10:00 Hiroyuki Kamiguchi (RIKEN/Brain Science Institute, Japan) “The Role of Ca2+ signals in axon guidance” 10:00-10:30 Kyong Tai Kim (Pohang University of Science & Technology, Korea) “Regulation of nerve differentiation by VRK3” 10:30-11:00 Kozo Kaibuchi (Nagoya University Graduate School of Medicine, Japan) “Neuronal polarity and axonal vesicle transport” 11:00-11:15 Coffee Break Session 2. Synaptic Plasticity (Chair, H. Kamiguchi) 11:15-11:45 Kazuhiko Yamaguchi (RIKEN/Brain Science Institute, Japan) “Regulatory roles of actin dynamics in constitutive and activity-dependent trafficking of AMPA-receptors in cerebellar Purkinje cell” 11:45-12:15 Bong-Kiun Kaang (Seoul National University, Korea) “Synaptic plasticity and transcription factors: Role of a retrograde transcription factor CAMAP in synaptic plasticity” 12:15-12:45 Toshiya Manabe (Tokyo University, Institute of Medical Sciences, Japan) “The role of tyrosine phosphorylation of the NMDA receptor in synaptic plasticity and higher brain functions” 12:45-14:00 Lunch Session 3. Neuroscience of Amyotrophic Lateral Sclerosis (Chair, T. Saido) 14:00-14:30 Koji Yamanaka (RIKEN/Brain Science Institute, Japan) "Onset and progression in inherited ALS determined by motor neurons and their neighboring glial cells" 14:30-15:00 Kwang-Woo Lee (Seoul National University, Korea) “Pathomechanism of ALS and neuroprotective effects of the novel dihydroxy bile acid ursodeoxycholic acid derivate (Yoo's solution) in ALS” 15:00-15:30 Shin Kwak (Tokyo University Graduate School of Medicine, Japan) “RNA editing and motor neuron diseases” 15:30-15:45 Coffee Break Session 4. Neuroscience of Alzheimer’s Disease (Chair, K. Yamanaka) 15:45-16:15 Takaomi Saido (RIKEN/Brain Science Institute, Japan) “Metabolism of amyloid-β peptide and Alzheimer's disease” 16:15-16:45 Yoo-Hun Suh (Seoul National University, Korea) “Molecular pathogenesis and peripheral markers of α-synucleinopathy” 16:45-17:15 Takeshi Iwatsubo (University of Tokyo, Japan) "Molecular pathology of Alzheimer's disease: β-amyloid and γ-secretase" 18:00-20:00 Reception 2 Session 1. Growth and Differentiation of Neurons 3 The role of Ca2+ signals in axon guidance Hiroyuki Kamiguchi Laboratory for Neuronal Growth Mechanisms RIKEN Brain Science Institute, Japan Axonal growth cones migrate along the correct paths during development, not only directed by diffusible guidance cues but also contacted by local environment via cell adhesion molecules (CAMs). Extracellular gradients of many guidance cues attract or repel the growth cone via an asymmetric elevation of cytosolic free Ca2+ concentration ([Ca2+]c). Interestingly, a [Ca2+]c gradient across the growth cone can trigger turning to the side with higher [Ca2+]c (attraction) as well as to the side with lower [Ca2+]c (repulsion). Then, what determines the growth cone responses to the [Ca2+]c gradient? In this symposium, I will present evidence that the turning direction of growth cones depends on the occurrence of Ca2+-induced Ca2+ release (CICR) through the ryanodine receptor type 3 (RyR3): Ca2+ signals that are accompanied by RyR3-mediated CICR trigger growth cone attraction whereas Ca2+ signals without CICR induce growth cone repulsion. The activity of RyR3 is regulated by local environment contacting the growth cone: CAMs such as L1 and N-cadherin facilitate RyR3-mediated CICR by activating cAMP-dependent protein kinase (PKA), whereas extracellular matrix molecules such as laminin inactivate RyR3 by down-regulating PKA. In this way, axon-guiding and CAM-derived signals are integrated at the level of RyR3, which serves as a key regulator of growth cone guidance. Next I will examine the molecular machinery downstream of Ca2+ signals and present evidence that asymmetric membrane trafficking in the growth cone mediates attractive axon guidance. A localized elevation of [Ca2+]c together with CICR (attractive Ca2+ signals) on one side of the growth cone facilitates microtubule-dependent centrifugal transport of vesicles towards the leading front and subsequent vesicle-associated membrane-protein 2 (VAMP2)-mediated exocytosis on the side with elevated Ca2+. In contrast, Ca2+ signals without CICR (repulsive Ca2+ signals) have no effect on the vesicle transport. Furthermore, pharmacological inhibition of VAMP2-mediated exocytosis prevents growth cone attraction but not repulsion. Our study provides a simple mechanisms for attractive axon guidance: the growth cone turns by preferentially supplying membrane components and associated molecules to the side facing the new direction. Our results also suggest that growth cone attraction and repulsion are driven by distinct mechanisms, rather than using the same molecular machinery with opposing polarities. Ooashi N, Futatsugi A, Yoshihara F, Mikoshiba K, Kamiguchi H: Cell adhesion molecules regulate Ca2+-mediated steering of growth cones via cyclic AMP and ryanodine receptor type 3. J Cell Biol 170: 1159-1167, 2005 Tojima T, Akiyama H, Itofusa R, Li Y, Katayama H, Miyawaki A, Kamiguchi H: Attractive axon guidance involves asymmetric membrane transport and exocytosis in the growth cone. Nat Neurosci 10: 58-66, 2007 4 Regulation of Nerve Differentiation by VRK3 Kyong-Tai Kim Department of Life Science, Pohang University of Science and Technology, Pohang, Korea Extracellular signal regulated kinases (ERKs) represent a signalling hub in many physiological responses and have pivotal functions in cell proliferation, differentiation, development and death, as well as in synaptic plasticity. Mitogen-activated protein kinase phosphatases (MKPs) selectively inactivate ERKs by dephosphorylating critical phosphothreonine and phosphotyrosine residues. Transcriptional induction of MKP expression and posttranscriptional stabilization of MKP mRNA are well-documented as negative-feedback mechanisms for ERK signalling. Vaccinia-related kinase 3 (VRK3) is a member of the novel VRK family, but its function has not been defined. Here, we show that VRK3 suppresses ERK activity through direct binding to one of the MKPs, vaccinia H1-related (VHR), which specifically dephosphorylates and inactivates ERK in the nucleus. Notably, VRK3 enhances the phosphatase activity of VHR by a mechanism independent of its kinase activity. VRK3 is therefore a member of a new class of phosphatase-activating kinases that regulate the activity of ERK. Our findings show that direct interaction of VHR with VRK3 posttranslationally regulates ERK signalling. ERK regulates nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells. Transient expression of VRK3 strongly suppressed both ERK activation and neurite outgrowth induced by NGF in PC12 cells. Phorbol 12-myristate 13-acetate (PMA), a well-known activator of protein kinase C (PKC), has been shown to induce accumulation of ERK in the nucleus and neurite outgrowth in neuroblastoma HT22 cells. Overexpression of VRK3 also inhibited PMA-induced nurite outgrowth in HT22 cells. Consistently, knockdown of VRK3 promoted neurite outgrowth in both NGF-treated PC12 cells and PMA-treated HT22 cells. Our study provides evidence for a negative-feedback mechanism of MAPK signalling, where VRK3 modulates MKP activity. This emphasizes the multiplicity and importance of precise control of MAPK signaling in neuronal differentiation. 5 Neuronal polarity and axonal vesicle transport Kozo Kaibuchi Nagoya University Graduate School of Medicine, Japan Neurons are highly polarized cells that have axons and dendrites, both of which are differentiated from common immature neurites in cultured hippocampal neurons. One of the key events for neuronal polarization is the directional trafficking of signaling molecules including a neurotrophin receptor (Trk), which plays a critical role in axon specification. Here we report that collapsin response mediator protein-2 (CRMP-2) links the vesicles containing TrkB to Kinesin-1 through synaptotagmin-like protein 1 (Slp1) and Rab27, and regulates the anterograde transport of TrkB in growing axons. The velocity of TrkB transport is much higher in growing axons than in the immature neurites. Glycogen synthase kinase-3ß (GSK-3ß) phosphorylates CRMP-2, prevents the association of CRMP-2 with Kinesin-1 and Slp1, and impairs TrkB transport and neuronal polarization. Because the activity GSK-3ß lower in the distal part of growing axons than in other immature neurites, we propose that local inactivation of GSK-3ß in growing axons promotes the complex formation of Kinesin-1/CRMP-2/Slp1/Rab27 and anterograde TrkB transport for neuronal polarization. Reference Arimura, N and Kaibuchi, K. Nat Rev Neurosci, 8, 194-205, 2007 6 Session 2. Synaptic Plasticity 7 Regulatory roles of actin dynamics in constitutive and activity-dependent trafficking of AMPA-receptors in cerebellar Purkinje cell Kazuhiko Yamaguchi Lab. for Memory and Learning, RIKEN Brain Science Institute, Japan In mammalian cerebral neurons, the balance between exocytosis and endocytosis maintains postsynaptic expression of AMPA-type glutamate receptors (AMPA-Rs), and any activity-dependent shift in this balance is the basis for postsynaptic type of plasticity. In the cerebellar Purkinje cell, relationship between constitutive and activity-dependent trafficking of AMPA-Rs is not clear. We analyzed this relationship in parallel fiber (PF) synapses of cerebellar Purkinje cells by recording EPSC using a whole-cell patch-clamp method. Constitutive endocytosis of AMPA-Rs was observed as a rapid decrease in synaptic current when we blocked exocytosis by tetanus toxin (TeTx). Some populations of AMPA-Rs were TeTx-resistant, and this TeTx-resistant pool of AMPA-Rs may be the stabilized AMPA-Rs seen at the PF-synapse. We examined the role of actin in stabilizing AMPA-Rs at the PF-synapse. Latrunculin A (Lat), a blocker of actin-polymerization, reduced the stable pool of AMPA-Rs while jasplakinolide (Jas), a blocker of actin-depolymerization, enhanced this pool of AMPA-Rs, indicating that actin dynamics regulated AMPA-Rs stabilization at PF-synapse. To examine whether constitutive endocytosis of AMPA-Rs and long-term depression (LTD) of EPSC share the same mechanism, we induced LTD at the steady state of TeTx-induced EPSC-reduction. LTD did not occlude constitutive endocytosis of AMPA-Rs. Jas blocked LTD and Lat enhanced it, suggesting the involvement of actin-depolymerization in the induction of LTD. Toxin B of Clostridium difficile, an inhibitor for Rho-family monomeric GTPases (Rho, Rac and Cdc42), suppressed LTD induction, while exoenzyme C3, a Rho-specific blocker, did not. Thus, Cdc42 and/or Rac most likely mediate LTD-induction. Internalization of surface-expressed GluR2 was visualized using monoclonal antibody recognizing GluR2 N-terminus. Stimulation with glutamate and KCl caused a substantial increase in the internalization of surface-expressed GluR2, and Lat enhanced this internalization. Taken together, these results suggest that actin-depolymerization is involved in LTD-induction in cerebellar Purkinje cell. 8 Synaptic plasticity and transcription factors: Role of a retrograde transcription factor CAMAP in synaptic plasticity Bong-Kiun Kaang, Ph.D. Department of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul, Korea The formation of long-term memory requires both new RNA and protein synthesis, whereas short-term memory requires only covalent modifications of constitutively expressed preexisting proteins. The core molecular features of the transcriptional regulation involved in long-term memory is to be evolutionally conserved in Aplysia and Drosophila and in the mouse. A growing body of evidence indicates that gene regulation by different combinations of transcriptional factors may be involved in specific forms of long-term memory. In the marine snail Aplysia, the molecular mechanisms of long-term memory have been extensively studied in sensory neuron-to-motor neuron synapses of the gill-withdrawal reflex. Multiple pulses of 5-hydroxytryptamine (5-HT) produce long-term synaptic facilitation (LTF) and depends on transcription and translation. These pulses of 5-HT upregulate the levels of cAMP within the sensory cell via G-protein coupled receptors, and activate protein kinase A (PKA) and mitogen-activated protein kinase (MAPK). Both kinases then translocate into the nucleus where they can activate transcription factors such as ApCREB1, ApCREB2, and ApAF, expressed in sensory neurons. Repeated pulses of serotonin (5-HT) induce long-term facilitation (LTF) of the synapses between sensory and motor neurons of the gill-withdrawal reflex in Aplysia. To explore how the apCAM down-regulation at the plasma membrane and the CREB-mediated transcription in the nucleus, both of which are required for the formation of LTF, might relate to each other, we have cloned an apCAM-associated protein (CAMAP) by yeast two-hybrid screening. We found that 5-HT signaling at the synapse activates PKA which in turn phosphorylates CAMAP to induce the dissociation of CAMAP from apCAM and the subsequent translocation of CAMAP into the nucleus of sensory neurons. In the nucleus, CAMAP acts as a transcriptional co-activator for CREB1 essential for the activation of the immediate early gene ApC/EBP. Combined, our data suggest that CAMAP is one of the critical retrograde signaling components that translocates from activated synapses to the nucleus during synapse-specific LTF. 9 The role of tyrosine phosphorylation of the NMDA receptor in synaptic plasticity and higher brain functions Toshiya Manabe Division of Neuronal Network, Institute of Medical Science, University of Tokyo, Tokyo, Japan Long-lasting synaptic modification, such as long-term potentiation (LTP) of synaptic transmission, has been thought to be involved in memory formation in the central nervous system. The hippocampus plays a critical role in the memory of facts and episodes, while the amygdala is associated with the memory of emotions such as fear. The expression of LTP is usually mediated by long-lasting modification of intracellular biochemical processes in neurons. Phosphorylation of neural proteins in response to a variety of external stimuli is one of the main mechanisms underlying dynamic changes in the neural circuitry. The NR2B (GluRε2) subunit of the N-methyl-D-aspartate (NMDA) receptor is tyrosine-phosphorylated in the brain, with Tyr-1472 its major phosphorylation site. We have generated mutant mice with a knockin mutation of the Tyr-1472 site to phenylalanine (Y1472F). These mutant mice (YF/YF mice) show that Tyr-1472 phosphorylation is essential for the functions of the amygdala. The YF/YF mice show impaired auditory fear conditioning and reduced LTP in the lateral nucleus of the amygdala. In addition, the calcium/calmodulin-dependent protein kinase II (CaMKII) signaling mediated by NMDA receptor activation is impaired in YF/YF mice. Furthermore, electron-microscopic analyses reveal that the Y1472F mutant of the NR2B subunit shows improper localization on postsynaptic spines at synapses. We have thus identified Tyr-1472 phosphorylation of the NR2B subunit as a key mediator of synaptic plasticity in the amygdala and fear-related learning. 10 Session 3. Neuroscience of Amyotrophic Lateral Sclerosis 11 Onset and progression in inherited ALS determined by motor neurons and their neighboring glial cells. Koji Yamanaka Yamanaka Research Unit, RIKEN Brain Science Institute, Japan Dominant mutations in the ubiquitously expressed Cu/Zn superoxide dismutase (SOD1) lead to amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting adult motor neurons. Although ubiquitous expression of mutant SOD1 provokes progressive, selective motor neuron degeneration in human and rodents due to an acquired toxic property(ies) of the mutant, the cell types that contribute to the onset and progression of the motor neuron disease are not known. To test whether mutant SOD1 toxicity within specific cell types contributes to motor neuron degeneration, we have generated a mouse ubiquitously expressing a “floxed” mutant SOD1G37R transgene (LoxSOD1G37R) which can be removed within specific cell populations by the action of Cre recombinase. To eliminate mutant SOD1 within motor neurons or non-neuronal neighboring cells, these lox SOD1G37R mice were mated to Islet1-Cre, CD11b-Cre, or GFAP-Cre that express Cre specifically in motor neurons, microglia, or astrocytes, respectively. Removing mutant SOD1 from motor neurons slowed the timing of disease onset and early disease progression, indicating mutant action in neurons as an initiating factor in triggering disease. More importantly, silencing of SOD1 mutant expression selectively within microglial cells or astrocytes has minimal effect on age of disease onset, but sharply slows disease progression. Thus, onset and progression represent distinct disease phases defined by mutant action within different cell types to generate non-cell-autonomous killing of motor neurons, findings that validate therapies, including cell replacement, targeted to the glial cells. 12 Pathomechanism of ALS and neuroprotective effects of the novel dihydroxy bile acid ursodeoxycholic acid derivate (Yoo's solution) in ALS Kwang-Woo Lee, MD, PhD Department of Neurology and Neuroscience Research Institute, College of Medicine, Seoul National University, Seoul, Korea Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by selective death of motor neurons. Approximately 10% of ALS cases are familial, and about 20% of these familial cases (FALS) are associated with dominantly inherited mutations in the gene encoding the enzyme Cu, Zn-superoxide dismutase (SOD1). Although the eitiology of ALS pathology is not fully understood, the observed death of motoneurons is thought to occur through oxidative stress-induced apoptosis. The dihydroxy bile acid ursodeoxycholic acid (UDCA) is hydrophilic bile acid that has been in widespread clinical use for the past 20 years for the treatment of chronic cholestatic liver disease. Recent evidence have reported that UDCA is neuroprotective in pharmachological and transgenic animal model of Huntington disease, but also in acute ischemic stroke through reducing infarct size and improving neurological function. UDCA plays a unique role in modulating the apoptotic threshold in both heapatic and nonhepatic cell including neuronal cells through interaction with the mitochondrial membrane to prevent mitochondrial membrane depolarization. UDCA also modulates the mitogen-activated protein kinase and phosphoinositol-3-kinase survival pathways. Yoo's solution is an aqueous clear solution that is composed of intact UDCA and aqueous soluble starch which has low Dextrose Equivalency. UDCA in Yoo's solution has about 30,000 times higher aqueous solubility than that of commercizlized UDCA (solubility about; 3.5 mg/I) without any chemical modification of original UDCA molecule. UDCA of Yoo's solution is solubilized in water with assistance of aqueous soluble strarch. Because of coexistence with soluble starch, UDCA in Yoo's solution should be protected from biotransformation to hydrophobic bile acid. Yoo's solution does not produce any precipitation at any pH conditions, peculiary in acidic environment. Therefore, free UDCA or its protonated form can freely penetrate various membranes including BBB. Treatment with Yoo's solution increased significantly the proliferation of motor neuronal cells expressing mutant SOD1 (A4V, G93A), while the effect was not significant in cells expressing wild type SOD1 (WT). The Yoo's solution-induced proliferation of mutant cells was attenuated by pretreatment with PD98050, the inhibitor for MAP kinase. In addition, we investigated neuroprotective effect of Yoo's solution against oxidative stress. Exogenous nitric oxide did reduce the viability of mutant cells, which was attenuated by Yoo's solution treatment. We also investigated effects of Yoo's solution on G93A SOD1 transgenic mice, which are the most widely used animal model of familial ALS. G93A transgenic mice were treated with Yoo's solution daily from 70days of age (500mg/kg). It prolonged the average lifespan, and improved motor perfomance of G93A mice. Our data suggests that Yoo's solution may contribute to the reduction of degeneration of motoneuron with the SOD1 mutation through activation of survival signal pathways or action as an anti-apoptotic agent. Therefore, it may provide a potentially useful treatment in FALS patients. 13 RNA editing and motor neuron diseases Shin Kwak Department of Neurology, Graduate School of Medicine, The University of Tokyo, Japan Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease, leading patients to inevitable death from respiratory failure within a few years. AMPA receptor-mediated excitotoxity has been proposed to play a major role in the selective motor neuron death in ALS. We recently demonstrated that a significant proportion of mRNA of the AMPA receptor subunit GluR2 was unedited at the Q/R site in motor neurons of sporadic ALS, the most common motor neuron disease. This molecular change occurs in a region-selective and disease-specific manner and has been demonstrated to be a direct cause of neuronal death in animal experiments, hence is highly relevant to ALS pathogenesis. We have found that the efficiency of RNA editing at the GluR2 Q/R site was reduced in all the sporadic ALS cases irrespective to the phenotypic variation but not in motor neurons of the rat modes of SOD1-associated familial ALS or those of bulbar and spinal muscular atrophy (SBMA). Therefore, underediting of GluR2 at the Q/R site may be the molecular change that leads neurons to death in sporadic ALS, but not in familial ALS associated with mutated SOD1 or spinal muscular atrophy. Because RNA editing at this site is specifically catalyzed by adenosine deaminase acting on RNA type 2 (ADAR2), and because the expression level of ADAR2 mRNA was reduced in the ventral gray of the spinal cord, it is likely that a reduction of ADAR2 activity in motor neurons caused death of motor neurons in sporadic ALS. The role of deficient GluR2 underediting in pathogenesis of sporadic ALS will be discussed. 14 Session 4. Neuroscience of Alzheimer’s Disease 15 Metabolism of amyloid peptide and Alzheimer’s disease Takaomi C. Saido Laboratory for Proteolytic Neuroscience, RIKEN Brain Science Institute Wako-shi, Saitama 351-0198, JAPAN The conversion of normal brain aging to Alzheimer’s disease (AD) via a transition state appears to be a continuous and chronic process primarily caused by aging-dependent accumulation of amyloid ß peptide (Aß) in the brain. This notion gives us a hope that, by manipulating the Aß levels in the brain, we may be able not only to prevent and cure the disease but also to partially control some very significant aspects of brain aging. Aß is constantly produced from its precursor and immediately catabolized under normal conditions, whereas dysmetabolism of Aß seems to lead to pathological deposition upon aging. We have focused our attention on elucidation of the unresolved mechanism of Aß catabolism in the brain. We discovered neprilysin as a major Aß-degrading enzyme, the aging-dependent reduction of which is likely to account for pathogenesis of sporadic AD. This peptidase stands out as a unique Aß-degrading enzyme among other candidate mechanisms because only neprilysin can degrade Aß at neuronal synapses. Moreover, deficiency of neprilysin resulted in generation of metabolically stable and pathologically mature Aß3(pE)-42 via conversion of Aß1-42 to Aß3(E)-42. It should be noted that Aß starting with pyroglultamate (pE) at position 3, Aß3(pE)-42, represents the predominant species deposited in Alzheimer’s disease (AD) brains, whereas transgenic mice overexpressing amyloid precursor protein (APP) accumulate mostly full-length Aß1-40 and Aß1-42. We also found that calpain is deeply involved in regulation AD pathology, such as Aß amyloidosis, tau phosphorylation, microgliosis and somato-dendritic dystrophy. Combining medications targeting at up-, mid- and down-stream processes of disease cascade shall be the most effective strategy for prevention and treatment of AD. 16 Molecular pathogenesis and peripheral markers of α-Synucleinopathy Yoo-Hun Suh Department of Pharmacology, College of Medicine, The National Creative Research Initiative Center for Alzheimer’s Dementia and Neuroscience Research Institute, MRC, Seoul National University, Seoul, Korea α-Synuclein (α-SN) is a ubiquitous protein that is especially abundant in the brain and has been postulated to play a central role in the pathogenesis of Parkinson’s disease (PD), Alzheimer’s disease (AD), and other neurodegenerative disorders. However, little is known about the neuronal functions of α-SN and the molecular and cellular mechanisms underlying neuronal loss and immune abnormalities in PD. Here, we show that α-SN plays dual roles of neuroprotection and neurotoxicity depending on its concentration or level of expression. At nanomolar concentrations, α-SN protected neurons against serum deprivation, oxidative stress, and excitotoxicity through the PI3/Akt signaling pathway. At both low micromolar and overexpressed levels in the cell, α-SN resulted in cytotoxicity, through decreased Bcl-xL and increased bax expression, followed by cytochrome c release and caspase activation and also by microglia-mediated inflammatory responses. In addition, our study shows that -SN is differentially expressed in human peripheral blood mononuclear cells. PD patients expressed more -SN than healthy controls. Those expressions were shown to be correlated with glucocorticoid sensitive apoptosis possibly caused by caspase activations (casapase-8, caspase-9), CD95 up-regulation, and reactive oxygen radical (ROS) production. And we hypothesize that α-SN may activate microglia to migrate into the SNpc affecting neuronal cytotoxicity. We demonstrate that α-SN induces the CD44 expression on microglia which participates in cell adhesion with surrounding extracellular matrix (ECM) and it also enhances MT1-MMP (membrane-type 1 matrix metalloproteinase) to degrade ECM opening the migratory pathway. Same as in the transfectants, extracellularly treated α-SN also induces CD44 and MT1-MMP expressions. All those events are probably regulated through ERK1/2 pathway. We confirmed α-SN induced cell migration in the brain of both A53T α-SN transgenic mice and human PD patients. In this way, α-SN forms a functional link with microglial migration in Parkinson’s disease. We also demonstrated that nuclear translocation of α –SN that was mediated by the karyopherin α6 and regulated by the SUMO and in nucleus, α-synuclein attend to DNA repair by PCNA binding for neuronal cell survival. 17 Molecular pathology of Alzheimer's disease: β-amyloid and γ-secretase Takeshi Iwatsubo University of Tokyo, Graduate Schools of Medicine and Pharmaceutical Sciences Alzheimer’s disease (AD) is characterized by the deposition of amyloid ß peptides (Aß) as senile plaques in brains. Aß is a 40-42 amino acid fragment of its precursor APP, and Aß42 species ending at position 42 forms amyloid fibrils much faster than Aß40. Mutations in APP (Suzuki et al. 1994) as well as presenilin (PS) genes, that are major causative genes for familial AD, enhance the production of Aß42, by shifting the preferred γ-secretase cleavage site from position 40 to 42, resulting in an increase in Aß deposition in brains, supporting the pathogenic significance of Aß42. PS has been demonstrated to comprise the catalytic center of γ-secretase, that is responsible for the intramembrane proteolysis of APP, Notch and other type I membrane proteins. These findings highlighted γ-secretase as one of the prime therapeutic targets for the “disease-modifying therapy” of AD. Protein chemical as well as genetic studies identified three “cofactor” proteins, i.e., nicastrin, APH-1 and PEN-2, that are essential to the formation and function of γ-secretase complex. Reconstitution studies in cells suggested that the four proteins, i.e., PS, nicastrin, APH-1 and PEN-2, are the minimal set of components that constitute the framework of catalytically “active” γ-secretase complex. Furthermore, structural analysis of γ-secretase complex by cysteine scanning unequivocally demonstrated the presence of a water-permeable pore-like structure around the catalytic center of γ-secretase, providing structural basis for the intramembrane proteolysis. In view of the emerging new therapies for AD, e.g. secretase inhibitors and Aß immunotherapy, an establishment of methods to monitor the progression of AD using imaging and biofluid surrogate markers would be vital to the successful completion of clinical trials. In this regard, a large-scale longitudinal clinical study, e.g. AD neuroimaging initiative (ADNI), should be crucial to the development of effective disease-modifying therapies for AD. 18