- Email: [email protected]
Diffusion tensor imaging in primary progresive aphasia
Poster Presentations: P3 Conclusions: These results suggest that the topographic distribution of CAA is due in part to regional differences in the efficiency of perivascular drainage from the aging brain along cerebrovascular basement membranes. P3-075
MODE OF ACTION OF THE ALZHEIMER’S DISEASE–DERIVED, HIGHLY TOXIC, HIGH-MASS, BETA-AMYLOID ASSEMBLY AMYLOSPHEROID
Takayuki Ohnishi1, Masahumi Inoue1, Hitomi Komura2, Mari Tada3, Yo-ichi Nabeshima1, Masatoshi Hagiwara4, Akiyoshi Kakita3, Minako Hoshi4, 1Institute of Biomedical Research and Innovation, Kobe, Japan; 2Foundation for Biomedical Research and Innovation, Kobe, Japan; 3 Niigata University, Niigata, Japan; 4Kyoto University, Kyoto, Japan. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD) is a neurodegenerative disorder associated with depositions of amyloid-b protein (Ab) and neurofibrillary tangles (NFTs).Previously, we have isolated highly toxic 10-15-nm spherical Ab assemblies termed "amylospheroids" (ASPDs) from AD brains (Hoshi M et al., 2003 PNAS, Noguchi A et al., 2009 JBC). Our studies supported AD-derived ASPD is pathologically relevant to AD because native ASPD isolated from patient brains is indeed toxic to human mature neurons and its level in AD brains correlated well with the pathological severity of AD. These findings suggested ASPD is an effector of amyloid-neurotoxicity in humans. Methods: In order to elucidate the mode of action of the AD-derived ASPDs, we examined the effects of channel inhibitors on the ASPD neurotoxicity. We also monitored intracellular calcium level using furaPE3. Results: We first examined whether either N -methyl- D -aspartic acid (NMDA) receptor or a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor serves as a target protein responsible for the ASPD neurotoxicity. However, the antagonists against these receptors failed to protect neurons against the ASPD neurotoxicity. This finding indicates that ASPDs induce neurodegeneration through novel target protein(s) on the mature neurons. To further elucidate the molecular mechanism of the ASPD neurotoxicity, we examined whether the treatment of mature neurons with ASPDs affected their intracellular free calcium level ([Ca 2+]i). We found the ASPD treatment increased [Ca 2+]i of mature neurons markedly. Since the progressive increase in [Ca 2+]i was completely blocked by the addition of EGTA, a calcium chelator, and BAPTA-AM, another calcium chelator, inhibited the ASPD neurotoxicity. These results suggest that the elevation of [Ca 2+]i induced by the calcium influx from the outside of the neurons is required for the ASPD neurotoxicity.Therefore, to clarify the calcium channels involved in the calcium influx by ASPD treatment, we examined the inhibition of ASPD neurotoxicity using their inhibitors or antagonists. We found that N-type Ca 2+ channel, the mitochondrial Na +/Ca 2+ exchanger and mPTP opening were involved in the ASPD neurotoxicity. Conclusions: These results suggest that the abnormal increase of intracellular calcium level causes the neuronal cell death by ASPDs through novel target protein(s) on mature neurons. P3-076
PALMITATE INDUCES TRANSCRIPTIONAL REGULATION OF BACE1 AND PRESENILIN BY STAT3 IN NEURONS MEDIATED BY ASTROCYTES
Li Liu1, Rebecca Martin1, Garrett Kohler2, Christina Chan1, 1Michigan State University, East Lansing, Michigan, United States; 2MSU, East Lansing, Michigan, United States. Contact e-mail: [email protected] Background: Dysregulation of calcium homeostasis has been implicated in neurodegenerative diseases, including Alzheimer’s disease (AD). The accumulation of amyloid beta peptide in the brain generated from sequential cleavage of BACE1 and g-secretase, is a hallmark of AD. Previously, we showed that saturated free-fatty acid, palmitate, causes amyloidogenesis in primary cortical neurons mediated by astrocytes. However, the molecular mechanisms by which conditioned media from palmitate-treated astrocytes upregulates amyloid peptide production in neurons are unknown. In particular, the molecular mechanism by which palmitate-astrocyte conditioned media regulates BACE1 and g-secretase levels is not clear. Methods: Western blot, Calcium imaging, Nuclear extracts, Quantitative real time polymerase chain reaction,
P577
and Enzyme-linked immunosorbent assay. Results: Palmitate-astrocyte conditioned media deregulates calcium level and activates calpain, a calcium-dependent protease in primary cortical neurons. Sequentially, the accumulated p25 cleaved by calpain increases Cdk5 activity. Inhibiting calpain and Cdk5 significantly reduce the upregulation of pSTAT3 in the nucleus, thereby suggesting that calpain and p25/Cdk5 regulate STAT3 activity in primary cortical neurons. Both the mRNA levels of BACE1 and presenilin-1, the catalytic subunit of gsecretase, are significantly increased in neurons treated with conditioned media from astrocytes cultured in palmitate, and inhibition of pSTAT3 markedly reduces the upregulation of both BACE1 and presenilin-1. Conclusions: Our data demonstrate the upregulation in the signaling pathway calcium-calpainp25/Cdk5-STAT3 in primary cortical neurons treated with conditioned media from astrocytes cultured in palmitate. An elevated level of the transcription factor, pSTAT3, regulates both BACE1 and presenilin-1expression, two executive proteins involved in the generation of amyloid peptide. Therefore, these results support that STAT3 is an important therapeutic target for AD pathogenesis. P3-077
INHIBITION OF THE CAMKK2-AMPK-TAU SIGNALING PATHWAY PROTECTS HIPPOCAMPAL NEURONS FROM BETAAMYLOID OLIGOMER–INDUCED SYNAPTOTOXICITY
Georges Mairet-Coello1, Julien Courchet1, Simon Pieraut1, Virginie Courchet1, Anton Maximov1, Franck Polleux1, 1The Scripps Research Institute, La Jolla, California, United States. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD) is characterized by a decrease in synapse density in the cerebral cortex and hippocampus which correlates with the degree of cognitive impairment. Considerable evidences indicate that soluble amyloid-b 1-42 (Ab42) oligomers trigger reduction of dendritic spine density in excitatory cortical and hippocampal neurons and might play a role in early stages of AD. However, the signaling pathways mediating Ab42-induced spine loss are poorly defined. Interestingly, recent reports indicate that Ab42 oligomers can trigger activation of the cellular energy sensor AMP-activated Kinase (AMPK). Methods: In this study, we performed in vitro and in vivo experiments, using pharmacological, molecular and genetic tools, to determine whether the CAMKK2-AMPK-Tau signaling pathway mediates the synaptotoxic effects of Ab42 oligomers. Results: We report that AMPK is activated in cortical and hippocampal neurons upon application of Ab42 oligomers or by calcium influx triggered by NMDA administration or membrane depolarization, and this activation is dependent on the calcium/calmodulin-dependent kinase kinase 2 (CAMKK2). Importantly, CAMKK2 or AMPK over-activation induces dendritic spine loss in hippocampal neurons. Furthermore, we found that AMPK activity is abnormally increased in the hippocampus of J20 transgenic mouse model as early as 4 months of age, a time when Ab oligomer levels are high and signs of hippocampal network dysfunction already detectable. Whereas AMPK over-activation had deleterious effects on spine integrity, inhibition of either CAMKK2 or AMPK catalytic activity protects hippocampal neurons against Ab42 oligomer-induced spine loss in vitro and against the loss of dendritic spines observed in the J20 mice in vivo. Finally, we show that AMPK phosphorylates Tau in the microtubule binding domain on the KxGS-motif S262, and expression of a non-phosphorylatable form (tau-S262A) protects hippocampal neurons from the loss of spines induced by Ab42 oligomers in vitro and in vivo. Conclusions: Our results suggest that the CAMKK2AMPK-Tau pathway is a critical mediator of the synaptotoxic effects of Ab42 oligomers, and impinging on this pathway may be of therapeutic value. P3-078
DIFFUSION TENSOR IMAGING IN PRIMARY PROGRESIVE APHASIA
Alejandra Amengual, Patricio Chrem Mendez, Jorge Campos, Griselda Russo, Gabriela Cohen, Liliana Sabe, Cristina Medina, Jorge Calvar, Francisco Meli, Silvia Vazquez, Ricardo Allegri, FLENI, Buenos Aires, Argentina. Contact e-mail: [email protected] Background: Primary progressive aphasia (PPA) is diagnosed when a progressive difficulty in language emerges as the principal feature of
P578
Poster Presentations: P3
a neurodegenerative disease. Three main variants have been described: nonfluent/agrammatic, semantic and logopenic. Each variant is more closely related to the involvement of defined parts of the language network, usually in the left hemisphere. Diffusion tensor images allow study the different anatomical tracts invivo patients. Objective: To evaluate the potential of Diffusion tensor tractography in the diagnosis of variants of primary progressive aphasia. Methods: Fifteen patients with clinical diagnosis of PPA were enrolled in this study. They were evaluated by a neurologist and the diagnosis or PPA and its variants was determined by clinical and neurolinguistic features following the diagnostic process according Gorno Tempini et al (2011). We selected the most paradigmatic cases for each variant according to the criteria above. The selected cases underwent 3T MRI with diffusion tensor images (DTI) and tractography was performed to evaluate the inferior longitudinal, uncinate and superior longitudinal fasciculus. Results: The patient with the non-fluent/agrammatic variant showed differences in the superior longitudinal and uncinate fasciculus, logopenic variant showed fiber dispersion in
the superior and inferior longitudinal fasciculus and the semantic variant in the inferior longitudinal and uncinate fasciculus. Conclusions: DTI seems to be a useful tool in thedifferential diagnosis of the variants of PPA and could be consider in the diagnosis characterization of PPA. P3-079
SPARSE BAYESIAN LEARNING FOR IDENTIFYING THE NEUROANATOMICAL BASIS OF COGNITIVE IMPAIRMENT IN ALZHEIMER’S DISEASE
Jing Wan1, Zhilin Zhang2, Shiaofen Fang3, Shannon Risacher4, Andrew Saykin4, Li Shen4 FOR THE ALZHEIMER’S DISEASE NEUROIMAGING INITIATIVE (ADNI)5, 1Purdue University, Indianapolis, Indianapolis, Indiana, United States; 2Samsung R&D America, Dallas, Texas, United States; 3Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States; 4Indiana University School of Medicine,
Figure 1. Heat maps of average regression weights of 5 fold cross -validation trails for (a) T-MSBL-FP, (b) the Mixed L2/L1, and (c) RIDGE regression. Each row corresponds to a MRI measure and each column corresponds to a cognitive score. Blue indicates negative correlation while red indicates positive correlation. The bigger the value of a coefficient, the more important its VBM measure is in predicting the corresponding cognitive score.
MODE OF ACTION OF THE ALZHEIMER’S DISEASE–DERIVED, HIGHLY TOXIC, HIGH-MASS, BETA-AMYLOID ASSEMBLY AMYLOSPHEROID
Takayuki Ohnishi1, Masahumi Inoue1, Hitomi Komura2, Mari Tada3, Yo-ichi Nabeshima1, Masatoshi Hagiwara4, Akiyoshi Kakita3, Minako Hoshi4, 1Institute of Biomedical Research and Innovation, Kobe, Japan; 2Foundation for Biomedical Research and Innovation, Kobe, Japan; 3 Niigata University, Niigata, Japan; 4Kyoto University, Kyoto, Japan. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD) is a neurodegenerative disorder associated with depositions of amyloid-b protein (Ab) and neurofibrillary tangles (NFTs).Previously, we have isolated highly toxic 10-15-nm spherical Ab assemblies termed "amylospheroids" (ASPDs) from AD brains (Hoshi M et al., 2003 PNAS, Noguchi A et al., 2009 JBC). Our studies supported AD-derived ASPD is pathologically relevant to AD because native ASPD isolated from patient brains is indeed toxic to human mature neurons and its level in AD brains correlated well with the pathological severity of AD. These findings suggested ASPD is an effector of amyloid-neurotoxicity in humans. Methods: In order to elucidate the mode of action of the AD-derived ASPDs, we examined the effects of channel inhibitors on the ASPD neurotoxicity. We also monitored intracellular calcium level using furaPE3. Results: We first examined whether either N -methyl- D -aspartic acid (NMDA) receptor or a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor serves as a target protein responsible for the ASPD neurotoxicity. However, the antagonists against these receptors failed to protect neurons against the ASPD neurotoxicity. This finding indicates that ASPDs induce neurodegeneration through novel target protein(s) on the mature neurons. To further elucidate the molecular mechanism of the ASPD neurotoxicity, we examined whether the treatment of mature neurons with ASPDs affected their intracellular free calcium level ([Ca 2+]i). We found the ASPD treatment increased [Ca 2+]i of mature neurons markedly. Since the progressive increase in [Ca 2+]i was completely blocked by the addition of EGTA, a calcium chelator, and BAPTA-AM, another calcium chelator, inhibited the ASPD neurotoxicity. These results suggest that the elevation of [Ca 2+]i induced by the calcium influx from the outside of the neurons is required for the ASPD neurotoxicity.Therefore, to clarify the calcium channels involved in the calcium influx by ASPD treatment, we examined the inhibition of ASPD neurotoxicity using their inhibitors or antagonists. We found that N-type Ca 2+ channel, the mitochondrial Na +/Ca 2+ exchanger and mPTP opening were involved in the ASPD neurotoxicity. Conclusions: These results suggest that the abnormal increase of intracellular calcium level causes the neuronal cell death by ASPDs through novel target protein(s) on mature neurons. P3-076
PALMITATE INDUCES TRANSCRIPTIONAL REGULATION OF BACE1 AND PRESENILIN BY STAT3 IN NEURONS MEDIATED BY ASTROCYTES
Li Liu1, Rebecca Martin1, Garrett Kohler2, Christina Chan1, 1Michigan State University, East Lansing, Michigan, United States; 2MSU, East Lansing, Michigan, United States. Contact e-mail: [email protected] Background: Dysregulation of calcium homeostasis has been implicated in neurodegenerative diseases, including Alzheimer’s disease (AD). The accumulation of amyloid beta peptide in the brain generated from sequential cleavage of BACE1 and g-secretase, is a hallmark of AD. Previously, we showed that saturated free-fatty acid, palmitate, causes amyloidogenesis in primary cortical neurons mediated by astrocytes. However, the molecular mechanisms by which conditioned media from palmitate-treated astrocytes upregulates amyloid peptide production in neurons are unknown. In particular, the molecular mechanism by which palmitate-astrocyte conditioned media regulates BACE1 and g-secretase levels is not clear. Methods: Western blot, Calcium imaging, Nuclear extracts, Quantitative real time polymerase chain reaction,
P577
and Enzyme-linked immunosorbent assay. Results: Palmitate-astrocyte conditioned media deregulates calcium level and activates calpain, a calcium-dependent protease in primary cortical neurons. Sequentially, the accumulated p25 cleaved by calpain increases Cdk5 activity. Inhibiting calpain and Cdk5 significantly reduce the upregulation of pSTAT3 in the nucleus, thereby suggesting that calpain and p25/Cdk5 regulate STAT3 activity in primary cortical neurons. Both the mRNA levels of BACE1 and presenilin-1, the catalytic subunit of gsecretase, are significantly increased in neurons treated with conditioned media from astrocytes cultured in palmitate, and inhibition of pSTAT3 markedly reduces the upregulation of both BACE1 and presenilin-1. Conclusions: Our data demonstrate the upregulation in the signaling pathway calcium-calpainp25/Cdk5-STAT3 in primary cortical neurons treated with conditioned media from astrocytes cultured in palmitate. An elevated level of the transcription factor, pSTAT3, regulates both BACE1 and presenilin-1expression, two executive proteins involved in the generation of amyloid peptide. Therefore, these results support that STAT3 is an important therapeutic target for AD pathogenesis. P3-077
INHIBITION OF THE CAMKK2-AMPK-TAU SIGNALING PATHWAY PROTECTS HIPPOCAMPAL NEURONS FROM BETAAMYLOID OLIGOMER–INDUCED SYNAPTOTOXICITY
Georges Mairet-Coello1, Julien Courchet1, Simon Pieraut1, Virginie Courchet1, Anton Maximov1, Franck Polleux1, 1The Scripps Research Institute, La Jolla, California, United States. Contact e-mail: [email protected] Background: Alzheimer’s disease (AD) is characterized by a decrease in synapse density in the cerebral cortex and hippocampus which correlates with the degree of cognitive impairment. Considerable evidences indicate that soluble amyloid-b 1-42 (Ab42) oligomers trigger reduction of dendritic spine density in excitatory cortical and hippocampal neurons and might play a role in early stages of AD. However, the signaling pathways mediating Ab42-induced spine loss are poorly defined. Interestingly, recent reports indicate that Ab42 oligomers can trigger activation of the cellular energy sensor AMP-activated Kinase (AMPK). Methods: In this study, we performed in vitro and in vivo experiments, using pharmacological, molecular and genetic tools, to determine whether the CAMKK2-AMPK-Tau signaling pathway mediates the synaptotoxic effects of Ab42 oligomers. Results: We report that AMPK is activated in cortical and hippocampal neurons upon application of Ab42 oligomers or by calcium influx triggered by NMDA administration or membrane depolarization, and this activation is dependent on the calcium/calmodulin-dependent kinase kinase 2 (CAMKK2). Importantly, CAMKK2 or AMPK over-activation induces dendritic spine loss in hippocampal neurons. Furthermore, we found that AMPK activity is abnormally increased in the hippocampus of J20 transgenic mouse model as early as 4 months of age, a time when Ab oligomer levels are high and signs of hippocampal network dysfunction already detectable. Whereas AMPK over-activation had deleterious effects on spine integrity, inhibition of either CAMKK2 or AMPK catalytic activity protects hippocampal neurons against Ab42 oligomer-induced spine loss in vitro and against the loss of dendritic spines observed in the J20 mice in vivo. Finally, we show that AMPK phosphorylates Tau in the microtubule binding domain on the KxGS-motif S262, and expression of a non-phosphorylatable form (tau-S262A) protects hippocampal neurons from the loss of spines induced by Ab42 oligomers in vitro and in vivo. Conclusions: Our results suggest that the CAMKK2AMPK-Tau pathway is a critical mediator of the synaptotoxic effects of Ab42 oligomers, and impinging on this pathway may be of therapeutic value. P3-078
DIFFUSION TENSOR IMAGING IN PRIMARY PROGRESIVE APHASIA
Alejandra Amengual, Patricio Chrem Mendez, Jorge Campos, Griselda Russo, Gabriela Cohen, Liliana Sabe, Cristina Medina, Jorge Calvar, Francisco Meli, Silvia Vazquez, Ricardo Allegri, FLENI, Buenos Aires, Argentina. Contact e-mail: [email protected] Background: Primary progressive aphasia (PPA) is diagnosed when a progressive difficulty in language emerges as the principal feature of
P578
Poster Presentations: P3
a neurodegenerative disease. Three main variants have been described: nonfluent/agrammatic, semantic and logopenic. Each variant is more closely related to the involvement of defined parts of the language network, usually in the left hemisphere. Diffusion tensor images allow study the different anatomical tracts invivo patients. Objective: To evaluate the potential of Diffusion tensor tractography in the diagnosis of variants of primary progressive aphasia. Methods: Fifteen patients with clinical diagnosis of PPA were enrolled in this study. They were evaluated by a neurologist and the diagnosis or PPA and its variants was determined by clinical and neurolinguistic features following the diagnostic process according Gorno Tempini et al (2011). We selected the most paradigmatic cases for each variant according to the criteria above. The selected cases underwent 3T MRI with diffusion tensor images (DTI) and tractography was performed to evaluate the inferior longitudinal, uncinate and superior longitudinal fasciculus. Results: The patient with the non-fluent/agrammatic variant showed differences in the superior longitudinal and uncinate fasciculus, logopenic variant showed fiber dispersion in
the superior and inferior longitudinal fasciculus and the semantic variant in the inferior longitudinal and uncinate fasciculus. Conclusions: DTI seems to be a useful tool in thedifferential diagnosis of the variants of PPA and could be consider in the diagnosis characterization of PPA. P3-079
SPARSE BAYESIAN LEARNING FOR IDENTIFYING THE NEUROANATOMICAL BASIS OF COGNITIVE IMPAIRMENT IN ALZHEIMER’S DISEASE
Jing Wan1, Zhilin Zhang2, Shiaofen Fang3, Shannon Risacher4, Andrew Saykin4, Li Shen4 FOR THE ALZHEIMER’S DISEASE NEUROIMAGING INITIATIVE (ADNI)5, 1Purdue University, Indianapolis, Indianapolis, Indiana, United States; 2Samsung R&D America, Dallas, Texas, United States; 3Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States; 4Indiana University School of Medicine,
Figure 1. Heat maps of average regression weights of 5 fold cross -validation trails for (a) T-MSBL-FP, (b) the Mixed L2/L1, and (c) RIDGE regression. Each row corresponds to a MRI measure and each column corresponds to a cognitive score. Blue indicates negative correlation while red indicates positive correlation. The bigger the value of a coefficient, the more important its VBM measure is in predicting the corresponding cognitive score.