- Email: [email protected]
REGULATED RELEASE OF HYPER-PHOSPHORYLATED, AGGREGATED AND SEEDING COMPETENT TAU FROM RODENT BRAINS AND HUMAN SYNAPTOSOMES
Podium Presentations: Sunday, July 16, 2017
generated Ab with a lower 42:40 ratio and higher 38:42 ratio than rostral neurons. Further, we show that APPV717I neurons express higher levels of total and phospho-Tau proteins relative to control neurons when directed to a rostral neuronal fate, but not when directed to a caudal neuronal fate. Finally, we demonstrate that neurons of these different cell fates respond differentially to soluble extracts of clinically and neuropathologically typical ‘sporadic’ AD brains. The AD extracts induce an elevation in the phosphorylation of Tau in forebrain neurons, and this is specifically dependent upon the Ab present in these extracts. However, when exposed to the same AD extracts, Tau phosphorylation is not affected in neurons directed to caudal fates. Conclusions: Taken together, our results suggest that both APP processing and Tau homeostasis are differentially altered between neuronal subtypes that are relatively vulnerable or resistant to AD.
O1-07-03
SYNAPTIC RESILIENCE TO TAU AND AMYLOID BETA OLIGOMERS INDUCED BY NEURAL STEM CELL-DERIVED EXOSOMES
Maria-Adelaide Micci1, Balaji Krishnan1, Wenru Zhang1, Elizabeth Bishop1, Steve Kernie2, Rakez Kayed1, Giulio Taglialatela1, 1 University of Texas Medical Branch, Galveston, TX, USA; 2Columbia University, New York, NY, USA. Contact e-mail: [email protected] Background: Certain individuals remain cognitively intact
despite the presence of Alzheimer’s Disease (AD) neuropathology, suggesting that there is a way for the brain to evade AD-dementia. Understanding the involved mechanism(s) would reveal a novel therapeutic concept for AD based on inducing cognitive resilience. We previously found that these resilient individuals have synapses resistant to the binding of toxic oligomers of both tau and amyloid beta (which have been shown to synergistically converge onto synapses and disrupt their function) along with displaying higher numbers of neural stem cells (NSC) in the hippocampus. Our objective was to investigate a possible link between the two phenomena testing the hypothesis that NSC-derived exosomes render synapse resistant to toxic tau and Abeta oligomers, thus preventing oligomer-driven synaptic dysfunction and memory deficits. Methods: Exosomes from the culture medium of undifferentiated and differentiated (MN) NSC were administered ex vivo and in vivo to test their effect on oligomer synaptic binding, oligomer-induced synaptic dysfunction and memory deficits using wt and tg mice with modifiable levels of NSC. Exosome miRNA’s were analyzed by deep sequencing. Results: NSC exosomes, not MN exosomes, decreased oligomer synaptic binding, prevented oligomer-induced LTP deficit and opposed oligomerdriven memory impairment. Abolishing NSC in vivo increased oligomer synaptic binding (a phenomenon reversed by NSC exosomes but not MN exosomes). Specific miRNA present only in NSC exosomes, possibly mediating such effects, were also identified. Conclusions: These results suggest a novel mechanism involving NSC-derived exosomes reducing synaptic vulnerability to both Tau and Ab oigomers, thus allowing individuals with increased neurogenesis to resist AD cognitive decline. They also illustrate a previously unappreciated target for the development of a new treatment concept for AD centered on inducing brain resilience by delivery of NSC-derived exosome or their cargo miRNAs. Supported by NIA/NIH 5R01AG042890 and the Kleberg Foundation.
O1-07-04
P205
PHENOTYPIC RESCUE IN A MOUSE MODEL OF TAUOPATHY BY EARLY MODULATION OF TAU ISOFORMS’ RELATIVE CONTENT
Sonia Espindola1, Ana Damianich1, Manuela Sartor1, Juan Belforte2, JeanMarc Gallo3, Maria Elena Avale1, 1Instituto de Investigaciones en Ingenierıa genetica y Biologıa Molecular (INGEBI-CONICET), Buenos Aires, Argentina; 2Facultad de Medicina UBA, Buenos Aires, Argentina; 3 Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom. Contact e-mail: elena.avale@conicet. gov.ar Background: Tauopathies including Alzheimer’s disease are characterized by the presence of neuronal aggregates of the protein tau in insoluble paired helical filaments. Tau is a microtubule-associated protein, which participates in microtubule dynamics and axonal transport. Alternative splicing of exon 10 (E10) in the Tau transcript produces protein isoforms with three (3R) or four (4R) microtubule binding repeats, expressed in equal amounts in the normal adult human brain. Several tauopathies are associated with mutations affecting E10 alternative splicing, leading to an imbalance between 3R/4R isoforms concomitant with the neurodegenerative process. Methods: We used a genetic engineering strategy to modulate Tau isoforms in vivo which were tested it in a mouse model of tauopathy (Htau). Htau mice show insoluble Tau accumulation in cortical areas with cognitive deficit from 9 months old and early motor impairment in the rotarod task. The relative content of Tau isoforms was modulated in specific brain nuclei (Prefrontal cortex, striatum or hippocampus) of adult hTau mice, by delivering trans-splicing constructs that induce RNA reprogramming of the endogenous tau transcript using lentiviral vectors (Avale et al 2013, Lacovich er al 2016). Results: Treated mice displayed significant changes in 3R:4R tau relative contents, showed reductions of insoluble Tau in the cortex, and a significant functional recovery, evidenced by biochemical, electrophysiological and behavioural analyses. Conclusions: Our results indicate that early local modulation of Tau isoform balance prevent tauopathy-phenotypes in the htau model, rising new perspectives for future therapeutic interventions.
O1-07-05
REGULATED RELEASE OF HYPERPHOSPHORYLATED, AGGREGATED AND SEEDING COMPETENT TAU FROM RODENT BRAINS AND HUMAN SYNAPTOSOMES
Emanuele Sher1, Francesca Mazzo1, MIchael Hutton2, Michael J. O’Neill2, Suchira Bose2, Caroline Kerridge2, Tracey K. Murray2, Olivera Grubisha2, Daniel Ursu2, Lisa Broad2, Helen Elizabeth Sanger1, Yaming Wang3, Feng Pan4, James Monn4, Jeffrey M. Witkin5, Xia Li5, Giampietro Schiavo6, Michel Goedert7, 1Eli Lilly, Windlesham, United Kingdom; 2Eli Lilly & Co Ltd, Windlesham, United Kingdom; 3Eli Lilly and Company, Indianapolis, IN, USA; 4Eli Lilly and Co, Indianapolis, IN, USA; 5Eli-Lilly and Company, Indianapolis, IN, USA; 6University College London, London, United Kingdom; 7MRC Laboratory of Molecular Biology, Cambridge, United Kingdom. Contact e-mail: [email protected] Background: Tau is a microtubule binding protein expressed in
neuronal axons and nerve terminals. Mutations in tau are known to cause different neurological diseases and tau pathology, in the form of aggregates and tangles, is a hallmark of Alzheimer’s disease. Tau pathology in AD starts in the entorhinal cortex but “spreads” along synaptically connected areas as the disease progresses. Understanding how tau is trafficked to the nerve terminal, secreted, and taken up by postsynaptic neurons could lead to the
P206
Podium Presentations: Sunday, July 16, 2017
identification of novel mechanisms aimed at halting disease progression in AD. Methods: Synaptic structures (synaptosomes) were purified from the brains of transgenic mice harbouring pathological human tau (P301S and tg4510) and from human control and AD subjects. Western blots were used to detect synaptic proteins and tau. STED microscopy was used to evalaute tau sub-cellular localisation. The ability of synaptic tau to “seed” pathological tau aggregation was evaluated in transfected HEK293 and rat cortical neurons. Calcium dependent release was induced by KCl or ionomycin, while botulinum toxins and pharmacological agents were used to cleave SNARE proteins and block exocytosis. Results: Pathologically hyper-phosphorylated (AT8+) aggregated (Sarcosylinsoluble) and seeding-competent tau was found in synaptosomes from both transgenic mice and human AD brains. Pathological tau was enriched in synaptosomes of the most affected brain areas in the mice, while in human brain synaptosomes the levels of pathological tau were correlated with the patient’s Braak stage. STED analysis demonstrated that pathological tau was enriched in the presynaptic compartment. Pathological tau was released in a calcium dependent manner by both KCl and ionomycin. Botulinum toxin A and D were found to cleave synaptosomal SNAP25 and synaptobrevin, respectively, and at the same time inhibit calcium-dependent tau release. Conclusions: All together these data build on previous evidence of pathological tau presence in presynaptic terminals and demonstrate its calcium-dependent release. Pathological tau release requires intact SNARE proteins, suggesting a vesicular, exocytotic, process. This could represent a critical step in the spreading of tau in AD brain. Therapeutic interventions aimed at blocking tau release could be beneficial in reducing tau propagation and disease progression in AD. O1-07-06
1
2
SUNDAY, JULY 16, 2017 ORAL SESSION O1-08 NEUROPATHOLOGY: BIOMARKERS OR IMAGING CORRELATION WITH NEUROPATHOLOGY O1-08-01
PATTERNS OF REGIONAL TAU ACCUMULATION INDICATIVE OF THREE DIFFERENT TYPES OF ALZHEIMER’S DISEASE (AD): THK5351-PET-BASED REPLICATION OF PATHOLOGY-BASED AD CLASSIFICATION
Jihye Hwang1, Minyoung Oh1, Jungsu S. Oh1, Sang Won Seo2, Seung Jun Oh1, Jae-Hong Lee1, Jee Hoon Roh1, Jae Seung Kim2, 1Asan Medical Center, Seoul, Republic of South Korea; 2Samsung Medical Center, Seoul, Republic of South Korea. Contact e-mail: [email protected]
SOLUBLE AMYLOID PRECURSOR PROTEIN IS AN ISOFORM-SPECIFIC GABA(B) RECEPTOR LIGAND THAT SUPPRESSES SYNAPTIC RELEASE PROBABILITY 1
R antagonists. Finally, we performed extracellular recordings on acute hippocampal slices to analyze GABA(B)R-dependent effects of sAPP on synaptic transmission at the CA3-CA1 pathway. Results: Our proteomics screen led to the identification of GABA(B) receptor as a synaptic APP interactor. A conserved 17aa peptide within the extension domain of sAPP directly interacts with the sushi-1 domain specific to the GABA(B)R1a isoform. sAPP reduces both the frequency of mEPSCs and synaptic vesicle exocytosis in hippocampal cultures. The 17aa GABA(B)R1a-specific binding region of sAPP is both required and sufficient to suppress synaptic release. Finally, sAPP decreases the strength of basal synaptic transmission and enhances short-term synaptic facilitation in hippocampal slices, implying a reduced probability of release. The effect of sAPP on synaptic release both in cultures and in slices is blocked by pretreatment with a GABA(B)R antagonist, demonstrating that sAPP decreases the probability of release via presynaptic GABA(B) receptors. Conclusions: sAPP directly interacts with GABA(B)R1a and acts a positive modulator of GABA(B) receptor signaling to reduce synaptic release probability.
Background: Recent autopsy studies demonstrated that neuropatho2
Heather C. Rice , Keimpe D. Wierda , Samuel Frere , Irena Vertkin , Inge Van Molle3, Fanomezana Ranaivoson4, Davide Comoletti4, Jeffrey N. Savas5, Inna Slutsky2, Bart De Strooper1,6, Joris de Wit1, 1VIB, KU Leuven, Leuven, Belgium; 2Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; 3VIB, VUB, Brussels, Belgium; 4Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, USA; 5 Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; 6 Dementia Research Institute, University College London, London, United Kingdom. Contact e-mail: [email protected] Background: Amyloid Precursor Protein has been extensively studied for its generation of the amyloid-beta peptide implicated in Alzheimer’s disease. However, the physiological function of APP and its processing products remains elusive. Soluble APP (sAPP), the product of APP ectodomain shedding, is sufficient to restore synaptic deficits in APP knockout mice, suggesting the presence of a synaptic receptor for sAPP. However, the putative synaptic receptor for sAPP has yet to be identified. Methods: To identify candidate synaptic interactors for sAPP, we performed a shotgun proteomics screen using purified sAPP-Fc as bait and synaptosome extracts from rat brain as prey. We performed cell surface binding assays and isothermal titration calorimetry to validate binding of sAPP to GABA(B) receptors. To access if sAPP modulates GABA(B)R function, we analyzed both miniature excitatory postsynaptic currents (mEPSCs) and exocytosis of FM1-43 labeled vesicles in hippocampal cultures in response to acute application of sAPP and GABA(B)
logically defined subtypes of Alzheimer’s disease (AD) represent distinctive cortical atrophy patterns and clinical characteristics. We investigated whether the neurofibrillary tangle pathology assessed by THK-5351 PET scan can replicate the pathology-based clustering. Methods: A total of 82 AD and mild cognitive impairment (MCI) subjects from the MEMORI study who underwent detailed neuropsychological tests, 3T MRI, [18F]-Florbetaben PET, and [18F]-THK5351 PET were enrolled. Subjects were clustered into three groups according to the degree of THK53551 uptakes in AD signature areas, including medial temporal, mid-frontal, inferior parietal and superior temporal cortices, as has been described. Detailed neuropsychological tests and image findings were compared among the groups. Results: Three subtypes of THK-5351 uptake patterns were noted: limbic-predominant or medial temporal (MT; 12.1%), typical or diffuse (D; 76.8%), and hippocampal sparing or parietal dominant (P; 10.9%) subtypes. The P subtype showed the youngest age at onset (57.269.7) compared to the MT (71.367.4) and D (68.768.4) subtypes. As has been described in autopsy studies, the P subtype showed the most prominent cognitive decline in verbal and visual memory, attention, visuospatial, and frontal executive functions. The P subtype also had a tendency to have more cerebral beta-amyloid deposition compared to other subtypes. Conclusions: Clustering of AD and MCI subjects with the THK5351-PET uptake patterns replicate the pathology-based clustering of AD. The regional distribution of
generated Ab with a lower 42:40 ratio and higher 38:42 ratio than rostral neurons. Further, we show that APPV717I neurons express higher levels of total and phospho-Tau proteins relative to control neurons when directed to a rostral neuronal fate, but not when directed to a caudal neuronal fate. Finally, we demonstrate that neurons of these different cell fates respond differentially to soluble extracts of clinically and neuropathologically typical ‘sporadic’ AD brains. The AD extracts induce an elevation in the phosphorylation of Tau in forebrain neurons, and this is specifically dependent upon the Ab present in these extracts. However, when exposed to the same AD extracts, Tau phosphorylation is not affected in neurons directed to caudal fates. Conclusions: Taken together, our results suggest that both APP processing and Tau homeostasis are differentially altered between neuronal subtypes that are relatively vulnerable or resistant to AD.
O1-07-03
SYNAPTIC RESILIENCE TO TAU AND AMYLOID BETA OLIGOMERS INDUCED BY NEURAL STEM CELL-DERIVED EXOSOMES
Maria-Adelaide Micci1, Balaji Krishnan1, Wenru Zhang1, Elizabeth Bishop1, Steve Kernie2, Rakez Kayed1, Giulio Taglialatela1, 1 University of Texas Medical Branch, Galveston, TX, USA; 2Columbia University, New York, NY, USA. Contact e-mail: [email protected] Background: Certain individuals remain cognitively intact
despite the presence of Alzheimer’s Disease (AD) neuropathology, suggesting that there is a way for the brain to evade AD-dementia. Understanding the involved mechanism(s) would reveal a novel therapeutic concept for AD based on inducing cognitive resilience. We previously found that these resilient individuals have synapses resistant to the binding of toxic oligomers of both tau and amyloid beta (which have been shown to synergistically converge onto synapses and disrupt their function) along with displaying higher numbers of neural stem cells (NSC) in the hippocampus. Our objective was to investigate a possible link between the two phenomena testing the hypothesis that NSC-derived exosomes render synapse resistant to toxic tau and Abeta oligomers, thus preventing oligomer-driven synaptic dysfunction and memory deficits. Methods: Exosomes from the culture medium of undifferentiated and differentiated (MN) NSC were administered ex vivo and in vivo to test their effect on oligomer synaptic binding, oligomer-induced synaptic dysfunction and memory deficits using wt and tg mice with modifiable levels of NSC. Exosome miRNA’s were analyzed by deep sequencing. Results: NSC exosomes, not MN exosomes, decreased oligomer synaptic binding, prevented oligomer-induced LTP deficit and opposed oligomerdriven memory impairment. Abolishing NSC in vivo increased oligomer synaptic binding (a phenomenon reversed by NSC exosomes but not MN exosomes). Specific miRNA present only in NSC exosomes, possibly mediating such effects, were also identified. Conclusions: These results suggest a novel mechanism involving NSC-derived exosomes reducing synaptic vulnerability to both Tau and Ab oigomers, thus allowing individuals with increased neurogenesis to resist AD cognitive decline. They also illustrate a previously unappreciated target for the development of a new treatment concept for AD centered on inducing brain resilience by delivery of NSC-derived exosome or their cargo miRNAs. Supported by NIA/NIH 5R01AG042890 and the Kleberg Foundation.
O1-07-04
P205
PHENOTYPIC RESCUE IN A MOUSE MODEL OF TAUOPATHY BY EARLY MODULATION OF TAU ISOFORMS’ RELATIVE CONTENT
Sonia Espindola1, Ana Damianich1, Manuela Sartor1, Juan Belforte2, JeanMarc Gallo3, Maria Elena Avale1, 1Instituto de Investigaciones en Ingenierıa genetica y Biologıa Molecular (INGEBI-CONICET), Buenos Aires, Argentina; 2Facultad de Medicina UBA, Buenos Aires, Argentina; 3 Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom. Contact e-mail: elena.avale@conicet. gov.ar Background: Tauopathies including Alzheimer’s disease are characterized by the presence of neuronal aggregates of the protein tau in insoluble paired helical filaments. Tau is a microtubule-associated protein, which participates in microtubule dynamics and axonal transport. Alternative splicing of exon 10 (E10) in the Tau transcript produces protein isoforms with three (3R) or four (4R) microtubule binding repeats, expressed in equal amounts in the normal adult human brain. Several tauopathies are associated with mutations affecting E10 alternative splicing, leading to an imbalance between 3R/4R isoforms concomitant with the neurodegenerative process. Methods: We used a genetic engineering strategy to modulate Tau isoforms in vivo which were tested it in a mouse model of tauopathy (Htau). Htau mice show insoluble Tau accumulation in cortical areas with cognitive deficit from 9 months old and early motor impairment in the rotarod task. The relative content of Tau isoforms was modulated in specific brain nuclei (Prefrontal cortex, striatum or hippocampus) of adult hTau mice, by delivering trans-splicing constructs that induce RNA reprogramming of the endogenous tau transcript using lentiviral vectors (Avale et al 2013, Lacovich er al 2016). Results: Treated mice displayed significant changes in 3R:4R tau relative contents, showed reductions of insoluble Tau in the cortex, and a significant functional recovery, evidenced by biochemical, electrophysiological and behavioural analyses. Conclusions: Our results indicate that early local modulation of Tau isoform balance prevent tauopathy-phenotypes in the htau model, rising new perspectives for future therapeutic interventions.
O1-07-05
REGULATED RELEASE OF HYPERPHOSPHORYLATED, AGGREGATED AND SEEDING COMPETENT TAU FROM RODENT BRAINS AND HUMAN SYNAPTOSOMES
Emanuele Sher1, Francesca Mazzo1, MIchael Hutton2, Michael J. O’Neill2, Suchira Bose2, Caroline Kerridge2, Tracey K. Murray2, Olivera Grubisha2, Daniel Ursu2, Lisa Broad2, Helen Elizabeth Sanger1, Yaming Wang3, Feng Pan4, James Monn4, Jeffrey M. Witkin5, Xia Li5, Giampietro Schiavo6, Michel Goedert7, 1Eli Lilly, Windlesham, United Kingdom; 2Eli Lilly & Co Ltd, Windlesham, United Kingdom; 3Eli Lilly and Company, Indianapolis, IN, USA; 4Eli Lilly and Co, Indianapolis, IN, USA; 5Eli-Lilly and Company, Indianapolis, IN, USA; 6University College London, London, United Kingdom; 7MRC Laboratory of Molecular Biology, Cambridge, United Kingdom. Contact e-mail: [email protected] Background: Tau is a microtubule binding protein expressed in
neuronal axons and nerve terminals. Mutations in tau are known to cause different neurological diseases and tau pathology, in the form of aggregates and tangles, is a hallmark of Alzheimer’s disease. Tau pathology in AD starts in the entorhinal cortex but “spreads” along synaptically connected areas as the disease progresses. Understanding how tau is trafficked to the nerve terminal, secreted, and taken up by postsynaptic neurons could lead to the
P206
Podium Presentations: Sunday, July 16, 2017
identification of novel mechanisms aimed at halting disease progression in AD. Methods: Synaptic structures (synaptosomes) were purified from the brains of transgenic mice harbouring pathological human tau (P301S and tg4510) and from human control and AD subjects. Western blots were used to detect synaptic proteins and tau. STED microscopy was used to evalaute tau sub-cellular localisation. The ability of synaptic tau to “seed” pathological tau aggregation was evaluated in transfected HEK293 and rat cortical neurons. Calcium dependent release was induced by KCl or ionomycin, while botulinum toxins and pharmacological agents were used to cleave SNARE proteins and block exocytosis. Results: Pathologically hyper-phosphorylated (AT8+) aggregated (Sarcosylinsoluble) and seeding-competent tau was found in synaptosomes from both transgenic mice and human AD brains. Pathological tau was enriched in synaptosomes of the most affected brain areas in the mice, while in human brain synaptosomes the levels of pathological tau were correlated with the patient’s Braak stage. STED analysis demonstrated that pathological tau was enriched in the presynaptic compartment. Pathological tau was released in a calcium dependent manner by both KCl and ionomycin. Botulinum toxin A and D were found to cleave synaptosomal SNAP25 and synaptobrevin, respectively, and at the same time inhibit calcium-dependent tau release. Conclusions: All together these data build on previous evidence of pathological tau presence in presynaptic terminals and demonstrate its calcium-dependent release. Pathological tau release requires intact SNARE proteins, suggesting a vesicular, exocytotic, process. This could represent a critical step in the spreading of tau in AD brain. Therapeutic interventions aimed at blocking tau release could be beneficial in reducing tau propagation and disease progression in AD. O1-07-06
1
2
SUNDAY, JULY 16, 2017 ORAL SESSION O1-08 NEUROPATHOLOGY: BIOMARKERS OR IMAGING CORRELATION WITH NEUROPATHOLOGY O1-08-01
PATTERNS OF REGIONAL TAU ACCUMULATION INDICATIVE OF THREE DIFFERENT TYPES OF ALZHEIMER’S DISEASE (AD): THK5351-PET-BASED REPLICATION OF PATHOLOGY-BASED AD CLASSIFICATION
Jihye Hwang1, Minyoung Oh1, Jungsu S. Oh1, Sang Won Seo2, Seung Jun Oh1, Jae-Hong Lee1, Jee Hoon Roh1, Jae Seung Kim2, 1Asan Medical Center, Seoul, Republic of South Korea; 2Samsung Medical Center, Seoul, Republic of South Korea. Contact e-mail: [email protected]
SOLUBLE AMYLOID PRECURSOR PROTEIN IS AN ISOFORM-SPECIFIC GABA(B) RECEPTOR LIGAND THAT SUPPRESSES SYNAPTIC RELEASE PROBABILITY 1
R antagonists. Finally, we performed extracellular recordings on acute hippocampal slices to analyze GABA(B)R-dependent effects of sAPP on synaptic transmission at the CA3-CA1 pathway. Results: Our proteomics screen led to the identification of GABA(B) receptor as a synaptic APP interactor. A conserved 17aa peptide within the extension domain of sAPP directly interacts with the sushi-1 domain specific to the GABA(B)R1a isoform. sAPP reduces both the frequency of mEPSCs and synaptic vesicle exocytosis in hippocampal cultures. The 17aa GABA(B)R1a-specific binding region of sAPP is both required and sufficient to suppress synaptic release. Finally, sAPP decreases the strength of basal synaptic transmission and enhances short-term synaptic facilitation in hippocampal slices, implying a reduced probability of release. The effect of sAPP on synaptic release both in cultures and in slices is blocked by pretreatment with a GABA(B)R antagonist, demonstrating that sAPP decreases the probability of release via presynaptic GABA(B) receptors. Conclusions: sAPP directly interacts with GABA(B)R1a and acts a positive modulator of GABA(B) receptor signaling to reduce synaptic release probability.
Background: Recent autopsy studies demonstrated that neuropatho2
Heather C. Rice , Keimpe D. Wierda , Samuel Frere , Irena Vertkin , Inge Van Molle3, Fanomezana Ranaivoson4, Davide Comoletti4, Jeffrey N. Savas5, Inna Slutsky2, Bart De Strooper1,6, Joris de Wit1, 1VIB, KU Leuven, Leuven, Belgium; 2Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; 3VIB, VUB, Brussels, Belgium; 4Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, USA; 5 Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; 6 Dementia Research Institute, University College London, London, United Kingdom. Contact e-mail: [email protected] Background: Amyloid Precursor Protein has been extensively studied for its generation of the amyloid-beta peptide implicated in Alzheimer’s disease. However, the physiological function of APP and its processing products remains elusive. Soluble APP (sAPP), the product of APP ectodomain shedding, is sufficient to restore synaptic deficits in APP knockout mice, suggesting the presence of a synaptic receptor for sAPP. However, the putative synaptic receptor for sAPP has yet to be identified. Methods: To identify candidate synaptic interactors for sAPP, we performed a shotgun proteomics screen using purified sAPP-Fc as bait and synaptosome extracts from rat brain as prey. We performed cell surface binding assays and isothermal titration calorimetry to validate binding of sAPP to GABA(B) receptors. To access if sAPP modulates GABA(B)R function, we analyzed both miniature excitatory postsynaptic currents (mEPSCs) and exocytosis of FM1-43 labeled vesicles in hippocampal cultures in response to acute application of sAPP and GABA(B)
logically defined subtypes of Alzheimer’s disease (AD) represent distinctive cortical atrophy patterns and clinical characteristics. We investigated whether the neurofibrillary tangle pathology assessed by THK-5351 PET scan can replicate the pathology-based clustering. Methods: A total of 82 AD and mild cognitive impairment (MCI) subjects from the MEMORI study who underwent detailed neuropsychological tests, 3T MRI, [18F]-Florbetaben PET, and [18F]-THK5351 PET were enrolled. Subjects were clustered into three groups according to the degree of THK53551 uptakes in AD signature areas, including medial temporal, mid-frontal, inferior parietal and superior temporal cortices, as has been described. Detailed neuropsychological tests and image findings were compared among the groups. Results: Three subtypes of THK-5351 uptake patterns were noted: limbic-predominant or medial temporal (MT; 12.1%), typical or diffuse (D; 76.8%), and hippocampal sparing or parietal dominant (P; 10.9%) subtypes. The P subtype showed the youngest age at onset (57.269.7) compared to the MT (71.367.4) and D (68.768.4) subtypes. As has been described in autopsy studies, the P subtype showed the most prominent cognitive decline in verbal and visual memory, attention, visuospatial, and frontal executive functions. The P subtype also had a tendency to have more cerebral beta-amyloid deposition compared to other subtypes. Conclusions: Clustering of AD and MCI subjects with the THK5351-PET uptake patterns replicate the pathology-based clustering of AD. The regional distribution of