- Email: [email protected]
DIFFERENTIAL SUSCEPTIBILITY OF STRIATAL, HIPPOCAMPAL AND CORTICAL NEURONS TO CASPASE-6
Poster Presentations: Monday, July 17, 2017 P2-154
DIFFERENTIAL SUSCEPTIBILITY OF STRIATAL, HIPPOCAMPAL AND CORTICAL NEURONS TO CASPASE-6
Anastasia Noel1,2, Benedicte Foveau3, Andrea Claire LeBlanc2, 1 Lady Davis Institute - McGill University, Montreal, QC, Canada; 2 McGill University, Montreal, QC, Canada; 3Lady Davis Institute, Montreal, QC, Canada. Contact e-mail: anastasia.noel@mail. mcgill.ca Background: Caspase-6 (Casp6), a cysteinyl protease of the caspase
family, is activated early in Huntington disease (HD) and thought to contribute to its pathogenesis by generating a toxic fragment of huntingtin (Htt). Methods: Active Casp6 and TauDCasp6 were assessed in 50-70 yr old grade II HD and age-matched control brains by immunohistochemistry with neoepitope antisera against active Casp6 and Tau cleaved by Casp6 (TauDCasp6). To assess whether Casp6 activity induces HD-like pathogenesis, a transgenic knock-in mouse (ACK) expressing a self-activated form of human Casp6 in the medium spiny neurons of the indirect striatopallidal pathway, the main brain circuit affected in HD, was generated. Results: Occasional intra-nuclear inclusions immunopositive for active Casp6 and TauDCasp6 were observed in HD, but not in control, striatal neurons. Conversely, inclusions were absent while active Casp6 and TauDCasp6 immunopositive neurofibrillary tangles were frequent in HD, but rare, in the control hippocampus. Relative to non-transgenic mice, Casp6 protein was increased 5.2, 2.5, and 2.6 fold in the striatum, cortex and hippocampus of the ACK brains, respectively. Detection of Tubulin cleaved by Casp6 (TubDCasp6) confirmed Casp6 activity. ACK and control littermate mice were subjected to psychiatric, motor, and cognitive behavioral tests. No evidence of depression was evident with the forced swim and sucrose consumption tests. No sensorimotor or locomotor deficits were noticed in the nesting, clasping, rotarod, vertical pole, gait and open field analyses. However, ACK mice developed agedependent episodic and spatial memory deficits identified by the novel object recognition test and the Barnes or Morris water maze, respectively. Synaptic protein levels and neuron numbers were maintained in the ACK striatum, hippocampus and cortex. Iba1 positive microglia of the phagocytic type 4 and GFAP positive astroglial staining were increased in the ACK hippocampal stratum lacunosum molecular and in the cortex, but not in the striatum. Conclusions: These data suggest that active Casp6 in the striatal medium spiny neurons does not induce HD-like motor deficits or inflammation, whereas active Casp6 in the hippocampus and cortex impairs episodic and spatial memory and increases inflammation. These results reveal neuron specific vulnerability to Casp6 activation. P2-155
PROTEOMICS OF THE ALZHEIMER’S DISEASE BRAIN: NEUROPATHOLOGY AND NEURORESILIENCE
Anne Poljak1,2,3, Nady Braidy4, Catriona MacLean5, Claire Shepherd6, Mark J. Raftery3, Perminder S. Sachdev7,8, 1 School of Medical Sciences, University of New South Wales, Sydney, Australia; 2Centre for Healthy Brain Ageing (CHeBA), School of Psychiatry, University of New South Wales, Sydney, Australia; 3Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, Australia; 4Centre for Healthy Brain Ageing, University of New South Wales, Sydney, Australia; 5 Howard Florey Institute, Melbourne, Australia; 6Neuroscience Research Australia, Sydney, Australia; 7Centre for Healthy Brain Ageing, School of Psychiatry, University of New South Wales, Sydney, Australia; 8Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, Australia. Contact e-mail: [email protected]
P667
Background: Occipital lobe is relatively spared in Alzheimer’s disease (AD) and is one of the last cortical regions to develop AD pathology, implying resilience against AD pathology. Altered expression levels of specific proteins within its proteome may make occipital lobe a particularly good post-mortem tissue model for exploring early events in AD, since such events may still be apparent here, while other more severely affected brain regions have a paucity of early changes and a preponderance of late or secondary changes. Methods: We explore differences in the expression profiles of proteins in human control and AD brain cortex, using two proteomics approaches; (1) 2D PAGE protein separation followed by LCMSMS protein analysis to compare control and AD occipital lobe protein expression level changes and (2) iTRAQ 8plex labeling followed by 2D LCMSMS and ProteinPilot analysis to compare occipital and temporal lobes using both control and AD tissue. Occipital and temporal lobes were chosen, as representative of relatively mildly and severely affected cortical regions respectively. Results: Dysregulation of proteins in a variety of functional clusters was identified, including; upregulation of several antioxidant proteins and metabolic enzymes related to the TCA cycle and glycolysis. Furthermore, the expression level of several proteins involved in cell cycle regulation, neuronal remodeling or structural roles, were dysregulated in AD compared with controls, suggesting possible mechanisms of cellular repair or regeneration. Conclusions: The biological roles of these proteins implies a protective or homeostatic response to AD pathology. The variety of functional clusters to which they belong indicates that the cellular response to pathology is diverse rather than directed through a single pathway.
P2-156
INCREASED SUSCEPTIBILITY TO NECROPTOSIS IN APP/PS1 MICE
Antonella Caccamo, Caterina Branca, Eric Ferreira, Salvatore Oddo, Arizona State University, Tempe, AZ, USA. Contact e-mail: [email protected] Background: Brain atrophy caused by neuronal loss is a major pathological feature of Alzheimer’s disease (AD). Nevertheless, the cause of this profound neuronal loss are not clear. Necroptosis is a form of programmed cell death executed by the mixed lineage kinase (MLKL). It has been found to play a major role in several neurodegenerative disorders including multiple sclerosis and amyotrophic lateral sclerosis. However, it remains to be determined whether necroptosis plays a role in AD. Methods: Using a genetic approach. Results: Here we show that increasing necroptosis in APP/ PS1 mice, a widely used animal model of AD, exacerbates cognitive deficits and leads to a more profound neurodegeneration than in nontransgenic controls. Conclusions: These results suggest that mice with AD pathology are more susceptible to necroptosis-induced neuronal loss. Overall, these data provide the first direct in vivo evidence that necroptosis is a mechanism involved in neurodegeneration in AD.
P2-157
TOWARD A MORE ROBUST GENE EXPRESSION SIGNATURE FOR ALZHEIMER’S DISEASE NEURODEGENERATION
Carol Huseby, Jeff Kuret, The Ohio State University, Columbus, OH, USA. Contact e-mail: [email protected] Background: There continues to be a need for basic science insight
into the Alzheimer’s disease phenotype. One approach to this end
DIFFERENTIAL SUSCEPTIBILITY OF STRIATAL, HIPPOCAMPAL AND CORTICAL NEURONS TO CASPASE-6
Anastasia Noel1,2, Benedicte Foveau3, Andrea Claire LeBlanc2, 1 Lady Davis Institute - McGill University, Montreal, QC, Canada; 2 McGill University, Montreal, QC, Canada; 3Lady Davis Institute, Montreal, QC, Canada. Contact e-mail: anastasia.noel@mail. mcgill.ca Background: Caspase-6 (Casp6), a cysteinyl protease of the caspase
family, is activated early in Huntington disease (HD) and thought to contribute to its pathogenesis by generating a toxic fragment of huntingtin (Htt). Methods: Active Casp6 and TauDCasp6 were assessed in 50-70 yr old grade II HD and age-matched control brains by immunohistochemistry with neoepitope antisera against active Casp6 and Tau cleaved by Casp6 (TauDCasp6). To assess whether Casp6 activity induces HD-like pathogenesis, a transgenic knock-in mouse (ACK) expressing a self-activated form of human Casp6 in the medium spiny neurons of the indirect striatopallidal pathway, the main brain circuit affected in HD, was generated. Results: Occasional intra-nuclear inclusions immunopositive for active Casp6 and TauDCasp6 were observed in HD, but not in control, striatal neurons. Conversely, inclusions were absent while active Casp6 and TauDCasp6 immunopositive neurofibrillary tangles were frequent in HD, but rare, in the control hippocampus. Relative to non-transgenic mice, Casp6 protein was increased 5.2, 2.5, and 2.6 fold in the striatum, cortex and hippocampus of the ACK brains, respectively. Detection of Tubulin cleaved by Casp6 (TubDCasp6) confirmed Casp6 activity. ACK and control littermate mice were subjected to psychiatric, motor, and cognitive behavioral tests. No evidence of depression was evident with the forced swim and sucrose consumption tests. No sensorimotor or locomotor deficits were noticed in the nesting, clasping, rotarod, vertical pole, gait and open field analyses. However, ACK mice developed agedependent episodic and spatial memory deficits identified by the novel object recognition test and the Barnes or Morris water maze, respectively. Synaptic protein levels and neuron numbers were maintained in the ACK striatum, hippocampus and cortex. Iba1 positive microglia of the phagocytic type 4 and GFAP positive astroglial staining were increased in the ACK hippocampal stratum lacunosum molecular and in the cortex, but not in the striatum. Conclusions: These data suggest that active Casp6 in the striatal medium spiny neurons does not induce HD-like motor deficits or inflammation, whereas active Casp6 in the hippocampus and cortex impairs episodic and spatial memory and increases inflammation. These results reveal neuron specific vulnerability to Casp6 activation. P2-155
PROTEOMICS OF THE ALZHEIMER’S DISEASE BRAIN: NEUROPATHOLOGY AND NEURORESILIENCE
Anne Poljak1,2,3, Nady Braidy4, Catriona MacLean5, Claire Shepherd6, Mark J. Raftery3, Perminder S. Sachdev7,8, 1 School of Medical Sciences, University of New South Wales, Sydney, Australia; 2Centre for Healthy Brain Ageing (CHeBA), School of Psychiatry, University of New South Wales, Sydney, Australia; 3Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, Australia; 4Centre for Healthy Brain Ageing, University of New South Wales, Sydney, Australia; 5 Howard Florey Institute, Melbourne, Australia; 6Neuroscience Research Australia, Sydney, Australia; 7Centre for Healthy Brain Ageing, School of Psychiatry, University of New South Wales, Sydney, Australia; 8Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, Australia. Contact e-mail: [email protected]
P667
Background: Occipital lobe is relatively spared in Alzheimer’s disease (AD) and is one of the last cortical regions to develop AD pathology, implying resilience against AD pathology. Altered expression levels of specific proteins within its proteome may make occipital lobe a particularly good post-mortem tissue model for exploring early events in AD, since such events may still be apparent here, while other more severely affected brain regions have a paucity of early changes and a preponderance of late or secondary changes. Methods: We explore differences in the expression profiles of proteins in human control and AD brain cortex, using two proteomics approaches; (1) 2D PAGE protein separation followed by LCMSMS protein analysis to compare control and AD occipital lobe protein expression level changes and (2) iTRAQ 8plex labeling followed by 2D LCMSMS and ProteinPilot analysis to compare occipital and temporal lobes using both control and AD tissue. Occipital and temporal lobes were chosen, as representative of relatively mildly and severely affected cortical regions respectively. Results: Dysregulation of proteins in a variety of functional clusters was identified, including; upregulation of several antioxidant proteins and metabolic enzymes related to the TCA cycle and glycolysis. Furthermore, the expression level of several proteins involved in cell cycle regulation, neuronal remodeling or structural roles, were dysregulated in AD compared with controls, suggesting possible mechanisms of cellular repair or regeneration. Conclusions: The biological roles of these proteins implies a protective or homeostatic response to AD pathology. The variety of functional clusters to which they belong indicates that the cellular response to pathology is diverse rather than directed through a single pathway.
P2-156
INCREASED SUSCEPTIBILITY TO NECROPTOSIS IN APP/PS1 MICE
Antonella Caccamo, Caterina Branca, Eric Ferreira, Salvatore Oddo, Arizona State University, Tempe, AZ, USA. Contact e-mail: [email protected] Background: Brain atrophy caused by neuronal loss is a major pathological feature of Alzheimer’s disease (AD). Nevertheless, the cause of this profound neuronal loss are not clear. Necroptosis is a form of programmed cell death executed by the mixed lineage kinase (MLKL). It has been found to play a major role in several neurodegenerative disorders including multiple sclerosis and amyotrophic lateral sclerosis. However, it remains to be determined whether necroptosis plays a role in AD. Methods: Using a genetic approach. Results: Here we show that increasing necroptosis in APP/ PS1 mice, a widely used animal model of AD, exacerbates cognitive deficits and leads to a more profound neurodegeneration than in nontransgenic controls. Conclusions: These results suggest that mice with AD pathology are more susceptible to necroptosis-induced neuronal loss. Overall, these data provide the first direct in vivo evidence that necroptosis is a mechanism involved in neurodegeneration in AD.
P2-157
TOWARD A MORE ROBUST GENE EXPRESSION SIGNATURE FOR ALZHEIMER’S DISEASE NEURODEGENERATION
Carol Huseby, Jeff Kuret, The Ohio State University, Columbus, OH, USA. Contact e-mail: [email protected] Background: There continues to be a need for basic science insight
into the Alzheimer’s disease phenotype. One approach to this end