P3-214 Regulation of presenilin 1-dependent β-catenin-signaling in the central nervous system
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$416 Poster Session P3: Molecular Mechanisms of Neurodegeneration - Cell Cycle Disruption • INHIBITION OF HISTONE DEACETYLATION ENHANCES THE NEUROTOXICITY INDUCED BY THE C-TERMINAL FRAGMENTS OF AMYLOID PRECURSOR PROTEIN Eun-Mee Kim*, Hye-Sun Kim, Keun-A. Chang, Yoori Choi, Kwang-Woo Ahn, Seonghan Kim, Cheol Hyoung Park, Yoo-Hun Suh. Seoul National Univ., Seoul, Republic of Korea. Contact e-maih esther96 @ snu.ac.kr Background: The AICD (APP intracellular Domain) and C31, caspase- cleaved C-terminal fragment of APE have been found in Alzheimer's disease (AD) patients' brain and have been reported to induce apoptosis in neuronal cells. In recent, the C-terminal fragments of amyldid precursor protein (APP-CTs) have been reported to form a complex with Fe65 and the histone acetyltransferase Tip60 and thought to be involved in gene transcription. Objective(s): In this study, based on the hypothesis that APP-CTs might exert neurotoxicity by inducing some gene transcription, we investigated the effects of APP-CTs on histone acetylation which indicates that transcription is actively going on and also on the relationship between histone acetylation and the cytotoxicity induced by APP-CTs in NGF-differentiated PC 12 cells and rat primary cortical neurons. Methods: LDH assay, Western blotting, Immunocytochemislry, TUNEL Results: we demonstrate that the expression of APP-CTs [C31, AICD (C59) and C99] induces increases in acetylation of histone 3 and histone 4 and that treatment with sodium butyrate, an inhibitor of histone deacetylase, significantly enhances the cytotoxicity induced by APP-CTs. The acetylation of histone plays an important role in allowing regulatory proteins to access DNA and is likely to be a major factor in the regulation of gene transcription. Conclusions: HereTaken together, our results suggest that APP-CTs exert neurotoxicity by transcription-dependent mechanisms and this might contribute to the pathogenesis of AD. Poster Session P3: Molecular Mechanisms of Neurodegeneration - Cell Cycle Disruption • REGULATION OF PRESENILIN 1-DEPENDENT [~-CATENIN-SIGNALING IN THE CENTRAL NERVOUS SYSTEM Ana Andres*, Salvador Soriano. Institute of Psychiatry, London, United Kingdom. Contact e-maih [email protected] Background: Mutations in presenilin 1 (PS 1) are linked to early onset famil- ial Alzheimer's disease (FAD). In addition to its role in regulated intramem- brane proteolysis (RIP), PS1 has been shown to interact with [~-catenin and to regulate [3-catenin signalling through an axin-independent degra- dation mechanism. PSI deficiency as well as FAD-linked PSI mutations result in accumulation of cytosolic [~-catenin leading to a [3-catenin/LEF- dependent increase in cyclin D1 transcription and accelerated entry into the S phase of the cell cycle. PSI knockout mice develop skin tumors and their keratinocytes exhibit higher levels of cytosolic [~-catenin and elevation of [3-catenin/LEF signalling. Objectlve(s): Investigate whether this abnormal PSI-dependent [~-catenin signalfing phenotype might occur in the central nervous system (CNS) and whether it might be relevant to the pathogenesis of FAD. Methods: In the present work, we have character- ized PS 1-dependent [~-catenin/TCF signaling, as well as cell-cycle kinetics, differentiation rates, and susceptibility to cytotoxic stimuli, of primary neurons from PS1 knockout mice, mice expressing the FAD-linked PS1 M146V mutation, and/or cyclin D1 knockout mice. Results: We have found that primary neurons from mice expressing PS1 M146V mutation display increased cyclin Dl-dependent susceptibility to cytotoxic stimuli, consistent with the finding that PS 1 acts as a negative regulator of [~-catenin, increasing its stability and causing higher cyclin D1 protein levels. Conclusions: Our results are consistent with the hypothesis that aberrant cell cycle control secondary to abnormal b-cateniu signaling in primary neurons expressing FAD-linked mutations may induce cell-cycle related neurodegeneration. We will discuss our data in the context of their possible relevance to the pathogenesis of FAD. • MECHANISM OF SYNAPTIC LOSS, FORMATION OF EXTRA PROTEINS & NERVE CELL DEATH Farhan U. Subhani*. Bolam Medical College Quetta Balochistan Pakistan, Quetta, Pakistan. Contact e-mail: [email protected] The normal synaptic gap is 200-300 nm, when this gap reduces to 70- 140 nm then following events occur, When the nerve cell lost the synaptic connection or the synaptic gap reduces then the presynaptic and postsynaptic resting membrane potentials decreases. The result influences the activity of nucleus which greatly increases and the production of extra amount of different proteins, breakdown of large proteins to form smaller insoluble proteins, occur. These toxic proteins like beta amyloid & tan ultimately lead to decreased activity and initiation of cell death especially in hippocampus. At the same time the over activity of nucleus leads to the initiation of mitotic division of nerve cell, which may has a role to the cell death. Synaptic loss also decreases the release of acetylcholine, by inhibiting the activity of its formation & also destroying the receptors. The synaptic loss could be prevented be the use of black seed.(its role) with Vitamin A as an antioxidant, this would be effective to cure the disease, too, up to 35-40% progress of disease. If the synaptic loss between the nerve cells, prevented, then this would be the vaccination or probably the cure for the Alzheimer's disease, until the stage 3 of disease. • NEURONAL IMMUNOREACTIVITY FOR COX-2 AND PHOSPHORYLATION OF PRB PRECEDE P38 MAPK ACTIVATION AND NEUROFIBRILLARY CHANGES IN AD TEMPORAL CORTEX Jeroen Hoozemans* l, Robert Veerhuis 1, Annernieke Rozemuller 2, Thomas Arendt 3, Piet Eikelenboom 1,2.1 VU university medical hospital, Amsterdam, Netherlands; 2Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands; 3Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany. Contact e-mail: jjm.hoozemans @ vumc.nl Background: Epidemiological studies suggest that regular use of non- steroidal anti-inflammatory drugs (NSAIDs) reduces the risk of developing several types of cancer and Alzheimer's disease (AD). In vitro and in vivo studies show that NSAIDs can modulate cell-cycle progression. One of the main targets of NSA1Ds is the enzyme cyclooxygenase (COX). The isoform COX-2 is expressed in neurons in control and AD brain. Depending on the expression level, COX-2 may either serve physiological functions or induce pathological pathways leading to neuronal injury. In AD brain, increased levels of COX-2, cell cycle markers, as well as p38 MAP kinase (MAPK) can be detected in neuronal cells. Besides mediating COX-2 expression, p38 MAPK is suggested to mediate cell cycle progression through phosphoryla- tion of the retinoblastoma protein (pRb). Uncoordinated expression of cell cycle molecules and the consequent breach of cell cycle checkpoints could be one of the primary mechanisms by which post-mitotic neurons undergo apoptotic death. Objectives: To get an indication whether COX-2, pRb and p38 MAPK are interrelated during disease progression we have studied the expression of these markers in the temporal cortex at different stages of AD pathology. Methods: Neuronal immunoreactivity for COX-2, activated p38 MAPK and phosphorylated (inactivated) pRb, were compared with the Braak scores for A~ deposition and neurofibrillary changes, as well as with the occurrence of A[~ plaques, neuritic plaques and neurofibrillary tangles. Results: In this study we show that neuronal immunoreactivity for phospho- rylated p38 MAPK does not correlate with COX-2 or phosphorylated pRb (ppRb) in control and AD temporal cortex. Immunoreactivity for activated p38 MAPK co-localizes with AT8 immunoreactivity and increases with the occurrence of neurofibfillary tangles and plaques. On the other hand, COX-2 immunoreactivity co-localizes and correlates with ppRb immunoreactivity in pyramidal neurons. COX-2 and ppRb do not co-localize with AT8 and decrease with increasing pathology. Conclusions: These results suggest that COX-2 and ppRb are involved early during the amyloid and neurofibrillary mediated pathology. So far, there are no indications that p38 MAPK medi- ates COX-2 expression and pRb inactivation in pyramidal neurons during AD pathogenesis.
Transcript of P3-214 Regulation of presenilin 1-dependent β-catenin-signaling in the central nervous system
$416 Poster Session P3: Molecular Mechanisms of Neurodegeneration - Cell Cycle Disruption
• INHIBITION OF HISTONE DEACETYLATION ENHANCES THE NEUROTOXICITY INDUCED BY THE C-TERMINAL FRAGMENTS OF AMYLOID P R E C U R S O R PROTEIN
Eun-Mee Kim*, Hye-Sun Kim, Keun-A. Chang, Yoori Choi, Kwang-Woo Ahn, Seonghan Kim, Cheol Hyoung Park, Yoo-Hun Suh. Seoul National Univ., Seoul, Republic of Korea. Contact e-maih esther96 @ snu.ac.kr
Background: The AICD (APP intracellular Domain) and C31, caspase- cleaved C-terminal fragment of APE have been found in Alzheimer's disease (AD) patients' brain and have been reported to induce apoptosis in neuronal cells. In recent, the C-terminal fragments of amyldid precursor protein (APP-CTs) have been reported to form a complex with Fe65 and the histone acetyltransferase Tip60 and thought to be involved in gene transcription. Objective(s): In this study, based on the hypothesis that APP-CTs might exert neurotoxicity by inducing some gene transcription, we investigated the effects of APP-CTs on histone acetylation which indicates that transcription is actively going on and also on the relationship between histone acetylation and the cytotoxicity induced by APP-CTs in NGF-differentiated PC 12 cells and rat primary cortical neurons. Methods: LDH assay, Western blotting, Immunocytochemislry, TUNEL Results: we demonstrate that the expression of APP-CTs [C31, AICD (C59) and C99] induces increases in acetylation of histone 3 and histone 4 and that treatment with sodium butyrate, an inhibitor of histone deacetylase, significantly enhances the cytotoxicity induced by APP-CTs. The acetylation of histone plays an important role in allowing regulatory proteins to access DNA and is likely to be a major factor in the regulation of gene transcription. Conclusions: HereTaken together, our results suggest that APP-CTs exert neurotoxicity by transcription-dependent mechanisms and this might contribute to the pathogenesis of AD.
Poster Session P3: Molecular Mechani sms of Neurodegenerat ion - Cell Cycle Disrupt ion
• REGULATION OF PRESENILIN 1-DEPENDENT [~-CATENIN-SIGNALING IN THE CENTRAL NERVOUS SYSTEM
Ana Andres*, Salvador Soriano. Institute of Psychiatry, London, United Kingdom. Contact e-maih [email protected]
Background: Mutations in presenilin 1 (PS 1) are linked to early onset famil- ial Alzheimer's disease (FAD). In addition to its role in regulated intramem- brane proteolysis (RIP), PS1 has been shown to interact with [~-catenin and to regulate [3-catenin signalling through an axin-independent degra- dation mechanism. PSI deficiency as well as FAD-linked PSI mutations result in accumulation of cytosolic [~-catenin leading to a [3-catenin/LEF- dependent increase in cyclin D1 transcription and accelerated entry into the S phase of the cell cycle. PSI knockout mice develop skin tumors and their keratinocytes exhibit higher levels of cytosolic [~-catenin and elevation of [3-catenin/LEF signalling. Objectlve(s): Investigate whether this abnormal PSI-dependent [~-catenin signalfing phenotype might occur in the central nervous system (CNS) and whether it might be relevant to the pathogenesis of FAD. Methods: In the present work, we have character- ized PS 1-dependent [~-catenin/TCF signaling, as well as cell-cycle kinetics, differentiation rates, and susceptibility to cytotoxic stimuli, of primary neurons from PS1 knockout mice, mice expressing the FAD-linked PS1 M146V mutation, and/or cyclin D1 knockout mice. Results: We have found that primary neurons from mice expressing PS1 M146V mutation display increased cyclin Dl-dependent susceptibility to cytotoxic stimuli, consistent with the finding that PS 1 acts as a negative regulator of [~-catenin, increasing its stability and causing higher cyclin D1 protein levels. Conclusions: Our results are consistent with the hypothesis that aberrant cell cycle control secondary to abnormal b-cateniu signaling in primary neurons expressing FAD-linked mutations may induce cell-cycle related neurodegeneration. We will discuss our data in the context of their possible relevance to the pathogenesis of FAD.
• MECHANISM OF SYNAPTIC LOSS, FORMATION OF EXTRA PROTEINS & NERVE CELL DEATH
Farhan U. Subhani*. Bolam Medical College Quetta Balochistan Pakistan, Quetta, Pakistan. Contact e-mail: [email protected]
The normal synaptic gap is 200-300 nm, when this gap reduces to 70- 140 nm then following events occur, When the nerve cell lost the synaptic connection or the synaptic gap reduces then the presynaptic and postsynaptic resting membrane potentials decreases. The result influences the activity of nucleus which greatly increases and the production of extra amount of different proteins, breakdown of large proteins to form smaller insoluble proteins, occur. These toxic proteins like beta amyloid & tan ultimately lead to decreased activity and initiation of cell death especially in hippocampus. At the same time the over activity of nucleus leads to the initiation of mitotic division of nerve cell, which may has a role to the cell death. Synaptic loss also decreases the release of acetylcholine, by inhibiting the activity of its formation & also destroying the receptors. The synaptic loss could be prevented be the use of black seed.(its role) with Vitamin A as an antioxidant, this would be effective to cure the disease, too, up to 35-40% progress of disease. If the synaptic loss between the nerve cells, prevented, then this would be the vaccination or probably the cure for the Alzheimer's disease, until the stage 3 of disease.
• NEURONAL IMMUNOREACTIVITY F O R COX-2 AND PHOSPHORYLATION OF PRB PRECEDE P38 MAPK ACTIVATION AND NEUROFIBRILLARY CHANGES IN AD T E M P O R A L CORTEX
Jeroen Hoozemans* l, Robert Veerhuis 1, Annernieke Rozemuller 2, Thomas Arendt 3 , Piet Eikelenboom 1,2.1 VU university medical hospital, Amsterdam, Netherlands; 2Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands; 3Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany. Contact e-mail: jjm.hoozemans @ vumc.nl
Background: Epidemiological studies suggest that regular use of non- steroidal anti-inflammatory drugs (NSAIDs) reduces the risk of developing several types of cancer and Alzheimer's disease (AD). In vitro and in vivo studies show that NSAIDs can modulate cell-cycle progression. One of the main targets of NSA1Ds is the enzyme cyclooxygenase (COX). The isoform COX-2 is expressed in neurons in control and AD brain. Depending on the expression level, COX-2 may either serve physiological functions or induce pathological pathways leading to neuronal injury. In AD brain, increased levels of COX-2, cell cycle markers, as well as p38 MAP kinase (MAPK) can be detected in neuronal cells. Besides mediating COX-2 expression, p38 MAPK is suggested to mediate cell cycle progression through phosphoryla- tion of the retinoblastoma protein (pRb). Uncoordinated expression of cell cycle molecules and the consequent breach of cell cycle checkpoints could be one of the primary mechanisms by which post-mitotic neurons undergo apoptotic death. Objectives: To get an indication whether COX-2, pRb and p38 MAPK are interrelated during disease progression we have studied the expression of these markers in the temporal cortex at different stages of AD pathology. Methods: Neuronal immunoreactivity for COX-2, activated p38 MAPK and phosphorylated (inactivated) pRb, were compared with the Braak scores for A~ deposition and neurofibrillary changes, as well as with the occurrence of A[~ plaques, neuritic plaques and neurofibrillary tangles. Results: In this study we show that neuronal immunoreactivity for phospho- rylated p38 MAPK does not correlate with COX-2 or phosphorylated pRb (ppRb) in control and AD temporal cortex. Immunoreactivity for activated p38 MAPK co-localizes with AT8 immunoreactivity and increases with the occurrence of neurofibfillary tangles and plaques. On the other hand, COX-2 immunoreactivity co-localizes and correlates with ppRb immunoreactivity in pyramidal neurons. COX-2 and ppRb do not co-localize with AT8 and decrease with increasing pathology. Conclusions: These results suggest that COX-2 and ppRb are involved early during the amyloid and neurofibrillary mediated pathology. So far, there are no indications that p38 MAPK medi- ates COX-2 expression and pRb inactivation in pyramidal neurons during AD pathogenesis.
