- Email: [email protected]
Aberrant adult neurogenesis in transgenic mice expressing APP intracellular domain
Poster Presentations P4 oligomers in initiating and sustaining the chronic inflammatory response observed in AD. P4-175
RESOLUTION OF NEUROINFLAMMATION BY CYTOCHROME P4504F: IMPLICATION IN ALZHEIMER’S DISEASE
Neha Sehgal, National Brain Research Center, Gurgaon, India. Contact e-mail: [email protected] Background: Inflammatory processes are known to be involved in the progression of Alzheimer’s disease (AD). Microglia contributes to the neurodegenerative process by augmenting the production of inflammatory mediators. Resolution of inflammation could potentially alter the progression of the disease and afford neuroprotection. Cytochrome P450 (P450) are an important family of enzymes involved in the metabolism of xenobiotics. The P4504f subfamily hydroxylate the potent pro-inflammatory mediator, leukotriene B4 (LTB4) to 20-hydroxy-LTB4,thereby inactivating its inflammatory response. Thus, P4504f could be an attractive target for anti-inflammatory action in the brain. The objective of this study is to examine the role of Cyp4f in modulating inflammation in the brain, affording neuroprotection in acute and chronic inflammatory conditions, such as AD. Methods: The acute model of neuro-inflammation was generated by systemic injection of LPS to male C57Bl6j mice. The transgenic APPswe/PSEN1dE9 (PS1-APP) mice were used to model AD. The individual P4504fs were cloned by RT-PCR using mRNA from mouse brain cortex. Levels of cytokines and chemokine were measured using cytokine bead array and quantitative real time PCR. Results: P4504f13, 14, 15, 16 and 18 were all expressed in robust amounts in the mouse brain. Amongst these P4504f15 was present in highest amount and also hydroxylated LTB4 very efficiently. Administration of LPS resulted in increased levels of chemokine and cytokines which was exacerbated when a chemical inhibitor of P4504f was pre-administered. In BV-2 microglial cells, downregulation of P4504f using shRNA resulted in increased inflammatory response while induction of P4504f protected the cells. In the AD transgenic mice P4504fs were induced at 3 months of age, when inflammation was minimal. However, in 10-12 month old mice, when the inflammation was rampant, P4504f expression was significantly reduced. P4504Fs are also expressed in human brain and induction of P4504f represents an attractive target for reducing neuroinflammation. Conclusions: We demonstrate for the first time that P4504f may play a prominent role in the regulation of inflammation in brain through the metabolism of LTB4 to 20-hydroxy-LTB4 . Thus, we present a new drug target which can be considered for therapeutic intervention in AD to reduce the inflammation which contributes to the progression of the disease. P4-176
CASPASE-4 AS A KEY FACTOR IN ALZHEIMER PATHOLOGY
Joseph D. Buxbaum, Yuji Kajiwara, Takeshi Sakurai, Vahram Haroutunian, Gregory Elder, Miguel Gama Sosa, Afia Akram, Pavel Katsel, Mount Sinai School of Medicine, New York, NY, USA. Contact e-mail: [email protected] Background: The Alzheimer amyloid protein precursor (APP) can be metabolized to produce Abeta, which accumulates in plaques in Alzheimer disease (AD). Several groups have shown that APP can bind the FE65 adaptor proteins and that this complex can regulate gene expression. In order to better understand the proteome that is associated with APP and FE65, we carried out two-hybrid studies to identify proteins interacting with a PTB domain of FE65 and identified and validated Teashirt proteins as FE65 interactors. Teashirt proteins recruit HDAC and led to gene silencing. We identified caspase-4 as a target of the FE65/Teashirt complex. Caspase-4 is a primate specific inflammatory caspase. The objectives of the current study are to evaluate the role of caspase 4 in AD and to develop a mouse model that shows AD neurodegeneration. Methods: We carried out mRNA expression studies in a large sample of postmortem cases with or without AD. In addition, we made use of BAC transgenesis to
P483
express the human CASP4 gene in mice, which should show the spatial and temporal localization of the human gene. Results: In postmortem samples we observed increased expression of caspase-4 that correlates with progressive cognitive decline. We also saw a dramatic increase in caspase-4 expression associated with the earliest neuritic changes in AD and this elevation remained throughout disease progression. Furthermore, we have identified and begun to characterize mice expressing the human CASP4 gene as models for AD neurodegeneration. Conclusions: Caspase-4 expression increases by two-fold with the earliest increases in neuritic pathology. As caspase-4 is a primate-specific gene, current murine models of AD, and in fact of other neurodegenerative conditions, may be incomplete in part because of the absence of this gene. Creating a mouse line with the human CASP4 gene may give rise to an improved model of AD pathology. P4-177
ABERRANT ADULT NEUROGENESIS IN TRANSGENIC MICE EXPRESSING APP INTRACELLULAR DOMAIN
Sanjay W. Pimplikar, Kaushik Ghosal, Cleveland Clinic, Cleveland, OH, USA. Contact e-mail: [email protected] Background: Gamma-secretase mediated processing of amyloid precursor protein (APP) results in the generation of Abeta and APP intracellular domain (AICD). Whereas contribution of the Abeta fragments to Alzheimer’s disease (AD) pathology are well documented, relatively little is known whether and to what extent AICD also contributes to AD features. We generated AICD transgenic mice and found these mice to recapitulate several features of AD including neurodegeneration. Neuronal loss is an important pathology observed in AD brains and could be contributed by the death of neurons or decreased adult neurogenesis. This study was aimed examining the status of adult neurogenesis in the AICD transgenic mice. Methods: We generated transgenic mice coexpressing AICD and Fe65. These mice were injected with BrdU (i.p) and adult neurogenesis in the dentate gyrus was measured by immunohistochemistry. We measured proliferation and maturation of newly generated cells. These experiments were performed in mice at 1.5, 3 or 12 months of age. Results: We find that proliferation of newly generated cells was not different in 1.5 month-old AICD transgenic mice when compared to non-transgenic controls or mice expressing Fe65 alone. However, adult neurogenesis was significantly reduced in 3 month-old AICD transgenic mice. We also observed increased neuroinflammation in these mice indicated by altered cytokine profile and the presence of activated microglia. Impaired neurogenesis was also observed in 12 months mice. Interestingly, maturation or differentiation of newly generated cells was not altered by AICD. Conclusions: Our data show that expression of AICD significantly inhibits adult hippocampal neurogenesis without affecting the maturation of differentiation of the newly generated cells. It has been suggested that adult neurogenesis is impaired in human AD brains some studies have shown decreased neurogenesis in mouse models of AD. Since AICD transgenic mice show reduced adult neurogenesis in addition to several pathological features of AD, these results collectively indicate that AICD could make significant contributions to AD. P4-178
SUSTAINED INTERLEUKIN-1 EXPRESSION DRIVES PLAQUE CLEARANCE IN A MOUSE MODEL OF ALZHEIMER’S DISEASE
M. K. O’Banion, Sarah B. Matousek, Solomon S. Shaftel, Stephanos Kyrkanides, John A. Olschowka, University of Rochester, Rochester, NY, USA. Contact e-mail: [email protected] Background: Neuroinflammation, characterized by glial reactivity, vascular permeability, and induction of cytokines and chemokines, is a local tissue response to injurious stimuli in the central nervous system (CNS). A key participant in this response is the proinflammatory cytokine interleukin(IL)-1b, which is rapidly induced in microglia following acute CNS insult and chronically overexpressed in neurodegenerative disorders such as Alzheimer’s
RESOLUTION OF NEUROINFLAMMATION BY CYTOCHROME P4504F: IMPLICATION IN ALZHEIMER’S DISEASE
Neha Sehgal, National Brain Research Center, Gurgaon, India. Contact e-mail: [email protected] Background: Inflammatory processes are known to be involved in the progression of Alzheimer’s disease (AD). Microglia contributes to the neurodegenerative process by augmenting the production of inflammatory mediators. Resolution of inflammation could potentially alter the progression of the disease and afford neuroprotection. Cytochrome P450 (P450) are an important family of enzymes involved in the metabolism of xenobiotics. The P4504f subfamily hydroxylate the potent pro-inflammatory mediator, leukotriene B4 (LTB4) to 20-hydroxy-LTB4,thereby inactivating its inflammatory response. Thus, P4504f could be an attractive target for anti-inflammatory action in the brain. The objective of this study is to examine the role of Cyp4f in modulating inflammation in the brain, affording neuroprotection in acute and chronic inflammatory conditions, such as AD. Methods: The acute model of neuro-inflammation was generated by systemic injection of LPS to male C57Bl6j mice. The transgenic APPswe/PSEN1dE9 (PS1-APP) mice were used to model AD. The individual P4504fs were cloned by RT-PCR using mRNA from mouse brain cortex. Levels of cytokines and chemokine were measured using cytokine bead array and quantitative real time PCR. Results: P4504f13, 14, 15, 16 and 18 were all expressed in robust amounts in the mouse brain. Amongst these P4504f15 was present in highest amount and also hydroxylated LTB4 very efficiently. Administration of LPS resulted in increased levels of chemokine and cytokines which was exacerbated when a chemical inhibitor of P4504f was pre-administered. In BV-2 microglial cells, downregulation of P4504f using shRNA resulted in increased inflammatory response while induction of P4504f protected the cells. In the AD transgenic mice P4504fs were induced at 3 months of age, when inflammation was minimal. However, in 10-12 month old mice, when the inflammation was rampant, P4504f expression was significantly reduced. P4504Fs are also expressed in human brain and induction of P4504f represents an attractive target for reducing neuroinflammation. Conclusions: We demonstrate for the first time that P4504f may play a prominent role in the regulation of inflammation in brain through the metabolism of LTB4 to 20-hydroxy-LTB4 . Thus, we present a new drug target which can be considered for therapeutic intervention in AD to reduce the inflammation which contributes to the progression of the disease. P4-176
CASPASE-4 AS A KEY FACTOR IN ALZHEIMER PATHOLOGY
Joseph D. Buxbaum, Yuji Kajiwara, Takeshi Sakurai, Vahram Haroutunian, Gregory Elder, Miguel Gama Sosa, Afia Akram, Pavel Katsel, Mount Sinai School of Medicine, New York, NY, USA. Contact e-mail: [email protected] Background: The Alzheimer amyloid protein precursor (APP) can be metabolized to produce Abeta, which accumulates in plaques in Alzheimer disease (AD). Several groups have shown that APP can bind the FE65 adaptor proteins and that this complex can regulate gene expression. In order to better understand the proteome that is associated with APP and FE65, we carried out two-hybrid studies to identify proteins interacting with a PTB domain of FE65 and identified and validated Teashirt proteins as FE65 interactors. Teashirt proteins recruit HDAC and led to gene silencing. We identified caspase-4 as a target of the FE65/Teashirt complex. Caspase-4 is a primate specific inflammatory caspase. The objectives of the current study are to evaluate the role of caspase 4 in AD and to develop a mouse model that shows AD neurodegeneration. Methods: We carried out mRNA expression studies in a large sample of postmortem cases with or without AD. In addition, we made use of BAC transgenesis to
P483
express the human CASP4 gene in mice, which should show the spatial and temporal localization of the human gene. Results: In postmortem samples we observed increased expression of caspase-4 that correlates with progressive cognitive decline. We also saw a dramatic increase in caspase-4 expression associated with the earliest neuritic changes in AD and this elevation remained throughout disease progression. Furthermore, we have identified and begun to characterize mice expressing the human CASP4 gene as models for AD neurodegeneration. Conclusions: Caspase-4 expression increases by two-fold with the earliest increases in neuritic pathology. As caspase-4 is a primate-specific gene, current murine models of AD, and in fact of other neurodegenerative conditions, may be incomplete in part because of the absence of this gene. Creating a mouse line with the human CASP4 gene may give rise to an improved model of AD pathology. P4-177
ABERRANT ADULT NEUROGENESIS IN TRANSGENIC MICE EXPRESSING APP INTRACELLULAR DOMAIN
Sanjay W. Pimplikar, Kaushik Ghosal, Cleveland Clinic, Cleveland, OH, USA. Contact e-mail: [email protected] Background: Gamma-secretase mediated processing of amyloid precursor protein (APP) results in the generation of Abeta and APP intracellular domain (AICD). Whereas contribution of the Abeta fragments to Alzheimer’s disease (AD) pathology are well documented, relatively little is known whether and to what extent AICD also contributes to AD features. We generated AICD transgenic mice and found these mice to recapitulate several features of AD including neurodegeneration. Neuronal loss is an important pathology observed in AD brains and could be contributed by the death of neurons or decreased adult neurogenesis. This study was aimed examining the status of adult neurogenesis in the AICD transgenic mice. Methods: We generated transgenic mice coexpressing AICD and Fe65. These mice were injected with BrdU (i.p) and adult neurogenesis in the dentate gyrus was measured by immunohistochemistry. We measured proliferation and maturation of newly generated cells. These experiments were performed in mice at 1.5, 3 or 12 months of age. Results: We find that proliferation of newly generated cells was not different in 1.5 month-old AICD transgenic mice when compared to non-transgenic controls or mice expressing Fe65 alone. However, adult neurogenesis was significantly reduced in 3 month-old AICD transgenic mice. We also observed increased neuroinflammation in these mice indicated by altered cytokine profile and the presence of activated microglia. Impaired neurogenesis was also observed in 12 months mice. Interestingly, maturation or differentiation of newly generated cells was not altered by AICD. Conclusions: Our data show that expression of AICD significantly inhibits adult hippocampal neurogenesis without affecting the maturation of differentiation of the newly generated cells. It has been suggested that adult neurogenesis is impaired in human AD brains some studies have shown decreased neurogenesis in mouse models of AD. Since AICD transgenic mice show reduced adult neurogenesis in addition to several pathological features of AD, these results collectively indicate that AICD could make significant contributions to AD. P4-178
SUSTAINED INTERLEUKIN-1 EXPRESSION DRIVES PLAQUE CLEARANCE IN A MOUSE MODEL OF ALZHEIMER’S DISEASE
M. K. O’Banion, Sarah B. Matousek, Solomon S. Shaftel, Stephanos Kyrkanides, John A. Olschowka, University of Rochester, Rochester, NY, USA. Contact e-mail: [email protected] Background: Neuroinflammation, characterized by glial reactivity, vascular permeability, and induction of cytokines and chemokines, is a local tissue response to injurious stimuli in the central nervous system (CNS). A key participant in this response is the proinflammatory cytokine interleukin(IL)-1b, which is rapidly induced in microglia following acute CNS insult and chronically overexpressed in neurodegenerative disorders such as Alzheimer’s