Odulate Sirt3, but not Sirt5 mRNA expression, demonstrating that mitochondrial ROS per se has acute effects specifically on Sirt3 mRNA expression levels. Whilst it is known that SIRT3 plays a role in regulating ROS levels, we demonstrate responsiveness of CNS Sirt3 mRNA expression to mitochondrial ROS, suggesting SIRT3 regulation by the CNS mechanisms sensing mitochondrial health. Furthermore, we demonstrate that an increase specifically in long-form Sirt3 results in significant extension of neuronal lifespan in the face of mitochondrial AZP-531 biological activity oxidative stress, although this is presumably just one of many mechanisms by which neurons respond to this pathology. Interestingly, SIRT3 was shown to be a prosurvival factor in NMDA-mediated excitotoxic injury in vitro [23].Materials and MethodsDetailed methods can be found in the Supporting Information (Text S1).Primary Hippocampal Cell CultureIsolation of primary rat hippocampal cultures was carried out as described previously [25]. Cultures were transfected 3 days postisolation.Transfection and ImmunofluorescenceLong-form and short-form SIRT3 were amplified from mouse brain cDNA and cloned in-frame into pEGFP N1 expression vector (Clontech Laboratories). HeLa and HEK293T cells and primary hippocampal cultures were transfected using FuGENE 6 (Roche Diagnostics GmBH, Mannheim, Germany) and Lipofectamine 2000 (Invitrogen Life Technologies) transfection reagents respectively, according to manufacturers’ instructions. Primary hippocampal cultures were fixed with 10 formalin and labeled immunofluorescently as previously described [25].Sirt3 AZP-531 Upregulation in ADOur data from PDAPP mice and human post-mortem AD 1317923 samples demonstrate that Sirt3 is upregulated in association 11138725 with Ab-accumulation. This constitutes the first demonstration of Sirt3 involvement in AD neurodegenerative disease. As AD is associated with significant increases in neuronal ROS production [2] and our in vitro data shows that Sirt3 mRNA expression is regulated by mitochondrial ROS levels, it seems likely that Sirt3 upregulation in AD may be a consequence of Ab-related oxidative stress. Given that Sirt3 upregulation subsequently increases neuronal lifespan, it is tempting to speculate that upregulation of SIRT3 in response to Ab-induced oxidative stress might prolong neuronal function by decreasing ROS, maintaining ATP-levels and sustaining synaptic activity, but this will need further investigation. SIRT3 has indeed been demonstrated to reduce ROS and maintain ATP levels in other peripheral tissues [7]. In the PDAPP mouse, Sirt3 mRNA upregulation mirrored spatiotemporal Ab deposition. In PDAPP mice, Ab levels rise first and ultimately to a much higher degree in the hippocampus, in comparison to cortex, while the cerebellum remains unaffected [22]. Similarly, Sirt3 mRNA is upregulated in hippocampus at 6 months, while cortical Sirt3 upregulation followed at a later stagecDNA Generation and Real-Time PCRRNA was extracted from human tissue as described previously [23]. Human and mouse brain tissue was homogenized in TRIzol reagent (Invitrogen Life Technologies) and reverse transcribed according to manufacturer’s instructions. Multiplex Real-Time PCR was performed using TaqMan Assay-on-demand probes (Applied Biosystems, Foster City, CA).In vitro Antimycin A and NAC Treatment6-day-old primary hippocampal cultures were loaded with MitoSOX (0.5 mM, Invitrogen Life technologies) according to manufacturers instructions. Cultures were pretreated wi.Odulate Sirt3, but not Sirt5 mRNA expression, demonstrating that mitochondrial ROS per se has acute effects specifically on Sirt3 mRNA expression levels. Whilst it is known that SIRT3 plays a role in regulating ROS levels, we demonstrate responsiveness of CNS Sirt3 mRNA expression to mitochondrial ROS, suggesting SIRT3 regulation by the CNS mechanisms sensing mitochondrial health. Furthermore, we demonstrate that an increase specifically in long-form Sirt3 results in significant extension of neuronal lifespan in the face of mitochondrial oxidative stress, although this is presumably just one of many mechanisms by which neurons respond to this pathology. Interestingly, SIRT3 was shown to be a prosurvival factor in NMDA-mediated excitotoxic injury in vitro [23].Materials and MethodsDetailed methods can be found in the Supporting Information (Text S1).Primary Hippocampal Cell CultureIsolation of primary rat hippocampal cultures was carried out as described previously [25]. Cultures were transfected 3 days postisolation.Transfection and ImmunofluorescenceLong-form and short-form SIRT3 were amplified from mouse brain cDNA and cloned in-frame into pEGFP N1 expression vector (Clontech Laboratories). HeLa and HEK293T cells and primary hippocampal cultures were transfected using FuGENE 6 (Roche Diagnostics GmBH, Mannheim, Germany) and Lipofectamine 2000 (Invitrogen Life Technologies) transfection reagents respectively, according to manufacturers’ instructions. Primary hippocampal cultures were fixed with 10 formalin and labeled immunofluorescently as previously described [25].Sirt3 Upregulation in ADOur data from PDAPP mice and human post-mortem AD 1317923 samples demonstrate that Sirt3 is upregulated in association 11138725 with Ab-accumulation. This constitutes the first demonstration of Sirt3 involvement in AD neurodegenerative disease. As AD is associated with significant increases in neuronal ROS production [2] and our in vitro data shows that Sirt3 mRNA expression is regulated by mitochondrial ROS levels, it seems likely that Sirt3 upregulation in AD may be a consequence of Ab-related oxidative stress. Given that Sirt3 upregulation subsequently increases neuronal lifespan, it is tempting to speculate that upregulation of SIRT3 in response to Ab-induced oxidative stress might prolong neuronal function by decreasing ROS, maintaining ATP-levels and sustaining synaptic activity, but this will need further investigation. SIRT3 has indeed been demonstrated to reduce ROS and maintain ATP levels in other peripheral tissues [7]. In the PDAPP mouse, Sirt3 mRNA upregulation mirrored spatiotemporal Ab deposition. In PDAPP mice, Ab levels rise first and ultimately to a much higher degree in the hippocampus, in comparison to cortex, while the cerebellum remains unaffected [22]. Similarly, Sirt3 mRNA is upregulated in hippocampus at 6 months, while cortical Sirt3 upregulation followed at a later stagecDNA Generation and Real-Time PCRRNA was extracted from human tissue as described previously [23]. Human and mouse brain tissue was homogenized in TRIzol reagent (Invitrogen Life Technologies) and reverse transcribed according to manufacturer’s instructions. Multiplex Real-Time PCR was performed using TaqMan Assay-on-demand probes (Applied Biosystems, Foster City, CA).In vitro Antimycin A and NAC Treatment6-day-old primary hippocampal cultures were loaded with MitoSOX (0.5 mM, Invitrogen Life technologies) according to manufacturers instructions. Cultures were pretreated wi.
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