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Phospholipase A2 reduction ameliorates cognitive deficits in a mouse model of Alzheimer's disease.

Sanchez-Mejia RO, Newman JW, Toh S, Yu GQ, Zhou Y, Halabisky B, Cissé M, Scearce-Levie K, Cheng IH, Gan L, Palop JJ, Bonventre JV, Mucke L - Nat. Neurosci. (2008)

Bottom Line: We used a lipidomics approach to generate a broad profile of fatty acids in brain tissues of hAPP-expressing mice and found an increase in arachidonic acid and its metabolites, suggesting increased activity of the group IV isoform of phospholipase A(2) (GIVA-PLA(2)).Abeta caused a dose-dependent increase in GIVA-PLA(2) phosphorylation in neuronal cultures.Inhibition of GIVA-PLA(2) diminished Abeta-induced neurotoxicity.

View Article: PubMed Central - PubMed

Affiliation: Gladstone Institute of Neurological Disease, San Francisco, California 94158, USA. rene_sanchez@post.harvard.edu

ABSTRACT
Neuronal expression of familial Alzheimer's disease-mutant human amyloid precursor protein (hAPP) and hAPP-derived amyloid-beta (Abeta) peptides causes synaptic dysfunction, inflammation and abnormal cerebrovascular tone in transgenic mice. Fatty acids may be involved in these processes, but their contribution to Alzheimer's disease pathogenesis is uncertain. We used a lipidomics approach to generate a broad profile of fatty acids in brain tissues of hAPP-expressing mice and found an increase in arachidonic acid and its metabolites, suggesting increased activity of the group IV isoform of phospholipase A(2) (GIVA-PLA(2)). The levels of activated GIVA-PLA(2) in the hippocampus were increased in individuals with Alzheimer's disease and in hAPP mice. Abeta caused a dose-dependent increase in GIVA-PLA(2) phosphorylation in neuronal cultures. Inhibition of GIVA-PLA(2) diminished Abeta-induced neurotoxicity. Genetic ablation or reduction of GIVA-PLA(2) protected hAPP mice against Abeta-dependent deficits in learning and memory, behavioral alterations and premature mortality. Inhibition of GIVA-PLA(2) may be beneficial in the treatment and prevention of Alzheimer's disease.

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Inhibition of GIVA-PLA2 prevents Aβ1−42 toxicity in primary neuronal cultures. Primary rat neurons were treated with Aβ1−42 oligomers as indicated after 14 days in vitro. Quantitative results were obtained from three wells per condition in five independent experiments and normalized to untreated controls. a, Levels of phosphorylated and unphosphorylated GIVA-PLA2 in cell lysates were determined by western blot analysis. Aβ increased levels of phosphorylated GIVA-PLA2 in a dose- and time-dependent manner (P<0.0001 by two-way ANOVA, mean ± s.e.m.). b–d, Percentage of viable cells determined by trypan blue exclusion and counting of unlabeled cells. b, Aβ caused neuronal cell death in a dose- and time-dependent manner (P<0.001 by repeated-measures ANOVA, mean and s.e.m.). c, AA also led to neuronal death (P<0.01 by repeated-measures ANOVA). d, Pretreatment of cells with AACOCF3, a GIVA-PLA2-specific inhibitor, for 10 min ameliorated Aβ-induced neuronal death (P<0.01 by repeated-measures ANOVA, P<0.001 at 6 and 12 h by paired t test). e, Surface levels of GluR1 were assessed by biotinylation assay 10 min after the indicated treatments. Aβ1−42 (10 μM) increased surface levels of GluR1 compared with Aβ42−1, an effect that could be blocked with AACOCF3 pretreatment and replicated with AA (mean ± s.e.m). f, Surface levels of GluR1 decreased to baseline levels after 30 and 60 min of exposure to Aβ1−42 or AA (mean ± s.e.m.). ****P<0.0001 versus Aβ42−1 (Tukey test).
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Figure 3: Inhibition of GIVA-PLA2 prevents Aβ1−42 toxicity in primary neuronal cultures. Primary rat neurons were treated with Aβ1−42 oligomers as indicated after 14 days in vitro. Quantitative results were obtained from three wells per condition in five independent experiments and normalized to untreated controls. a, Levels of phosphorylated and unphosphorylated GIVA-PLA2 in cell lysates were determined by western blot analysis. Aβ increased levels of phosphorylated GIVA-PLA2 in a dose- and time-dependent manner (P<0.0001 by two-way ANOVA, mean ± s.e.m.). b–d, Percentage of viable cells determined by trypan blue exclusion and counting of unlabeled cells. b, Aβ caused neuronal cell death in a dose- and time-dependent manner (P<0.001 by repeated-measures ANOVA, mean and s.e.m.). c, AA also led to neuronal death (P<0.01 by repeated-measures ANOVA). d, Pretreatment of cells with AACOCF3, a GIVA-PLA2-specific inhibitor, for 10 min ameliorated Aβ-induced neuronal death (P<0.01 by repeated-measures ANOVA, P<0.001 at 6 and 12 h by paired t test). e, Surface levels of GluR1 were assessed by biotinylation assay 10 min after the indicated treatments. Aβ1−42 (10 μM) increased surface levels of GluR1 compared with Aβ42−1, an effect that could be blocked with AACOCF3 pretreatment and replicated with AA (mean ± s.e.m). f, Surface levels of GluR1 decreased to baseline levels after 30 and 60 min of exposure to Aβ1−42 or AA (mean ± s.e.m.). ****P<0.0001 versus Aβ42−1 (Tukey test).

Mentions: To determine if exposure to extracellular Aβ was sufficient to activate neuronal GIVA-PLA2, we assessed the effect of synthetic Aβ1−42 oligomers on GIVA-PLA2 phosphorylation in primary neuronal cultures. Treatment with Aβ1−42, but not Aβ42−1 control peptide, caused a dose- and time-dependent increase in phosphorylated GIVA-PLA2 (Fig. 3a). Treatment with cell-secreted hAPP had no such effect (Supplementary Fig. 8a). Similarly, AA release was increased by Aβ1−42, but not by Aβ42−1 or cell-secreted hAPP (Supplementary Fig. 8b). Aβ1−42-induced phosphorylation of GIVA-PLA2 was blocked by the broad–spectrum MAPK inhibitor PD98059 and by the MEK inhibitor SB203580 (Supplementary Fig. 8a), suggesting mediator roles of these kinases. Aβ1−42-dependent AA release was blocked by pretreatment of neuronal cultures with the Ca2+ chelators EGTA and BAPTA, inhibitors of MAPK or MEK, or the GIVA-PLA2 inhibitor arachidonyl trifluoromethyl ketone (AACOCF3) 5, but not by pretreatment with the GVIA-PLA2 inhibitor bromoenolactone (BEL) (Supplementary Fig. 8b).


Phospholipase A2 reduction ameliorates cognitive deficits in a mouse model of Alzheimer's disease.

Sanchez-Mejia RO, Newman JW, Toh S, Yu GQ, Zhou Y, Halabisky B, Cissé M, Scearce-Levie K, Cheng IH, Gan L, Palop JJ, Bonventre JV, Mucke L - Nat. Neurosci. (2008)

Inhibition of GIVA-PLA2 prevents Aβ1−42 toxicity in primary neuronal cultures. Primary rat neurons were treated with Aβ1−42 oligomers as indicated after 14 days in vitro. Quantitative results were obtained from three wells per condition in five independent experiments and normalized to untreated controls. a, Levels of phosphorylated and unphosphorylated GIVA-PLA2 in cell lysates were determined by western blot analysis. Aβ increased levels of phosphorylated GIVA-PLA2 in a dose- and time-dependent manner (P<0.0001 by two-way ANOVA, mean ± s.e.m.). b–d, Percentage of viable cells determined by trypan blue exclusion and counting of unlabeled cells. b, Aβ caused neuronal cell death in a dose- and time-dependent manner (P<0.001 by repeated-measures ANOVA, mean and s.e.m.). c, AA also led to neuronal death (P<0.01 by repeated-measures ANOVA). d, Pretreatment of cells with AACOCF3, a GIVA-PLA2-specific inhibitor, for 10 min ameliorated Aβ-induced neuronal death (P<0.01 by repeated-measures ANOVA, P<0.001 at 6 and 12 h by paired t test). e, Surface levels of GluR1 were assessed by biotinylation assay 10 min after the indicated treatments. Aβ1−42 (10 μM) increased surface levels of GluR1 compared with Aβ42−1, an effect that could be blocked with AACOCF3 pretreatment and replicated with AA (mean ± s.e.m). f, Surface levels of GluR1 decreased to baseline levels after 30 and 60 min of exposure to Aβ1−42 or AA (mean ± s.e.m.). ****P<0.0001 versus Aβ42−1 (Tukey test).
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Figure 3: Inhibition of GIVA-PLA2 prevents Aβ1−42 toxicity in primary neuronal cultures. Primary rat neurons were treated with Aβ1−42 oligomers as indicated after 14 days in vitro. Quantitative results were obtained from three wells per condition in five independent experiments and normalized to untreated controls. a, Levels of phosphorylated and unphosphorylated GIVA-PLA2 in cell lysates were determined by western blot analysis. Aβ increased levels of phosphorylated GIVA-PLA2 in a dose- and time-dependent manner (P<0.0001 by two-way ANOVA, mean ± s.e.m.). b–d, Percentage of viable cells determined by trypan blue exclusion and counting of unlabeled cells. b, Aβ caused neuronal cell death in a dose- and time-dependent manner (P<0.001 by repeated-measures ANOVA, mean and s.e.m.). c, AA also led to neuronal death (P<0.01 by repeated-measures ANOVA). d, Pretreatment of cells with AACOCF3, a GIVA-PLA2-specific inhibitor, for 10 min ameliorated Aβ-induced neuronal death (P<0.01 by repeated-measures ANOVA, P<0.001 at 6 and 12 h by paired t test). e, Surface levels of GluR1 were assessed by biotinylation assay 10 min after the indicated treatments. Aβ1−42 (10 μM) increased surface levels of GluR1 compared with Aβ42−1, an effect that could be blocked with AACOCF3 pretreatment and replicated with AA (mean ± s.e.m). f, Surface levels of GluR1 decreased to baseline levels after 30 and 60 min of exposure to Aβ1−42 or AA (mean ± s.e.m.). ****P<0.0001 versus Aβ42−1 (Tukey test).
Mentions: To determine if exposure to extracellular Aβ was sufficient to activate neuronal GIVA-PLA2, we assessed the effect of synthetic Aβ1−42 oligomers on GIVA-PLA2 phosphorylation in primary neuronal cultures. Treatment with Aβ1−42, but not Aβ42−1 control peptide, caused a dose- and time-dependent increase in phosphorylated GIVA-PLA2 (Fig. 3a). Treatment with cell-secreted hAPP had no such effect (Supplementary Fig. 8a). Similarly, AA release was increased by Aβ1−42, but not by Aβ42−1 or cell-secreted hAPP (Supplementary Fig. 8b). Aβ1−42-induced phosphorylation of GIVA-PLA2 was blocked by the broad–spectrum MAPK inhibitor PD98059 and by the MEK inhibitor SB203580 (Supplementary Fig. 8a), suggesting mediator roles of these kinases. Aβ1−42-dependent AA release was blocked by pretreatment of neuronal cultures with the Ca2+ chelators EGTA and BAPTA, inhibitors of MAPK or MEK, or the GIVA-PLA2 inhibitor arachidonyl trifluoromethyl ketone (AACOCF3) 5, but not by pretreatment with the GVIA-PLA2 inhibitor bromoenolactone (BEL) (Supplementary Fig. 8b).

Bottom Line: We used a lipidomics approach to generate a broad profile of fatty acids in brain tissues of hAPP-expressing mice and found an increase in arachidonic acid and its metabolites, suggesting increased activity of the group IV isoform of phospholipase A(2) (GIVA-PLA(2)).Abeta caused a dose-dependent increase in GIVA-PLA(2) phosphorylation in neuronal cultures.Inhibition of GIVA-PLA(2) diminished Abeta-induced neurotoxicity.

View Article: PubMed Central - PubMed

Affiliation: Gladstone Institute of Neurological Disease, San Francisco, California 94158, USA. rene_sanchez@post.harvard.edu

ABSTRACT
Neuronal expression of familial Alzheimer's disease-mutant human amyloid precursor protein (hAPP) and hAPP-derived amyloid-beta (Abeta) peptides causes synaptic dysfunction, inflammation and abnormal cerebrovascular tone in transgenic mice. Fatty acids may be involved in these processes, but their contribution to Alzheimer's disease pathogenesis is uncertain. We used a lipidomics approach to generate a broad profile of fatty acids in brain tissues of hAPP-expressing mice and found an increase in arachidonic acid and its metabolites, suggesting increased activity of the group IV isoform of phospholipase A(2) (GIVA-PLA(2)). The levels of activated GIVA-PLA(2) in the hippocampus were increased in individuals with Alzheimer's disease and in hAPP mice. Abeta caused a dose-dependent increase in GIVA-PLA(2) phosphorylation in neuronal cultures. Inhibition of GIVA-PLA(2) diminished Abeta-induced neurotoxicity. Genetic ablation or reduction of GIVA-PLA(2) protected hAPP mice against Abeta-dependent deficits in learning and memory, behavioral alterations and premature mortality. Inhibition of GIVA-PLA(2) may be beneficial in the treatment and prevention of Alzheimer's disease.

Show MeSH
Related in: MedlinePlus