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α-Synuclein-induced synapse damage in cultured neurons is mediated by cholesterol-sensitive activation of cytoplasmic phospholipase A2.

Bate C, Williams A - Biomolecules (2015)

Bottom Line: The accumulation of aggregated forms of the α-synuclein (αSN) is associated with the pathogenesis of Parkinson's disease (PD) and Dementia with Lewy Bodies.The loss of synapses is an important event in the pathogenesis of these diseases.They also indicate that αSN-induced activation of cPLA2 is influenced by the cholesterol content of membranes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Herts AL9 7TA, UK. cbate@rvc.ac.uk.

ABSTRACT
The accumulation of aggregated forms of the α-synuclein (αSN) is associated with the pathogenesis of Parkinson's disease (PD) and Dementia with Lewy Bodies. The loss of synapses is an important event in the pathogenesis of these diseases. Here we show that aggregated recombinant human αSN, but not βSN, triggered synapse damage in cultured neurons as measured by the loss of synaptic proteins. Pre-treatment with the selective cytoplasmic phospholipase A2 (cPLA2) inhibitors AACOCF3 and MAFP protected neurons against αSN-induced synapse damage. Synapse damage was associated with the αSN-induced activation of synaptic cPLA2 and the production of prostaglandin E2. The activation of cPLA2 is the first step in the generation of platelet-activating factor (PAF) and PAF receptor antagonists (ginkgolide B or Hexa-PAF) also protect neurons against αSN-induced synapse damage. αSN-induced synapse damage was also reduced in neurons pre-treated with the cholesterol synthesis inhibitor (squalestatin). These results are consistent with the hypothesis that αSN triggered synapse damage via hyperactivation of cPLA2. They also indicate that αSN-induced activation of cPLA2 is influenced by the cholesterol content of membranes. Inhibitors of this pathway that can cross the blood brain barrier may protect against the synapse damage seen during PD.

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Squalestatin protects neurons against αSN-induced synapse damage—The amounts of synaptophysin (A) and CSP (B) in neurons pre-treated with control medium (○) or 200 nM squalestatin (●) and incubated with αSN as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) The amounts of synaptophysin in neurons pre-treated with control medium (□) or squalestatin as shown (■) and incubated with 1 μM aggregated αSN. Values are means ± SD from triplicate experiments performed three times, n = 9; (D) There was a significant inverse correlation between the concentrations of cholesterol in neurons treated with squalestatin (200 nM to 25 nM) and the amounts of synaptophysin in these neurons after incubation with 1μM aggregated αSN, Pearson’s coefficient = −0.908, p < 0.01.
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biomolecules-05-00178-f006: Squalestatin protects neurons against αSN-induced synapse damage—The amounts of synaptophysin (A) and CSP (B) in neurons pre-treated with control medium (○) or 200 nM squalestatin (●) and incubated with αSN as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) The amounts of synaptophysin in neurons pre-treated with control medium (□) or squalestatin as shown (■) and incubated with 1 μM aggregated αSN. Values are means ± SD from triplicate experiments performed three times, n = 9; (D) There was a significant inverse correlation between the concentrations of cholesterol in neurons treated with squalestatin (200 nM to 25 nM) and the amounts of synaptophysin in these neurons after incubation with 1μM aggregated αSN, Pearson’s coefficient = −0.908, p < 0.01.

Mentions: The role of cholesterol in αSN-mediated synapse damage was examined. Pre-treatment with 200 nM squalestatin protected neurons against the αSN-induced loss of synaptophysin (Figure 6A) or CSP (Figure 6B). The efficacy of squalestatin was also tested; pre-treatment with squalestatin produced a dose-dependent increase in the synaptophysin content of neurons subsequently incubated with 1 µM αSN (Figure 6C). The effects of squalestatin on concentrations of cholesterol in neurons were also dose dependent; there were significant correlations between the concentrations of cholesterol and synaptophysin, Pearson’s coefficient = −0.908, p < 0.01 (Figure 6D) following the addition of 1 μM αSN.


α-Synuclein-induced synapse damage in cultured neurons is mediated by cholesterol-sensitive activation of cytoplasmic phospholipase A2.

Bate C, Williams A - Biomolecules (2015)

Squalestatin protects neurons against αSN-induced synapse damage—The amounts of synaptophysin (A) and CSP (B) in neurons pre-treated with control medium (○) or 200 nM squalestatin (●) and incubated with αSN as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) The amounts of synaptophysin in neurons pre-treated with control medium (□) or squalestatin as shown (■) and incubated with 1 μM aggregated αSN. Values are means ± SD from triplicate experiments performed three times, n = 9; (D) There was a significant inverse correlation between the concentrations of cholesterol in neurons treated with squalestatin (200 nM to 25 nM) and the amounts of synaptophysin in these neurons after incubation with 1μM aggregated αSN, Pearson’s coefficient = −0.908, p < 0.01.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384118&req=5

biomolecules-05-00178-f006: Squalestatin protects neurons against αSN-induced synapse damage—The amounts of synaptophysin (A) and CSP (B) in neurons pre-treated with control medium (○) or 200 nM squalestatin (●) and incubated with αSN as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) The amounts of synaptophysin in neurons pre-treated with control medium (□) or squalestatin as shown (■) and incubated with 1 μM aggregated αSN. Values are means ± SD from triplicate experiments performed three times, n = 9; (D) There was a significant inverse correlation between the concentrations of cholesterol in neurons treated with squalestatin (200 nM to 25 nM) and the amounts of synaptophysin in these neurons after incubation with 1μM aggregated αSN, Pearson’s coefficient = −0.908, p < 0.01.
Mentions: The role of cholesterol in αSN-mediated synapse damage was examined. Pre-treatment with 200 nM squalestatin protected neurons against the αSN-induced loss of synaptophysin (Figure 6A) or CSP (Figure 6B). The efficacy of squalestatin was also tested; pre-treatment with squalestatin produced a dose-dependent increase in the synaptophysin content of neurons subsequently incubated with 1 µM αSN (Figure 6C). The effects of squalestatin on concentrations of cholesterol in neurons were also dose dependent; there were significant correlations between the concentrations of cholesterol and synaptophysin, Pearson’s coefficient = −0.908, p < 0.01 (Figure 6D) following the addition of 1 μM αSN.

Bottom Line: The accumulation of aggregated forms of the α-synuclein (αSN) is associated with the pathogenesis of Parkinson's disease (PD) and Dementia with Lewy Bodies.The loss of synapses is an important event in the pathogenesis of these diseases.They also indicate that αSN-induced activation of cPLA2 is influenced by the cholesterol content of membranes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Herts AL9 7TA, UK. cbate@rvc.ac.uk.

ABSTRACT
The accumulation of aggregated forms of the α-synuclein (αSN) is associated with the pathogenesis of Parkinson's disease (PD) and Dementia with Lewy Bodies. The loss of synapses is an important event in the pathogenesis of these diseases. Here we show that aggregated recombinant human αSN, but not βSN, triggered synapse damage in cultured neurons as measured by the loss of synaptic proteins. Pre-treatment with the selective cytoplasmic phospholipase A2 (cPLA2) inhibitors AACOCF3 and MAFP protected neurons against αSN-induced synapse damage. Synapse damage was associated with the αSN-induced activation of synaptic cPLA2 and the production of prostaglandin E2. The activation of cPLA2 is the first step in the generation of platelet-activating factor (PAF) and PAF receptor antagonists (ginkgolide B or Hexa-PAF) also protect neurons against αSN-induced synapse damage. αSN-induced synapse damage was also reduced in neurons pre-treated with the cholesterol synthesis inhibitor (squalestatin). These results are consistent with the hypothesis that αSN triggered synapse damage via hyperactivation of cPLA2. They also indicate that αSN-induced activation of cPLA2 is influenced by the cholesterol content of membranes. Inhibitors of this pathway that can cross the blood brain barrier may protect against the synapse damage seen during PD.

Show MeSH
Related in: MedlinePlus