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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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α-synuclein (αSN) triggered the loss of synaptic proteins from neurons—The amounts of synaptophysin (A) and cysteine string protein (CSP) (B) in neurons incubated with αSN (○) or βSN (●) as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) Immunoblots showing the amounts of synapsin-1, vesicle-associated membrane protein (VAMP)-1 and caveolin in neurons incubated with control medium (1), 1 µM αSN (2), 1 µM βSN (3); (D) Immunoblot showing aggregates of recombinant human αSN separated by non-denaturing polyacrylamide gel electrophoresis (PAGE).
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biomolecules-05-00178-f001: α-synuclein (αSN) triggered the loss of synaptic proteins from neurons—The amounts of synaptophysin (A) and cysteine string protein (CSP) (B) in neurons incubated with αSN (○) or βSN (●) as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) Immunoblots showing the amounts of synapsin-1, vesicle-associated membrane protein (VAMP)-1 and caveolin in neurons incubated with control medium (1), 1 µM αSN (2), 1 µM βSN (3); (D) Immunoblot showing aggregates of recombinant human αSN separated by non-denaturing polyacrylamide gel electrophoresis (PAGE).

Mentions: The synapse damage seen in PD and Dementia with Lewy Bodies is closely associated with αSN oligomers [7,8,9]. In an in vitro model the addition of aggregated recombinant human αSN, but not βSN, caused a dose-dependent reduction in synaptic proteins including synaptophysin [15] (Figure 1A) and CSP (Figure 1B) from cultured neurons. Immunoblots showed that the loss of synaptophysin and CSP from cultured neurons was accompanied by the loss of other synaptic proteins including synapsin-1 and vesicle-associated membrane protein (VAMP)-1 (Figure 1C). Incubation with αSN did not affect the amounts of caveolin in neuronal cultures, nor did it significantly reduce cell viability as measured by the thiazolyl blue tetrazolium (MTT) method, indicating that there was no significant neuronal death in these cultures (98% cell viability ± 6 compared with 100% ± 5, n = 9, p = 0.43).


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

Bate C, Williams A - Biomolecules (2015)

α-synuclein (αSN) triggered the loss of synaptic proteins from neurons—The amounts of synaptophysin (A) and cysteine string protein (CSP) (B) in neurons incubated with αSN (○) or βSN (●) as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) Immunoblots showing the amounts of synapsin-1, vesicle-associated membrane protein (VAMP)-1 and caveolin in neurons incubated with control medium (1), 1 µM αSN (2), 1 µM βSN (3); (D) Immunoblot showing aggregates of recombinant human αSN separated by non-denaturing polyacrylamide gel electrophoresis (PAGE).
© Copyright Policy
Related In: Results  -  Collection

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

biomolecules-05-00178-f001: α-synuclein (αSN) triggered the loss of synaptic proteins from neurons—The amounts of synaptophysin (A) and cysteine string protein (CSP) (B) in neurons incubated with αSN (○) or βSN (●) as shown. Values are means ± SD from triplicate experiments performed three times, n = 9; (C) Immunoblots showing the amounts of synapsin-1, vesicle-associated membrane protein (VAMP)-1 and caveolin in neurons incubated with control medium (1), 1 µM αSN (2), 1 µM βSN (3); (D) Immunoblot showing aggregates of recombinant human αSN separated by non-denaturing polyacrylamide gel electrophoresis (PAGE).
Mentions: The synapse damage seen in PD and Dementia with Lewy Bodies is closely associated with αSN oligomers [7,8,9]. In an in vitro model the addition of aggregated recombinant human αSN, but not βSN, caused a dose-dependent reduction in synaptic proteins including synaptophysin [15] (Figure 1A) and CSP (Figure 1B) from cultured neurons. Immunoblots showed that the loss of synaptophysin and CSP from cultured neurons was accompanied by the loss of other synaptic proteins including synapsin-1 and vesicle-associated membrane protein (VAMP)-1 (Figure 1C). Incubation with αSN did not affect the amounts of caveolin in neuronal cultures, nor did it significantly reduce cell viability as measured by the thiazolyl blue tetrazolium (MTT) method, indicating that there was no significant neuronal death in these cultures (98% cell viability ± 6 compared with 100% ± 5, n = 9, p = 0.43).

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