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Alzheimer's therapeutics targeting amyloid beta 1-42 oligomers I: Abeta 42 oligomer binding to specific neuronal receptors is displaced by drug candidates that improve cognitive deficits.

Izzo NJ, Staniszewski A, To L, Fa M, Teich AF, Saeed F, Wostein H, Walko T, Vaswani A, Wardius M, Syed Z, Ravenscroft J, Mozzoni K, Silky C, Rehak C, Yurko R, Finn P, Look G, Rishton G, Safferstein H, Miller M, Johanson C, Stopa E, Windisch M, Hutter-Paier B, Shamloo M, Arancio O, LeVine H, Catalano SM - PLoS ONE (2014)

Bottom Line: We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers.The therapeutic lead compounds we have found are pharmacological antagonists of Abeta oligomers, reducing the binding of Abeta oligomers to neurons in vitro, preventing spine loss in neurons and preventing and treating oligomer-induced deficits in membrane trafficking.These studies demonstrate that synthetic and human-derived Abeta oligomers act as pharmacologically-behaved ligands at neuronal receptors--i.e. they exhibit saturable binding to a target, they exert a functional effect related to their binding and their displacement by small molecule antagonists blocks their functional effect.

View Article: PubMed Central - PubMed

Affiliation: Cognition Therapeutics Inc., Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
Synaptic dysfunction and loss caused by age-dependent accumulation of synaptotoxic beta amyloid (Abeta) 1-42 oligomers is proposed to underlie cognitive decline in Alzheimer's disease (AD). Alterations in membrane trafficking induced by Abeta oligomers mediates reduction in neuronal surface receptor expression that is the basis for inhibition of electrophysiological measures of synaptic plasticity and thus learning and memory. We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers. Synthetic Abeta oligomers bind saturably to a single site on neuronal synapses and induce deficits in membrane trafficking in neuronal cultures with an EC50 that corresponds to its binding affinity. The therapeutic lead compounds we have found are pharmacological antagonists of Abeta oligomers, reducing the binding of Abeta oligomers to neurons in vitro, preventing spine loss in neurons and preventing and treating oligomer-induced deficits in membrane trafficking. These molecules are highly brain penetrant and prevent and restore cognitive deficits in mouse models of Alzheimer's disease. Counter-screening these compounds against a broad panel of potential CNS targets revealed they are highly potent and specific ligands of the sigma-2/PGRMC1 receptor. Brain concentrations of the compounds corresponding to greater than 80% receptor occupancy at the sigma-2/PGRMC1 receptor restore cognitive function in transgenic hAPP Swe/Ldn mice. These studies demonstrate that synthetic and human-derived Abeta oligomers act as pharmacologically-behaved ligands at neuronal receptors--i.e. they exhibit saturable binding to a target, they exert a functional effect related to their binding and their displacement by small molecule antagonists blocks their functional effect. The first-in-class small molecule receptor antagonists described here restore memory to normal in multiple AD models and sustain improvement long-term, representing a novel mechanism of action for disease-modifying Alzheimer's therapeutics.

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Small molecule Abeta binding antagonists prevent Abeta 1–42 oligomer-induced synaptic regression in cultured neurons.A, Abeta oligomers bound to a subset of neurites (red) reduces synaptophysin-immunoreactive synaptic puncta (green). B, Treatment with sigma-2/PGRMC1 antagonists reduces oligomer binding and restores normal immunoreactivity for the synaptic marker. C, Oligomers induce an average 18%±2 s.e.m. loss in the number of immunoreactive puncta per micron length of neurite (red bar) compared to vehicle-treated cultures (blue bar). Treatment of cultures with sigma-2/PGRMC1 antagonists (closed bars) restores synaptophysin immunoreactivity to normal, but has no effect when antagonists are dosed alone (open bars). *p = 0.05, Student's paired t-test.
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pone-0111898-g012: Small molecule Abeta binding antagonists prevent Abeta 1–42 oligomer-induced synaptic regression in cultured neurons.A, Abeta oligomers bound to a subset of neurites (red) reduces synaptophysin-immunoreactive synaptic puncta (green). B, Treatment with sigma-2/PGRMC1 antagonists reduces oligomer binding and restores normal immunoreactivity for the synaptic marker. C, Oligomers induce an average 18%±2 s.e.m. loss in the number of immunoreactive puncta per micron length of neurite (red bar) compared to vehicle-treated cultures (blue bar). Treatment of cultures with sigma-2/PGRMC1 antagonists (closed bars) restores synaptophysin immunoreactivity to normal, but has no effect when antagonists are dosed alone (open bars). *p = 0.05, Student's paired t-test.

Mentions: In addition to altering rates of membrane trafficking, oligomers have been shown to induce reversible spine retraction in vitro[22] and to cause a corresponding loss of synapses and synaptic proteins including synaptophysin [21], [47]. Addition of synthetic Abeta oligomers to neuronal cultures caused an 18% loss of synaptophysin-immunoreactive puncta in vitro (Fig. 12A,C) compared to vehicle treatment; this is similar to the degree of synapse loss seen using ultrastructural stereology methods in post-mortem hippocampus from humans diagnosed with Mild Cognitive Impairment [61]. Small molecule anti-Abeta compounds eliminate oligomer-induced loss of synaptophysin-positive puncta (Fig. 12B, C), with no effect on puncta number when dosed alone.


Alzheimer's therapeutics targeting amyloid beta 1-42 oligomers I: Abeta 42 oligomer binding to specific neuronal receptors is displaced by drug candidates that improve cognitive deficits.

Izzo NJ, Staniszewski A, To L, Fa M, Teich AF, Saeed F, Wostein H, Walko T, Vaswani A, Wardius M, Syed Z, Ravenscroft J, Mozzoni K, Silky C, Rehak C, Yurko R, Finn P, Look G, Rishton G, Safferstein H, Miller M, Johanson C, Stopa E, Windisch M, Hutter-Paier B, Shamloo M, Arancio O, LeVine H, Catalano SM - PLoS ONE (2014)

Small molecule Abeta binding antagonists prevent Abeta 1–42 oligomer-induced synaptic regression in cultured neurons.A, Abeta oligomers bound to a subset of neurites (red) reduces synaptophysin-immunoreactive synaptic puncta (green). B, Treatment with sigma-2/PGRMC1 antagonists reduces oligomer binding and restores normal immunoreactivity for the synaptic marker. C, Oligomers induce an average 18%±2 s.e.m. loss in the number of immunoreactive puncta per micron length of neurite (red bar) compared to vehicle-treated cultures (blue bar). Treatment of cultures with sigma-2/PGRMC1 antagonists (closed bars) restores synaptophysin immunoreactivity to normal, but has no effect when antagonists are dosed alone (open bars). *p = 0.05, Student's paired t-test.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4229098&req=5

pone-0111898-g012: Small molecule Abeta binding antagonists prevent Abeta 1–42 oligomer-induced synaptic regression in cultured neurons.A, Abeta oligomers bound to a subset of neurites (red) reduces synaptophysin-immunoreactive synaptic puncta (green). B, Treatment with sigma-2/PGRMC1 antagonists reduces oligomer binding and restores normal immunoreactivity for the synaptic marker. C, Oligomers induce an average 18%±2 s.e.m. loss in the number of immunoreactive puncta per micron length of neurite (red bar) compared to vehicle-treated cultures (blue bar). Treatment of cultures with sigma-2/PGRMC1 antagonists (closed bars) restores synaptophysin immunoreactivity to normal, but has no effect when antagonists are dosed alone (open bars). *p = 0.05, Student's paired t-test.
Mentions: In addition to altering rates of membrane trafficking, oligomers have been shown to induce reversible spine retraction in vitro[22] and to cause a corresponding loss of synapses and synaptic proteins including synaptophysin [21], [47]. Addition of synthetic Abeta oligomers to neuronal cultures caused an 18% loss of synaptophysin-immunoreactive puncta in vitro (Fig. 12A,C) compared to vehicle treatment; this is similar to the degree of synapse loss seen using ultrastructural stereology methods in post-mortem hippocampus from humans diagnosed with Mild Cognitive Impairment [61]. Small molecule anti-Abeta compounds eliminate oligomer-induced loss of synaptophysin-positive puncta (Fig. 12B, C), with no effect on puncta number when dosed alone.

Bottom Line: We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers.The therapeutic lead compounds we have found are pharmacological antagonists of Abeta oligomers, reducing the binding of Abeta oligomers to neurons in vitro, preventing spine loss in neurons and preventing and treating oligomer-induced deficits in membrane trafficking.These studies demonstrate that synthetic and human-derived Abeta oligomers act as pharmacologically-behaved ligands at neuronal receptors--i.e. they exhibit saturable binding to a target, they exert a functional effect related to their binding and their displacement by small molecule antagonists blocks their functional effect.

View Article: PubMed Central - PubMed

Affiliation: Cognition Therapeutics Inc., Pittsburgh, Pennsylvania, United States of America.

ABSTRACT
Synaptic dysfunction and loss caused by age-dependent accumulation of synaptotoxic beta amyloid (Abeta) 1-42 oligomers is proposed to underlie cognitive decline in Alzheimer's disease (AD). Alterations in membrane trafficking induced by Abeta oligomers mediates reduction in neuronal surface receptor expression that is the basis for inhibition of electrophysiological measures of synaptic plasticity and thus learning and memory. We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers. Synthetic Abeta oligomers bind saturably to a single site on neuronal synapses and induce deficits in membrane trafficking in neuronal cultures with an EC50 that corresponds to its binding affinity. The therapeutic lead compounds we have found are pharmacological antagonists of Abeta oligomers, reducing the binding of Abeta oligomers to neurons in vitro, preventing spine loss in neurons and preventing and treating oligomer-induced deficits in membrane trafficking. These molecules are highly brain penetrant and prevent and restore cognitive deficits in mouse models of Alzheimer's disease. Counter-screening these compounds against a broad panel of potential CNS targets revealed they are highly potent and specific ligands of the sigma-2/PGRMC1 receptor. Brain concentrations of the compounds corresponding to greater than 80% receptor occupancy at the sigma-2/PGRMC1 receptor restore cognitive function in transgenic hAPP Swe/Ldn mice. These studies demonstrate that synthetic and human-derived Abeta oligomers act as pharmacologically-behaved ligands at neuronal receptors--i.e. they exhibit saturable binding to a target, they exert a functional effect related to their binding and their displacement by small molecule antagonists blocks their functional effect. The first-in-class small molecule receptor antagonists described here restore memory to normal in multiple AD models and sustain improvement long-term, representing a novel mechanism of action for disease-modifying Alzheimer's therapeutics.

Show MeSH
Related in: MedlinePlus