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Upregulation of alpha7 Nicotinic Receptors by Acetylcholinesterase C-Terminal Peptides.

Bond CE, Zimmermann M, Greenfield SA - PLoS ONE (2009)

Bottom Line: Of more long-term significance, these peptides also induce upregulation of alpha7-nAChR mRNA and protein expression, as well as enhancing receptor trafficking to the plasma membrane.The results reported here demonstrate a hitherto unknown relationship between the alpha7-nAChR and the non-enzymatic functions of acetylcholinesterase, mediated independently by its C-terminal domain.Such an interaction may prove valuable as a pharmacological tool, prompting new approaches for understanding, and combating, the process of neurodegeneration.

View Article: PubMed Central - PubMed

Affiliation: Institute for the Future of the Mind, Department of Pharmacology, Oxford University, Oxford, UK. cherie.bond@pharm.ox.ac.uk

ABSTRACT

Background: The alpha-7 nicotinic acetylcholine receptor (alpha7-nAChR) is well known as a potent calcium ionophore that, in the brain, has been implicated in excitotoxicity and hence in the underlying mechanisms of neurodegenerative disorders such as Alzheimer's disease. Previous research implied that the activity of this receptor may be modified by exposure to a peptide fragment derived from the C-terminal region of the enzyme acetylcholinesterase. This investigation was undertaken to determine if the functional changes observed could be attributed to peptide binding interaction with the alpha7-nAChR, or peptide modulation of receptor expression.

Methodology/principal findings: This study provides evidence that two peptides derived from the C-terminus of acetylcholinesterase, not only selectively displace specific bungarotoxin binding at the alpha7-nAChR, but also alter receptor binding properties for its familiar ligands, including the alternative endogenous agonist choline. Of more long-term significance, these peptides also induce upregulation of alpha7-nAChR mRNA and protein expression, as well as enhancing receptor trafficking to the plasma membrane.

Conclusions/significance: The results reported here demonstrate a hitherto unknown relationship between the alpha7-nAChR and the non-enzymatic functions of acetylcholinesterase, mediated independently by its C-terminal domain. Such an interaction may prove valuable as a pharmacological tool, prompting new approaches for understanding, and combating, the process of neurodegeneration.

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Related in: MedlinePlus

Acute membrane binding in GH4-hα7 cells.Data shown are the combined results of a minimum of 2 experiments each performed in triplicate and expressed as percent control specific binding±SEM. A. Competition binding with T14 and T30 concentrations varying from 1 pM to 10 µM. B. Effect of varying concentrations of T30 on α-BTX competition binding with ACh, MLA, and choline. C. Competition binding curve for ACh vs. ACh+T30 (100 nM). D. Competition binding curve for MLA vs. MLA+T30 (100 nM). E. Competition binding curve for choline vs. choline+T30 at various concentrations of T30.
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pone-0004846-g003: Acute membrane binding in GH4-hα7 cells.Data shown are the combined results of a minimum of 2 experiments each performed in triplicate and expressed as percent control specific binding±SEM. A. Competition binding with T14 and T30 concentrations varying from 1 pM to 10 µM. B. Effect of varying concentrations of T30 on α-BTX competition binding with ACh, MLA, and choline. C. Competition binding curve for ACh vs. ACh+T30 (100 nM). D. Competition binding curve for MLA vs. MLA+T30 (100 nM). E. Competition binding curve for choline vs. choline+T30 at various concentrations of T30.

Mentions: We then appraised peptide binding to α7-nAChR in purified membrane preparations. Unexpectedly, neither T14, nor T30, had a significant effect on [125I]α-BTX binding to GH4-hα7 cell membranes in the 1 pM to 100 nM range (Fig. 3A). As compared with control maximum specific binding values, a statistically significant increase in [125I]α-BTX binding was observed in the presence of 1 µM (Mean±SEM = 110.9±3.6%, p = 0.0271) or 10 µM (117.3±4.9%, p = 0.0172) T30. Conversely, T14 displayed a small but significant displacement of [125I]α-BTX binding at high concentrations (1 µM = 90.11±3.5%, p = 0.0378; 10 µM = 87.91±1.9%, p = 0.0014).


Upregulation of alpha7 Nicotinic Receptors by Acetylcholinesterase C-Terminal Peptides.

Bond CE, Zimmermann M, Greenfield SA - PLoS ONE (2009)

Acute membrane binding in GH4-hα7 cells.Data shown are the combined results of a minimum of 2 experiments each performed in triplicate and expressed as percent control specific binding±SEM. A. Competition binding with T14 and T30 concentrations varying from 1 pM to 10 µM. B. Effect of varying concentrations of T30 on α-BTX competition binding with ACh, MLA, and choline. C. Competition binding curve for ACh vs. ACh+T30 (100 nM). D. Competition binding curve for MLA vs. MLA+T30 (100 nM). E. Competition binding curve for choline vs. choline+T30 at various concentrations of T30.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2654408&req=5

pone-0004846-g003: Acute membrane binding in GH4-hα7 cells.Data shown are the combined results of a minimum of 2 experiments each performed in triplicate and expressed as percent control specific binding±SEM. A. Competition binding with T14 and T30 concentrations varying from 1 pM to 10 µM. B. Effect of varying concentrations of T30 on α-BTX competition binding with ACh, MLA, and choline. C. Competition binding curve for ACh vs. ACh+T30 (100 nM). D. Competition binding curve for MLA vs. MLA+T30 (100 nM). E. Competition binding curve for choline vs. choline+T30 at various concentrations of T30.
Mentions: We then appraised peptide binding to α7-nAChR in purified membrane preparations. Unexpectedly, neither T14, nor T30, had a significant effect on [125I]α-BTX binding to GH4-hα7 cell membranes in the 1 pM to 100 nM range (Fig. 3A). As compared with control maximum specific binding values, a statistically significant increase in [125I]α-BTX binding was observed in the presence of 1 µM (Mean±SEM = 110.9±3.6%, p = 0.0271) or 10 µM (117.3±4.9%, p = 0.0172) T30. Conversely, T14 displayed a small but significant displacement of [125I]α-BTX binding at high concentrations (1 µM = 90.11±3.5%, p = 0.0378; 10 µM = 87.91±1.9%, p = 0.0014).

Bottom Line: Of more long-term significance, these peptides also induce upregulation of alpha7-nAChR mRNA and protein expression, as well as enhancing receptor trafficking to the plasma membrane.The results reported here demonstrate a hitherto unknown relationship between the alpha7-nAChR and the non-enzymatic functions of acetylcholinesterase, mediated independently by its C-terminal domain.Such an interaction may prove valuable as a pharmacological tool, prompting new approaches for understanding, and combating, the process of neurodegeneration.

View Article: PubMed Central - PubMed

Affiliation: Institute for the Future of the Mind, Department of Pharmacology, Oxford University, Oxford, UK. cherie.bond@pharm.ox.ac.uk

ABSTRACT

Background: The alpha-7 nicotinic acetylcholine receptor (alpha7-nAChR) is well known as a potent calcium ionophore that, in the brain, has been implicated in excitotoxicity and hence in the underlying mechanisms of neurodegenerative disorders such as Alzheimer's disease. Previous research implied that the activity of this receptor may be modified by exposure to a peptide fragment derived from the C-terminal region of the enzyme acetylcholinesterase. This investigation was undertaken to determine if the functional changes observed could be attributed to peptide binding interaction with the alpha7-nAChR, or peptide modulation of receptor expression.

Methodology/principal findings: This study provides evidence that two peptides derived from the C-terminus of acetylcholinesterase, not only selectively displace specific bungarotoxin binding at the alpha7-nAChR, but also alter receptor binding properties for its familiar ligands, including the alternative endogenous agonist choline. Of more long-term significance, these peptides also induce upregulation of alpha7-nAChR mRNA and protein expression, as well as enhancing receptor trafficking to the plasma membrane.

Conclusions/significance: The results reported here demonstrate a hitherto unknown relationship between the alpha7-nAChR and the non-enzymatic functions of acetylcholinesterase, mediated independently by its C-terminal domain. Such an interaction may prove valuable as a pharmacological tool, prompting new approaches for understanding, and combating, the process of neurodegeneration.

Show MeSH
Related in: MedlinePlus