Agonist and blocking effects of choline at the neuromuscular junction

Sterz, Raimund; Peper, K.; Simon, József; Ebert, John P.; Edge, Mark T.; Pagala, Murali; Bradley, Ronald J.

doi:10.1016/0006-8993(86)91551-9

Cited by 8 publications

(6 citation statements)

References 31 publications

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“…The analysis of the saturable binding of [ 3 H]ACh showed that PX can function as a low affinity cholinergic receptor on the cell membrane of KC. These results were expected, because choline, which itself serves as a pharmacological agonist of cholinergic receptors (73,74), has been shown to specifically bind to annexin-1, -2, and -3 (35). Likewise, rPX-His could be specifically tagged with a covalent cholinergic radioligand [ 3 H]PrBCM, which was previously used by us to label keratinocyte membrane proteins immunoprecipitated by 85% of pemphigus patients (5).…”

Section: Discussionmentioning

confidence: 63%

Pemphigus Vulgaris Antibody Identifies Pemphaxin

Nguyen

Ndoye

Grando

2000

Journal of Biological Chemistry

119

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Because pemphigus vulgaris (PV) IgGs adsorbed on the rDsg3-Ig-His baculoprotein induced blisters in neonatal mice, it was proposed that anti-desmoglein 3 (Dsg 3) autoantibody causes PV. However, we found that rDsg3-Ig-His absorbs autoantibodies to different antigens, including a non-Dsg 3 keratinocyte protein of 130 kDa. This prompted our search for novel targets of PV autoimmunity. The PV IgG eluted from a 75-kDa keratinocyte protein band both stained epidermis in a pemphigus-like pattern and induced acantholysis in keratinocyte monolayers. Screening of a keratinocyte gt11 cDNA library with this antibody identified clones carrying cDNA inserts encoding a novel molecule exhibiting ϳ40% similarity with annexin-2, named pemphaxin (PX). Recombinant PX (rPX-His) was produced in Escherichia coli M15 cells, and, because annexins can act as cholinergic receptors, its conformation was tested in a cholinergic radioligand binding assay. rPX-His specifically bound [3 H]acetylcholine, suggesting that PX is one of the keratinocyte cholinergic receptors known to be targeted by disease-causing PV antibodies. Preabsorption of PV sera with rPX-His eliminated acantholytic activity, and eluted antibody immunoprecipitated native PX. This antibody alone did not cause skin blisters in vivo, but its addition to the preabsorbed PV IgG fraction restored acantholytic activity, indicating that acantholysis in PV results from synergistic action of antibodies to different keratinocyte self-antigens, including both acetylcholine receptors and desmosomal cadherins.

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Section: Discussionmentioning

confidence: 63%

Pemphigus Vulgaris Antibody Identifies Pemphaxin

Nguyen

Ndoye

Grando

2000

Journal of Biological Chemistry

119

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“…This conclusion is supported by the crystal structure of pepsin (which includes two bound ethanol molecules) and by functional data obtained in electrophysiology studies of the acetylcholine receptor (AChR). Studies of the AChR from muscle [16,17,83,84] and from Torpedo [85,86] have established that there is a site for small chain alcohols (B hexanol) that is associated with facilitation of channel opening. This effect of the alcohols is measured as a reduction in the apparent dissociation constant for the agonist, ACh [16,17].…”

Section: Functional Consequences Of Alcohol Bindingmentioning

confidence: 99%

Chemical properties of alcohols and their protein binding sites

Dwyer¹,

Bradley²

2000

CMLS, Cell. Mol. Life Sci.

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Alcohols affect a wide array of biological processes including protein folding, neurotransmission and immune responses. It is becoming clear that many of these effects are mediated by direct binding to proteins such as neurotransmitter receptors and signaling molecules. This review summarizes the unique chemical properties of alcohols which contribute to their biological effects. It is concluded that alcohols act mainly as hydrogen bond donors whose binding to the polypeptide chain is stabilized by hydrophobic interactions. The electronegativity of the O atom may also play a role in stabilizing contacts with the protein. Properties of alcohol binding sites have been derived from X-ray crystal structures of alcohol-protein complexes and from mutagenesis studies of ion channels and enzymes that bind alcohols. Common amino acid sequences and structural features are shared among the protein segments that are involved in alcohol binding. The alcohol binding site is thought to consist of a hydrogen bond acceptor in a turn or loop region that is often situated at the N-terminal end of an alpha-helix. The methylene chain of the alcohol molecule appears to be accommodated by a hydrophobic groove formed by two or more structural elements, frequently a turn and an alpha-helix. Binding at these sites may alter the local protein structure or displace bound solvent molecules and perturb the function of key proteins.

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“…Both products are unable to activate postsynaptic muscle nicotinic receptors (nAChRs) to any significant extent. Enzymatic inactivation of ACh enables the neuromuscular junction to respond to up to 50 excitatory events per second (Del Castillo and Katz, 1957;Sterz et al, 1986;Prinz and Maelicke, 1992).…”

Section: Introductionmentioning

confidence: 99%

Choline is a Selective Agonist of α7 Nicotinic Acetylcholine Receptors in the Rat Brain Neurons

Alkondon

Pereira

Cortês

et al. 1997

Eur J of Neuroscience

419

318

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In the present study, we demonstrate that choline, a precursor of acetylcholine (ACh) and a product of acetylcholine hydrolysis by acetylcholinesterase (AChE), acts as an efficient and relatively selective agonist of alpha7-containing nicotinic acetylcholine receptors (nAChR) in neurons cultured from the rat hippocampus, olfactory bulb and thalamus as well as in PC12 cells. Choline was able to activate postsynaptic and presynaptic alpha7 nAChRs, with the latter action resulting in the release of other neurotransmitters. Although choline was approximately one order of magnitude less potent than ACh (EC50 of 1.6 mM for choline and 0.13 mM for ACh), it acted as a full agonist at alpha7 nAChRs. In contrast, choline did not activate alpha4beta2 agonist-bearing nAChRs on hippocampal neurons, and acted as a partial agonist at alpha3beta4-containing nAChRs on PC12 cells. The ethyl alcohol moiety of choline is required for the selective action on alpha7 nAChR. Exposure of cultured hippocampal neurons for 10 min to choline (10-100 microM) resulted in desensitization of the native alpha7 nAChRs. Moreover, chronic exposure (10 days) of the cultured hippocampal neurons to a desensitizing concentration of choline (approximately 30 microM) decreased their responsiveness to ACh. The selective action of choline on native alpha7 nAChRs suggests that this naturally occurring compound may act in vivo as an endogenous ligand for these receptors. Putative physiological actions of choline include retrograde messenger activity during the development of the mammalian central nervous system and during periods of elevated synaptic activity that leads to long-term potentiation.

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Agonist and blocking effects of choline at the neuromuscular junction

Cited by 8 publications

References 31 publications

Pemphigus Vulgaris Antibody Identifies Pemphaxin

Pemphigus Vulgaris Antibody Identifies Pemphaxin

Chemical properties of alcohols and their protein binding sites

Choline is a Selective Agonist of α7 Nicotinic Acetylcholine Receptors in the Rat Brain Neurons

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