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Local Accumulation of Acetylcholine Receptors is Neither Necessary Nor Sufficient to Induce Cluster Formation

Stollberg, Jes and Fraser, Scott E. (1990) Local Accumulation of Acetylcholine Receptors is Neither Necessary Nor Sufficient to Induce Cluster Formation. Journal of Neuroscience, 10 (1). pp. 247-255. ISSN 0270-6474. PMCID PMC6570350. doi:10.1523/jneurosci.10-01-00247.1990.

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Acetylcholine receptors (AChRs) accumulate at developing neuromuscular junctions in part via lateral migration of diffusely expressed receptors. Using a model system--cultured Xenopus muscle cells exposed to electric fields--we have shown that AChRs, concentrated at the cathode-facing cell pole, continue to aggregate there after the field is terminated (Stollberg and Fraser, 1988). These observations are consistent with the possibility that the field-induced increase in receptor concentration triggers the aggregation event. Only 2 other molecular events could initiate the electric field-induced receptor aggregation: (1) a local increase in the density of some other molecules, or (2) a voltage-sensitive mechanism. Treatment of muscle cell cultures with neuraminidase changes the cell surface charge and has been reported to reverse the direction of electromigration for AChRs and concanavalin A binding sites (Orida and Poo, 1978). Using digitally analyzed fluorescence videomicroscopy, we find that AChRs in neuraminidase-treated cultures accumulate at both cell poles in an electric field. After termination of the field, the AChR continues to aggregate at the cathode-facing pole, as in cells not treated with neuraminidase. However, receptor density decreases at the anode-facing pole, indicating that elevated AChR density does not initiate receptor aggregation. Cells pretreated with neuraminidase and trypsin (which blocks receptor aggregation) display reversed receptor distributions compared to untreated controls, indicating that electromigration has indeed been reversed. The rate at which neuraminidase- and trypsin- treated cells approach steady-state distributions indicates a receptor diffusion constant of ≈ 1.2 x 10^(-9) cm^2/sec, consistent with a diffusion trap mechanism of receptor aggregation. These results are the first conclusive demonstration that the local concentration of receptors is neither necessary nor sufficient to induce receptor clustering. Our observations suggest that receptor clustering is triggered by the accumulation of some other molecules, or by a voltage-sensitive mechanism.

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Fraser, Scott E.0000-0002-5377-0223
Additional Information:© 1990 Society for Neuroscience. For the first six months after publication SfN’s license will be exclusive. Beginning six months after publication the Work will be made freely available to the public on SfN’s website to copy, distribute, or display under a Creative Commons Attribution 4.0 International (CC BY 4.0) license ( Received May 3, 1989; revised July 21, 1989; accepted July 25, 1989. This work was supported by a grant from the Monsanto Corporation and by N.I.H. Training Grant HD07029.
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Monsanto CorporationUNSPECIFIED
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PubMed Central ID:PMC6570350
Record Number:CaltechAUTHORS:20160331-083818580
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Official Citation:Local accumulation of acetylcholine receptors is neither necessary nor sufficient to induce cluster formation J Stollberg and SE Fraser The Journal of Neuroscience, 1 January 1990, 10(1):247-255
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65785
Deposited By: Ruth Sustaita
Deposited On:31 Mar 2016 20:23
Last Modified:10 Nov 2021 23:49

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