alexa Differential involvement of α4β2, α7 and α9α10 nicotinic acetylcholine receptors in B lymphocyte activation in vitro.
Molecular Biology

Molecular Biology

Journal of Cell Science & Therapy

Author(s): Koval L, Lykhmus O, Zhmak M, Khruschov A, Tsetlin V,

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Abstract Mouse B lymphocytes express several nicotinic acetylcholine receptor (nAChR) subtypes, their exact functions being not clearly understood. Here we show that α7 nAChR was present in about 60\%, while α4β2 and α9(α10) nAChRs in about 10\% and 20\% of mouse spleen B lymphocytes, respectively; Balb/c and C57Bl/6 mice possessed different relative amounts of these nAChR subtypes. α4β2 and α7, but not α9(α10) nAChRs, were up-regulated upon B lymphocyte activation in vitro. Flow cytometry and sandwich ELISA studies demonstrated that α7 and α9(α10) nAChRs are coupled to CD40, whereas α4β2 nAChR is coupled to IgM. B lymphocytes of both α7(-/-) and β2(-/-) mice responded to anti-CD40 stronger than those of the wild-type mice, whereas the cells of β2(-/-) mice responded to anti-IgM worse than those of the wild-type or α7(-/-) mice. Inhibition of α7 and α9(α10) nAChRs with methyllicaconitine resulted in considerable augmentation of CD40-mediated B lymphocyte proliferation in cells of all genotypes; stimulation of α4β2 nAChRs with epibatidine increased the IgM-mediated proliferation of the wild-type and α7(-/-), but not β2(-/-) cells. Inhibition of α9(α10) nAChRs with α-conotoxin PeAI exerted weak stimulating effect on CD40-mediated proliferation. This nAChR subtype was up-regulated in α7(-/-) B-cells. α7 nAChRs were found recruited to immune synapses between human T and B lymphocytes, both of which produced acetylcholine. It is concluded that α7 nAChR fulfills inhibitory CD40-related mitogenic function, α4β2 nAChR produces a stimulatory IgM-related effect, while α9α10 nAChR is a "reserve" receptor, which partly compensates the absence of α7 nAChR in α7(-/-) cells. Acetylcholine is an additional mediator to modulate activation of interacting T and B lymphocytes. Copyright © 2010 Elsevier Ltd. All rights reserved. This article was published in Int J Biochem Cell Biol and referenced in Journal of Cell Science & Therapy

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