title: Differential involvement of α4β2, α7 and α9α10 nicotinic acetylcholine receptors in B lymphocyte activation in vitro.
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.
authors.affiliation: Palladin Institute of Biochemistry, 9 Leontovicha str., 01601 Kyiv, Ukraine. skok@biochem.kiev.ua
authors.forename: Lyudmyla
authors.initials: L
authors.lastname: Koval
authors.forename: Olena
authors.initials: O
authors.lastname: Lykhmus
authors.forename: Maxim
authors.initials: M
authors.lastname: Zhmak
authors.forename: Alexey
authors.initials: A
authors.lastname: Khruschov
authors.forename: Victor
authors.initials: V
authors.lastname: Tsetlin
authors.forename: Elena
authors.initials: E
authors.lastname: Magrini
authors.forename: Antonella
authors.initials: A
authors.lastname: Viola
authors.forename: Alexander
authors.initials: A
authors.lastname: Chernyavsky
authors.forename: Jing
authors.initials: J
authors.lastname: Qian
authors.forename: Sergei
authors.initials: S
authors.lastname: Grando
authors.forename: Sergei
authors.initials: S
authors.lastname: Komisarenko
authors.forename: Maryna
authors.initials: M
authors.lastname: Skok
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D054992:Immunological Synapses / Q000378:metabolism; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D009154:Mutation; D021122:Protein Subunits / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013379:Substrate Specificity; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: C526014:Chrna10 protein, mouse; C579167:Chrna7 protein, human; C579166:Chrna7 protein, mouse; C402445:Chrna9 protein, mouse; D021122:Protein Subunits; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; C403531:nicotinic receptor alpha4beta2