[Analysis of signaling pathways activated by nicotinic acetylcholine receptors in B-lymphocyte-derived cells]

The expression of nicotinic acetylcholine receptors (nAChRs) in the chicken pre-B-lymphoma DT40 cell line was investigated. DT40 cells were shown to express at least alpha7-containing nAChRs; their amount increased upon incubation with 10 microM nicotine. Addition of 10 microM choline favoured the inclusion of 3-[4.5dimethylthiazol-2-yl]-2.5-diphenyltetrazolium bromide (MTT); the effect of choline was inhibited by 2.5-25 nM methyllicaconitine (MLA) or 10-100 nM alpha-cobra-toxin indicating the alpha7 nAChR role in maintaining the proliferative potential of DT40 cells. Nicotine and choline potentiated the effect of 0.5 microM ionomycin, which suppresses cell viability via Ca2+ ions influx. Contrariwise, the suppressive effect of 1 microM hydrogen peroxide, mainly affecting cell mitochondria, was weakened by choline, but was increased by 2.5 nM MLA. MEK1/2 and PKC kinases activity was necessary for maintaining the proliferative potential of DT40 cells. MLA increased the effect of the MEK1/2 kinase inhibitor (U0126), while suppressive effect of MLA itself was decreased. The presence of CaMKII kinase inhibitor (KN-62) also decreased MLA effect. MLA favoured cell survival in the presence of PKC inhibitor (chelerythrine). These data indicate that MEK1/2 and CaMKII kinases are involved in alpha7-containing nAChR signaling in DT40 cells and that PKC plays a key role in this process.