Involvement of nicotinic acetylcholine receptor in the proliferation of mouse induced pluripotent stem cells.

Aims: As the clinical use of induced pluripotent stem (iPS) cells may have the potential to overcome current obstacles in stem cell-based therapy, the molecular mechanisms that regulate the proliferation of iPS cells are of great interest. However, to our knowledge, no previous studies have examined whether stimulation with nicotinic acetylcholine receptor (nAchR) enhances the growth of iPS cells. In the present study, we examined the involvement of nAchR in the proliferation of mouse iPS cells.

Main Methods: We performed immunofluorescence staining to determine whether mouse iPS cells could express nAchRs. Mouse iPS cells were treated with nicotine for 24h under feeder-free conditions in the presence of leukemia inhibitory factor (LIF). The DNA synthesis was examined by the BrdU incorporation assay. Intracellular calcium levels were measured using Fluo-4-acetoxymethyl (a cell-permeable calcium indicator). In addition, we examined the involvement of the CaMKП pathway in nicotine-enhanced proliferation of mouse iPS cells.

Key Findings: The fluorescence images revealed that α(4)-nAchR and α(7)-nAchR are expressed on mouse iPS cells. Treatment of the cells with 300nM nicotine significantly increases DNA synthesis. This is significantly inhibited by pretreatment with antagonists of α(4)-nAchR and α(7)-nAchR or a CaMKП inhibitor. In addition, treatment with nicotine increases the intracellular Ca(2+) level dose-dependently in mouse iPS cells. Treatment with nicotine significantly enhances CaMKП phosphorylation.

Significance: The present study indicates that stimulation of α(4)-nAchR and α(7)-nAchR may lead to a significant increase in the rate of mouse iPS cell proliferation through enhancement of the CaMKП signaling pathway.