M.D. and R.P. contributed equally to this work.
Role of L-type Ca2+ channels in neural stem/progenitor cell differentiation
Article first published online: 2 MAR 2006
European Journal of Neuroscience
Volume 23, Issue 4, pages 935–944, February 2006
How to Cite
D'Ascenzo, M., Piacentini, R., Casalbore, P., Budoni, M., Pallini, R., Azzena, G. B. and Grassi, C. (2006), Role of L-type Ca2+ channels in neural stem/progenitor cell differentiation. European Journal of Neuroscience, 23: 935–944. doi: 10.1111/j.1460-9568.2006.04628.x
- Issue published online: 2 MAR 2006
- Article first published online: 2 MAR 2006
- Received 7 October 2005, revised 7 December 2005, accepted 12 December 2005
- confocal Ca2+ imaging;
- mouse brain cortex;
- patch-clamp recordings;
- voltage-gated Ca2+ channels
Ca2+ influx through voltage-gated Ca2+ channels, especially the L-type (Cav1), activates downstream signaling to the nucleus that affects gene expression and, consequently, cell fate. We hypothesized that these Ca2+ signals may also influence the neuronal differentiation of neural stem/progenitor cells (NSCs) derived from the brain cortex of postnatal mice. We first studied Ca2+ transients induced by membrane depolarization in Fluo 4-AM-loaded NSCs using confocal microscopy. Undifferentiated cells (nestin+) exhibited no detectable Ca2+ signals whereas, during 12 days of fetal bovine serum-induced differentiation, neurons (β-III-tubulin+/MAP2+) displayed time-dependent increases in intracellular Ca2+ transients, with ΔF/F ratios ranging from 0.4 on day 3 to 3.3 on day 12. Patch-clamp experiments revealed similar correlation between NSC differentiation and macroscopic Ba2+ current density. These currents were markedly reduced (−77%) by Cav1 channel blockade with 5 µm nifedipine. To determine the influence of Cav1-mediated Ca2+ influx on NSC differentiation, cells were cultured in differentiative medium with either nifedipine (5 µm) or the L-channel activator Bay K 8644 (10 µm). The latter treatment significantly increased the percentage of β-III-tubulin+/MAP2+ cells whereas nifedipine produced opposite effects. Pretreatment with nifedipine also inhibited the functional maturation of neurons, which responded to membrane depolarization with weak Ca2+ signals. Conversely, Bay K 8644 pretreatment significantly enhanced the percentage of responsive cells and the amplitudes of Ca2+ transients. These data suggest that NSC differentiation is strongly correlated with the expression of voltage-gated Ca2+ channels, especially the Cav1, and that Ca2+ influx through these channels plays a key role in promoting neuronal differentiation.