Role of L-type Ca2+ channels in neural stem / progenitor cell differentiation.

Ca(2+) influx through voltage-gated Ca(2+) channels, especially the L-type (Ca(v)1), activates downstream signaling to the nucleus that affects gene expression and, consequently, cell fate. We hypothesized that these Ca(2+) signals may also influence the neuronal differentiation of neural stem/progenitor cells (NSCs) derived from the brain cortex of postnatal mice. We first studied Ca(2+) transients induced by membrane depolarization in Fluo 4-AM-loaded NSCs using confocal microscopy. Undifferentiated cells (nestin(+)) exhibited no detectable Ca(2+) signals whereas, during 12 days of fetal bovine serum-induced differentiation, neurons (beta-III-tubulin(+)/MAP2(+)) displayed time-dependent increases in intracellular Ca(2+) transients, with DeltaF/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 Ba(2+) current density. These currents were markedly reduced (-77%) by Ca(v)1 channel blockade with 5 microm nifedipine. To determine the influence of Ca(v)1-mediated Ca(2+) influx on NSC differentiation, cells were cultured in differentiative medium with either nifedipine (5 microm) or the L-channel activator Bay K 8644 (10 microm). The latter treatment significantly increased the percentage of beta-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 Ca(2+) signals. Conversely, Bay K 8644 pretreatment significantly enhanced the percentage of responsive cells and the amplitudes of Ca(2+) transients. These data suggest that NSC differentiation is strongly correlated with the expression of voltage-gated Ca(2+) channels, especially the Ca(v)1, and that Ca(2+) influx through these channels plays a key role in promoting neuronal differentiation. PMID: 16519658 [PubMed - indexed for MEDLINE] Related LinksVoltage-gated K+ current: a marker for apoptosis in differentiating neuronal progenitor cells? [Eur J Neurosci. 2004] PMID: 15255975 Functional maturation of isolated neural progenitor cells from the adult rat hippocampus. [Eur J Neurosci. 2004] PMID: 15128395 In vitro and in vivo analyses of human embryonic stem cell-derived dopamine neurons. [J Neurochem. 2005] PMID: 15715675 Immunocytochemical and physiological characterization of a population of cultured human neural precursors. [J Neurophysiol. 2000] PMID: 10899225 Repeated cocaine administration increases voltage-sensitive calcium currents in response to membrane depolarization in medial prefrontal cortex pyramidal neurons.