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Role of L‐type Ca 2+ channels in neural stem/progenitor cell differentiation
Author(s) -
D'Ascenzo Marcello,
Piacentini Roberto,
Casalbore Patrizia,
Budoni Manuela,
Pallini Roberto,
Azzena Gian Battista,
Grassi Claudio
Publication year - 2006
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2006.04628.x
Subject(s) - depolarization , neural stem cell , nestin , voltage dependent calcium channel , microbiology and biotechnology , nifedipine , progenitor cell , chemistry , membrane potential , patch clamp , bay k8644 , biophysics , biology , stem cell , electrophysiology , calcium , neuroscience , organic chemistry
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 (β‐III‐tubulin + /MAP2 + ) displayed time‐dependent increases in intracellular Ca 2+ transients, with Δ F / 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 µ m 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 µ m ) or the L‐channel activator Bay K 8644 (10 µ m ). 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 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.