Distinct Neural Stem Cells Proliferate in Response to EGF and FGF in the Developing Mouse Telencephalon

Abstract

Multipotent, self-renewing neural stem cells reside in the embryonic mouse telencephalic germinal zone. Using an in vitro neurosphere assay for neural stem cell proliferation, we demonstrate that FGF-responsive neural stem cells are present as early as E8.5 in the anterior neural plate, but EGF-responsive neural stem cells emerge later in development in a temporally and spatially specific manner. By separately blocking EGF and FGF2 signaling, we also show that EGF alone and FGF2 alone can independently elicit neural stem cell proliferation and at relatively high cell densities separate cell nonautonomous effects can substantially enhance the mitogen-induced proliferation. At lower cell densities, neural stem cell proliferation is additive in the presence of EGF and FGF2 combined, revealing two different stem cell populations. However, both FGF-responsive and EGF-responsive neural stem cells retain their self-renewal and multilineage potential, regardless of growth factor conditions. These results support a model in which separate, lineage-related EGF- and FGF-responsive neural stem cells are present in the embryonic telencephalic germinal zone.

Impaired neural stem cell expansion and hypersensitivity to epileptic seizures in mice lacking the EGFR in the brain

“…Utilizing in vitro neurosphere assays we showed that EGFR −/− neurospheres did not show the cardinal stem cell traits of self‐renewal (symmetric stem cell division) or full differentiation capability illustrating that EGFR signaling is critical for these processes. These findings support previously published results that EGF and FGF growth factors are important for neural stem cell proliferation 28, 30 but report for the first time the effect complete loss of EGFR has on the neurogenic niche in vivo in postnatal mice. Previous studies have reported the importance of EGFR expression during neural stem cell division with differential EGFR distribution to daughter cells resulting in progenitors with different proliferative, migratory, and differentiation responses to EGFR ligands 7.…”

Distinctive effects of eicosapentaenoic and docosahexaenoic acids in regulating neural stem cell fate are mediated via endocannabinoid signalling pathways

“…In experiments employing the selective cannabinoid antagonists AM251 (0.5 µM) and AM630 (0.5 µM), dissociated neurospheres were treated with either antagonists and then diluted, as above, and number of spheres counted after 7 days in culture. In this experiment, the number of new neurospheres was plotted against the initial number of cells plated, and the slope of the lines obtained after the linear regression was used to compare the experimental conditions, from which the behaviour of the NSCs was evaluated (Campos et al, 2004;Tropepe et al, 1999).…”

Transforming growth factor α promotes sequential conversion of mature astrocytes into neural progenitors and stem cells

“…Embryos were collected from timemated C57/Bl6 mice. The cortex was dissected and mechanically dissociated as described (Tropepe et al, 1999). The cells were spun down and cultured in a 75 cm 2 flask at 10 cells/ml in neurosphere medium composed of a 1:1 mixture of DMEM and F12 nutrient (Invitrogen) containing 0.6% glucose, 2 mM glutamine, 13 mM sodium bicarbonate, 5 mM N-2-hydroxyethylpiperazine-N 0 -2-ethanesulfonic acid (HEPES) buffer, 5 IU/ml penicillin and 5 mg/ml streptomycin, and the B27, N-2 and G5 supplements (10 ml/ml each, Invitrogen).…”