Folic Acid Supplementation Stimulates Notch Signaling and Cell Proliferation in Embryonic Neural Stem Cells

Abstract

The present study investigated the effect of folic acid supplementation on the Notch signaling pathway and cell proliferation in rat embryonic neural stem cells (NSCs). The NSCs were isolated from E14–16 rat brain and grown as neurospheres in serum-free suspension culture. Individual cultures were assigned to one of 3 treatment groups that differed according to the concentration of folic acid in the medium: Control (baseline folic acid concentration of 4 mg/l), low folic acid supplementation (4 mg/l above baseline, Folate-L) and high folic acid supplementation (40 mg/l above baseline, Folate-H). NSCs were identified by their expression of immunoreactive nestin and proliferating cells by incorporation of 5'bromo-2'deoxyuridine. Cell proliferation was also assessed by methyl thiazolyl tetrazolium assay. Notch signaling was analyzed by real-time PCR and western blot analyses of the expression of Notch1 and hairy and enhancer of split 5 (Hes5). Supplementation of NSCs with folic acid increased the mRNA and protein expression levels of Notch1 and Hes5. Folic acid supplementation also stimulated NSC proliferation dose-dependently. Embryonic NSCs respond to folic acid supplementation with increased Notch signaling and cell proliferation. This mechanism may mediate the effects of folic acid supplementation on neurogenesis in the embryonic nervous system.

Folic acid stimulates proliferation of transplanted neural stem cells after focal cerebral ischemia in rats

“…An intervention that stimulates the proliferation and migration of transplanted NSCs would be a beneficial adjunct to this replacement therapy. FA supplementation may be such an intervention because our previous studies found that FA stimulates NSC proliferation in vitro [6]. Additionally, FA supplementation may stimulate the proliferation of endogenous NSCs in vivo, since we observed that FA enhances the stimulatory effects of focal cerebral ischemia on hippocampal neurogenesis in adult rat brain, while lessening the impairment of cognitive function that occurs after experimental stroke [3].…”

“…Identification of NSCs in vitro was performed by immunocytochemistry as we described previously [6]. Briefly, neurospheres on the sixth day in culture were incubated with 5-bromo-20-deoxyuridine (BrdU; 10 μg/ml; Sigma) for 24 h. Cells were subsequently fixed with 4% paraformaldehyde for 20 min and washed for 10 min thrice with phosphate-buffered saline (PBS).…”

“…Replacement therapy by transplantation of exogenous NSCs is a potential therapy for neurodegenerative diseases, especially stroke [4,5]. Because FA stimulates NSC proliferation in vitro [6], it seems possible that FA supplementation may be developed as an adjunct to NSC replacement therapy for stroke.…”

NK Cell–Mediated Antitumor Effects of a Folate-Conjugated Immunoglobulin Are Enhanced by Cytokines

“…Although it is not known whether FR‐expression is needed by malignant cells, folic acid supplementation increases tumor cell growth and decreases patient survival in the context of FR + tumors (35). Conversely, a blockade of folate uptake decreases tumor cell proliferation, migration, invasion, and tumor burden, implicating folate in the survival, growth, and injury repair of malignant cells (34, 36-38). The reason for FR overexpression in tumor versus normal tissues remains elusive.…”

Folic Acid Modulates Matrix Metalloproteinase-2 Expression, Alleviates Neuropathic Pain, and Improves Functional Recovery in Spinal Cord-Injured Rats

“…The implications of FA supplementation in stimulating notch signaling, cell proliferation, and differentiation of neural stem cells have been reported [34,35] . Underlying mechanisms revealed a significant upregulation of Notch1 mRNA and protein expression, decline in expression of inflammatory proteins in nerve cells under hypoxia condition by preventing Ca 2+ overload, and protective effect on nerve cells.…”