The downregulation of Wnt/β-catenin signaling pathway is associated with zinc deficiency-induced proliferative deficit of C17.2 neural stem cells.

Zinc is an essential nutrient that is important for normal brain development. Zinc deficiency has been linked to aberrant neurological development and functioning. However, the molecular mechanisms underlying Zinc deficiency-induced neurological disorders remain largely elusive. In the present study, we showed that the proliferation of C17.2 neural stem cells (NSCs) was evidently impaired after exposed to low levels of Zinc chelator, N,N,N',N'-tetrakis-(2-pyridylmethy) ethylenediamine (TPEN). In addition, we found that TPEN-induced proliferative deficit of NSCs was related with significant downregulation of Wnt/β-catenin signaling. Zinc deficiency impaired the proliferation of neural stem cells in dose- and time-dependent manners. Western blot revealed that the levels of p-Ser9-glycogensynthase kinase-3β (p-GSK-3β) and β-catenin were remarkably downregulated during TPEN-induced C17.2 proliferative impairment. Moreover, immunofluorescent analysis indicated that the level of nuclear β-catenin was apparently decreased following TPEN exposure. Furthermore, application with GSK-3β inhibitor lithium chloride (LiCl) reversed TPEN-induced downregulation of β-catenin and impairment of cell proliferation. Flow cytometry analysis also showed that TPEN-induced impairment of NSC proliferation could be reversed by LiCl. Taken together, these findings suggested that the disturbance of canonical Wnt/β-catenin signaling pathway partially accounted for Zinc deficiency-induced proliferative impairment of NSCs.

Zhao J ，Han J ，Jiang J ，Shi S ，Ma X ，Liu X ，Wang C ，Nie X ，He Y ，Jiang S ，Wan C ... -  《-》

Perfluorooctane sulfonate (PFOS) impairs the proliferation of C17.2 neural stem cells via the downregulation of GSK-3β/β-catenin signaling.

The neurotoxic effects of perfluorooctane sulfonate (PFOS) have attracted significant research attention in recent years. In the present study, we investigated the impact of PFOS exposure on the physiology of neural stem cells (NSCs) in vitro. We showed that PFOS exposure markedly attenuated the proliferation of C17.2 neural stem cells in both dose- and time-dependent manners. Additionally, we found that PFOS decreased Ser9 phosphorylation of glycogen synthase kinase-3β (pSer9-GSK-3β), leading to the activation of GSK-3β and resultant downregulation of cellular β-catenin. Furthermore, blockage of GSK-3β with lithium chloride significantly attenuated both the PFOS-induced downregulation of GSK-3β/β-catenin and the proliferative impairment of C17.2 cells. Notably, the expression of various downstream targets was altered accordingly, such as c-myc, cyclin D1 and survivin. In conclusion, the present study demonstrated that PFOS decreased the proliferation of C17.2 cells via the negative modulation of the GSK-3β/β-catenin pathway. We present the potential mechanisms underlying the PFOS-induced toxic effects on NSCs to provide novel insights into the neurotoxic mechanism of PFOS. Copyright © 2016 John Wiley & Sons, Ltd.

Dong X ，Yang J ，Nie X ，Xiao J ，Jiang S ... -  《-》

Zinc deficiency impairs the renewal of hippocampal neural stem cells in adult rats: involvement of FoxO3a activation and downstream p27(kip1) expression.

Zinc plays an important role in the development and maintenance of central neural system. Zinc deficiency has been known to alter normal brain function, whose molecular mechanism remains largely elusive. In the present study, we established a zinc deficiency-exposed rat model, and, using western blot and immunohistochemical analyses, found that the expression of FoxO3a and p27(kip1) was remarkably up-regulated in the rat brain hippocampus. Immunofluorescence assay showed that FOXO3a and p27(kip1) were significantly co-localized with nestin, the marker of neural stem cells (NSCs). Furthermore, we identified that the proportion of proliferating NSCs was markedly decreased in zinc-deficient rat hippocampaus. Using C17.2 neural stem cells, it was revealed that exposure to zinc chelator N,N,N',N'-tetrakis-(2-pyridylmethy) ethylenediamine induced the expression of FoxO3a and p27(kip1) , which coincided with reduced NSC proliferation. Furthermore, depletion of FoxO3a inhibited p27(kip1) expression and restored the growth of NSCs. On the basis of these data, we concluded that FoxO3a/p27(kip1) signaling might play a significant role in zinc deficiency-induced growth impairment of NSCs and consequent neurological disorders. We describe here that zinc deficiency induces the proliferative impairment of hippocampal neural stem cells partially through the activation of FOXO3a-p27 axis in rats. Neural progenitor cells exhibited significantly up-regulated expression of FOXO3a and p27 after zinc deficiency in vivo and in vitro. Depletion of FOXO3a ameliorates zinc deficiency-induced expression of p27 and growth impairment of neural stem cells. We provide novel insight into the mechanisms underlying zinc deficiency-induced neurological deficits.

Han J ，Zhao J ，Jiang J ，Ma X ，Liu X ，Wang C ，Jiang S ，Wan C ... -  《-》

Toxoplasma gondii inhibits differentiation of C17.2 neural stem cells through Wnt/β-catenin signaling pathway.

Toxoplasma gondii is a major cause of congenital brain disease. T. gondii infection in the developing fetus frequently results in major neural developmental damage; however, the effects of the parasite infection on the neural stem cells, the key players in fetal brain development, still remain elusive. This study is aiming to explore the role of T. gondii infection on differentiation of neural stem cells (NSCs) and elucidate the underlying molecular mechanisms that regulate the inhibited differentiation of NSCs induced by the infection. Using a differentiation medium, i.e. , DMEM: F12 (1:1 mixture) supplemented with 2% N2, C17.2 neural stem cells (NSCs) were able to differentiate to neurons and astrocytes, respectively evidenced by immunofluorescence staining of differentiation markers including βIII-tubulin and glial fibrillary acidic protein (GFAP). After 5-day culture in the differentiation medium, the excreted-secreted antigens of T. gondii (Tg-ESAs) significantly down-regulated the protein levels of βIII-tubulin and GFAP in C17.2 NSCs in a dose-dependent manner. The protein level of β-catenin in the nucleus of C17.2 cells treated with both wnt3a (a key activator for Wnt/β-catenin signaling pathway) and Tg-ESAs was significantly lower than that in the cells treated with only wnt3a, but significantly higher than that in the cells treated with only Tg-ESAs. In conclusion, the ESAs of T. gondii RH blocked the differentiation of C17.2 NCSs and downregulated the expression of β-catenin, an essential component of Wnt/β-catenin signaling pathway. The findings suggest a new mechanism underlying the neuropathogenesis induced by T. gondii infection, i.e. inhibition of the differentiation of NSCs via blockade of Wnt/β-catenin signaling pathway, such as downregulation of β-catenin expression by the parasite ESAs.

Gan X ，Zhang X ，Cheng Z ，Chen L ，Ding X ，Du J ，Cai Y ，Luo Q ，Shen J ，Wang Y ，Yu L ... -  《-》

Nicotine contributes to the neural stem cells fate against toxicity of microglial-derived factors induced by Aβ via the Wnt/β-catenin pathway.

Jiang DQ ，Wei MD ，Wang KW ，Lan YX ，Zhu N ，Wang Y ... -  《-》