Article

Caspases and p53 modulate FOXO3A/Id1 signaling during mouse neural stem cell differentiation

iMed.UL, University of Lisbon, Portugal.
Journal of Cellular Biochemistry (Impact Factor: 3.37). 07/2009; 107(4):748-58. DOI: 10.1002/jcb.22172
Source: PubMed

ABSTRACT Neural stem cells (NSCs) differentiate into neurons and glia, and a large percentage undergoes apoptosis. The engagement and activity of apoptotic pathways may favor either cell death or differentiation. In addition, Akt represses differentiation by up-regulating the inhibitor of differentiation 1 (Id1), through phosphorylation of its repressor FOXO3A. The aim of this study was to investigate the potential cross-talk between apoptosis and proliferation during mouse NSC differentiation. We determined the time of neurogenesis and gliogenesis using neuronal beta-III tubulin and astroglial GFAP to confirm that both processes occurred at approximately 3 and 8 days, respectively. p-Akt, p-FOXO3A, and Id1 were significantly reduced throughout differentiation. Caspase-3 processing, p53 phosphorylation, and p53 transcriptional activation increased at 3 days of differentiation, with no evidence of apoptosis. Importantly, in cells exposed to the pancaspase inhibitor z-VAD.fmk, p-FOXO3A and Id1 were no longer down-regulated, p53 phosphorylation and transcriptional activation were reduced, while neurogenesis and gliogenesis were significantly delayed. The effect of siRNA-mediated silencing of p53 on FOXO3A/Id1 was similar to that of z-VAD.fmk only at 3 days of differentiation. Interestingly, caspase inhibition further increased the effect of p53 knockdown during neurogenesis. In conclusion, apoptosis-associated factors such as caspases and p53 temporally modulate FOXO3A/Id1 signaling and differentiation of mouse NSCs.

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Available from: Cecilia Rodrigues, Dec 23, 2013
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    • "It is also thought to play a role in cell differentiation . The Id1 gene is downregulated as murine bone marrow cells mature, suggesting that it regulates the differentiation of immature hematopoietic cells [12], and also inhibits neural differentiation [9]. Other studies reveal that Id1 may have different functions under different conditions. "
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    ABSTRACT: The inhibitor of DNA binding (Id) family of genes encodes negative regulators of basic helix-loop-helix transcription factors and has been implicated in such diverse cellular processes as differentiation, proliferation, apoptosis and migration. Id knockout mouse embryos display multiple cardiac defects but the specific role of Id1 in cardiac differentiation is unclear. In the present study, we investigated the function of Id1 in DMSO-induced P19CL6 cells, a widely-accepted cell model of cardiac differentiation. We found that Id1 was upregulated during the cardiac differentiation of P19CL6 cells. The expression of cardiac specific marker genes, Gata4, α-MHC and ISL1, was upregulated in P19CL6 cells stably transfected with Id1 (P19CL6-Id1) during cardiac differentiation. The overexpression of Id1 reduced the number of cells in G1 phase and increased the cell population in G2, M and S phases, while knockdown of Id1 increased the number of cells in G1 phase from 48.6 ± 2.51% to 62.2 ± 1.52% at day 0 of cardiac induction, and from 52.5 ± 3.41% to 63.7 ± 1.02% at day 3 after cardiac induction, indicating that Id1 promoted proliferation of P19CL6 cells. Luciferase assays showed that the activity of TOP flash was higher in P19CL6-Id1 cells than wildtype P19CL6 cells, while Id1 expression was also upregulated in P19CL6 cells treated with Wnt3a or LiCl. This indicates that there may be positive feedback between Id1 and Wnt signaling which plays an important role in cardiac differentiation.
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    • "Studies in mouse have shown that Foxos play significant roles in the homeostasis of the central nervous system. Specifically , Foxo3a plays a prominent role in maintaining the neural stem cell (NSC) pool by regulating genes involved in cellular proliferation, differentiation, and oxygen metabolism (Aranha et al., 2009; Paik et al., 2009; Renault et al., 2009). The regulation of the FOXO proteins is highly conserved. "
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    • "An increasing number of studies are reporting the important role of p53 in the control of the balance between differentiation and proliferation. In this line, it has been proved that p53 favors neurogenesis by controlling the expression of Id proteins, inhibitors of proneuronal genes (Aranha et al., 2009). Despite the already reported interaction between Bcl-X L and p53 in cell death models (Hagn et al., 2010; Nair et al., 2006), such a direct protein– protein binding was unlikely to occur due to the different subcellular localization of the two proteins in the forebrain hNSCs differentiation model, where cell death stimuli is lacking (E. "
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