Notch pathway molecules are essential for the maintenance, but not the generation, of mammalian neural stem cells

Abstract

Neural stem cells, which exhibit self-renewal and multipotentiality, are generated in early embryonic brains and maintained throughout the lifespan. The mechanisms of their generation and maintenance are largely unknown. Here, we show that neural stem cells are generated independent of RBP-J , a key molecule in Notch signaling, by using RBP-J −/− embryonic stem cells in an embryonic stem cell-derived neurosphere assay. However, Notch pathway molecules are essential for the maintenance of neural stem cells; they are depleted in the early embryonic brains of RBP-J −/− or Notch1 −/− mice. Neural stem cells also are depleted in embryonic brains deficient for the presenilin1 (PS1) gene, a key regulator in Notch signaling, and are reduced in PS1 +/− adult brains. Both neuronal and glial differentiation in vitro were enhanced by attenuation of Notch signaling and suppressed by expressing an active form of Notch1. These data are consistent with a role for Notch signaling in the maintenance of the neural stem cell, and inconsistent with a role in a neuronal/glial fate switch.[Key Words: Presenilin; RBP-J ; embryonic stem cell; self-renewal; multipotentiality; cell cycle time]Received August 31, 2001; revised version accepted February 11, 2002. Neural stem cells, which are considered the ultimate lineage precursors to all neuronal and glial cells in the mammalian nervous system, are present not only in the developing brain but also in the adult brain Gage 2000). Although neural stem cells have a fundamental role in generating cellular diversity in the developing mammalian nervous system and in maintaining normal brain functions in adult brains (Lois and Alvarez-Buylla 1994;Tropepe et al. 1999;Shors et al. 2001), little is known concerning molecular mechanisms regulating the generation and maintenance of neural stem cells. In vitro, single neural stem cells proliferate to form clonally derived floating sphere colonies (neurospheres), which contain cells that, upon dissociation into single cells, give rise to new sphere colonies (self-renewal) and cells that can differentiate into neurons or glia (multipotentiality). Fibroblast growth factor-2 (FGF2)-responsive neural stem cells first appear in vivo at embryonic day (E) 8.5 and a separate and additive population of epidermal growth factor (EGF)-responsive neural stem cells arises from the earlier born FGF2-responsive stem cells by asymmetric division between E11 and E13 (Burrows et al. 1997;Mayer-Proschel et al. 1997;Tropepe et al. 1999). Both FGF2-responsive and EGF-responsive neural stem cells expand their populations and extend their cell cycle times during later embryogenesis (Martens et al. 2000). In the adult forebrain, neural stem cells are present as a relatively quiescent subpopulation in the subependyma, a remnant of the embryonic germinal zone (Morshead et al. 1994). This population persists into senescence, and the number is maintained throughout life (Tropepe et al. 1997). Thus, the generation and the size of the neural stem-cell population are tightly regul...

Uniform, optimal signal processing of mapped deep-sequencing data

“…6e). Notably, Notch1 targets that were predicted by using the de novo motif highlighted control of telomerase activity and cell cycle, both functions previously linked to Notch signaling 43,44 ( Fig. 6f).…”

“…Furthermore, transcription factor functions can also be inferred from the same data, through analysis of enriched target-gene annotations. Notably, we uncovered an ACTACAnnTCCCAnRR motif in the promoters of mouse forebrain-specific genes, which may mediate the known effects of Notch signaling on telomerase activity and cell cycle control during brain development 43,44 . Although the exact degree of heterogeneity in e11.5 forebrain (or in e14.5 anatomical structures) is not known, it is possible that other samples could be even more heterogeneous, and therefore refractory to the methods described here.…”

The microenvironment of the embryonic neural stem cell: Lessons from adult niches?

“…Key roles for notch signaling in maintaining the VZ stem cell population have been revealed in a number of ways. First, neural stem cells differentiated from ES cells lacking RBJkappa show a failure of maintenance (Hitoshi et al, 2002). Second, depletion of stem cells is seen in the brains of mice lacking notch 1 or RBJkappa (Hitoshi et al, 2002).…”

“…First, neural stem cells differentiated from ES cells lacking RBJkappa show a failure of maintenance (Hitoshi et al, 2002). Second, depletion of stem cells is seen in the brains of mice lacking notch 1 or RBJkappa (Hitoshi et al, 2002). Third, there are increased numbers of newly-generated precursor cells following intraventricular injection of notch ligands (Androutsellis- Theotokis et al, 2006).…”

MicroRNA-146a Inhibits Glioma Development by Targeting Notch1

“…miR-199b-5p and miR-34a impair cancer stem-like cells through the negative regulation of several components of the Notch pathway in brain tumors (18,21). The Notch pathway is an evolutionarily conserved signaling pathway that plays an important role in neurogenesis (3,10,23). Upon binding to its ligand, Delta, the Notch intracellular domain (NICD; the activated form of Notch) is released from the membrane by presenilin/␥-secretase-mediated cleavage and translocates to the nucleus.…”