Sox2 and Pax6 maintain the proliferative and developmental potential of gliogenic neural stem cells In vitro

Abstract

Radial-glia-like neural stem (NS) cells may be derived from neural tissues or via differentiation of pluripotent embryonic stem (ES) cells. However, the mechanisms controlling NS cell propagation and differentiation are not yet fully understood. Here we investigated the roles of Sox2 and Pax6, transcription factors widely expressed in central nervous system (CNS) progenitors, in mouse NS cells. Conditional deletion of either Sox2 or Pax6 in forebrain-derived NS cells reduced their clonogenicity in a gene dosage-dependent manner. Cells heterozygous for either gene displayed moderate proliferative defects, which may relate to human pathologies attributed to SOX2 or PAX6 deficiencies. In the complete absence of Sox2, cells exited the cell cycle with concomitant downregulation of neural progenitor markers Nestin and Blbp. This occurred despite expression of the close relative Sox3. Ablation of Pax6 also caused major proliferative defects. However, a subpopulation of cells was able to expand continuously without Pax6. These Pax6-null cells retained progenitor markers but had altered morphology. They exhibited compromised differentiation into astrocytes and oligodendrocytes, highlighting that the role of Pax6 extends beyond neurogenic competence. Overall these findings indicate that Sox2 and Pax6 are both critical for self-renewal of differentiation-competent radial glia-like NS cells.

Elevated FOXG1 and SOX2 in glioblastoma enforces neural stem cell identity through transcriptional control of cell cycle and epigenetic regulators

“…Sox2 has been shown previously to be essential for NS cell self-renewal in vitro (Gómez-López et al 2011). To test whether Foxg1 is required for in vitro self-renewal of NS cells, we derived a new NS cell line (termed FF) from the subventricular zone (SVZ) of a previously reported adult Foxg1 flox/flox mouse (Supplemental Fig.…”

“…Previous studies have suggested that Sox2 is required for self-renewal of forebrain NS cells: Homozygous knockout by conditional deletion or CRISPR/Cas9 targeting is incompatible with colony formation (Gómez-López et al 2011;Bressan et al 2017). Here, CRISPR/Cas9 was used to mutate the single coding exon of SOX2 (Supplemental Fig.…”

Pax6 Is Essential for the Maintenance and Multi-Lineage Differentiation of Neural Stem Cells, and for Neuronal Incorporation into the Adult Olfactory Bulb

“…Although this role of Pax6 could extend to other NSC populations, it appears to be modulated in a cell-and/ or genetic context. In fact, NSCs isolated from the embryonic forebrain of Pax6 conditional KO mice showed both reduced oligodendrocyte and astrocyte differentiation [20], whereas NSC/progenitors isolated from the embryonic forebrain of Pax6 heterozygous ( + /Sey) and homozygous (Sey/Sey) rats and mice developed excessive numbers of immature astrocytes [22,42].…”

“…In fact, in Pax6 homozygous mutant mice, an ectopic OB-like structure is formed [16,17]; whereas in humans, heterozygous mutations in Pax6 result in forebrain abnormalities [18]. In addition to these functions in brain patterning, Pax6 regulates the proliferation, self-renewal, differentiation, and apoptosis of embryonic NSCs and progenitor cells in multiple brain regions [19][20][21][22][23][24][25][26][27]. However, a few studies have evaluated the role of this TF in the maintenance and cell fate of NSCs from the adult SVZ and hippocampus [28][29][30], and no studies have yet been published on the putative role of Pax6 in NSCs isolated from the adult OB [12].…”

“…Pax6 overexpression in progenitor cells induces neuronal differentiation [6,19,[39][40][41] and results in an increase in the number of dopaminergic PG neurons [6], which is evidence that this TF exerts a neurogenic role. Furthermore, Pax6 has been proposed to act as a general neuronal determinant that might regulate the balance between neurogenesis and the formation of astrocytes or oligodendrocytes [20,22,29,42].…”