Tis21 is required for adult neurogenesis in the subventricular zone and for olfactory behavior regulating cyclins, BMP4, Hes1/5 and Ids

Abstract

Bone morphogenic proteins (BMPs) and the Notch pathway regulate quiescence and self-renewal of stem cells of the subventricular zone (SVZ), an adult neurogenic niche. Here we analyze the role at the intersection of these pathways of Tis21 (Btg2/PC3), a gene regulating proliferation and differentiation of adult SVZ stem and progenitor cells. In Tis21-null SVZ and cultured neurospheres, we observed a strong decrease in the expression of BMP4 and its effectors Smad1/8, while the Notch anti-neural mediators Hes1/5 and the basic helix-loop-helix (bHLH) inhibitors Id1-3 increased. Consistently, expression of the proneural bHLH gene NeuroD1 decreased. Moreover, cyclins D1/2, A2, and E were strongly up-regulated. Thus, in the SVZ Tis21 activates the BMP pathway and inhibits the Notch pathway and the cell cycle. Correspondingly, the Tis21-null SVZ stem cells greatly increased; nonetheless, the proliferating neuroblasts diminished, whereas the post-mitotic neuroblasts paradoxically accumulated in SVZ, failing to migrate along the rostral migratory stream to the olfactory bulb. The ability, however, of neuroblasts to migrate from SVZ explants was not affected, suggesting that Tis21-null neuroblasts do not migrate to the olfactory bulb because of a defect in terminal differentiation. Notably, BMP4 addition or Id3 silencing rescued the defective differentiation observed in Tis21-null neurospheres, indicating that they mediate the Tis21 pro-differentiative action. The reduced number of granule neurons in the Tis21-null olfactory bulb led to a defect in olfactory detection threshold, without effect on olfactory memory, also suggesting that within olfactory circuits new granule neurons play a primary role in odor sensitivity rather than in memory.

Terminal Differentiation of Adult Hippocampal Progenitor Cells Is a Step Functionally Dissociable from Proliferation and Is Controlled by Tis21, Id3 and NeuroD2

“…The construct pCAG-IRES-GFP-Tis21 had been generated as previously described (Farioli-Vecchioli et al, 2014a). The construct pCAG-IRES-GFP-shId3 was generated by cloning in the SfiI-5′/PmeI-3′ sites of pCAG-IRES-GFP the whole 64-mer containing the 19-nucleotide siRNA from the pSUPER.retro-neo-GFP-shId3-190 vector, preceded by the H1 promoter and the TATA box sequence driving the transcription.…”

“…We and others have demonstrated, by silencing Tis21, that Tis21 exerts on neural cells of the dentate gyrus and subventricular zone an intrinsic pro-differentiative action (Farioli-Vecchioli et al, 2009, 2014a; Attardo et al, 2010). This Tis21 knockout-dependent selective impairment of the terminal differentiation suggests that this step is functionally separable from the cell cycle.…”

Pre-reproductive maternal enrichment influences rat maternal care and offspring developmental trajectories: behavioral performances and neuroplasticity correlates

“…Quantitative analysis of hippocampal cell populations was performed by means of design-based (assumption-free, unbiased) stereology as previously described (Cutuli et al, 2014; Farioli-Vecchioli et al, 2014). …”

Control of the Normal and Pathological Development of Neural Stem and Progenitor Cells by the PC3/Tis21/Btg2 and Btg1 Genes

“…Thus, PC3/Tis21 acts according to a two‐step process, i.e., arrest of the cell cycle, followed by terminal differentiation. This is also evident in the stem cells of the adult SVZ, where ablation of PC3/Tis21 leads to increase of their proliferation and impairment of the terminal differentiation of neuroblasts (A cells) (Farioli‐Vecchioli et al, ).…”

“…Remarkably, the arrest of differentiation observed in primary SVZ cells is reverted by BMP4 and by Id3 silencing. Modified from Farioli‐Vecchioli et al, (). (C) Postnatal cerebellum.…”