In the brain, the hippocampus has a crucial role in learning and memory. In mammals, neurogenesis (the birth of new neurons) occurs in the dentate gyrus region of the hippocampus throughout adulthood, and this activity is thought to be the basis for the acquisition of new memories. In this study we describe for the first time the functional roles of the transcription factor Prox1 during brain development and adult neurogenesis. We demonstrate that in mammals, Prox1 is required for the differentiation of granule cells during dentate gyrus development. We also show that conditional inactivation of Prox1 results in the absence of specific intermediate progenitors in the subgranular zone of the dentate gyrus, which prevents adult neurogenesis from occurring. This is the first report showing blockade of adult neurogenesis at the level of progenitor cells. Next, we demonstrate that in the absence of Prox1-expressing intermediate progenitors, the stem cell population of the subgranular zone becomes depleted. Further, we show that Prox1-expressing intermediate progenitors are required for adult neural stem cell self-maintenance in the subgranular zone. Finally, we demonstrate that Prox1 ectopic expression induces premature granule cell differentiation in the subgranular zone. Therefore, our results identify a previously unknown non-cell autonomous feedback mechanism that links adult stem cell self-maintenance with neuronal differentiation in the dentate gyrus and could have important implications for neurogenesis in other brain regions.
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"Les astrocytes jouentégalementjouentégalement un rôle essentiel dans la différenciation neuronale des progéniteurs ainsi que dans l'intégration des nouveaux neurones (Song et al., 2002 ;Ma et al., 2005). Concernant les facteurs spécifiques participantàparticipant`participantà l'environnement optimal de la niche neurogénique, on peut citer les g` enes Prospero homeobox protein 1 (Prox-1) et SRY box-containing gene-2 qui jouent un rôle dans le maintien des cellules progénitrices (Lavado et al., 2010 ;Mu et al., 2012), les facteurs Sonic hedgehog, Brain derived neurotrophic factor (BDNF), Insulin-like growth factor 2, la protéine disrupted-inschizophrenia 1 ou encore le régulateurrégulateurépigénétique Growth arrest and DNA damage qui sont nécessaires nécessairesà la prolifération des cellules progénitrices (pour re- vueMu et al., 2010 ;Benarroch, 2013). Le GABA joué egalement un rôle essentiel au sein de la niche dans le taux de prolifération des cellules progénitrices (Duveau et al., 2011 ;Giachino et al., 2014). "
[Show abstract][Hide abstract]ABSTRACT: A defining characteristic of the brain is its remarkable capacity to undergo activity-dependent functional and structural remodelling via mechanisms of plasticity that form the basis of our capacity to encode and retain memories. The prevailing model of how our brain stores new information about relationships between events or new abstract constructs suggests it resides in activity-driven modifications of synaptic strength and remodelling of neural networks brought about by cellular and molecular changes within the neurons activated during learning. To date, the idea that a form of activity-dependent synaptic plasticity known as long-term potentiation, or LTP, and the associated synaptic growth play a central role in the laying down of memories has received considerable support. Beyond this mechanism of plasticity at the synapse, adult neurogenesis, i.e. the birth and growth of new neurons, is another form of neural plasticity that occurs continuously in defined brain regions such as the dentate gyrus of the hippocampus. Here, based on work in the hippocampus, we review the processes and mechanisms of the generation and selection of new neurons in the adult brain and the accumulating evidence that supports the idea that this form of neural plasticity is essential to store and lead to retrievable hippocampal-dependent memories.
Full-text · Article · Jan 2016 · Biologie Aujourd'hui
"Indeed, NeuroD1 or Prox1 overexpression promotes neuronal differentiation of neural stem cells in vitro (Hsieh et al. 2004; Gao et al. 2009; Karalay et al. 2011). Conditional ablation of NeuroD1 as well as deletion of Prox1 via conditional ablation or knockdown from the hippocampal neurogenic lineage reduced the generation of DCX-positive immature neurons (Gao et al. 2009; Lavado et al. 2010; Karalay et al. 2011). Whether the reduction in neurogenesis was the consequence of impaired neuronal fate determination or of another mechanism remained to be determined. "
", prosperorelated homeobox gene 1, is necessary for the preservation of IPCs (intermediate progenitor cells) and is needed to promote granule cells to maturate during the procedure of adult neurogenesis . It is absent in nestin + or Sox2 + cells but can be found in DCX + cells and calretinin + cells in the adult granule cells . "
[Show abstract][Hide abstract]ABSTRACT: The procedure of neurogenesis has made numerous achievements in the past decades, during which various molecular biomarkers have been emerging and have been broadly utilized for the investigation of embryonic and adult neural stem cell (NSC). Nevertheless, there is not a consistent and systematic illustration to depict the functional characteristics of the specific markers expressed in distinct cell types during the different stages of neurogenesis. Here we gathered and generalized a series of NSC biomarkers emerging during the procedures of embryonic and adult neural stem cell, which may be used to identify the subpopulation cells with distinguishing characters in different timeframes of neurogenesis. The identifications of cell patterns will provide applications to the detailed investigations of diverse developmental cell stages and the extents of cell differentiation, which will facilitate the tracing of cell time-course and fate determination of specific cell types and promote the further and literal discoveries of embryonic and adult neurogenesis. Meanwhile, via the utilization of comprehensive applications under the aiding of the systematic knowledge framework, researchers may broaden their insights into the derivation and establishment of novel technologies to analyze the more detailed process of embryogenesis and adult neurogenesis.
Full-text · Article · Sep 2015 · BioMed Research International