Biology subjects

Alunni, A.

Publications and source records attributed to Alunni, A..

3 recordsLinked to original sources

bioRxiv2024

Notch signaling blockade links transcriptome heterogeneity in quiescent neural stem cells with their reactivation routes and potential

In the vertebrate brain, neural stem cell (NSC) quiescence is necessary for stemness maintenance. Using single cell RNA sequencing (scRNAseq) in the zebrafish adult telencephalon, we identified different molecular clusters of quiescent NSCs, interpreted to sign different quiescence depths(1). Here, we show that these clusters, when challenged in vivo with an inhibitor of Notch signaling -a major quiescence promoting pathway-, unfold different behaviors. Notably, deeply quiescent NSCs with astrocytic features display a unique activation phenotype that combines the maintenance of astrocytic markers with the rapid upregulation of activation and neuronal commitment genes, reminiscent to murine periventricular astrocytes activating upon lesion. In contrast, an NSC cluster predicted to be in the deepest quiescence state resists Notch blockade, and we demonstrate that the transcription factor Nr2f1b mediates this resistance to activation in vivo. These results together link the molecular heterogeneity of quiescent NSCs with bona fide biological properties and their molecular regulators.

neuroscience↗

bioRxiv2023

Integrative single-cell transcriptomics clarifies adult neurogenesis and macroglia evolution

Macroglia fulfill essential functions in the adult vertebrate brain, producing and maintaining neurons and regulating neuronal communication. However, we still know little about their emergence and diversification. We used the zebrafish D. rerio as a distant vertebrate model with moderate glial diversity as anchor to reanalyze datasets covering over 600 million years of evolution. We identify core features of adult neurogenesis and innovations in the mammalian lineage with a potential link to the rarity of radial glia-like cells in adult humans. Our results also suggest that functions associated with astrocytes originated in a multifunctional cell type fulfilling both neural stem cell and astrocytic functions before these diverged. Finally, we identify conserved elements of macroglial cell identity and function and their time of emergence during evolution. One-Sentence SummaryRadial glia of the adult zebrafish forebrain associate transcriptomic features of adult neural stem cells and astrocytes

neuroscience↗

bioRxiv2019

Lineage hierarchies and stochasticity ensure the long-term maintenance of adult neural stem cells

The cellular basis and extent of neural stem cell (NSC) self-renewal in adult vertebrates, and their heterogeneity, remain controversial. To explore the functional behavior and dynamics of individual NSCs within brain germinal pools, we combined genetic lineage tracing, quantitative clonal analysis, intravital imaging and global population assessments in the adult zebrafish telencephalon. We show that adult neurogenesis is organized in a hierarchy where a subpopulation of reservoir NSCs with longterm self-renewal potential generate a pool of operational NSCs taking stochastic fates biased towards neuronal differentiation. To fuel the long-term growth of the adult germinal niche, we provide evidence for the existence of an additional, upstream, progenitor population that supports the continuous generation of new reservoir NSCs, contributing to their overall expansion. Hence, the dynamics of vertebrate neurogenesis relies on a hierarchical organization where growth, self-renewal and neurogenic functions are segregated between different NSC types.

neuroscience↗