Single-cell sequencing unravels the cellular diversity that shapes neuro- and gliogenesis in the fast aging killifish (N. furzeri) brain

Abstract

The African turquoise killifish uniquely combines a short lifespan with vertebrate-specific features, including age-dependent loss of neuroregenerative capacity, that are missing from the currently used model organisms. In this study, we investigate the cellular landscape that shapes adult neuro- and gliogenesis using single-cell sequencing. Our analysis identifies seventeen cell types including neuronal cells (NC), and progenitors (PC) of glial and non-glial nature in the adult killifish telencephalon. PC subclustering unveils four radial glia types, one atypical non-glial progenitor (NGP) and two clusters representing transitioning states. NC subclustering classified neurons into immature and mature excitatory or inhibitory sub-clusters. Using lineage inference analysis, we discovered neuroepithelial-like radial glia to be the source of neuro- and gliogenesis, and a central role for NGP. Our findings are evidence for specialized progenitors within telencephalon and the data is accessible via an online database, providing a resource to understand normal brain function, as well as the role of cellular relationships in response to injury and disease.

Early life growth and cellular heterogeneity in the short-lived African turquoise killifish telencephalon

“…3D-G). This strengthens the idea of a lineage relationship during development between these progenitor types and confirms the trajectory analysis in the young-adult killifish telencephalon (Ayana et al ., 2023).…”

“…In the killifish telencephalon, it are the NGPs, and not the RG populations, that are responsible for the bulk of proliferation from post-embryonic development until adulthood (Coolen et al ., 2020; Van houcke et al ., 2021; Ayana et al ., 2023). In the developing post-embryonic killifish, we could identify the NGPs close to NE-RGs up until 2w (Fig.…”

“…One emerges from HER4 + RGs at the dorsomedial pallium, giving rise to neurons and new RGs. The other originates at the lateral pallium and has a neuroepithelial and amplifying character which thus resembles the NE-RG progenitors discovered in killifish (Dirian et al ., 2014; Ayana et al ., 2023). Than-Trong and colleagues (2020) also described a HER4 - progenitor pool as the source of the gradual expansion of the RG population in the adult zebrafish (Than-Trong et al ., 2020).…”

“…Than-Trong and colleagues (2020) also described a HER4 - progenitor pool as the source of the gradual expansion of the RG population in the adult zebrafish (Than-Trong et al ., 2020). While HER4 + (HES5) RGs are also found in killifish telencephalon, expansive growth is supported by NGPs in all neurogenic regions during post-embryonic development and in the adult killifish telencephalon (Coolen et al ., 2020; Ayana et al ., 2023). The spatial proximity of NGP and NE-RG marker expression at the subpallial midline and posterior pallium is prominent around hatching (1-5dph), suggestive of a lineage relationship between these progenitor subtypes from the early stages onwards.…”

“…Our study reveals the neuronal diversity in the developing killifish telencephalon by spatially delineating the immature and mature excitatory and inhibitory neurons. In the young-adult killifish telencephalon, single-cell sequencing revealed a more extensive diversity of cell types, including 12 excitatory and 5 inhibitory neuronal clusters (Ayana et al ., 2023). The advent of large-scale single-cell studies is likely to discover an even more impressive diversity, such as the recently generated neuronal cell type atlas of the goldfish telencephalon, generated by combining scRNA-sequencing and spatial transcriptomics, which uncovered 88 GABAergic and glutamatergic neuronal subclusters (Tibi et al ., 2023).…”