Single cell sequencing of radial glia progeny reveals the diversity of newborn neurons in the adult zebrafish brain.

Christian Lange,Andreas Dahl,Michael Brand,Matthias Lesche,Susanne Reinhardt,Steffen Rulands,Fabian Rost,Veronika Kuscha,Anja Machate,Anke Weber

doi:10.1242/dev.185595

Abstract

ABSTRACTZebrafish display widespread and pronounced adult neurogenesis, which is fundamental for their regeneration capability after central nervous system injury. However, the cellular identity and the biological properties of adult newborn neurons are elusive for most brain areas. Here, we have used short-term lineage tracing of radial glia progeny to prospectively isolate newborn neurons from the her4.1+ radial glia lineage in the homeostatic adult forebrain. Transcriptome analysis of radial glia, newborn neurons and mature neurons using single cell sequencing identified distinct transcriptional profiles, including novel markers for each population. Specifically, we detected two separate newborn neuron types, which showed diversity of cell fate commitment and location. Further analyses showed that these cell types are homologous to neurogenic cells in the mammalian brain, identified neurogenic commitment in proliferating radial glia and indicated that glutamatergic projection neurons are generated in the adult zebrafish telencephalon. Thus, we prospectively isolated adult newborn neurons from the adult zebrafish forebrain, identified markers for newborn and mature neurons in the adult brain, and revealed intrinsic heterogeneity among adult newborn neurons and their homology with mammalian adult neurogenic cell types.

Highlights

Adult neurogenesis, the generation and integration of additional neurons to the brain circuitry in adulthood, is widespread across vertebrates, the extent greatly varies among species (Kaslin et al, 2008; Grandel and Brand, 2013; Alunni and BallyCuif, 2016)
Lineage tracing of radial glia-derived newborn neurons in the adult zebrafish telencephalon In order to prospectively isolate the neuronal progeny of radial glia (i.e. Newborn neurons (NBNs)) in the adult zebrafish telencephalon, we developed a short-term lineage-tracing protocol, based on retention of fluorescent proteins in cell type-specific, fluorescent reporter lines
The results show that cells forming the RG cluster in the adult zebrafish brain mainly correspond to various glial cell types in the murine brain, i.e. astrocytes and radial glia-like neural stem cells (RGLs) of different maturation stages, neurogenic intermediate progenitor cells with minor proportions corresponding to neuroblasts, OPCs and microglia

Summary

Introduction

The generation and integration of additional neurons to the brain circuitry in adulthood, is widespread across vertebrates, the extent greatly varies among species (Kaslin et al, 2008; Grandel and Brand, 2013; Alunni and BallyCuif, 2016). Newborn neurons (NBNs) integrate only into the granular zone of the dentate gyrus, and into the olfactory bulb in rodents or into the striatum in humans (Aimone et al, 2014; Ernst and Frisén, 2015). Outside these target zones for adult neurogenesis, integration of NBNs is essentially absent or minimal, and most brain areas (including the cerebral cortex) show limited potential for NBN integration and survival, even after injury-induced neuronal cell death (Bhardwaj et al, 2006; Ohab et al, 2006; Saha et al, 2013; Huttner et al, 2014). To develop therapeutic strategies for cell replacement, a better understanding of the mechanisms that might allow neurogenesis and neuron integration in such brain areas is needed

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