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

Abstract

Zebrafish 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.

Comparative Transcriptome Analysis of the Regenerating Zebrafish Telencephalon Unravels a Resource With Key Pathways During Two Early Stages and Activation of Wnt/β-Catenin Signaling at the Early Wound Healing Stage

“…The proliferative response of the injured zebrafish telencephalon is driven by the RGCs and reaches a peak at the lesioned site around 3 dpl ( Marz et al, 2011 ; Kizil et al, 2012c ). At this stage, we observed that some quiescent RGC genes such as fabp7a , mt-atp8 , hipk1a , s100b , and mgll were upregulated in both hemispheres, while ptn , luzp2 , psap , hepacama , and anxa11b were only upregulated in the lesioned side ( Kaslin et al, 2017 ; Lange et al, 2020 ). On the other hand, proliferating RGC genes including tmsb4x , hmgb2a , hmga1a , rps23 , and ran were exclusively upregulated in the lesioned half, whereas the general proliferation marker ccnd1 was upregulated in both halves ( Lange et al, 2020 ).…”

“…At this stage, we observed that some quiescent RGC genes such as fabp7a , mt-atp8 , hipk1a , s100b , and mgll were upregulated in both hemispheres, while ptn , luzp2 , psap , hepacama , and anxa11b were only upregulated in the lesioned side ( Kaslin et al, 2017 ; Lange et al, 2020 ). On the other hand, proliferating RGC genes including tmsb4x , hmgb2a , hmga1a , rps23 , and ran were exclusively upregulated in the lesioned half, whereas the general proliferation marker ccnd1 was upregulated in both halves ( Lange et al, 2020 ). Besides, we found that many cell cycle-associated genes such as pcna , mki67 , rpl35 , mdka , ccna2 , and cdk1 were upregulated predominantly in the lesioned hemisphere ( Sobecki et al, 2017 ).…”

“…Accordingly, these cells express different markers including glial fibrillary acidic protein (Gfap), S100β, nestin, brain lipid-binding protein (Blbp), aromatase, and SRY-box 2 (Sox2), confirming their radial glia-like nature ( Adolf et al, 2006 ; Pellegrini et al, 2007 ; Lam et al, 2009 ; Ganz et al, 2010 ; Marz et al, 2010 ; Kroehne et al, 2011 ). A recent study on transcriptome analysis has identified novel markers for radial glia, newborn neurons, and mature neurons ( Lange et al, 2020 ). Several inflammation-related programs including the chemokine receptor Cxcr5, the zinc finger transcription factor Gata3, and cysteinyl leukotriene signaling have been shown to promote the proliferation and generation of newborn neurons, thus enhancing neuronal regeneration in response to injury ( Kizil et al, 2012a , b ; Kyritsis et al, 2012 ).…”

Conserved and Divergent Features of Adult Neurogenesis in Zebrafish

“…However so far only low numbers of stem cells were captured in scRNAseq experiments conducted on the hippocampus, which prevents proper analysis of their intrinsic heterogeneity. Two reports were recently published in zebrafish, based on NSCs isolated from her4.1-driven transgenes (Cosacak et al, 2019;Lange et al, 2020). However these studies only captured small numbers of NSCs (609 and 76, respectively).…”

“…These observations suggest that oligodendrocytes are produced within the parenchyma from OPCs. A recent publication based on scRNAseq argues that her4.1-positive NSCs express olig2 at very low level, suggesting nascent NSC progeny differentiating toward OPCs (Lange et al, 2020). Likewise, pseudo-lineages inferred from scRNAseq in the mouse SEZ reveal a molecular connection between NSCs and oligodendrocytes (Mizrak et al, 2019).…”