Gompers, A. | Search bioRxiv

bioRxiv2023

A wound-induced differentiation trajectory for neurons

Animals capable of whole-body regeneration can replace any missing cell type and regenerate fully-functional new organs, de novo. The regeneration of a new brain requires the formation of diverse neuronal cell types and their assembly into an organized structure and correctly-wired circuits. Recent work in various regenerative animals has revealed transcriptional programs required for the differentiation of distinct neuronal subpopulations, however how these transcriptional programs are initiated upon amputation remains unknown. Here, we focused on the highly regenerative acoel worm, Hofstenia miamia, to study wound-induced transcriptional regulatory events that lead to the production of neurons. Footprinting analysis using chromatin accessibility data on an improved genome assembly revealed that binding sites for the NFY transcription factor complex were significantly bound during regeneration, showing a dynamic increase in binding within one hour upon amputation specifically in tail fragments, which will regenerate a new brain. Strikingly, NFY targets were highly enriched for genes with neuronal functional. Single-cell transcriptome analysis combined with functional studies identified sox4+stem cells as the likely progenitor population for multiple neuronal subtypes. Further, we found that wound-induced sox4 expression is likely under direct transcriptional control by NFY, uncovering a mechanism for how early wound-induced binding of a transcriptional regulator results in the initiation of a neuronal differentiation pathway. HighlightsO_LIA new chromosome-scale assembly for Hofstenia enables comprehensive analysis of transcription factor binding during regeneration C_LIO_LINFY motifs become dynamically bound by 1hpa in regenerating tail fragments, particularly in the loci of neural genes C_LIO_LIA sox4+ neural-specialized stem cell is identified using scRNA-seq C_LIO_LIsox4 is wound-induced and required for differentiation of multiple neural cell types C_LIO_LINFY regulates wound-induced expression of sox4 during regeneration C_LI

developmental biology↗

bioRxiv2019

Deletion of a non-canonical promoter regulatory element causes loss of Scn1a expression and epileptic phenotypes in mice

Genes with multiple co-active promoters appear common in brain, yet little is known about functional requirements for these potentially redundant genomic regulatory elements. SCN1A, which encodes the NaV1.1 sodium channel alpha subunit, is one such gene with two co-active promoters. Mutations in SCN1A are associated with epilepsy, including Dravet Syndrome (DS). The majority of DS patients harbor coding mutations causing SCN1A haploinsufficiency, however putative causal non-coding promoter mutations have been identified. To determine the functional role of one of these potentially redundant Scn1a promoters, we focused on the non-coding Scn1a 1b regulatory region, previously described as a non-canonical alternative transcriptional start site. Mice harboring a deletion of the extended evolutionarily-conserved 1b non-coding interval exhibited surprisingly severe reductions of Scn1a and NaV1.1 expression in brain with accompanying electroencephalographic seizures and behavioral deficits. This work identified the 1b region as a critical disease-relevant regulatory element and provides evidence that non-canonical and seemingly redundant promoters can have essential function.

neuroscience↗