Knockout of a singleSoxgene resurrects an ancestral cell type in the sea anemoneNematostella vectensis

Abstract

Cnidocytes are the explosive stinging cells found only in cnidarians (corals, jellyfish, etc). Specialized for prey capture and defense, cnidocytes are morphologically complex and vary widely in form and function across taxa; how such diversity evolved is unknown. Using CRISPR/Cas9-mediated genome editing in the burrowing sea anemone Nematostella vectensis, we show that a single transcription factor (NvSox2) acts as a binary switch between two alternative cnidocyte fates. Knockout of NvSox2 caused a complete transformation of nematocytes (piercing cells) into spirocytes (ensnaring cells). The type of spirocyte induced by NvSox2 knockout (robust spirocyte) is not normally found in N. vectensis but is common in sea anemones from other habitats. Homeotic control of cell fate provides a mechanistic explanation for the discontinuous distribution of cnidocyte types across cnidarians and demonstrates how simple counts of cell types can underestimate biodiversity.

Optimized husbandry and targeted gene-editing for the cnidarianNematostella vectensis

“…vectensis have been demonstrated since a few years (Ikmi et al, 2014). Several studies have been addressing from a functional point of view the generation of knockouts in N. vectensis, most of these studies rely on the fertilized oocyte injection of two or several sgRNA's in parallel to drive CRISPR/Cas9 mutagenesis (Babonis et al, 2021;Chen et al, 2020;He et al, 2018;Ikmi et al, 2020;Nakanishi and Martindale, 2018;Servetnick et al, 2017;Wijesena et al, 2017;Zang and Nakanishi, 2020). Our study reveals the possibility of generating CRISPR/Cas9 N. vectensis mutants using a single guide RNA (Ehrlich et al, 2022;Gahan et al, 2022;Kraus et al, 2016;Tournière et al, 2020) each designed at different location in the coding region, thus reducing the risk of offsite targets (Höijer et al, 2022).…”

Single cell transcriptomics identifies conserved regulators of neurosecretory lineages

“…Our reconstructed cnidocyte trajectory predicts several upstream regulators of cnidogenesis such as Sox2, which is a member of a Nematostella specific group of Sox genes (and not a homolog of vertebrate Sox2, (Babonis, Enjolras, Reft, et al, 2021;Magie et al, 2005;Schwaiger et al, 2021). Sox2 is coexpressed with other transcription factors such as ZNF845, Myc4, and PRDM13.…”