A DEAD-box helicase drives the partitioning of a pro-differentiation NAB protein into nuclear foci

How cells regulate gene expression in a precise spatiotemporal manner during organismal development is a fundamental question in biology. Recent studies have demonstrated the role of transcriptional condensates in gene regulation ^1–5 . However, little is known about the function and regulation of these transcriptional condensates in the context of animal development and physiology. We found that the evolutionarily conserved DEAD-box helicase DDX-23 controls stem cell fate in C. elegans at least in part by binding to and facilitating the condensation of MAB-10, the C. elegans homolog of mammalian NAB protein. MAB-10 is a transcriptional cofactor that functions with the EGR protein LIN-29 to regulate the transcription of genes required for exiting the cell cycle, terminal differentiation, and the larval-to-adult transition ⁶ . We suggest that DEAD-box helicase proteins function more generally during animal development to control the condensation of NAB proteins important in cell-fate decisions and that this mechanism is evolutionarily conserved. In mammals, a comparable mechanism might underlie terminal cell differentiation and when misregulated might promote cancerous growth.