The chromodomain helicase Chd4 is required for Polycomb-mediated inhibition of astroglial differentiation

Polycomb group (PcG) proteins form transcriptional repressor complexes with well-established functions during cell-fate determination. Yet, the mechanisms underlying their regulation remain poorly understood. Here, we extend the role of Polycomb complexes in the temporal control of neural progenitor cell (NPC) commitment by demonstrating that the PcG protein Ezh2 is necessary to prevent the premature onset of gliogenesis. In addition, we identify the chromodomain helicase DNA-binding protein 4 (Chd4) as a critical interaction partner of Ezh2 required specifically for PcG-mediated suppression of the key astrogenic marker gene GFAP. Accordingly, in vivo depletion of Chd4 in the developing neocortex promotes astrogenesis. Collectively, these results demonstrate that PcG proteins operate in a highly dynamic, developmental stage-dependent fashion during neural differentiation and suggest that target gene-specific mechanisms regulate Polycomb function during sequential cell-fate decisions

CRISPR memories in single cells

CRISPR‐Cas systems allow bacteria to memorize prior infections as a means to combat the same invader if it attempts another attack in the future. While the underlying mechanisms of this bacterial immunity have been intensely studied over the past decade, little attention has been paid to CRISPR defense at the single‐cell level. In their recent work, Brouns and colleagues (McKenzie et al, 2022) track memory acquisition and defense in individual cells and find a wide range of temporal dynamics that shape how a cell population experiences and combats an active infection