[Illustrated case study of a patient with pediatric multisystem inflammatory syndrome]. / Cas clinique illustré autour d'un patient atteint d'un syndrome inflammatoire multisystémique pédiatrique.

Between November 2020 and June 2021, twelve children were treated at a university hospital in western France for pediatric multisystem inflammatory syndrome (PIMS). While the clinical presentation may have been reminiscent of Kawasaki disease, PIMS, a new nosological entity, was mentioned in the media in the context of the Covid-19 pandemic. In 2023, research into this syndrome will continue in France and Europe.

A dual, catalytic role for the fission yeast Ccr4-Not complex in gene silencing and heterochromatin spreading.

Heterochromatic gene silencing relies on combinatorial control by specific histone modifications, the occurrence of transcription, and/or RNA degradation. Once nucleated, heterochromatin propagates within defined chromosomal regions and is maintained throughout cell divisions to warrant proper genome expression and integrity. In the fission yeast Schizosaccharomyces pombe, the Ccr4-Not complex partakes in gene silencing, but its relative contribution to distinct heterochromatin domains and its role in nucleation versus spreading have remained elusive. Here, we unveil major functions for Ccr4-Not in silencing and heterochromatin spreading at the mating type locus and subtelomeres. Mutations of the catalytic subunits Caf1 or Mot2, involved in RNA deadenylation and protein ubiquitinylation, respectively, result in impaired propagation of H3K9me3 and massive accumulation of nucleation-distal heterochromatic transcripts. Both silencing and spreading defects are suppressed upon disruption of the heterochromatin antagonizing factor Epe1. Overall, our results position the Ccr4-Not complex as a critical, dual regulator of heterochromatic gene silencing and spreading.