Genome-wide screening for genes involved in the epigenetic basis of fragile X syndrome

Stem Cell Reports. 2022 May 10;17(5):1048-1058. doi: 10.1016/j.stemcr.2022.03.011. Epub 2022 Apr 14.

Abstract

Fragile X syndrome (FXS), the most prevalent heritable form of intellectual disability, is caused by the transcriptional silencing of the FMR1 gene. The epigenetic factors responsible for FMR1 inactivation are largely unknown. Here, we initially demonstrated the feasibility of FMR1 reactivation by targeting a single epigenetic factor, DNMT1. Next, we established a model system for FMR1 silencing using a construct containing the FXS-related mutation upstream to a reporter gene. This construct was methylated in vitro and introduced into a genome-wide loss-of-function (LOF) library established in haploid human pluripotent stem cells (PSCs), allowing the identification of genes whose functional loss reversed the methylation-induced silencing of the FMR1 reporter. Selected candidate genes were further analyzed in haploid- and FXS-patient-derived PSCs, highlighting the epigenetic and metabolic pathways involved in FMR1 regulation. Our work sheds light on the mechanisms responsible for CGG-expansion-mediated FMR1 inactivation and offers novel targets for therapeutic FMR1 reactivation.

Keywords: fragile X syndrome; genetic screening; human pluripotent stem cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA Methylation / genetics
  • Epigenesis, Genetic
  • Epigenomics
  • Fragile X Mental Retardation Protein / genetics
  • Fragile X Mental Retardation Protein / metabolism
  • Fragile X Syndrome* / genetics
  • Humans

Substances

  • FMR1 protein, human
  • Fragile X Mental Retardation Protein