Differentiation Shifts from a Reversible to an Irreversible Heterochromatin State at the DM1 locus
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ABSTRACT: Epigenetic defects caused by hereditary or de novo mutations are implicated in various human diseases. It remains uncertain whether correcting the underlying mutation can reverse these defects in patient cells. Focusing on myotonic dystrophy type 1 (DM1), we discovered a fundamental difference between undifferentiated and differentiated cells. While in mutant human embryonic stem cells (hESCs), DNA methylation and H3K9me3 enrichments are completely abolished by repeat excision (2000CTG), in patients' myoblasts (CTG2600 expansion) repeat deletion fails to do so. This distinction stems from cell differentiation, and can be set back by reprogramming gene-edited myoblasts. We demonstrate that abnormal methylation in DM1 is distinctively maintained in the undifferentiated state by the activity of the de novo DNMTs (DNMT3b and/or DNMT3a). Overall, these findings highlight a crucial difference in heterochromatin maintenance between undifferentiated (sequence-dependent) and differentiated (sequence-independent) cells, underscoring the role of differentiation as a locking mechanism for repressive epigenetic modifications at the DM1 locus.
ORGANISM(S): Homo sapiens
PROVIDER: GSE128901 | GEO | 2024/02/06
REPOSITORIES: GEO
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