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Cell fusion-mediated pluripotent reprogramming triggers ordered changes in chromatin and gene expression across the human inactive X chromosome

ABSTRACT: Erasure of epigenetic memory is required to convert somatic cells towards pluripotency. Reactivation of the inactive X chromosome (Xi) has been used to model epigenetic reprogramming in mouse, but human studies are hampered by Xi epigenetic instability and difficulties in tracking partially reprogrammed iPSCs. Here we used cell fusion to examine the earliest events in the reprogramming-induced Xi reactivation of human female fibroblasts. We show a rapid and widespread loss of Xi-associated H3K27me3 and XIST in fused cells that precedes the bi-allelic expression of selected Xi-genes by many heterokaryons (30-50%). After cell division, RNA-FISH and RNA-Seq analysis confirmed that Xi reactivation remained partial and showed that induction of human pluripotency-specific XACT transcripts occurred, but was rare (1%). These data effectively separate pre- and post-mitotic events in reprogramming-induced Xi reactivation, and suggest a hierarchy where early events such as XIST-delocalisation, are required but are insufficient to establish stable human X reactivation. We performed RNA-sequencing of human fibroblast clones derived from TERT-immortalised NHDF17914 (Lonza) before and at 5 days after fusion with mouse ESC (E14Tg2a:puroR). Two biological replicates were performed and sequenced.

ORGANISM(S): Homo sapiens

SUBMITTER: Gopuraja Dharmalingam

PROVIDER: E-GEOD-77443 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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