GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE297nnn/GSE297122/primaryOK200GenomicsHomo sapiensGenome binding/occupancy profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE297122GEOGSEfalseDosage of the fusion transcription factor PAX3::FOXO1 controls cell state in rhabdomyosarcoma [ATAC-Seq]In the fusion-positive subset of rhabdomyosarcoma, the PAX3::FOXO1 oncoprotein is the most common fusion driver. We previously established a human myoblast system for inducible expression of PAX3::FOXO1. In the current study, we modulate PAX3::FOXO1 protein expression to understand the epigenetic and phenotypic functions at different PAX3::FOXO1 levels. Proliferative and oncogenic outcomes depend on PAX3::FOXO1 dosage in this system with transformation dominant at intermediate levels and growth suppression dominant at high levels. After prolonged PAX3::FOXO1 expression, there is dosage-dependent heterogeneity in single cell gene expression profiles. We observe a dosage-specific effect for PAX3::FOXO1 chromatin recognition and identify factors that modulate PAX3::FOXO1 chromatin binding. PAX3::FOXO1 dosage affects expression signatures related to cell cycle, epithelial-mesenchymal transition, and myogenesis. Whereas intermediate PAX3::FOXO1 expression maximizes chromatin binding to modulate gene expression, high PAX3::FOXO1 expression alters S phase progression and increases accessibility behind the replication fork. We conclude that PAX3::FOXO1 exerts dosage-dependent functions to influence epigenetic heterogeneity in fusion-positive rhabdomyosarcoma.2026/08/20GSE297122GSM9738025GSM9738024GSM9738023GSM9738022GSM8984243GSM9738021GSM9738020GSM8984242GSM8984241GSM8984240GSM9738029GSM9738028GSM9738027GSM9738026GSM9738036GSM8984236GSM9738035GSM8984235GSM8984234GSM9738034GSM9738033GSM8984233GSM8984232GSM9738032GSM9738031GSM9738030GSM8984239GSM8984238GSM8984237GSM9738039GSM9738038GSM973803724676297122Homo sapiens