Poster abstracts
Poster number 51 submitted by Tom Versosky
Characterizing the assembly and function of PAX3::FOXO1-associated biomolecular condensates in rhabdomyosarcoma
Tom Versosky (Department of Biological Chemistry and Pharmacology, Ohio State Biochemistry Program, The Ohio State University), Siou-Luan He (Department of Biological Chemistry and Pharmacology, The Ohio State University), Yu-Chieh Chung (Department of Biological Chemistry and Pharmacology, The Ohio State University), Li-Chun Tu (Department of Biological Chemistry and Pharmacology, The Ohio State University)
Abstract:
Fusion-positive rhabdomyosarcoma (FP-RMS) is an aggressive pediatric soft tissue cancer driven by the fusion transcription factors (TFs) arising from chromosomal translocations. Emerging evidence suggests that the most potent fusion TF, PAX3::FOXO1, functions to establish super-enhancers (SE) that drive high levels of oncogenic gene transcription. However, the mechanisms governing the assembly and maintenance of these super-enhancers remain unclear. Our preliminary data show that PAX3::FOXO1 forms puncta-like structures in live FP-RMS cells, suggestive of biomolecular condensates. Additionally, PAX3::FOXO1 stably interacts with BRD4, a bromodomain protein that recruits chromatin remodelers and activates transcription. To further characterize its role in SE stability and FP-RMS, we use CRISPR-Sirius to directly visualize super-enhancer-associated genes (MYCN, MYOD1, and FGFR4). By integrating live-cell imaging with RNA-FISH and RNA-seq, we aim to directly link chromatin organization with transcriptional output. We and others have previously observed reduced mobility in active chromatin compared to silenced regions. Measuring chromatin mobility in correlation to its transcriptional activities will further elucidate the regulatory role of PAX3::FOXO1 in transcription activation regulated by biomolecular condensates, providing mechanistic insight into how super enhancers coordinate the regulation of transcriptional output of multiple oncogenes in FP-RMS.
Keywords: fusion-positive rhabdomyosarcoma, CRISPR-Sirius imaging, super-enhancer