Growing evidence suggests prevalence of transcriptional condensates on chromatin, yet their mechanisms of formation and functional significance remain largely unclear. In human cancer, a series of mutations in the histone acetylation reader ENL create gain-of-function mutants with increased transcriptional activation ability. Here, we show that these mutations, clustered in ENL's structured acetyl-reading YEATS domain, trigger aberrant condensates at native genomic targets through multivalent homotypic and heterotypic interactions. Mechanistically, mutation-induced structural changes in the YEATS domain, ENL's two disordered regions of opposing charges, and the incorporation of extrinsic elongation factors are all required for ENL condensate formation. Extensive mutagenesis establishes condensate formation as a driver of oncogenic gene activation. Furthermore, expression of ENL mutants beyond the endogenous level leads to non-functional condensates. Our findings provide new mechanistic and functional insights into cancer-associated condensates and support condensate dysregulation as an oncogenic mechanism.
Organizational Affiliation: 
Department of Cancer Biology, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
MOE Key Laboratory of Protein Sciences, Beijing Frontier Research Center for Biological Structure, School of Medicine, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Beijing 100084, China.
Department of Cancer Biology, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of the School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA.
Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Center for Computational and Genomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
Department of Cancer Biology, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Center for Computational and Genomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
Center for Computational and Genomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
MOE Key Laboratory of Protein Sciences, Beijing Frontier Research Center for Biological Structure, School of Medicine, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Beijing 100084, China. Electronic address: liyuanyuan@tsinghua.edu.cn.
MOE Key Laboratory of Protein Sciences, Beijing Frontier Research Center for Biological Structure, School of Medicine, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Beijing 100084, China. Electronic address: lht@tsinghua.edu.cn.
Department of Cancer Biology, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. Electronic address: liling.wan@pennmedicine.upenn.edu.