RESEARCH ARTICLE FBXL19 recruits CDK-Mediator to CpG islands of developmental genes priming them for activation during lineage commitment Emilia Dimitrova1, Takashi Kondo2†, Angelika Feldmann1†, Manabu Nakayama3, Yoko Koseki2, Rebecca Konietzny4‡, Benedikt M Kessler4, Haruhiko Koseki2,5, Robert J Klose1* 1Department of Biochemistry, University of Oxford, Oxford, United Kingdom; 2Laboratory for Developmental Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan; 3Department of Technology Development, Kazusa DNA Research Institute, Kisarazu, Japan; 4Nuffield Department of Medicine, TDI Mass Spectrometry Laboratory, Target Discovery Institute, University of Oxford, Oxford, United Kingdom; 5CREST, Japan Science and Technology Agency, Kawaguchi, Japan Abstract CpG islands are gene regulatory elements associated with the majority of mammalian promoters, yet how they regulate gene expression remains poorly understood. Here, we identify *For correspondence: FBXL19 as a CpG island-binding protein in mouse embryonic stem (ES) cells and show that it
[email protected] associates with the CDK-Mediator complex. We discover that FBXL19 recruits CDK-Mediator to †These authors contributed CpG island-associated promoters of non-transcribed developmental genes to prime these genes equally to this work for activation during cell lineage commitment. We further show that recognition of CpG islands by Present address: ‡Agilent FBXL19 is essential for mouse development. Together this reveals a new CpG island-centric Technologies, Waldbronn, mechanism for CDK-Mediator recruitment to developmental gene promoters in ES cells and a Germany requirement for CDK-Mediator in priming these developmental genes for activation during cell lineage commitment. Competing interests: The DOI: https://doi.org/10.7554/eLife.37084.001 authors declare that no competing interests exist.