Centre for Molecular Medicine Norway, University of Oslo, Oslo, Norway
Kornel Labun
Department of Informatics, Computational Biology Unit, University of Bergen, Bergen, Norway
Salla Keskitalo
Center for Biotechnology, University of Helsinki, Helsinki, Finland
Inkeri Soppa
Centre for Molecular Medicine Norway, University of Oslo, Oslo, Norway; Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Oslo, Finland
Katariina Mamia
Centre for Molecular Medicine Norway, University of Oslo, Oslo, Norway
Eero Tolo
Faculty of Social Sciences, University of Helsinki, Oslo, Finland
Centre for Molecular Medicine Norway, University of Oslo, Oslo, Norway
Leonardo A Meza-Zepeda
Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
Susanne Lorenz
Department of Core Facilities, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
Artur Cieslar-Pobuda
Centre for Molecular Medicine Norway, University of Oslo, Oslo, Norway; Department of Cancer Immunology, Institute of Cancer Research, Oslo University Hospital, Oslo, Norway
Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden; Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom; Genome-Scale Biology Program, University of Helsinki, Oslo, Norway
Centre for Molecular Medicine Norway, University of Oslo, Oslo, Norway; Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Oslo, Finland; Department of Pediatrics, Oslo University Hospital, Oslo, Norway
Precision CRISPR gene editing relies on the cellular homology-directed DNA repair (HDR) to introduce custom DNA sequences to target sites. The HDR editing efficiency varies between cell types and genomic sites, and the sources of this variation are incompletely understood. Here, we have studied the effect of 450 DNA repair protein-Cas9 fusions on CRISPR genome editing outcomes. We find the majority of fusions to improve precision genome editing only modestly in a locus- and cell-type specific manner. We identify Cas9-POLD3 fusion that enhances editing by speeding up the initiation of DNA repair. We conclude that while DNA repair protein fusions to Cas9 can improve HDR CRISPR editing, most need to be optimized to the cell type and genomic site, highlighting the diversity of factors contributing to locus-specific genome editing outcomes.
