Tissue-specific activation of gene expression by the Synergistic Activation Mediator (SAM) CRISPRa system in mice
Charleen Hunt, Suzanne A. Hartford, Derek W. R. White, Evangelos Pefanis, Timothy Hanna, Clarissa Herman, Jarrell Wiley, Heather M. Brown, Qi Su, Yurong Xin, Dennis Voronin, Hien P. Nguyen, Judith Y. Altarejos, Keith Crosby, Jeffery D. Haines, Sarah Cancelarich, Meghan C. Drummond, Sven Møller-Tank, Ryan Malpass, Jacqueline Buckley, Maria del Pilar Molina‐Portela, Gustavo Droguett, David Frendewey, Eric Chiao, Brian Zambrowicz, Guochun Gong
Abstract
CRISPR-based transcriptional activation is a powerful tool for functional gene interrogation; however, delivery difficulties have limited its applications in vivo. Here, we created a mouse model expressing all components of the CRISPR-Cas9 guide RNA-directed Synergistic Activation Mediator (SAM) from a single transcript that is capable of activating target genes in a tissue-specific manner. We optimized Lipid Nanoparticles and Adeno-Associated Virus guide RNA delivery approaches to achieve expression modulation of one or more genes in vivo. We utilized the SAM mouse model to generate a hypercholesteremia disease state that we could bidirectionally modulate with various guide RNAs. Additionally, we applied SAM to optimize gene expression in a humanized Transthyretin mouse model to recapitulate human expression levels. These results demonstrate that the SAM gene activation platform can facilitate in vivo research and drug discovery.