Genome scale CRISPR screen for modifiers of PCSK9 secretion

A whole genome CRISPR screen was performed to identify genes involved in PCSK9 secretion. HEK293T cells were engineered to heterologously express PCSK9-eGFP and A1AT-mCherry fusion proteins. These cells were then mutagenized with the human GeCKOv2 library and sorted by flow cytometry to isolate mutants with unaffected mCherry signal (middle 67% fluorescence) and either eGFP-high (top 5%) or eGFP-low (bottom 5%) PCSK9-eGFP fluorescence. Genes whose perturbation results in a specific intracellular accumulation of PCSK9-eGFP are expected to have sgRNA sequences in the eGFP-high population relative to the eGFP-low population.