부산대학교 도서관

Hypercholesterolemia is a causal and modifiable risk factor for atherosclerotic cardiovascular disease. A critical pathway regulating cholesterol homeostasis involves the receptor-mediated endocytosis of low-density lipoproteins into hepatocytes, mediated by the LDL receptor. We applied genome-scale CRISPR screening to query the genetic determinants of cellular LDL uptake in HuH7 cells cultured under either lipoprotein-rich or lipoprotein-starved conditions. Candidate LDL uptake regulators were validated through the synthesis and secondary screening of a customized library of gRNA at greater depth of coverage. This secondary screen yielded significantly improved performance relative to the primary genome-wide screen, with better discrimination of internal positive controls, no identification of negative controls, and improved concordance between screen hits at both the gene and gRNA level. We then applied our customized gRNA library to orthogonal screens that tested for the specificity of each candidate regulator for LDL versus transferrin endocytosis, the presence or absence of genetic epistasis with LDLR deletion, the impact of each perturbation on LDLR expression and trafficking, and the generalizability of LDL uptake modifiers across multiple cell types. These findings identified several previously unrecognized genes with putative roles in LDL uptake and suggest mechanisms for their functional interaction with LDLR. Author summary: The level of cholesterol circulating in the blood in low-density lipoproteins (LDL) is an important determinant of overall risk for cardiovascular diseases, including heart attack and stroke. This level is regulated by the removal of LDL from circulation into liver cells. While many molecules involved in LDL uptake have been characterized, we hypothesized that other currently unrecognized genetic interactions are also involved in this process. We therefore applied CRISPR-mediated genome editing to systematically test the contribution of every gene in the human genome to the uptake of LDL by a liver-derived cell line. We synthesized a secondary CRISPR library targeting the top candidate genes from this initial genome-wide screen to confirm their role in LDL uptake and to test their influence on other cellular functions. Our findings confirm the role of genes previously known to participate in LDL uptake and also provide novel insight into the overall regulation of this process. [ABSTRACT FROM AUTHOR]