Construction of Humanized CYP1A2 Rats Using CRISPR/CRISPR-Associated Protein 9 to Promote Drug Metabolism and Pharmacokinetic Research

Cytochrome P450 family 1 subfamily A member 2 (CYP1A2) performs an indispensable role in the metabolism of both exogenous and endogenous substances. What is more, CYP1A2 functions in human diseases by regulating the homeostasis of cholesterol. Despite the emergence of gene-editing animal models, genetically humanized animals that overcome species differences for further exploring the role of CYP1A2 in drug metabolism and human diseases have not been constructed. In this study, we inserted human CYP1A2 cDNA into the rat Cyp1a2 gene by using CRISPR/CRISPR-associated protein 9 (Cas9) technology. The results showed that human CYP1A2 was successfully expressed in humanized rat liver, and there were no statistically significant differences of physiologic symptoms compared with wild-type (WT) rats. In vitro incubation results indicated the different inhibition of furafylline on CYP1A2 activity in human liver microsomes, humanized CYP1A2 (hCYP1A2) rat liver microsomes, and WT rat liver microsomes, with IC₅₀ values of 7.1 lM, 36.5 lM, and 285.8 lM, respectively. Meanwhile, pharmacokinetic characteristics of clozapine were conducted, and the results suggested that in hCYP1A2 rats, clozapine tended to be metabolized into norclozapine. Both the in vitro and in vivo results demonstrated the different metabolic functions of CYP1A2 in humanized and WT rats. We successfully constructed a novel humanized CYP1A2 rat model using the CRISPR/Cas9 system, providing a powerful tool for better predicting CYP1A2-mediated drug metabolism and pharmacokinetics. SIGNIFICANCE STATEMENT Human CYP1A2 takes active part in the biotransformation of both exogenous substances and endogenous substances. Meanwhile, it plays a regulatory role in human diseases, including hypercholesterolemia and hypertension. However, the results obtained from animal models cannot be directly applied to humans. This study successfully constructed a humanized CYP1A2 rat model by CRISPR/ CRISPR-associated protein 9 technology, providing a powerful model for promoting drug metabolism research as well as exploring the role of CYP1A2 in human diseases.