Hyperhomocysteinemia and Dyslipidemia in point mutation G307S of cystathionine β-synthase-deficient rabbit generated using CRISPR/Cas9

Abstract

Background: Congenital hyper-homocysteinemia (HHcy) is caused by a defective cystathionine β-synthase (CBS) gene, and is frequently associated with dyslipdemia. The aim of this study was to further elucidate the effect of mutated CBS gene on circulating lipids using a rabbit model harboring a homozygous G307S point mutation in CBS.Methods: CRISPR/Cas9 system was used in rabbit embryos to edit their CBS gene. The founder rabbits were sequenced, and their plasma Hcy and lipid profile were analyzed. Results: Six CBS-KO founder lines with biallelic modifications were obtained. Mutation in CBS caused significant growth retardation and high mortality rates within 6 weeks after birth. In addition, the 6-week old CBS-KO rabbits showed higher plasma levels of Hcy, TG, TC and LDL-C compared to the age-matched wild-type (WT) controls. Histological analysis of the mutants showed accumulation of micro-vesicular cytoplasmic lipid droplets in the hepatocytes. However, gastric infusion of vitamin B and betaine complex significantly decreased the plasma levels of TG, TC and LDL-C in the CBS-KO rabbits, as well as hepatic steatosis compared to the untreated animals. Conclusion: We generated CBSG307S rabbit model that exhibited severe dyslipidemia when fed on a normal diet, indicating that G307S mutation in the CBS gene is a causative factor for dyslipidemia.