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. CRISPR/Cas9 system was used to edit the CBS gene in rabbit embryos. The founder rabbits were sequenced, and their plasma homocysteine (Hcy) and lipid profile were analyzed. Six CBS-knockout (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, triglycerides (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (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, and alleviated hepatic steatosis compared to the untreated animals. A CBSG307S rabbit model was generated that exhibited severe dyslipidemia when fed on a normal diet, indicating that G307S mutation in the CBS gene is a causative factor for dyslipidemia.

中文翻译：

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使用 CRISPR/Cas9 产生的胱硫醚 β-合酶缺陷兔的点突变 G307S 中的高同型半胱氨酸血症和血脂异常

先天性高同型半胱氨酸血症 (HHcy) 是由缺陷型胱硫醚 β-合酶 (CBS) 基因引起的，通常与血脂异常有关。本研究的目的是使用在 CBS 中具有纯合 G307S 点突变的兔模型进一步阐明突变的 CBS 基因对循环脂质的影响。CRISPR/Cas9系统用于编辑兔胚胎中的CBS基因。对始祖兔进行了测序，并分析了它们的血浆同型半胱氨酸 (Hcy) 和脂质谱。获得了六个带有双等位基因修饰的 CBS 基因敲除 (CBS-KO) 创始人系。CBS 中的突变在出生后 6 周内导致显着的生长迟缓和高死亡率。此外，6 周龄的 CBS-KO 兔的血浆 Hcy、甘油三酯 (TG)、与年龄匹配的野生型 (WT) 对照相比，总胆固醇 (TC) 和低密度脂蛋白胆固醇 (LDL-C)。突变体的组织学分析显示肝细胞中微囊泡细胞质脂滴的积累。然而，与未治疗的动物相比，胃内灌注维生素 B 和甜菜碱复合物显着降低了 CBS-KO 兔的血浆 TG、TC 和 LDL-C 水平，并减轻了肝脏脂肪变性。生成的 CBSG307S 兔模型在正常饮食喂养时表现出严重的血脂异常，表明 CBS 基因中的 G307S 突变是血脂异常的致病因素。与未治疗的动物相比，胃内灌注维生素 B 和甜菜碱复合物显着降低了 CBS-KO 兔的血浆 TG、TC 和 LDL-C 水平，并减轻了肝脏脂肪变性。生成的 CBSG307S 兔模型在正常饮食喂养时表现出严重的血脂异常，表明 CBS 基因中的 G307S 突变是血脂异常的致病因素。与未治疗的动物相比，胃内灌注维生素 B 和甜菜碱复合物显着降低了 CBS-KO 兔的血浆 TG、TC 和 LDL-C 水平，并减轻了肝脏脂肪变性。生成的 CBSG307S 兔模型在正常饮食喂养时表现出严重的血脂异常，表明 CBS 基因中的 G307S 突变是血脂异常的致病因素。