ALPL缺陷加速高脂诱导小鼠肝内脂肪沉积

摘要 目的：明确肝/骨/肾型碱性磷酸酶基因（liver/bone/kidney alkaline phosphatase，ALPL）在高脂诱导肝内脂肪沉积的作用。方法：利用野生型（WT）和ALPL敲除小鼠（ALPL^+/-），给予高脂饮食8周诱导脂肪肝模型，检测小鼠肝内脂肪沉积和血清中葡糖糖、甘油三脂及胆固醇含量，并应用RT-PCR、Western blotting和免疫荧光染色检测肝组织中脂肪酸生成和转运相关基因表达变化。结果：ALPL^+/-组在正常饮食条件下较WT组肝内脂肪沉积无明显变化，而血清中葡萄糖和胆固醇含量增加；高脂条件下，敲除ALPL小鼠肝内脂肪沉积明显增加，且伴随血清中甘油三脂含量增加。RT-PCR和Western blotting结果显示，在高脂诱导下ALPL^+/-小鼠肝组织中关键脂肪酸生成基因ACC1、ACC2和 PPAR-γ，及脂肪酸生成基因LPL表达明显增加。此外，免疫荧光染色结果显示高脂诱导下敲除ALPL小鼠肝组织中的PPAR-γ阳性肝细胞明显增加。结论：ALPL敲除促进肝内脂肪酸生成和转运，加速高脂诱导小鼠肝内脂肪沉积，为阐明脂肪肝病变分子机制提供理论支持。

ALPL Deficiency Accelerates High-fat Diet-induced Hepatic Fat Deposition in Mice

ABSTRACT Objective: To clarify the role of the liver/bone/kidney alkaline phosphatase gene (ALPL) in high-fat diet-induced hepatic fat deposition. Methods: A fatty liver model was induced by administration of high-fat diet in wild-type (WT) and ALPL knockout (ALPL^+/-) mice for 8 weeks. Intrahepatic fat deposition and serum glucose, triglyceride and cholesterol levels in serum were measured. RT-PCR, Western blotting and immunofluorescence staining were used to detect the expression of genes related to fatty acid synthesis and transport in liver. Results: No significant change in liver of fat deposition was observed in the ALPL^+/- group compared with the WT group on normal diet, while serum glucose and cholesterol levels were increased; under high-fat conditions, intrahepatic fat deposition in the ALPL^+/- mice was significantly increased and accompanied by an increase in serum triglyceride. RT-PCR and Western blotting results showed that the expression of the key fatty acid synthesis genes ACC1, ACC2 and PPAR-γ, and the fatty acid synthesis gene LPL in the liver of ALPL^+/- mice were significantly increased under high-fat induction. In addition, immunofluorescence staining showed that PPAR-γ-positive hepatocytes were also significantly increased in the liver of ALPL^+/- mice under high-fat induction. Conclusion: ALPL knockdown promotes the synthesis and transport of intrahepatic fatty acid and accelerates the fat deposition in the liver of mice induced by high fat. Our study provides potential theory to elucidate the molecular mechanism of liver steatosis.