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目的探讨敲除PDZK1(Postsynaptic density-95,disks-large,ZO-1-domain K1,PDZK1)基因对小鼠肝脏胆固醇代谢调节和胆囊结石形成的影响。方法雄性成年PDZK1基因敲除小鼠(PDZK1 knockout,KO组)和野生型小鼠(wild type,WT组),每组各10只,以成石饲料分别喂养4周,观察胆囊成石情况,并收集肝脏和胆囊组织。采用蛋白印迹法测定肝脏PDZK1和清道夫受体B族1型(scavenger receptor B type 1,SRB1)表达。采用胆总管插管收集肝胆汁,测定胆汁分泌率和胆汁胆固醇含量。采用试剂盒酶法测定胆囊胆汁成分并计算胆汁胆固醇饱和指数(cholesterol saturation index,CSI)。以实时定量PCR检测肝脏脂质代谢相关基因的mRNA表达。结果成石饲料喂养4周后,WT组小鼠全部成石(10/10),KO组小鼠则为40%(4/10)成石。两组小鼠肝胆汁分泌率差异无统计学意义,但KO组小鼠肝胆汁胆固醇含量显著降低(P<0.05),胆汁酸含量增加(P<0.05),且CSI降低(P<0.05)。KO组小鼠肝脏SRB1蛋白表达降低(P<0.05),甾醇氧-酰基转移酶基因1/2mRNA表达降低(P<0.05),而肝型脂肪酸结合蛋白1和胆汁酸转运相关蛋白(ATP结合盒b11)表达则显著增加(P<0.05)。结论 PDZK1影响SRB1在小鼠肝脏中表达,降低对高密度脂蛋白胆固醇摄取,减少胆汁胆固醇分泌,继而降低胆囊结石形成。
Objective To investigate the effects of PDZK1 (Postsynaptic density-95, disks-large, ZO-1-domain K1, PDZK1) on hepatic cholesterol metabolism and gallstone formation in mice. Methods Male PDZK1 knockout mice (PDZK1 knockout KO group) and wild type (WT group) mice were randomly divided into 10 groups. Each group was fed with stone fodder for 4 weeks, and the gallstone formation was observed. Liver and gallbladder tissues were collected. Western blotting was used to detect the expression of PDZK1 and scavenger receptor B type 1 (SRB1) in the liver. Bile duct cannulation was used to collect liver bile, bile secretion and bile cholesterol levels were measured. The gallbladder bile composition was determined by kit enzymatic method and the cholesterol saturation index (CSI) was calculated. Real-time quantitative PCR was used to detect the mRNA expression of liver lipid metabolism related genes. Results After four weeks of feeding, the mice in WT group all formed stone (10/10), while those in KO group were 40% (4/10). There was no significant difference in hepatic bile excretion rate between the two groups. However, the levels of hepatic bile cholesterol in KO group were significantly decreased (P <0.05), bile acid content was increased (P <0.05), and CSI was decreased (P <0.05). The expression of SRB1 protein in the liver of KO group decreased (P <0.05) and the expression of sterol oxygenase acyltransferase 1/2 mRNA decreased (P <0.05), while the expression of hepatic fatty acid binding protein 1 and bile acid transport related protein b11) expression was significantly increased (P <0.05). Conclusion PDZK1 affects the expression of SRB1 in the liver of mice, reduces the uptake of high-density lipoprotein cholesterol, reduces the bile-cholesterol secretion, and then reduces the gallstone formation.