固醇调节元件结合蛋白-1c与肝脂肪变性

固醇调节元件结合蛋白-1c是一种核转录因子,可参与脂质生成相关基因表达的调控,增加肝脏脂质合成,与肝脂肪变性关系密切,并参与各种原因引起的脂肪肝的发生.一些药物可以通过抑制固醇调节元件结合蛋白-1c的表达而预防或改善肝脂肪变性,为脂肪肝的治疗提供了新的方向.     

核糖体蛋白S6激酶1基因沉默对高糖刺激下肝细胞固醇调节元件结合蛋白1 c表达的影响

目的 探讨核糖体蛋白S6激酶1(S6K1)基因沉默后对高糖刺激下小鼠肝细胞固醇调节元件结合蛋白1c(SREBP1c)表达的影响.方法 将构建的S6K1shRNA重组基因腺病毒(S6K1Ax)注射进db/db小鼠尾静脉,以注射含pU6启动子的腺病毒(pU6Ax)空载体的db/db小鼠作对照组,HE染色观察肝脏病理改变并检测肝脏甘油三酯含量变化.S6K1Ax转染小鼠肝细胞AML12细胞,转染pU6Ax的作为对照组,分别用高糖、高胰岛素,高糖高胰岛素刺激,逆转录聚合酶链式反应分析肝细胞在各种条件刺激后mSREBP1c等的表达,Western blot检测db/db小鼠肝脏及AML12细胞S6K1的蛋白表达.结果 db/db糖尿病小鼠注射S6K1Ax后1周,肝脏S6K1蛋白表达被抑制,对照组与实验组肝脏甘油三酯含量分别为(0.65±0.02)mmol/L和(0.56±0.01)mmol/L,t=4.312,P<0.01,差异有统计学意义.HE染色显示实验组肝细胞胞质含脂肪滴减少,空泡细胞数量减少,脂肪肝得到改善.AML12肝细胞mSREBP1c表达实验组为0.03±0.01,对照组为0.06±0.01,t=5.624,P<0.01,差异有统计学意义.与基础状态相比,给以胰岛素刺激后实验组和对照组mSREBP1c表达均增加,实验组上升至0.06±0.02,t=8.452,P<0.01,对照组上升至0.08±0.02,t=3.591,P<0.05.高糖刺激对实验组和对照组mSREBP1c表达均无明显影响.与高胰岛素刺激组相比,高糖高胰岛素刺激后实验组和对照组mSREBP1c表达均无明显差异.结论 S6K1通过影响脂代谢的关键调控基因mSREBP1c表达参与了脂肪的合成,推测S6K1在脂肪肝的形成中发挥了重要作用.     

六味地黄汤对非酒精性脂肪性肝病大鼠SREBP-1c和LXR-α基因表达的影响

[目的]探讨六味地黄汤对非酒精性脂肪性肝病大鼠固醇调节元件结合蛋白(SREBP-1c)和肝X受体(LXR-α)的影响.[方法]选择雄性SD大鼠,随机分3组:正常组,六味地黄汤组(治疗组)和模型组.正常组喂养普通饲料,模型组和治疗组喂养高脂饲料建立非酒精性脂肪性肝病模型,治疗组并用六味地黄汤干预治疗;荧光定量RT-PCR检测各组大鼠SREBP-1c和LXR-α的基因表达.[结果]模型组大鼠SREBP- 1cmRNA和LXRαmRNA的相对表达均高于正常组(分别为t=2.361,P＜0.05和t=3.118,P＜0.01);与模型组相比,治疗组能显著降低SREBP-1cmRNA和LXR-αmRNA的表达(分别为t=3.816,P＜0.01和t=3.36,P＜0.01).[结论]六味地黄汤能降低SREBP-1c和LXR-α的基因表达,改善脂质代谢.     

三七总皂甙对脂肪变性L02肝细胞TG水平及SREBP-1c mRNA表达的影响

目的观察三七总皂甙（PNS）对脂肪变性肝细胞的降脂作用及机制。方法采用50％小牛血清诱导L02肝细胞48h建立L02肝细胞脂肪变性模型,分为模型组、自然恢复组、PNS低剂量组、PNS高剂量组,并设正常组。除模型组继续予含50％小牛血清的1640培养基培养外,余组均改予含10％小牛血清培养。PNS低、高剂量组分别予10、50μg／ml PNS作用。药物作用24h后,油红O染色观察肝细胞内脂滴变化,全自动生化仪检测TG水平,RT—PCR法检测固醇元件结合蛋白-1C（SREBP—lc mRNA）表达。结果与自然恢复组比较,PNS各治疗组细胞内脂滴少于其他组,低剂量组更为明显;TG水平明显低于其他各组（P〈0．05）,低剂量组下降更为显著（P〈0．01）;SREBP—lc mRNA的表达量均有下降,低剂量组更为明显（P〈0．05）。结论PNS能显著降低脂肪变性肝细胞内TG水平,减轻肝细胞脂肪变性;机制可能与下调SREBP-1cm RNA的表达有关。     

固醇调节元件结合蛋白-1c基因54G/C多态性与新疆维吾尔族冠心病的相关性

目的: 探讨固醇调节元件结合蛋白-1c（SREBP-1c）基因18号外显子54G/C基因多态性与新疆地区维吾尔族人群冠心病的相关性。方法: 采用聚合酶链反应-限制性片段长度多态性方法,对260例冠心病患者和256例健康体检者SREBP-1c基因18号外显子54G/C位点进行分析,同时进行血糖及血脂水平检测。结果: SREBP-1c基因18号外显子54G/C在冠心病组和健康对照组中基因型频率分别为:CC型0.146和0.051,CG型0.346和0.387,GG型:0.508和0.563,两组CC基因型差异具有统计学意义（P<0.05）,且冠心病组C等位基因频率高于对照组（P<0.01）,而GC和GG基因型差异无统计学意义。不同基因型间血糖、血脂水平差异具有统计学意义（P<0.05）。结论: 固醇调节元件结合蛋白-1c基因CC基因型和等位基因C与新疆维吾尔族人群冠心病有关联,并可影响患者的血糖、三酰甘油代谢。     

慢性丙型肝炎合并非酒精性脂肪性肝病患者血清RBP4和SREBP-1c水平变化分析

目的 探讨慢性丙型肝炎(CHC)合并非酒精性脂肪性肝病(NAFLD)患者血清视黄醇结合蛋白4(RBP4)和固醇调节元件结合蛋白-1c(SREBP-1c)水平变化及其临床意义。方法 2019年2月～2022年2月我院收治的CHC患者94例,接受肝穿刺活检和重组人干扰素-α2a联合利巴韦林治疗24周。使用全自动生化分析仪检测血生化指标,计算稳态模型胰岛素抵抗指数(HOMA-IR),采用ELISA法检测血清RBP4和SREBP-1c水平。结果 经组织病理学检查发现,在94例CHC患者中,合并NAFLD患者50例(53.2%),其中肝轻度脂肪变22例(44.0%)和中重度脂肪变28例(56.0%);CHC合并中重度脂肪变患者血清AST、ALT、ALP和GGT水平分别为(62.2±12.8)U/L、(87.2±11.5)U/L、(99.0±14.4)U/L和(69.4±10.3)U/L,显著高于CHC合并轻度脂肪变患者【分别为(53.6±10.1)U/L、(75.7±12.5)U/L、(83.8±12.7)U/L和(58.5±7.7)U/L,P<0.05】或CHC患者【分别为(51.7±8...     

固醇调节元件结合蛋白1c的研究进展

固醇调节元件结合蛋白 1c(SREBP 1c)是一种重要的核转录因子 ,它主要调控脂肪合成和葡萄糖代谢相关酶基因的表达。SREBP 1c不但受到胰岛素 葡萄糖和瘦素等多种激素和营养物的调控 ,而且介导胰岛素对多种基因表达的调控。最近研究发现 ,SREBP 1c的过度表达与肝脏和胰岛等非脂肪组织的脂质积聚相关。实验研究提示 ,干预SREBP 1c的不适当表达可能是预防和治疗 2型糖尿病的一条有效途径     

同醇调节元件结合蛋白1c激活大鼠Patatin样磷酯酶结构域蛋白3基因转录

目的探讨固醇调节元件结合蛋白1c（SREBP-1e）对Patatin样磷酯酶结构域蛋白3（PNPLA3）基因的转录调控作用。方法构建7周龄雄性体重匹配的禁食（24h）以及禁食后再喂食（48h）SD大鼠（自由饮食组3只,饥饿组3只,再喂食组4只）和高脂及小剂量链脲佐菌素诱导的2型糖尿病sD大鼠（正常对照组5只,2型糖尿病组6只）。用逆转录聚合酶链反应（RT—PCR）和Western blotting法检测各组大鼠肝脏组织中SREBP一1c和PAPM3的表达水平。将大鼠PⅣP翻3启动子5’端上游-1000bp序列分成3段,分别构建荧光素酶报告载体（R—PⅣPM3．1、R—PM似3—2、R—PNPL43—3）,转染人正常肝细胞株L02,比较3个载体基础荧光素酶活性以及SREBP-1e过表达诱导的荧光素酶活性。分析上述实验中荧光素酶活性最高的PNPLA3启动子片段可能的SREBP-1c结合位点（SRE）,分别构建野生型和SRE突变型报告载体,比较两个载体荧光素酶活性。多组定量资料比较用方差分析,两组定量资料比较用t检验。结果与自由饮食组相比,饥饿组大鼠肝脏SREBP—lc、PNPLA3和脂肪酸合成酶FAS基因表达均下降,再喂食组三者表达显著升高,差异均有统计学意义（F=114．14,334．11,754．20,均P〈0．05）。与正常对照组相比,2型糖尿病组SREBP-1e、PNPLA3基因（t=-18．39,-30．07,均P〈0．05）及蛋白表达（t=4．58,6．81,均P〈0．05）均显著增高。R—PNPLA3-1报告载体基础荧光素酶活性较对照升高51．13倍（t=-28．93,P〈0．05）,R一删PM3—2和R—PNPLA3—3无基础荧光素酶活性;在L02细胞中,转染SREBP-1c表达质粒的R—PⅣPL43—1组荧光比值较转染空质粒的组升高2．63倍（t=-7．64,P〈0．05）,而R—PⅣPM3．2组及R—PNPLA3—3组转染SREBP-1e表达质粒荧光比值较转染空质粒组均无变化;PNPLA3启动子-100～-911）p存在SRE,SRE突变的报告载体（MUT—R—PNPLA３—1）荧光比值较野生型（R—PNPLA３-1）降低40．80％（t=4．99,P〈0．05）。结论SREBP-1c通过PNPLA３基因启动子－100～－91bp激活大鼠PNPLA3基因转录。     

非酒精性脂肪性肝病患者肝脏固醇调节元件结合蛋白-1c的表达及其意义

目的 研究非酒精性脂肪性肝病(NAFLD)患者肝组织因醇凋节元件结合蛋白-1c(SREBP-1c)的表达变化,探讨其在NAFLD中的作用. 方法对临床与病理确诊的NAFLD患者,检测肝组织SREBP-1c蛋白质和mRNA的表达变化及脂肪酸合成酶的表达,并对相应的临床资料进行分析. 结果 NAFLD患者肝脂肪变程度与血清甘油三酯和胆固醇含量呈明显正相关(r值分别为0.71和0.70,P值均<0.05);NAFLD患者肝SREBP-1c表达在蛋白质和mRNA水平都明显增强,分别为2.19±0.31和0.69±0.02,高于对照组的1.15±0.20和0.40±0.02(t值分别为11.06和-14.63,P值均<0.05),且其表达强度随脂变程度的加重,由1.47±0.08和0.67±0.08增加至2.82±0.78和0.85±0.04(F=24.54,P<0.01),而与是否合并糖尿病无关; NAFLD患者肝脂肪酸合成酶表达增加,脂肪酸合成增加. 结论肝细胞SREBP-1c表达增加,导致脂肪酸合成酶蛋白增加,脂肪合成增加是NAFLD患者肝脂肪蓄积的原因之一.     

法尼醇X受体对L02细胞脂肪代谢的调节作用

目的 观察法尼醇X受体(FXR)对人肝细胞株L02细胞脂肪代谢的调节作用.方法 油酸钠建立L02细胞脂肪变模型(脂肪变组),油酸钠及鹅去氧胆酸钠建立干预模型(干预组),设对照组(培养基中不加药物),3组均设立24、48、72 h时间点.油红O染色,细胞内甘油三酯含量测定,检测肝细胞脂肪变程度;Westem blot和RT-PCR方法检测核受体FXR及固醇调节元件结合蛋白1c(SREBP-1c)的表达变化.结果 脂肪变组随着肝细胞脂肪变性的发生发展,FXR表达呈逐渐降低趋势,但差异无统计学意义.SREBP-lc mRNA的表达明显升高,24、48,72 h图像半定量分析结果分别为0.495±0.062、0.579±0.064、0.612±0.067,SREBP-1c蛋白表达分别为0.394±0.044、0.488±0.066、0.543±0.064,均明显高于干预组和对照组,差异有统计学意义.干预组FXR mRNA表达明显上调,24、48,72 h分别为0.253±0.041、0.298±0.042、0.334±0.051,FXR蛋白分别为0.221±-0.022、0.313±0.041,0.341±0.046,与脂肪变组比较,,值为6.41～50.93,Jp值均<0.05或0.01,差异有统计学意义.脂变组甘油三酯含量各时间段均明显增加,干预组甘油三酯含量各时间段均明显降低.差异有统计学意义.结论 FXR表达下调与肝细胞脂肪沉积密切相关;刺激FXR表达增加可能通过抑制其靶基因SREBP-1c表达而改善L02细胞脂肪变性.     

Transgenic mice expressing nuclear sterol regulatory element-binding protein 1c in adipose tissue exhibit liver histology similar to nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is one of the life-threatening hepatic diseases associated with insulin resistance. Here we report that nuclear sterol regulatory element-binding protein 1c (nSREBP-1c) transgenic mice, an inherited lipodystrophic model with severe insulin resistance, spontaneously develop steatohepatitis. The animal had marked fatty liver accompanied by hyperglycemia, hypoleptinemia, and hypoadiponectinemia. Liver histology similar to NASH, that is, mononuclear cell infiltration, pericellular fibrosis, ballooning degeneration, and Mallory hyaline body formation were seen in the livers from transgenic mice 20 weeks or older. In contrast, no liver histologic abnormalities were noted in wild-type mice aged 30 weeks. Immunoreactive 8-hydroxy-2′-deoxyguanosine was observed in the nuclei of livers from transgenic mice, suggesting that in addition to insulin resistance, oxidative stress may be involved in the development of the NASH-like lesion. Thus, the nSREBP-1c transgenic mouse may serve as a unique model of spontaneously occurring NASH.     

肝脂肪酶基因-514C/T多态性与非酒精性脂肪性肝病发病的关系

目的 比较非酒精性脂肪性肝病(NAFLD)患者与正常人群肝脂肪酶基因(LIPC)-514C/T多态性的分布差异,探讨其与NAFLD发病易感性的关系.方法 选取NAFLD患者及配对的正常对照者各106例,用聚合酶链反应-限制性片段长度多态性法检测LIPC-514位点基因型,并测量其体重指数、腰臀比、血压、胆固醇、高密度脂蛋白、低密度脂蛋白、甘油三酯、空腹血糖、空腹胰岛素、胰岛素抵抗指数.比较各参数在不同基因型的差异,用非条件Logistic回归分析NAFLD发病的危险因素. 结果 NAFLD组和对照组CC基因型频率(31.1%比26.4%)和C等位基因频率(62.7%比54.2%)差异有统计学意义(P＜0.05).各基因型NAFLD发病相对危险度,CC型高于TT型(比值比为3.73,95%可信区间1.31～10.63),CT型高于TT型(比值比为3.60,95%可信区间1.35～9.60).CC基因型组腰臀比较CT及TT基因型组高(P＜0.05).多因素非条件Logistic回归分析显示LIPC-514 T变异令NAFLD发病易感胜降低(回归系数-1.28,95%可信区间0.10-0.74).结论 LIPC-514C/T基因多态性与腰臀比相关,LIPC-514 T变异令NAFLD发病易感性降低.     

白介素6基因启动子-572C/G多态性与非酒精性脂肪肝炎的关系

目的:探讨白介素6(IL-6)基因启动子-572C/G多态性与非酒精性脂肪肝炎(NASH)相关性.方法:应用聚合酶联反应-限制性片段长度多态性(PCR-RFLP)方法,分别检测NASH患者78例和正常者104例IL-6基因启动子-572C/G多态性的变异.采用ELISA法检测NASH患者组IL-6血清含量.结果:IL-6基因启动子-572位点的C等位基因频率高于健康对照组,两组基因分布频率有显著统计学差异(0.564 vs 0.404,P＜0.05);NASH患者组中CC基因型携带者IL-6血清含量显著高于其他基因型携带者(6.54±4.21vs 4.68±2.88,P＜0.05),但HOMA-IR及BMI与其他两组基因型相比较并无显著统计学差异.结论:IL-6基因启动子-572位点的C等位基因与NASH发病具有一定程度相关性.     

固醇调节元件结合蛋白与非酒精性脂肪性肝病

固醇调节元件结合蛋白(SREBP)是新发现的螺旋-环-螺旋-亮氨酸链转录因子家族的一员,合成后以无活性的前体形式结合在内质网上,细胞内胆固醇的含量通过反馈抑制蛋白水解加工过程而控制SREBP的激活。SREBP与肝脏脂质代谢紊乱、胰岛素抵抗、过氧化物酶体增殖物激活受体、氧化应激、肝脏X受体和解偶联蛋白2等有关,在非酒精性脂肪性肝病发病过程中起着重要作用。     

Association of nonalcoholic fatty liver disease with insulin resistance

BACKGROUND AND PURPOSE: Nonalcoholic fatty liver disease is frequently associated with type 2 diabetes mellitus, obesity, and dyslipidemia, but some patients have normal glucose tolerance or normal weight. We tested the hypothesis that there is an association between nonalcoholic fatty liver disease and insulin resistance that is independent of diabetes and obesity. SUBJECTS AND METHODS: We measured anthropometric and metabolic variables in 46 patients with chronically elevated serum aminotransferase levels, "bright liver" on ultrasound scan, and normal glucose tolerance. Indexes of insulin resistance and secretion were determined using the homeostasis model assessment method. They were compared with 92 normal subjects who were matched for age and sex. RESULTS: Patients with nonalcoholic fatty liver disease were characterized by fasting and glucose-induced hyperinsulinemia, insulin resistance, postload hypoglycemia, and hypertriglyceridemia. Insulin resistance [odds ratio (OR) = 15 per percent increase, 95% confidence interval (CI): 3.0 to 70], fasting triglyceride level (OR = 3.1 per mmol/liter increase, 95% CI: 1.1 to 8.9), 180-minute blood glucose level (OR = 4.3 per mmol/ liter decrease, 95% CI: 1.6 to 12), and average insulin concentration in response to oral glucose (OR = 3.0 per 100 pmol/liter increase, 95% CI: 1.5 to 6.2) were independently associated with nonalcoholic fatty liver disease. The exclusion of overweight and obese subjects did not change the results. CONCLUSION: Nonalcoholic fatty liver disease is associated with insulin resistance and hyperinsulinemia even in lean subjects with normal glucose tolerance. Genetic factors that reduce insulin sensitivity and increase serum triglyceride levels may be responsible for its development.     

Association of nonalcoholic fatty liver disease and liver cancer

AIM:To investigate the association between nonalcoholic fatty liver disease(NAFLD) and liver cancer,and NAFLD prevalence in different liver tumors.METHODS:This is a retrospective study of the clinical,laboratory and histological data of 120 patients diagnosed with primary or secondary hepatic neoplasms and treated at a tertiary center where they underwent hepatic resection and/or liver transplantation,with subsequent evaluation of the explant or liver biopsy.The following criteria were used to exclude patients from the study:a history of alcohol abuse,hepatitis B or C infection,no tumor detected in the liver tissue examined by histological analysis,and the presence of chronic autoimmune hepatitis,hemochromatosis,Wilson’s disease,or hepatoblastoma.The occurrence of NAFLD and the association with its known risk factors were studied.The risk factors considered were diabetes mellitus,impaired glucose tolerance,impaired fasting glucose,body mass index,dyslipidemia,and arterial hypertension.Presence of reticulin fibers in the hepatic neoplasms was assessed by histological analysis using slide-mounted specimens stained with either hematoxylin and eosin or Masson’s trichrome and silver impregnation.Analysis of tumor-free liver parenchyma was carried out to determine the association between NAFLD and its histological grade.RESULTS:No difference was found in the association of NAFLD with the general population(34.2% and 30.0% respectively,95%CI:25.8-43.4).Evaluation by cancer type showed that NAFLD was more prevalent in patients with liver metastasis of colorectal cancer than in patients with hepatocellular carcinoma and intrahepatic cholangiocarcinoma(OR = 3.99,95%CI:1.78-8.94,P < 0.001 vs OR = 0.60,95%CI:0.18-2.01,P = 0.406 and OR = 0.70,95%CI:0.18-2.80,P = 0.613,respectively).There was a higher prevalence of liver fibrosis in patients with hepatocellular carcinoma(OR = 3.50,95%CI:1.06-11.57,P = 0.032).Evaluation of the relationship between the presence of NAFLD,nonalcoholic steatohepatitis,and liver fibrosis,and their risk factors,showed no significant statistical association for any of the tumors studied.CONCLUSION:NAFLD is more common in patients with liver metastases caused by colorectal cancer.     

脂联素基因多态性和血清脂联素水平与非酒精性脂肪肝的相关性

目的:探讨脂联素基因单核苷酸多态性及血清脂联素水平与汉族人非酒精性脂肪肝(nonalcoholic fatty liver disease,NAFLD)的关系.方法:根据性别、年龄和体质量指数(body-mass index,BMI)配对入选NAFLD患者和对照组,各106例.测定基因多态性和血清脂联素水平,分析其与人体测量参数、生化、激素和代谢的关系.结果:在NAFLD和对照者中,SNP+45位点T/T、T/G和G/G基因型分别为64.2%、54.7%和23.6%、38.7%和12.2%、6.6%,NAFLD组G/G基因型频率比对照组高(2=6.47,P<0.05),但两组等位基因型频率(2=0.64,P>0.05)差异无显著性;S N P+276位点中G/G、T/G和T/T基因型分别为4.2%、47.2%和27.3%、36.8%和8.5%、16.0%,NAFLD组T/T基因型频率高于对照组(2=6.68,P<0.05),两组等位基因频率差异有显著性(2=7.86,P<0.05).NAFLD组的血清脂联素水平较对照组显著降低(3.75mg/L±3.94mg/Lvs6.18mg/L±4.12mg/L),而且有更高的胰岛素低抗(2.19±1.35vs1.33±0.93).Logistic回归分析显示:BMI、WHR、HOMA-IR、脂联素是NAFLD的主要危险因素.结论:SNP45G/G和SNP276T/T基因型可能是中国汉族人NAFLD的易感基因,高BMI、WHR、HOMA-IR、低脂联素血症是NAFLD的主要危险因素.