肝X受体α(LXRα)及三磷酸腺苷结合盒转运体A1(ABCA1)参与子痫前期发病的机理研究

目的探讨在子痫前期发病中LXRα和ABCA1的变化及二者与脂质代谢异常的关系。方法选取2019年10月至2023年6月在福建医科大学附属泉州第一医院妇产科分娩的子痫前期孕妇112例(子痫前期组),根据妊娠34周前是否诊断为子痫前期,将其分为早发组和晚发组;同期住院生产的70名正常孕产妇为正常对照组(正常组),采用生化方法测得血清中血脂水平(TG、TC、LDL及HDL);采用ELISA法检测2组患者血清中的LXRα与ABCA1蛋白表达水平;采用免疫组化及半定量PCR(RT-PCR)检测正常组及子痫前期组胎盘组织中LXRα与ABCA1的表达。分析LXRα和ABCA1表达与血脂异常的关系。结果子痫前期组TG、TC、LDL高于正常组,HDL低于正常组,差异均具有统计学意义(均P<0.05)。RT-PCR及免疫组化显示子痫前期组胎盘和血清的LXRα、ABCA1表达低于正常组(P<0.05)。胎盘上LXRαmRNA水平与LXRα蛋白表达水平呈正相关,差异具有统计学意义(P<0.05);两组患者血清ABCA1的表达水平与其胎盘上ABCA1蛋白浓度呈正相关,与血液循环中LDL的浓度水平呈负相关,与血液循环中HDL的浓度水平呈正相关,差异均有统计学意义(均P<0.05)。结论子痫前期妇女的血脂水平及血清中LXRα、ABCA1表达异常,且与病情严重程度相关;LXRα及ABCA1参与了子痫前期的血脂代谢异常的发生,可以作为临床上评判相关病程进展的依据。

Recent insights into farnesoid X receptor in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD) is the hepatic manifestation of metabolic syndrome and is one of the most prevalent liver disorders worldwide. NAFLD can gradually progress to liver inflammation, fibrosis, cirrhosis and even hepatocellular carcinoma. However, the pathogenesis of NAFLD is complex, and no efficient pharmaceutic treatments have yet been established for NAFLD. Accumulating data have shown that the farnesoid X receptor(FXR) plays important roles not only in bile acid metabolism, but also in lipid and carbohydrate homeostasis, inflammatory responses, among others. In this review, we aim to highlight the role of FXR in the pathogenesis and treatment of NAFLD.

Coronary heart disease:Significance of liver X receptor α genomics

Crosstalk between lipid peroxidation and inflammation is known to be a pathognomonic feature for the development of coronary heart disease(CHD).In this regard ligand activated liver X receptor(LXR)-α has emerged as a key molecular switch by its inherent ability to modulate an array of genes involved in these two fundamental cellular processes.In addition,LXR-α has also been found to play a role in hepatic lipogenesis and innate immunity.Although several lines of evidence in experimental model systems have established the atheroprotective nature of LXR-α,human subjects have been reported to possess a paradoxical situation in which increased blood cellular LXR-α gene expression is always accompanied by increased coronary occlusion.This apparent paradox was resolved recently by the finding that CHD patients possess a deregulated LXR-α transcriptome due to impaired ligand-receptor interaction.This blood cellular mutated LXR-α gene ex- pression correlated specifically with the extent of coro- nary occlusion and hence need is felt to devise new synthetic ligands that could restore the function of this mutated LXR-αprotein in order to modulate genes involved in reverse cholesterol transport and suppression of the inflammatory response leading to the effective treatment of CHD.

Pravastatin activates the expression of farnesoid X receptor and liver X receptor alpha in Hep3B cells

BACKGROUND: Statins are suggested to preserve gallbladder function by suppressing pro-inflammatory cytokines and preventing cholesterol accumulation in gallbladder epithelial cells. They also affect cross-talk among the nuclear hormone receptors that regulate cholesterol-bile acid metabolism in the nuclei of hepatocytes. However, there is controversy over whether or how statins change the expression of peroxisome proliferator-activated receptor(PPAR)α, PPARγ, liver X receptor α(LXRα), farnesoid X receptor(FXR), ABCG5, ABCG8, and 7α-hydroxylase(CYP7A1) which are directly involved in the cholesterol saturation index in bile. METHODS: Human Hep3B cells were cultured on dishes. MTT assays were performed to determine the appropriate concentrations of reagents to be used. The protein expression of PPARα and PPARγ was measured by Western blotting analysis, and the mRNA expression of LXRα, FXR, ABCG5, ABCG8 and CYP7A1 was estimated by RT-PCR. RESULTS: In cultured Hep3B cells, pravastatin activated PPARα and PPARγ protein expression, induced stronger expression of PPARγ than that of PPARα, increased LXRα mRNA expression, activated ABCG5 and ABCG8 mRNA expression mediated by FXR as well as LXRα, enhanced FXR mRNA expression, and increased CYP7A1 mRNA expression mediated by the PPARγ and LXRα pathways, together or independently. CONCLUSION: Our data suggested that pravastatin prevents cholesterol gallstone diseases via the increase of FXR, LXRαand CYP7A1 in human hepatocytes.

The LXRB-SREBP1 network regulates lipogenic homeostasis by controlling the synthesis of polyunsaturated fatty acids in goat mammary epithelial cells

Background:In rodents,research has revealed a role of liver X receptors(LXR) in controlling lipid homeostasis and regulating the synthesis of polyunsaturated fatty acids(PUFA).Recent data suggest that LXRB is the predominant LXR subtype in ruminant mammary cells,but its role in lipid metabolism is unknown.It was hypothesized that LXRB plays a role in lipid homeostasis via altering the synthesis of PUFA in the ruminant mammary gland.We used overexpression and knockdown of LXRB in goat primary mammary epithelial cells(GMEC) to evaluate abundance of lipogenic enzymes,fatty acid profiles,content of lipid stores and activity of the stearoyl-Co A desaturase(SCD1) promoter.Results:Overexpression of LXRB markedly upregulated the protein abundance of LXRB while incubation with si RNA targeting LXRB markedly decreased abundance of LXRB protein.Overexpression of LXRB plus T0901317(T09,a ligand for LXR) dramatically upregulated SCD1 and elongation of very long chain fatty acid-like fatty acid elongases 5–7(ELOVL 5–7),which are related to PUFA synthesis.Compared with the control,cells overexpressing LXRB and stimulated with T09 had greater concentrations of C16:0,16:1,18:1n7,18:1n9 and C18:2 as well as desaturation and elongation indices of C16:0.Furthermore,LXRB-overexpressing cells incubated with T09 had greater levels of triacylglycerol and cholesterol.Knockdown of LXRB in cells incubated with T09 led to downregulation of genes encoding elongases and desaturases.Knockdown of LXRB attenuated the increase in triacylglycerol and cholesterol that was induced by T09.In cells treated with dimethylsulfoxide,knockdown of LXRB increased the concentration of C16:0 at the expense of C18:0,while a significant decrease in C18:2 was observed in cells incubated with both si LXRB and T09.The abundance of sterol regulatory element binding transcription factor 1 precursor(p SREBP1) and its mature fragment(n SREBP1) was upregulated by T09,but not LXRB overexpression.In the cells cultured with T09,knockdown of LXRB downregulated the abundance for p SREBP1 and n SREBP1.Luciferase reporter assays revealed that the activities of wild type SCD1 promoter or fragment with SREBP1 response element(SRE) mutation were decreased markedly when LXRB was knocked down.Activity of the SCD1 promoter that was induced by T09 was blocked when the SRE mutation was introduced.Conclusion:The current study provides evidence of a physiological link between the LXRB and SREBP1 in the ruminant mammary cell.An important role was revealed for the LXRB-SREBP1 network in the synthesis of PUFA via the regulation of genes encoding elongases and desaturases.Thus,targeting this network might elicit broad effects on lipid homeostasis in ruminant mammary gland.

Mechanism of FXR alleviating the liver fibrosis by regulating perilipin 5

Objective:To investigate the regulatory mechanism in liver fibrosis progression by nuclear receptor of farnesoid X receptor(FXR)and the lipid droplet-associated protein of perilipin 5(PLIN5).Methods:FXR response element(FXRE)upstream of PLIN5 gene was found by bioinformatics,and confirmed by a dual luciferase reporter gene system;a hepatic fibrosis model based on human hepatic stellate cell LX-2 was established by induction of transforming growth factor-β1(TGF-β1);mRNA and protein levels ofα-smooth muscle actin(α-SMA)and collagen栺were measured by qPCR and Western blot after transient overexpression of FXR or PLIN5;Oil red O staining was used to study the formation of lipid droplets.Results:The promoter region of the PLIN5 gene contained a known reverse repeats-1(IR-1);the gene expression of PLIN5 in LX-2 cells was up-regulated after FXR activation(P<0.01);overexpression of PLIN5 promoted the formation of lipid droplets and significantly reduced the TGF-β1 induced fibrosis gene expression(P<0.05);FXR activation showed no effects on the inhibition of LX-2 cells activation.Conclusion:Overexpression of PLIN5 promotes the formation of lipid droplets and inhibits activation of LX-2 cells.FXR might bind to the FXRE site upstream of PLIN5 gene and regulate its gene expression.In summary,FXR may prevent liver fibrosis progression partially by regulating lipid droplet-associated protein of PLIN5.

Role of pregnane X-receptor in regulating bacterial translocation in chronic liver diseases

Bacterial translocation(BT) has been impeccably implicated as a driving factor in the pathogenesis of a spectrum of chronic liver diseases(CLD). Scientific evidence accumulated over the last four decades has implied that the disease pathologies in CLD and BT are connected as a loop in the gut-liver axis and exacerbate each other. Pregnane X receptor(PXR) is a ligandactivated transcription factor and nuclear receptor that is expressed ubiquitously along the gut-liver-axis. PXR has been intricately associated with the regulation of various mechanisms attributed in causing BT. The importance of PXR as the mechanistic linker molecule in the gutliver axis and its role in regulating bacterial interactions with the host in CLD has not been explored. Pub Med was used to perform an extensive literature search using the keywords PXR and bacterial translocation, PXR and chronic liver disease including cirrhosis. In an adequate expression state, PXR acts as a sensor for bile acid dysregulation and bacterial derived metabolites, and in response shapes the immune profile beneficial to the host. Activation of PXR could be therapeutic in CLD as it counter-regulates endotoxin mediated inflammation and maintains the integrity of intestinal epithelium. This review mainly focuses PXR function and its regulation in BT in the context of chronic liver diseases.

肝X受体激动剂直接激活肝细胞NgBR的表达

Nogo-B受体(Nogo-B receptor,NgBR)参与脂肪肝和胰岛素敏感性的形成,但是并不清楚肝X受体(liver X receptor,LXR)激动剂是否能够调控NgBR的表达。文章使用人工合成的LXR激动剂(T0901317和GW3965)分析其对肝源细胞系中NgBR表达的影响,构建正常或突变NgBR启动子,通过双荧光素酶报告基因系统检测LXR激动剂对启动子活性的影响;采用CRISPR-CAS9方法建立LXRα或LXRβ基因敲除的HepG2细胞系,通过Western Blot检测相关基因的表达变化;向ApoE-/-小鼠腹腔注射LXR激动剂T0901317,分析小鼠肝脏中NgBR的表达变化。结果发现,LXR激动剂能够通过激活LXR促进NgBR蛋白的表达,该诱导作用是以LXRE依赖的方式进行的,并且LXR的表达发挥着重要作用。在体内实验中,也证明了LXR激动剂T0901317上调NgBR蛋白表达。结果表明,NgBR是LXR的靶蛋白,LXR通过结合NgBR启动子LXRE序列促进其转录和翻译。

Liver as a new target organ in Alzheimer's disease:insight from cholesterol metabolism and its role in amyloid-beta clearance

Alzheimer's disease,the primary cause of dementia,is characterized by neuropathologies,such as amyloid plaques,synaptic and neuronal degeneration,and neurofibrillary tangles.Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs,targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment.Metabolic abnormalities are commonly observed in patients with Alzheimer's disease.The liver is the primary peripheral organ involved in amyloid-beta metabolism,playing a crucial role in the pathophysiology of Alzheimer's disease.Notably,impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease.In this review,we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism.Furthermore,we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.

Liver X receptors and epididymal epithelium physiology

Aim： To investigate the roles of liver X receptors （LXR） in the lipid composition and gene expression regulation in the murine caput epididymidis. LXR are nuclear receptors for oxysterols, molecules derived from cholesterol metabolism that are present in mammals as two isoforms： LXRα, which is more specifically expressed in lipid-metabolising tissues, such as liver, adipose and steroidogenic tissues, and macrophages, whereas LXRβ is ubiquitous. Their importance in reproductive physiology has been sustained by the fact that male mice in which the function of both LXR has been disrupted have fertility disturbances starting at the age of 5 months, leading to complete sterility by the age of 9 months. These defects are associated with epididymal epithelial degeneration in caput segments one and two, and with a sperm midpiece fragility, leading to the presence of isolated sperm heads and flagella when luminal contents are recovered from the cauda epididymidis. Methods： The lipid composition of the caput epididymidis of wild-type and LXR-deficient mice was assessed using oil red O staining on tissue cryosections and lipid extraction followed by high performance liquid chromatography or gas chromatography. Gene expression was checked by quantitative real time polymerase chain reaction. Results： Using LXR-deficient mice, we showed an alteration of the lipid composition of the caput epididymidis as well as a significantly decreased expression of the genes encoding SREBPlc, SCD1 and SCD2, involved in fatty acid metabolism. Conclusion： Altogether, these results show that LXR are important regulators of epididymal function, and play a critical role in the lipid maturation processes occurring during sperm epididymal maturation. （Asian J Androl 2007 July; 9： 574-582）

Role of liver X receptors alpha agonist on expressions of LPS-induced inflammatory response associated factor IRAK-4 and NF-kappaB in Kupffer cells

在 interleukin-1 受体的表情上探索激活的肝 X 受体(LXR ) 的角色的目的在在 Kupffer 房间并且到由 LPS 导致了的煽动性的反应联系了 kinase-4 (IRAK-4 ) 和 NF-kappaB (NF-B ) 调查煽动性的反应的 LXR 否定规定的可能的机制。Kupffer 房间被骨胶原灌注在 situ 从男 Kunming 老鼠孤立的方法。并且这些房间被划分成 4 个组：正常控制组， LPS 处理组， LXR 收缩筋 T0901317 处理组， LPS 和 T0901317 联合了处理组。 LPS 处理组在 RPMI 1640 与 1 g/ml LPS 的最后的集中被对待并且为 6 h 有教养， T0901317 处理组在 RPMI 1640 与 5 g/ml 的最后的集中被对待并且为 24 h 有教养，并且联合处理组在 RPMI 1640 与 1 g/ml T0901317 的最后的集中为 24 h 收到了文化前然后为有在 RPMI 1640 的 5 g/ml LPS 的最后的集中的 6 h 有教养。所有组为 30 h 是有教养的。在 mRNA 和蛋白质层次的 LXR， IRAK-4 和 NF-B 的表示被即时 PCR 并且西方的弄污检测，并且 TNF-1 和 IL-1 层次被 ELISA 检测。LXR mRNA 和蛋白质的层次是的结果在 LPS 组在 T0901317 组最高、最低(P < 0.05 ) 。IRAK4 和 NF-B mRNAs 和蛋白质的水平比在 LPS 组在联合对待的组是显然更低的(P < 0.05 ) 。并且 TNF-1 和 IL-1 的水平在 LPS 组最高被观察(P < 0.05 ) ，但是在控制组， T0901317 组和联合对待的组之中的没有差别(P > 0.05 ) 。这些标明日期的结论建议 LXR 收缩筋有效地装起来调整 LXR mRNA 和蛋白质的表情并且禁止煽动性的反应。这可能经由下面调整在 mRNA 和蛋白质层次的 IRAK4 和 NF-B 的表情。

FXR激动剂在非酒精性脂肪性肝炎治疗中的研究进展

非酒精性脂肪性肝炎(Non-alcoholic steatohepatitis,NASH),又称代谢性脂肪性肝炎,是病理变化与酒精性肝炎相似但无过量饮酒史的临床综合征,好发于中年特别是超重肥胖个体。非酒精性脂肪性肝炎与肥胖、胰岛素抵抗、2型糖尿病、高脂血症等代谢紊乱关系密切,主要特征为肝细胞大泡性脂肪变伴肝细胞损伤和炎症,严重者可发展为肝硬化,但至今NASH尚无得到批准的治疗方案。在寻找有效的治疗方法时,解决代谢失调、炎症和抗纤维化的新策略不断涌现。法尼类X受体(Farnesoid X receptor,FXR)除了是胆汁酸代谢和肠肝循环的关键调节剂外,还参与调节代谢稳态,使其成为NASH中有吸引力的治疗靶点。本文综述了FXR激动剂对NASH治疗的研究进展。

秦川牛LXRα基因第二外显子多态性及其与部分胴体、肉用性状关联性研究

旨在分析秦川牛肝X受体基因(LXRα)第二外显子的遗传变异与部分酮体、肉用性能指标的相关性。随机选择相同饲养条件下的497头18～20月龄秦川牛阉牛,采用PCR-SSCP技术进行了LXRα基因部分区段遗传变异检测,运用SPSS程序中的GLM模型分析所检测到的遗传变异与秦川牛部分肉用性能指标的关联性。结果,找到了LXRα基因DNA序列中的一个突变位点T1530C(NC_007313)。对该遗传变异结果进行分型并与114头秦川牛的肉用性状进行关联分析,结果表明,该位点的多态性与胴体长、大理石花纹评分和背膘厚之间存在显著相关(P<0.05);BB和AB基因型个体胴体长显著高于AA基因型个体(P<0.05),BB基因型个体大理石等级和背膘厚显著高于AA基因型个体(P<0.05),与AB基因型个体差异不显著(P>0.05)。试验结果表明该SNP位点的BB基因型为优势基因型,与胴体长、背膘厚、大理石花纹等肉用性状有相关性,提示LXRα基因能够作为分子标记辅助选择的候选基因。

疏肝健脾方药对非酒精性脂肪性肝病大鼠肝组织LXRα mRNA及蛋白表达的影响

目的探讨疏肝健脾方药对非酒精性脂肪性肝病(NAFLD)大鼠肝组织LXRαmRNA及蛋白表达的影响。方法选用SD大鼠55只,随机分为正常组、模型组、疏肝组(灌服3.2 g.kg-1·d-1剂量的柴胡疏肝散)、健脾组(灌服10.0 g.kg-1·d-1剂量的参苓白术散)、综合组(灌服11.9 g.kg-1·d-1剂量的柴胡疏肝散和参苓白术散合方),模型组15只,其余各组10只。采用灌饲高脂肪乳剂(10 ml/kg)的方法复制大鼠NAFLD实验动物模型,给药8 w后处死动物,腹主动脉采血,用全自动生化分析仪检测血脂及肝功;常规HE染色观察肝组织病理变化;RT-PCR方法检测肝组织LXRαmRNA的表达;免疫组织化学方法检测肝组织LXRα蛋白的表达。结果与正常组相比,模型组大鼠肝细胞脂肪变性明显,血脂及肝功均有不同程度的升高(P<0.05,P<0.01),大鼠肝组织LXRαmRNA及蛋白表达明显升高(P<0.01);各给药组血脂及肝功和肝组织LXRαmR-NA及蛋白的表达均较模型组显著降低(P<0.05,P<0.01),其中以健脾组下降最为明显。结论疏肝健脾方药对高脂饮食诱导的大鼠NAFLD有较好的治疗作用,其机制可能与其下调肝脏LXRα的表达有关。

两种LXR激动剂对ApoE基因敲除小鼠动脉粥样硬化影响的对照研究

目的 研究我校自行研制的LXR激动剂 (MHEC)和进口LXR激动剂 (T- 0 90 13 17)在抑制动脉粥样硬化病变形成方面的作用及主要机制。方法 以高脂饲养ApoE基因敲除 (ApoE / )小鼠为动脉粥样硬化模型 ,分为无药对照组、MHEC干预组和T -0 90 13 17干预组 ( 10mg·kg-1·d-1) ,每组 6只 ,灌胃 6周。检测血脂、分析主动脉壁中动脉粥样硬化病变的面积、用免疫组化SP法检测主动脉壁中ABCA1蛋白的表达。结果 T- 0 90 13 17组血浆总胆固醇 (TC)、甘油三酯 (TG)和高密度脂蛋白胆固醇 (HDL C)均显著高于对照组 (P <0 . 0 5 ,P <0 . 0 1) ,MHEC组仅HDL C显著高于对照组 (P <0. 0 1) ;药物干预组的动脉粥样硬化病变面积均显著降低 (P <0. 0 1) ,同时动脉壁中ABCA1的表达显著增强 (P <0 . 0 1)。结论 MHEC与T -0 90 13 17相比 ,有更好的血脂改善效果 ,二者均能显著抑制高脂饲养ApoE基因敲除小鼠动脉粥样硬化病变的形成。这可能与它们能促进动脉壁中ABCA1蛋白的表达 。

冠心康对ApoE^(-/-)动脉粥样硬化小鼠PPARγ-LXRα-ABCA1信号通路的影响

目的:观察中药复方冠心康对载脂蛋白E(apolipoprotein E,ApoE)基因敲除(ApoE-/-)动脉粥样硬化(atherosclerosis,AS)小鼠三磷酸腺苷结合盒转运体A1(ATP-binding cassette transporterA1,ABCA1)通路的影响。方法:70只ApoE-/-小鼠用高脂饲料喂养建立小鼠AS模型。14只C57BL/6J小鼠为正常对照组,给予普通饲料。70只ApoE-/-小鼠造模成功后随机分为5组,即模型组、高剂量冠心康组(生药浓度为3.456g/mL)、中剂量冠心康组(1.728g/mL)、低剂量冠心康组(0.864g/mL)和西药辛伐他汀组[3mg/(kg·d)]。每只小鼠灌胃0.5mL,每天1次。连续灌胃8周后取材,分离肝脏及主动脉。运用蛋白质印迹法检测各组小鼠过氧化物酶体增殖物激活型受体γ(peroxisome proliferator-activated receptorγ,PPARγ)、肝X受体α(liver X receptor α,LXRα)和ABCA1蛋白的表达,实时荧光定量聚合酶链反应法检测各组小鼠主动脉、肝脏PPARγ、LXRα和ABCA1mRNA的表达。结果:与C57BL/6J小鼠比较,ApoE-/-小鼠的主动脉、肝脏的PPARγ、LXRα、ABCA1mRNA的表达明显增高;与模型组小鼠比较,高、中剂量冠心康与辛伐他汀在不同程度上下调了主动脉、肝脏的PPARγ、LXRα、ABCA1mRNA的表达(P<0.05),而以高剂量冠心康的作用最为突出。低剂量组无明显改变(P>0.05)。与C57BL/6J小鼠比较,ApoE-/-小鼠的主动脉、肝脏的PPARγ、LXRα、ABCA1蛋白的表达明显增高;与模型组小鼠比较,各用药组主动脉、肝脏的PPARγ、LXRα、ABCA1蛋白的表达量下降(P<0.05),而以冠心康高剂量组作用最为突出。结论:PPARγ-LXRα-ABCA1通路在ApoE-/-小鼠脂质代谢紊乱、炎症反应方面扮演重要角色。复方冠心康能改善ApoE-/-小鼠动脉粥样硬化过程中的脂质代谢紊乱,抑制炎症反应的进展,可能与调控ApoE-/-小鼠的主动脉、肝脏PPARγ、LXRα、ABCA1 mRNA及蛋白的表达有关。

草鱼LXRα基因的克隆及表达研究

【目的】克隆草鱼肝X受体α亚型（Liver X Receptor α,LXRα）cDNA序列，分析其在草鱼不同组织中的表达情况及n-3 HUFA对草鱼肝胰脏LXRα基因表达的影响。【方法】以草鱼肝胰脏组织为材料，采用RT-PCR技术对其LXRα基因cDNA进行克隆分析，运用生物信息学的方法分析该基因序列同源性。检测LXRα基因在草鱼10种组织中的表达情况。以含0.52% n-3 HUFA的饲料饲喂草鱼95 d后，用实时定量PCR法检测n-3 HUFA对肝胰脏LXRα表达的影响。【结果】克隆得到了草鱼LXRα cDNA序列（GenBank注册号为：FJ965309），其ORF序列长度为1 230 bp，编码409个氨基酸，预测该蛋白分子式为C2083H3343N581O611S30，分子质量为47 263.7 u，等电点pI为7.91，半衰期为30 h。该蛋白质具有哺乳动物的LXRS特征：包括DNA结合位点（DBD）、p-box，配体结合域 （LBD）、激活功能-2（AF-2）区域、D-box、D区域（D region） 和属于2个锌指结构的8个半胱氨酸；与其他物种LXRα的同源性为70.7%～100%，其中与鲤鱼和斑马鱼的同源性分别达100%和94.6%。LXRα基因在草鱼肝胰脏、肌肉、心脏、鳃、精巢、肾脏、脑、脾脏、肠、腹腔脂肪等10种组织中均有表达，其中在精巢中表达水平最高（P＜0.05），在肌肉中表达水平最低 （P＜0.05）；饲喂n-3 HUFA可显著抑制草鱼肝胰脏LXRα基因的表达水平（P＜0.01）。【结论】克隆获得了草鱼LXRα基因cDNA序列，该基因在多种组织中均可表达，其编码的氨基酸序列与其他物种相似性较高，在动物进化中比较保守；n-3 HUFA可通过影响草鱼肝胰脏LXRα基因的表达，调控草鱼的脂质代谢。

三七总皂甙对脂肪变性L02肝细胞TG含量及LXRα mRNA表达的影响

目的:观察三七总皂甙(PNS)对脂肪变性L02肝细胞内甘油三酯(TG)含量及肝X受体α(LXRα)mRNA表达的影响,探讨其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48 h建立肝细胞脂肪变性模型,采用MTT法测定PNS作用于脂肪变性肝细胞的适宜浓度,随后将其分为5组,模型组、自然恢复组、PNS低剂量组(10 mg.L-1)、PNS高剂量组(50 mg.L-1),并设正常组,除模型组继续予含50%小牛血清的RPMI-1640培养基培养外,余组均改予含10%小牛血清培养。药物作用24 h后,油红O染色观察肝细胞内脂滴变化,全自动生化仪检测肝细胞内TG含量,运用RT-PCR法检测肝细胞内LXRα mRNA的表达。结果:与正常组比较,油红O染色示模型组肝细胞内橘红色脂滴明显增加,并出现脂滴融合现象,模型组TG含量明显升高(P<0.01)。PNS治疗24 h后,PNS各治疗组与自然恢复组比较,肝细胞内TG含量均明显减少(P<0.05),以低剂量组下降更为显著(P<0.01);油红O染色显示,PNS低剂量组肝细胞内脂滴数减少最为明显。与正常组比较,模型组肝细胞LXRαmRNA的表达明显上调(P<0.01);与自然恢复组比较,PNS各治疗组肝细胞LXRα mRNA的表达量均有下降,以低剂量组下降显著(P<0.05)。结论:PNS能显著降低脂肪变性肝细胞内TG含量,减轻肝细胞脂肪变性。LXRα mRNA的高表达与肝细胞脂肪蓄积密切相关,PNS可能是通过下调LXRαmRNA的表达来改善肝细胞的脂肪变性。

猪LXRα基因多态性及其与生长性状的相关性分析

肝X受体α(LXRα)是一类与脂类代谢有关的核受体,是重要的脂质传感器,LXRα基因参与调节生命代谢活动的诸多方面并且对动物生长发育过程起着重要作用。本研究采用PCR-SSCP的方法分析LXRα基因单核苷酸多态性与生长性状的相关性。结果发现TB3多态位点的BB基因型对法系长白猪个体的出生胸围的效应值最大。TB4多态位点的AA基因型对法系长白猪个体的断奶重和出生体长的效应值最大。