清道夫受体B类成员1(scavenger receptor class B member 1,Scarb1)作为细胞表面的膜受体蛋白,在动物体色形成过程中发挥重要作用。为了解Scarb1基因在虹鳟(Oncorhynchus mykiss)体色形成中的作用,通过RACE技术克隆虹鳟Scarb1基因的cDN...清道夫受体B类成员1(scavenger receptor class B member 1,Scarb1)作为细胞表面的膜受体蛋白,在动物体色形成过程中发挥重要作用。为了解Scarb1基因在虹鳟(Oncorhynchus mykiss)体色形成中的作用,通过RACE技术克隆虹鳟Scarb1基因的cDNA全长,并运用生物信息学方法分析该基因及其序列结构特征,同时使用实时定量PCR(qRT-PCR)检测Scarb1基因在虹鳟、金鳟及其杂交F_(1)代不同发育阶段和不同组织中的表达情况。结果显示,Scarb1基因cDNA序列全长为2032 bp,开放阅读框1479 bp,编码492个氨基酸,预测分子质量为55.59 ku,且存在保守的CD36结构域和2个跨膜区。序列同源性分析显示,虹鳟与其他硬骨鱼类的氨基酸序列相似度为71.69%~98.58%;进化分析发现虹鳟与大马哈鱼亲缘关系最近,与哺乳动物和两栖动物亲缘关系最远。qRT-PCR检测结果表明,在虹鳟与金鳟胚胎期及出膜后各发育阶段中Scarb1基因均有不同程度表达,且表现为受精期至桑葚期的表达显著高于其他时期(P<0.05),对虹鳟与金鳟同一时期的差异分析发现该基因在胚胎期及7 dph(days post hatch)、1 M(month post hatch)、2 M和3 M时期中表达存在显著差异(P<0.01)。Scarb1基因在虹鳟与金鳟背部皮肤和背部肌肉等色素沉着性组织中表达量较高,其中在金鳟背部皮肤的表达量显著高于虹鳟(P<0.01)。此外,Scarb1基因在杂交F_(1)代不同发育时期中的表达规律与双亲一致;在不同组织中,该基因在杂交F_(1)代背部皮肤中的表达量介于双亲之间。研究结果表明,Scarb1基因与虹鳟体色形成有着密切关系,且可能在金鳟黄色体色形成过程中发挥重要作用。展开更多
目的:探究核受体亚家族4A组成员1(nuclear receptor subfamily 4 group A member 1,Nr4a1)Nr4a1激动剂胞孢子酮B(cytosporone B,Csn-B)对小鼠噪声暴露后听力损失的治疗作用。方法:采用双氧水刺激HEI-OC1毛细胞系的方法构建氧化应激细胞...目的:探究核受体亚家族4A组成员1(nuclear receptor subfamily 4 group A member 1,Nr4a1)Nr4a1激动剂胞孢子酮B(cytosporone B,Csn-B)对小鼠噪声暴露后听力损失的治疗作用。方法:采用双氧水刺激HEI-OC1毛细胞系的方法构建氧化应激细胞模型;通过实时荧光定量PCR(quantitative real-time PCR,q PCR)检测细胞中Nr4a1的mRNA表达水平;分别通过细胞计数试剂盒(cell counting kit-8,CCK8)及流式细胞术的方法检测细胞活力和细胞凋亡水平以评估Csn-B预处理后经双氧水刺激的细胞状态。构建小鼠噪声性听力损失模型,运用qPCR和免疫荧光技术检测噪声暴露后Nr4a1在小鼠耳蜗中的表达;通过检测听性脑干反应(auditory brainstem response,ABR)评估噪声暴露后以及Csn-B连续治疗13 d后小鼠听力情况。结果:双氧水刺激后HEI-OC1毛细胞中Nr4a1表达上升,细胞活力显著下降,凋亡水平显著升高;Csn-B预处理HEI-OC1毛细胞经双氧水刺激,细胞活力显著高于对照组而凋亡水平则显著低于对照组。在体研究结果显示,噪声暴露后小鼠听力显著降低,Nr4a1在小鼠耳蜗中的表达水平显著升高。噪声暴露后经Csn-B治疗小鼠听力得到改善,主要表现为Click-ABR以及Tone Burst-ABR(4000、8000Hz处)阈值下降。结论:Nr4a1激动剂Csn-B增强内耳毛细胞对氧化应激损伤的抵御能力,部分改善噪声暴露后的小鼠听力。展开更多
随着年龄的增长,机体胆固醇代谢失调和叶黄素水平异常易导致视网膜异常脂质沉积和玻璃膜疣,进而增加年龄相关性黄斑变性(age-related macular degeneration,AMD)的患病风险。视网膜细胞上的B类1型清道夫受体(scavenger receptor class B...随着年龄的增长,机体胆固醇代谢失调和叶黄素水平异常易导致视网膜异常脂质沉积和玻璃膜疣,进而增加年龄相关性黄斑变性(age-related macular degeneration,AMD)的患病风险。视网膜细胞上的B类1型清道夫受体(scavenger receptor class B type 1,SR-B1)在脂质代谢和视网膜保护中至关重要。组织细胞表面的SR-B1通过识别并结合细胞外的高密度脂蛋白(high-density lipoprotein,HDL),将游离胆固醇逆向转运至肝脏,对维持全身包括视网膜的脂质代谢平衡与避免脂质沉积至关重要。此外,HDL同样作为转运体参与叶黄素的视网膜转运过程。叶黄素,以其独特的蓝光过滤和抗氧化功能,减少蓝光对视网膜的潜在损伤并清除有害的氧自由基,发挥保护视网膜的作用。本综述将详细探讨SR-B1在视网膜中的作用,尤其是在协助胆固醇清除和叶黄素抗氧化防御方面的重要性,并评述SR-B1以及携带的有益成分如HDL和叶黄素对缓解AMD发病的机制与最新研究进展。展开更多
Changes in lipid metabolism have been implicated in protection against infectious diseases. In the first experiment of this study, we measured clinical lipid parameters in a murine model where the unmethylated cytidin...Changes in lipid metabolism have been implicated in protection against infectious diseases. In the first experiment of this study, we measured clinical lipid parameters in a murine model where the unmethylated cytidine phosphate guanosine (CpG) oligodinucleotide (ODN1826), a Toll-like receptor 9 (TLR9) agonist was administered in combination with D-galactosamine (GalN) that caused relatively liver-specific inflammation and toxicity. In the control mice group injected with phosphate-buffered saline (PBS) (acute psychological stress model associated with blood sampling), the serum triglyceride (TG) levels showed a rapid decrease followed by a rebound at 24 h as we have recently reported. However, such a TG rebound was impaired in the CpG/GalN- and solely CpG-treated groups of mice despite an absence of liver injury based on serum alanine aminotransferase levels in the latter group. Thus, the stress-associated serum TG rebound was abrogated by the injection of a sub-hepatotoxic CpG dose. In the second experiment, we simply measured the hepatic CD36 and SACRB1 (the gene for scavenger receptor B1 (SR-B1)) transcripts after the i.p. administration of PBS, CpG or CpG/GalN. There was a remarkable elevation of hepatic CD36 transcript expression in both the CpG- and CpG/GalN-treated mice at 8 h post-CpG injection whereas the increase in the PBS-treated mice was slower than the former two groups, suggesting that hepatic CD36 transcript expression is more pronounced in the combined stress models than under psychological stress alone. The individual mice data showed that the increase in CD36 expression was accompanied by a reduction in SCARB1 mRNA, showing reciprocal regulation between these two genes. Together with our previously reported findings, these data suggest that, in a murine model combining psychological stress with TLR-triggered hepatic inflammation, the psychological stress facilitates liver uptake of plasma TG (and its components fatty acids), but the subsequent re-esterification and/or release of TG-rich lipoproteins from the liver is impaired due to the concomitant TLR-signaling. We hypothesize that lipid metabolism during acute stress shifts toward an elevated hepatic uptake of lipids due to concomitant TLR signaling, facilitating the clearance of bacterial lipids by the liver.展开更多
目的ATP结合盒B亚家族成员1(ATP binding cassette subfamily B member 1,ABCB1)的异常表达在多种癌症的发生发展中发挥关键作用。然而,G蛋白偶联受体C家族5组A型(G protein coupled receptor family C group5 type A,GPRC5A)调控的ABCB...目的ATP结合盒B亚家族成员1(ATP binding cassette subfamily B member 1,ABCB1)的异常表达在多种癌症的发生发展中发挥关键作用。然而,G蛋白偶联受体C家族5组A型(G protein coupled receptor family C group5 type A,GPRC5A)调控的ABCB1表达对肺腺癌增殖的影响仍不清楚。本研究探讨了GPRC5A调控的ABCB1表达对肺腺癌增殖的影响。方法我们采用RT-PCR、Western-blot或免疫组化实验,分析ABCB1在肺腺癌细胞系、人肺腺癌组织以及GPRC5A基因敲除小鼠和野生型小鼠的气管上皮细胞和肺组织中的表达。采用细胞计数试剂盒-8(CCK-8)分析GPRC5A基因敲除小鼠气管上皮细胞对化疗药物的敏感性。采用皮下肿瘤形成实验探讨下调ABCB1表达是否可抑制体内肺腺癌增殖。采用免疫荧光和免疫沉淀实验研究GPRC5A和ABCB1之间潜在的调控关系。结果ABCB1在肺腺癌细胞系和人类肺腺癌组织中表达上调。GPRC5A基因敲除小鼠的气管上皮细胞及肺组织的ABCB1表达高于野生型小鼠。与GPRC5A野生型小鼠的气管上皮细胞相比,GPRC5A基因敲除小鼠的气管上皮细胞对塔立奇达和多柔比星更敏感。注射移植细胞28天后,接受ABCB1基因敲除细胞移植的GPRC5A-/-C57BL/6小鼠的肺肿瘤的体积和重量均明显低于野生型细胞移植小鼠(P=0.0043,P=0.0060)。此外,免疫荧光和免疫沉淀实验表明,GPRC5A通过直接结合方式调控ABCB1的表达。结论GPRC5A通过抑制ABCB1表达降低肺腺癌增殖。GPRC5A调节ABCB1表达的途径有待研究。展开更多
The scavenger receptor class B type I (SR-BI) is a high-density lipoprotein (HDL) receptor involved in reverse cholesterol transport. Some studies reported the association to be stronger in the presence of diabetes. T...The scavenger receptor class B type I (SR-BI) is a high-density lipoprotein (HDL) receptor involved in reverse cholesterol transport. Some studies reported the association to be stronger in the presence of diabetes. The full length gene encoding SR-BI is comprised in 13 exons that are alternatively spliced to produce two major transcripts: the full length SR-BI and the splice variant SR-BII, in which exon 12 is skipped. Considering that type 2 diabetes status is characterized by changes in the concentration of plasma lipids, modifications in lipoprotein size and composition, which may be important modulators of the SR-BI expression;the aims of the study were to examine the influence of SR-BI polymorphism (rs838895) on lipid profile and SR-BI mRNA expression in a population of diabetic patients living in Juana Koslay City. Blood samples were drawn from controls (n = 40) and Type 2 diabetic patients (n = 66) and DNA and total RNA were obtained. SR-BI mRNA expression was measured by RT-PCR and SR-BI polymorphism was detected by Tetra Primer ARMSPCR. Compared to controls, diabetic patients had higher fasting serum glucose, glycated hemoglobin, triglycerides, total cholesterol, lowdensity lipoprotein cholesterol, and lower highdensity lipoprotein cholesterol. SR-BI mRNA expression was lower in T2DM when compared to controls, suggesting that the hyperglycemia presents in T2DM patients down-regulates SR-BI mRNA expression. Interestingly, we found that decreased SR-BI expression resulted in markedly increased plasma LDL concentrations in T2DM subjects, and the overexpression of SRBII isoform is responsible for the markedly increased plasma LDL-c concentrations. The polymorphism (rs838895) did not modify the mRNA level of SR-BI in leucocytes from control and diabetic patients. This study provides novel evidence suggesting that hyperglycemia may affect reverse cholesterol transport by controlling SRBI expression in diabetic patients. LDL cholesterol levels are associated with low SR-BI mRNA expression in T2DM.展开更多
Scavenger receptor class B type Ⅰ (SR-BI) is an important member of the scavenger receptor family of integral membrane glycoproteins. This review highlights studies in SR-BI knockout mice, which concern the role of S...Scavenger receptor class B type Ⅰ (SR-BI) is an important member of the scavenger receptor family of integral membrane glycoproteins. This review highlights studies in SR-BI knockout mice, which concern the role of SR-BI in cholesterol and steroid metabolism. SR-BI in hepatocytes is the sole molecule involved in selective uptake of cholesteryl esters from high-density lipoprotein (HDL). SR-BI plays a physiological role in binding and uptake of native apolipoprotein B (apoB)-containing lipoproteins by hepatocytes, which identif ies SR-BI as a multipurpose player in lipid uptake from the blood circulation into hepatocytes in mice. In adrenocortical cells, SR-BI mediates the selective uptake of HDL-cholesteryl esters, which is eff iciently coupled to the synthesis of glucocorticoids (i.e. corticosterone). SR-BI knockout mice suffer from adrenal glucocorticoid insuff iciency, which suggests that functional SR-BI protein is necessary for optimal adrenal steroidogenesis in mice. SR-BI in macrophages plays a dual role in cholesterol metabolism as it is able to take up cholesterol associated with HDL and apoBcontaining lipoproteins and can possibly facilitate cholesterol efflux to HDL. Absence of SR-BI is associated with thrombocytopenia and altered thrombosis susceptibility, which suggests a novel role for SR-BI in regulating platelet number and function in mice. Transgenic expression of cholesteryl ester transfer protein in humanized SR-BI knockout mice normalizes hepatic delivery of HDL-cholesteryl esters. However, other pathologies associated with SR-BI def iciency, i.e. increased atherosclerosis susceptibility, adrenal glucocorticoid insuffi ciency, and impaired platelet function are not normalized, which suggests an important role for SR-BI in cholesterol and steroid metabolism in man. In conclusion, generation of SR-BI knockout mice has signif icantly contributed to our knowledge of the physiological role of SR-BI. Studies using these mice have identif ied SR-BI as a multi-purpose player in cholesterol and steroid metabolism because it has distinct roles in reverse cholesterol transport, adrenal steroidogenesis, and platelet function.展开更多
B类1型清道夫受体(scavenger receptor class Btype1,SR-B1)是一种与清道夫受体CD36具有高度同源性的膜糖蛋白,其表达相对广泛且有着众多生物学作用.体内外多种因素可从转录或转录后水平对SR-B1表达进行调控:PPARα/γ激动剂、部分LXR...B类1型清道夫受体(scavenger receptor class Btype1,SR-B1)是一种与清道夫受体CD36具有高度同源性的膜糖蛋白,其表达相对广泛且有着众多生物学作用.体内外多种因素可从转录或转录后水平对SR-B1表达进行调控:PPARα/γ激动剂、部分LXR激动剂、LH/HCG、雌激素等能上调SR-B1的表达;维生素E、INFα、脂多糖、IGF-1、胆酸、PXR激动剂及高糖水平等能下调SR-B1的表达;而血管紧张素Ⅱ则可对SR-B1的表达进行双向调节,且它们具体的调节机制复杂.SR-B1作为一种具有多配体结合特性的膜受体,不同配体与其结合后可介导细胞内不同信号事件及生物学效应,如介导HDL激活细胞内PI3K/Akt及MAPK信号途径,增加内皮型一氧化氮合酶的磷酸化、促进内皮细胞迁移与内皮重构.此外,非HDL类配体如LDL激活p38MAPK途径、凋亡细胞、血清淀粉样蛋白A等激活胞内MAPK途径均可由SR-B1介导.本文对近年来B类1型清道夫受体表达调控机制及信号转导通路的相关研究进行综述.展开更多
目的 :研究成石饲料对小鼠肝脏脂质代谢相关基因表达的影响,以及PDZK1(PDZ domain-containing 1)的表达对B族Ⅰ型清道夫受体(scavenger receptor B type 1,SRB1)的调节作用。方法:以成石饲料喂养C57BL/6J雄性小鼠,观察肝脏基因表达的影...目的 :研究成石饲料对小鼠肝脏脂质代谢相关基因表达的影响,以及PDZK1(PDZ domain-containing 1)的表达对B族Ⅰ型清道夫受体(scavenger receptor B type 1,SRB1)的调节作用。方法:以成石饲料喂养C57BL/6J雄性小鼠,观察肝脏基因表达的影响。分别构建小鼠PDZK1基因过表达慢病毒载体和Si RNA干扰腺病毒载体,并以成石饲料喂养C57BL/6J小鼠。分别采用实时定量PCR检测小鼠肝脏脂质代谢相关基因的m RNA表达,Western印迹法检测肝脏PDZK1及SRB1的蛋白质表达。结果:成石饲料喂养4周后,小鼠肝脏胆固醇合成关键酶3-羟基-3甲基戊二酰辅酶A还原酶基因表达显著增加(P<0.01)、胆汁酸合成关键酶胆固醇7α-羟化酶基因表达显著下降(P<0.001);PDZK1基因的表达显著抑制,SRB1基因表达相应降低(P<0.001)。PDZK1过表达慢病毒载体经腹腔注射成石饲料喂养的小鼠,4周后肝脏PDZK1蛋白表达增加37%(P<0.01),SRB1在总蛋白的表达量未改变,但在膜蛋白中表达增加136%(P<0.05)。将PDZK1的Si RNA腺病毒载体经腹腔注射成石饲料喂养的小鼠,2周后肝脏PDZK1蛋白的表达量降低49%(P<0.05),SRB1在总蛋白中表达增加60%(P<0.05),但在膜蛋白中的表达则下降14%。结论:成石饲料影响小鼠肝脏脂质代谢相关基因的表达。SRB1表达降低可能与PDZK1的抑制有关。干预小鼠肝脏PDZK1的表达会影响SRB1在肝细胞膜上的表达。展开更多
文摘清道夫受体B类成员1(scavenger receptor class B member 1,Scarb1)作为细胞表面的膜受体蛋白,在动物体色形成过程中发挥重要作用。为了解Scarb1基因在虹鳟(Oncorhynchus mykiss)体色形成中的作用,通过RACE技术克隆虹鳟Scarb1基因的cDNA全长,并运用生物信息学方法分析该基因及其序列结构特征,同时使用实时定量PCR(qRT-PCR)检测Scarb1基因在虹鳟、金鳟及其杂交F_(1)代不同发育阶段和不同组织中的表达情况。结果显示,Scarb1基因cDNA序列全长为2032 bp,开放阅读框1479 bp,编码492个氨基酸,预测分子质量为55.59 ku,且存在保守的CD36结构域和2个跨膜区。序列同源性分析显示,虹鳟与其他硬骨鱼类的氨基酸序列相似度为71.69%~98.58%;进化分析发现虹鳟与大马哈鱼亲缘关系最近,与哺乳动物和两栖动物亲缘关系最远。qRT-PCR检测结果表明,在虹鳟与金鳟胚胎期及出膜后各发育阶段中Scarb1基因均有不同程度表达,且表现为受精期至桑葚期的表达显著高于其他时期(P<0.05),对虹鳟与金鳟同一时期的差异分析发现该基因在胚胎期及7 dph(days post hatch)、1 M(month post hatch)、2 M和3 M时期中表达存在显著差异(P<0.01)。Scarb1基因在虹鳟与金鳟背部皮肤和背部肌肉等色素沉着性组织中表达量较高,其中在金鳟背部皮肤的表达量显著高于虹鳟(P<0.01)。此外,Scarb1基因在杂交F_(1)代不同发育时期中的表达规律与双亲一致;在不同组织中,该基因在杂交F_(1)代背部皮肤中的表达量介于双亲之间。研究结果表明,Scarb1基因与虹鳟体色形成有着密切关系,且可能在金鳟黄色体色形成过程中发挥重要作用。
文摘随着年龄的增长,机体胆固醇代谢失调和叶黄素水平异常易导致视网膜异常脂质沉积和玻璃膜疣,进而增加年龄相关性黄斑变性(age-related macular degeneration,AMD)的患病风险。视网膜细胞上的B类1型清道夫受体(scavenger receptor class B type 1,SR-B1)在脂质代谢和视网膜保护中至关重要。组织细胞表面的SR-B1通过识别并结合细胞外的高密度脂蛋白(high-density lipoprotein,HDL),将游离胆固醇逆向转运至肝脏,对维持全身包括视网膜的脂质代谢平衡与避免脂质沉积至关重要。此外,HDL同样作为转运体参与叶黄素的视网膜转运过程。叶黄素,以其独特的蓝光过滤和抗氧化功能,减少蓝光对视网膜的潜在损伤并清除有害的氧自由基,发挥保护视网膜的作用。本综述将详细探讨SR-B1在视网膜中的作用,尤其是在协助胆固醇清除和叶黄素抗氧化防御方面的重要性,并评述SR-B1以及携带的有益成分如HDL和叶黄素对缓解AMD发病的机制与最新研究进展。
文摘Changes in lipid metabolism have been implicated in protection against infectious diseases. In the first experiment of this study, we measured clinical lipid parameters in a murine model where the unmethylated cytidine phosphate guanosine (CpG) oligodinucleotide (ODN1826), a Toll-like receptor 9 (TLR9) agonist was administered in combination with D-galactosamine (GalN) that caused relatively liver-specific inflammation and toxicity. In the control mice group injected with phosphate-buffered saline (PBS) (acute psychological stress model associated with blood sampling), the serum triglyceride (TG) levels showed a rapid decrease followed by a rebound at 24 h as we have recently reported. However, such a TG rebound was impaired in the CpG/GalN- and solely CpG-treated groups of mice despite an absence of liver injury based on serum alanine aminotransferase levels in the latter group. Thus, the stress-associated serum TG rebound was abrogated by the injection of a sub-hepatotoxic CpG dose. In the second experiment, we simply measured the hepatic CD36 and SACRB1 (the gene for scavenger receptor B1 (SR-B1)) transcripts after the i.p. administration of PBS, CpG or CpG/GalN. There was a remarkable elevation of hepatic CD36 transcript expression in both the CpG- and CpG/GalN-treated mice at 8 h post-CpG injection whereas the increase in the PBS-treated mice was slower than the former two groups, suggesting that hepatic CD36 transcript expression is more pronounced in the combined stress models than under psychological stress alone. The individual mice data showed that the increase in CD36 expression was accompanied by a reduction in SCARB1 mRNA, showing reciprocal regulation between these two genes. Together with our previously reported findings, these data suggest that, in a murine model combining psychological stress with TLR-triggered hepatic inflammation, the psychological stress facilitates liver uptake of plasma TG (and its components fatty acids), but the subsequent re-esterification and/or release of TG-rich lipoproteins from the liver is impaired due to the concomitant TLR-signaling. We hypothesize that lipid metabolism during acute stress shifts toward an elevated hepatic uptake of lipids due to concomitant TLR signaling, facilitating the clearance of bacterial lipids by the liver.
文摘目的ATP结合盒B亚家族成员1(ATP binding cassette subfamily B member 1,ABCB1)的异常表达在多种癌症的发生发展中发挥关键作用。然而,G蛋白偶联受体C家族5组A型(G protein coupled receptor family C group5 type A,GPRC5A)调控的ABCB1表达对肺腺癌增殖的影响仍不清楚。本研究探讨了GPRC5A调控的ABCB1表达对肺腺癌增殖的影响。方法我们采用RT-PCR、Western-blot或免疫组化实验,分析ABCB1在肺腺癌细胞系、人肺腺癌组织以及GPRC5A基因敲除小鼠和野生型小鼠的气管上皮细胞和肺组织中的表达。采用细胞计数试剂盒-8(CCK-8)分析GPRC5A基因敲除小鼠气管上皮细胞对化疗药物的敏感性。采用皮下肿瘤形成实验探讨下调ABCB1表达是否可抑制体内肺腺癌增殖。采用免疫荧光和免疫沉淀实验研究GPRC5A和ABCB1之间潜在的调控关系。结果ABCB1在肺腺癌细胞系和人类肺腺癌组织中表达上调。GPRC5A基因敲除小鼠的气管上皮细胞及肺组织的ABCB1表达高于野生型小鼠。与GPRC5A野生型小鼠的气管上皮细胞相比,GPRC5A基因敲除小鼠的气管上皮细胞对塔立奇达和多柔比星更敏感。注射移植细胞28天后,接受ABCB1基因敲除细胞移植的GPRC5A-/-C57BL/6小鼠的肺肿瘤的体积和重量均明显低于野生型细胞移植小鼠(P=0.0043,P=0.0060)。此外,免疫荧光和免疫沉淀实验表明,GPRC5A通过直接结合方式调控ABCB1的表达。结论GPRC5A通过抑制ABCB1表达降低肺腺癌增殖。GPRC5A调节ABCB1表达的途径有待研究。
文摘The scavenger receptor class B type I (SR-BI) is a high-density lipoprotein (HDL) receptor involved in reverse cholesterol transport. Some studies reported the association to be stronger in the presence of diabetes. The full length gene encoding SR-BI is comprised in 13 exons that are alternatively spliced to produce two major transcripts: the full length SR-BI and the splice variant SR-BII, in which exon 12 is skipped. Considering that type 2 diabetes status is characterized by changes in the concentration of plasma lipids, modifications in lipoprotein size and composition, which may be important modulators of the SR-BI expression;the aims of the study were to examine the influence of SR-BI polymorphism (rs838895) on lipid profile and SR-BI mRNA expression in a population of diabetic patients living in Juana Koslay City. Blood samples were drawn from controls (n = 40) and Type 2 diabetic patients (n = 66) and DNA and total RNA were obtained. SR-BI mRNA expression was measured by RT-PCR and SR-BI polymorphism was detected by Tetra Primer ARMSPCR. Compared to controls, diabetic patients had higher fasting serum glucose, glycated hemoglobin, triglycerides, total cholesterol, lowdensity lipoprotein cholesterol, and lower highdensity lipoprotein cholesterol. SR-BI mRNA expression was lower in T2DM when compared to controls, suggesting that the hyperglycemia presents in T2DM patients down-regulates SR-BI mRNA expression. Interestingly, we found that decreased SR-BI expression resulted in markedly increased plasma LDL concentrations in T2DM subjects, and the overexpression of SRBII isoform is responsible for the markedly increased plasma LDL-c concentrations. The polymorphism (rs838895) did not modify the mRNA level of SR-BI in leucocytes from control and diabetic patients. This study provides novel evidence suggesting that hyperglycemia may affect reverse cholesterol transport by controlling SRBI expression in diabetic patients. LDL cholesterol levels are associated with low SR-BI mRNA expression in T2DM.
基金Supported by Top Institute Pharma (TIPharma Project T2-110 Hoekstra M and Van Berkel TJC)+2 种基金Grant 2008T070 from the Netherlands Heart Foundation (Hoekstra M)VIDI Grant 917.66.301 from the Netherlands Organization for Scientific Research (Van Eck M)Van Eck Mis an Established Investigator of the Netherlands Heart Foundation (Grant 2007T056)
文摘Scavenger receptor class B type Ⅰ (SR-BI) is an important member of the scavenger receptor family of integral membrane glycoproteins. This review highlights studies in SR-BI knockout mice, which concern the role of SR-BI in cholesterol and steroid metabolism. SR-BI in hepatocytes is the sole molecule involved in selective uptake of cholesteryl esters from high-density lipoprotein (HDL). SR-BI plays a physiological role in binding and uptake of native apolipoprotein B (apoB)-containing lipoproteins by hepatocytes, which identif ies SR-BI as a multipurpose player in lipid uptake from the blood circulation into hepatocytes in mice. In adrenocortical cells, SR-BI mediates the selective uptake of HDL-cholesteryl esters, which is eff iciently coupled to the synthesis of glucocorticoids (i.e. corticosterone). SR-BI knockout mice suffer from adrenal glucocorticoid insuff iciency, which suggests that functional SR-BI protein is necessary for optimal adrenal steroidogenesis in mice. SR-BI in macrophages plays a dual role in cholesterol metabolism as it is able to take up cholesterol associated with HDL and apoBcontaining lipoproteins and can possibly facilitate cholesterol efflux to HDL. Absence of SR-BI is associated with thrombocytopenia and altered thrombosis susceptibility, which suggests a novel role for SR-BI in regulating platelet number and function in mice. Transgenic expression of cholesteryl ester transfer protein in humanized SR-BI knockout mice normalizes hepatic delivery of HDL-cholesteryl esters. However, other pathologies associated with SR-BI def iciency, i.e. increased atherosclerosis susceptibility, adrenal glucocorticoid insuffi ciency, and impaired platelet function are not normalized, which suggests an important role for SR-BI in cholesterol and steroid metabolism in man. In conclusion, generation of SR-BI knockout mice has signif icantly contributed to our knowledge of the physiological role of SR-BI. Studies using these mice have identif ied SR-BI as a multi-purpose player in cholesterol and steroid metabolism because it has distinct roles in reverse cholesterol transport, adrenal steroidogenesis, and platelet function.
文摘B类1型清道夫受体(scavenger receptor class Btype1,SR-B1)是一种与清道夫受体CD36具有高度同源性的膜糖蛋白,其表达相对广泛且有着众多生物学作用.体内外多种因素可从转录或转录后水平对SR-B1表达进行调控:PPARα/γ激动剂、部分LXR激动剂、LH/HCG、雌激素等能上调SR-B1的表达;维生素E、INFα、脂多糖、IGF-1、胆酸、PXR激动剂及高糖水平等能下调SR-B1的表达;而血管紧张素Ⅱ则可对SR-B1的表达进行双向调节,且它们具体的调节机制复杂.SR-B1作为一种具有多配体结合特性的膜受体,不同配体与其结合后可介导细胞内不同信号事件及生物学效应,如介导HDL激活细胞内PI3K/Akt及MAPK信号途径,增加内皮型一氧化氮合酶的磷酸化、促进内皮细胞迁移与内皮重构.此外,非HDL类配体如LDL激活p38MAPK途径、凋亡细胞、血清淀粉样蛋白A等激活胞内MAPK途径均可由SR-B1介导.本文对近年来B类1型清道夫受体表达调控机制及信号转导通路的相关研究进行综述.
