脂联素siRNA对3T3-L1细胞基础葡萄糖转运的影响(英文)

目的:构建携带小鼠脂联素(Acrp30)siRNA腺病毒载体,并检测其对小鼠脂肪细胞Acrp30表达以及对3T3-L1脂肪细胞基础葡萄糖转运的影响。方法:设计并化学合成小鼠脂肪细胞Acrp30 siRNA片断,将其亚克隆入AdEaxy XL腺病毒载体系统,在293细胞内包装扩增为重组腺病毒。用此重组腺病毒感染3T3-L1脂肪细胞,用RT-PCR和ELISA检测其Acrp30 mRNA和蛋白表达。采用2 Deoxy-[3H]D-glucose掺入法测定脂肪细胞葡萄糖转运。结果:设计并构建了小鼠Acrp30基因特异性siRNA腺病毒载体,该载体感染脂肪细胞后,能显著抑制Acrp30 mRNA和蛋白表达,影响3T3-L1脂肪细胞基础葡萄糖的转运,与对照组相比,差异有显著性意义(P<0.05)。结论:构建的Acrp30基因特异性siRNA腺病毒载体能有效的抑制脂联素在3T3-L1脂肪细胞中的表达,从而影响3T3-L1脂肪细胞基础葡萄糖转运。     

糖基化终末产物对3T3-L1脂肪细胞脂联素分泌的影响

目的糖基化终末产物(Advanced glycation end products,AGE)对3T3-L1脂肪细胞脂联素(adiponectin,APN)分泌的影响。方法3T3-L1小鼠前脂肪细胞体外培养并诱导分化为成熟的脂肪细胞,以PBS和BSA作为阴性对照,用含不同浓度梯度(50μg/ml、100μg/ml、150μg/ml)AGE的培养液对成熟的脂肪细胞体外培养48h,收集细胞和上清液,用RT-PCR方法检测脂联素mRNA的表达,ELISA方法检测培养液中脂联素蛋白的分泌情况。结果AGE干预组脂联素的表达在mRNA和蛋白水平较对照组均明显下降(P<0.05),并且随着AGE浓度的升高脂联素的合成和分泌逐渐减少,其中100μg/ml、150μg/ml AGE干预组脂联素的减少较对照组有显著差异(P<0.001)。结论糖基化终末产物能够通过抑制3T3-L1细胞脂联素mRNA的合成,近而抑制脂联素的分泌,且这种抑制呈浓度依赖性。     

SIRT1siRNA 对胰岛素抵抗模型小鼠脂代谢和血小板功能的影响

目的:构建携带小鼠沉默信息调节蛋白1(SIRT1)siRNA的腺病毒载体,并检测其对胰岛素抵抗模型小鼠脂代谢和血小板功能的影响。方法:首先化学合成小鼠SIRT1 shRNA片断,并将目的片断亚克隆入穿梭质粒pShuttle-U6,用PmeⅠ线性化后与pAdeasy-1在BJ5183内同源重组,筛选、鉴定、测序后,在XL10-Gold中扩增重组腺病毒质粒,最后在293细胞内包装扩增为重组腺病毒Ad-SIRT1 SiRNA。用此重组腺病毒感染3T3-L1脂肪细胞,用RT-PCR和ELISA检测其SIRT1 mRNA和蛋白表达从而鉴定其有效性。然后再将重组病毒导入胰岛素抵抗模型小鼠,检测其对小鼠脂代谢和血小板功能的影响。结果:HF组血清胆固醇、甘油三酯、游离脂肪酸和低密度脂蛋白胆固醇显著高于正常对照组(P<0.05),而在HR组上述指标则显著低于HF组(P<0.05)。且HF组高密度脂蛋白胆固醇显著低于正常对照组(P<0.05),在HR组,高密度脂蛋白胆固醇则显著高于HF组(P<0.05)。血小板活化测定结果显示,与正常对照组相比,HF组血小板早期活化程度显著增强(P<0.05),而HR组血小板早期活化程度则比HF组显著减弱(P<0.05),三个组中血小板晚期活化程度无显著性差异(P>0.05)。结论:携带目的基因的腺病毒载体感染脂肪细胞后,能显著影响其SIRT1 mRNA和蛋白表达,并影响胰岛素抵抗模型小鼠脂代谢和血小板功能。     

下调Perilipin 1基因表达对3T3-L1细胞脂解的影响

目的:研究下调围脂滴蛋白基因(PLIN1)表达对3T3-L1细胞脂解的影响。方法:采用RNA干扰技术,构建3组阳性及1组阴性sh-PLIN1重组载体,并进行菌液PCR和DNA测序鉴定。Western blot测定PLIN1A蛋白表达,评价载体下调效果。细胞转染有效载体2天后,Bodipy 493/503染色脂滴;酶学方法测定细胞中甘油三酯和甘油含量;Western blot检测甘油三酯脂肪酶(ATGL)、激素敏感性脂肪酶(HSL)及其磷酸化蛋白(p-HSL)的表达。酶联免疫吸附法(ELISA)测定细胞中环磷酸腺苷(c AMP)和蛋白激酶A(PKA)的浓度。结果:各sh-PLIN1干扰载体构建成功,且3组阳性载体均能显著下调PLIN1A蛋白的表达(P0.05)。转染有效载体后,与阴性转染组相比,sh-PLIN1转染组细胞中脂滴减小,甘油三酯含量降低,甘油含量升高,ATGL和HSL相对表达量显著升高(P0.05),p-HSL相对表达量及c AMP、PKA的浓度无显著性差异(P0.05)。结论:下调PLIN1基因表达可加快3T3-L1细胞脂解速率,其可能通过上调ATGL和HSL的表达而实现,c AMP/PKA信号通路对其无明显调节作用。     

脂联素的研究进展

脂联素（adiponectin）是一种由脂肪细胞特异性高分泌,具有多种生物学功能的特殊蛋白质它直接作用于肝脏、骨骼肌和血管,能提高胰岛素敏感性,增强脂肪酸β氧化,抵制血管炎症反应,最新研究还发现脂联素和骨生成密切相关。与其它脂肪因子不同的是,循环中脂联素的浓度与人体脂肪含量成反比,会因TNF-α的作用而上调,会被噻唑烷二酮类药物所抑制,还受到胰岛素抵抗和炎症反应的影响脂联素受体有2类,分别为AdipoR1和AdipoR2,AdipoR1主要分布在骨骼肌上,AdipoR2则高表达于肝脏组织。本文主要综述了脂联素及其受体的结构、生物学功能和研究进展。     

脂联素的信号转导通路

脂联素是一种由脂肪组织分泌的胶原样蛋白,其能降低血浆游离脂肪酸,具有抗动脉粥样硬化、改善胰岛素抵抗、降血糖、抗炎等作用,但其作用机制尚不十分明确。近期,脂联素的两型受体AdipoR1／R2已经被克隆,脂联素可能是通过其受体激活过氧化物酶体增殖物激活受体(PPAR)和AMPK信号转导通路而发挥作用。     

3脂联素受体表达调控的研究进展

脂联素是主要由脂肪细胞分泌的细胞因子,具有胰岛素增敏、抗炎、抗动脉粥样硬化和保护心肌等作用.脂联素的生物学效应需通过脂联素受体1/2的介导来完成.脂联素受体的表达水平直接影响到脂联素对下游信号通路的激活及生物学效应的发挥.对调节脂联素受体表达的因素进行研究,不但有助于揭示调控脂联素受体表达的分子机制,而且也为防治代谢紊乱和心血管疾病提供新思路.     

辣椒碱对3T3-L1 前脂肪细胞葡萄糖摄取的影响

目的:探讨辣椒碱对3T3-L1前脂肪细胞葡萄糖摄取的影响。方法:不同浓度的辣椒碱作用于3T3-L1前脂肪细胞,采用MTT测定细胞活性,GLU Test试剂盒法测定葡萄糖摄取,Western Blot法检测葡萄糖转运蛋白1(GLUT-1)表达的变化。结果:25μM辣椒碱作用72 h和50μM、100μM辣椒碱作用48 h、72 h,可显著抑制3T3-L1细胞增殖,6.25、12.5、25μM辣椒碱作用可显著促进3T3-L1细胞的葡萄糖摄入,Western Blot结果显示辣椒碱能够显著增加GLUT1蛋白表达量,差异均具有统计学意义(P0.05)。结论:低剂量辣椒碱具有降糖作用,其作用机制可能与增加GLUT-1蛋白表达有关。     

脂联素受体激动剂研究进展

脂联素是人和动物体内重要的内源性生物活性激素,具有改善胰岛素抵抗、调控脂类代谢、抗动脉粥样硬化、保护心脏、抗炎、抗氧化应激、抗纤维化以及调控细胞凋亡等作用。脂联素需要与其受体结合才能发挥生物学功能,但因其结构和浓度的影响,脂联素在临床上的应用受到一定程度限制。研究发现,多种脂联素受体激动剂通过激活脂联素受体发挥与脂联素相似的生物学功能,且脂联素受体激动剂多为人工合成的小分子或筛选的多肽,作用效果更加明确。本文整理了目前已经报道的脂联素受体激动剂及其研究进展,概述了脂联素受体激动剂对肝脏、肾脏、心脏、血管、眼和皮肤等相关器官或组织疾病的作用或影响,为开发以脂联素及其受体为靶点的治疗药物提供理论依据。     

脂联素及其受体抗肿瘤的研究进展

目前大量的研究已表明循环系统的脂联素浓度与恶性肿瘤的发病风险呈负相关。这些恶性肿瘤包括绝经后乳腺癌、子宫内膜癌、大肠癌、前列腺癌等。脂联素是在其受体(AdipoR1和AdipoR2)的介导下发挥其生物学作用。相关实验发现,AdipoR1/R2在乳腺癌、子宫内膜癌、结直肠癌等肿瘤组织中有表达。因此针对脂联素的研究可能揭示其与恶性肿瘤的发生、发展的相关性。     

Enhanced Glucose Uptake in Phenylbutyric Acid-Treated 3T3-L1 Adipocytes

Diabetes Mellitus is a chronic metabolic disease marked by altered glucose homeostasis and insulin resistance. The phosphatase PTEN antagonizes the insulin-induced-PI3K-driven cascade that normally leads to GLUT4 membrane translocation. This study investigates the effect of Phenylbutyric Acid (PBA), a chemical chaperone and a potential mediator of PTEN activity, on glucose uptake in differentiated 3T3-L1 adipocytes. Adipocyte differentiation status was quantified by Oil Red O staining and the expression of AP2. Baseline and insulin-induced adipocyte glucose uptake were assayed with and without PBA treatment. Expression of GLUT1, GLUT4, PIP3, pAkt, pPTEN, and PARK-7 was examined by western blot. Plasma membrane expression of GLUT4 was determined using immunofluorescence. Leptin and adiponectin secretion was measure by enzyme-linked immunosorbent assay. PBA treatment, alone or with insulin induction, significantly increased glucose uptake in 3T3-L1 adipocytes. PBA significantly increased GLUT1 but not GLUT4 total protein expression. However, a significant increase in membrane GLUT4 protein translocation was observed. The expression of PIP3 and pAkt increased indicating enhanced PI3k pathway activity. There was a significant decrease in PTEN activity as evident by a rise in the phosphorylated form of this protein. PARK7 protein expression increased with PBA. Treating differentiated adipocytes with PBA did not alter their differentiation status, but decreased the leptin to adiponectin ratio. Conclusion: this study showed that PBA enhances adipocyte glucose uptake potentially through its effect on glucose transporter expression and/or trafficking via the PI3K signaling pathway; suggesting PBA as a possible candidate for the ancillary management of diabetes.     

Biglycan Deletion Alters Adiponectin Expression in Murine Adipose Tissue and 3T3-L1 Adipocytes

Obesity promotes increased secretion of a number of inflammatory factors from adipose tissue. These factors include cytokines and very lately, extracellular matrix components (ECM). Biglycan, a small leucine rich proteoglycan ECM protein, is up-regulated in obesity and has recently been recognized as a pro-inflammatory molecule. However, it is unknown whether biglycan contributes to adipose tissue dysfunction. In the present study, we characterized biglycan expression in various adipose depots in wild-type mice fed a low fat diet (LFD) or obesity-inducing high fat diet (HFD). High fat feeding induced biglycan mRNA expression in multiple adipose depots. Adiponectin is an adipokine with anti-inflammatory and insulin sensitizing effects. Due to the importance of adiponectin, we examined the effect of biglycan on adiponectin expression. Comparison of adiponectin expression in biglycan knockout (bgn^−/0) and wild-type (bgn^+/0) reveals higher adiponectin mRNA and protein in epididymal white adipose tissue in bgn^−/0 mice, as well higher serum concentration of adiponectin, and lower serum insulin concentration. On the contrary, knockdown of biglycan in 3T3-L1 adipocytes led to decreased expression and secretion of adiponectin. Furthermore, treatment of 3T3-L1 adipocytes with conditioned medium from biglycan treated macrophages resulted in an increase in adiponectin mRNA expression. These data suggest a link between biglycan and adiponectin expression. However, the difference in the pattern of regulation between in vivo and in vitro settings reveals the complexity of this relationship.     

下调Fsp27基因表达联合杨梅素干预对3T3-L1细胞脂解的影响

目的:下调脂肪特异性蛋白27(Fsp27)基因表达联合杨梅素干预,观察对3T3-L1细胞中脂质代谢的影响,并探究脂滴发生、发展变化的调控机制。方法:常规培养3T3-L1前脂肪细胞,采用"鸡尾酒"法诱导其分化为成熟脂肪细胞。脂质体法转染sh-Fsp27干扰载体,以杨梅素浓度为100μmol/L的完全培养基干预成熟脂肪细胞72h。油红O染色,观察脂滴形态及大小的变化;酶法测定细胞内甘油及甘油三酯的含量,观察细胞脂质代谢的变化。Western blot检测Fsp27、激素敏感性甘油三酯脂肪酶(HSL)、甘油三酯脂肪酶(ATGL)以及丝裂原活化蛋白激酶(MAPK)信号通路蛋白的表达。结果:1. 3T3-L1细胞诱导分化后,形态由纤维样变成圆形,并伴随有细胞体积的增大。2.与对照组相比,杨梅素组和转染组细胞中甘油三酯含量下降,甘油含量升高(P 0. 05)。与其他三组相比,联合干预组细胞中甘油三酯含量减少,甘油含量增加(P 0. 05)。3.与对照组相比,其余三组细胞内Fsp27蛋白的表达量均降低,ATGL和PPARγ的表达量升高(P 0. 05)。另外,联合干预组和杨梅素组细胞内HSL的表达量和p-p38MAPK/p38MAPK的比值均大于sh-Fsp27组和对照组(P 0. 05)。结论:1. Fsp27基因沉默与杨梅素联合干预可以更大程度地促进脂肪分解代谢。2.杨梅素可通过激活MAPK信号通路,上调HSL和ATGL的蛋白表达来发挥其促脂解的作用; sh-Fsp27干扰载体通过调节PPARγ和Fsp27蛋白的表达,增加ATGL含量来加速脂肪分解。     

人源FGF-21在脂肪细胞糖代谢中的作用

近年来研究发现,成纤维细胞生长因子(FGF)-21是一种新的代谢调节因子.为了深入研究人源FGF-21（hFGF-21）的生物活性,本实验利用SUMO高效表达载体,高效表达成熟的hFGF-21,并利用小鼠3T3-L1脂肪细胞检测hFGF-21的糖代谢活性．实验结果表明,hFGF-21可促进脂肪细胞的葡萄糖吸收,且葡萄糖吸收效率呈剂量依赖性．hFGF-21作用4 h即可促进脂肪细胞糖吸收,其活性可持续24 h以上．hFGF-21与胰岛素共同作用的葡萄糖吸收效果,明显优于它们的单独作用结果,说明hFGF-21与胰岛素发挥协同作用．脂肪细胞经hFGF-21预处理后,显著增加了胰岛素促进脂肪细胞吸收葡萄糖的效率,说明hFGF-21可以增加胰岛素的敏感性．本实验为临床应用hFGF-21治疗糖尿病,增加胰岛素敏感性提供了依据．     

Regulation of Myosin Light Chain Kinase during Insulin-Stimulated Glucose Uptake in 3T3-L1 Adipocytes

Myosin II (MyoII) is required for insulin-responsive glucose transporter 4 (GLUT4)-mediated glucose uptake in 3T3-L1 adipocytes. Our previous studies have shown that insulin signaling stimulates phosphorylation of the regulatory light chain (RLC) of MyoIIA via myosin light chain kinase (MLCK). The experiments described here delineate upstream regulators of MLCK during insulin-stimulated glucose uptake. Since 3T3-L1 adipocytes express two MyoII isoforms, we wanted to determine which isoform was required for insulin-stimulated glucose uptake. Using a siRNA approach, we demonstrate that a 60% decrease in MyoIIA protein expression resulted in a 40% inhibition of insulin-stimulated glucose uptake. We also show that insulin signaling stimulates the phosphorylation of MLCK. We further show that MLCK can be activated by calcium as well as signaling pathways. We demonstrate that adipocytes treated with the calcium chelating agent, 1,2-b (iso-aminophenoxy) ethane-N,N,N'',N''-tetra acetic acid, (BAPTA) (in the presence of insulin) impaired the insulin-induced phosphorylation of MLCK by 52% and the RLC of MyoIIA by 45% as well as impairing the recruitment of MyoIIA to the plasma membrane when compared to cells treated with insulin alone. We further show that the calcium ionophore, A23187 alone stimulated the phosphorylation of MLCK and the RLC associated with MyoIIA to the same extent as insulin. To identify signaling pathways that might regulate MLCK, we examined ERK and CaMKII. Inhibition of ERK2 impaired phosphorylation of MLCK and insulin-stimulated glucose uptake. In contrast, while inhibition of CaMKII did inhibit phosphorylation of the RLC associated with MyoIIA, inhibition of CAMKIIδ did not impair MLCK phosphorylation or translocation to the plasma membrane or glucose uptake. Collectively, our results are the first to delineate a role for calcium and ERK in the activation of MLCK and thus MyoIIA during insulin-stimulated glucose uptake in 3T3-L1 adipocytes.     

Effect of Glucose Starvation on Glucose Transport in Neuronal Cells in Primary Culture from Rat Brain

The regulation of glucose transport into cultured brain cells during glucose starvation was studied. On glucose deprivation for 40 h, 2-deoxy-D-glucose (2-DG) uptake was stimulated twofold in neuronal cells but was not changed significantly in astrocytes. On refeeding, the increased activity of neuronal cells rapidly returned to the basal level, an observation indicating that the effect of glucose starvation was reversible. The increase was due solely to change in the Vmax, a finding suggesting that the number of glucose transporters on the plasma membrane is increased in starved cells. Cycloheximide inhibited this increase. In the presence of cycloheximide, the activity of 2-DG uptake of starved cells remained constant for 12 h and then slowly decreased, whereas that of fed cells decreased rapidly. These findings suggest that glucose starvation regulates glucose transport by changing the rate of net synthesis of the transporter in neuronal cells in culture.