海地瓜硫酸软骨素对3T3-L1前脂肪细胞增殖和分化的影响

目的研究海地瓜硫酸软骨素(Acaudina Molpadioideschondroitin sulfate,AM-CHS)对3T3-L1前脂肪细胞增殖和分化的影响,并探讨其作用机制。方法采用传统的鸡尾酒诱导剂诱导分化3T3-L1前脂肪细胞,以MTT法检测AM-CHS对3T3-L1前脂肪细胞及不同分化阶段3T3-L1细胞增殖活性的影响;分别采用油红O染色和甘油三酯(triglycerides,TG)含量测定法评价其对3T3-L1前脂肪细胞分化的影响。采用RT-PCR法检测脂肪细胞中过氧化物酶体增殖体激活受体γ(peroxisome proliferators-activated receptors gamma,PPARγ)、CCAAT增强子结合蛋白α(CCAAT/enhancer bind-ing protein alpha,C/EBPα)、固醇调节元件结合蛋白-1c(ste-rol regulatory element binding protein-1c,SREBP-1c)等分化相关基因的mRNA表达水平。结果 AM-CHS能明显抑制3T3-L1前脂肪细胞和成熟脂肪细胞的增殖,抑制3T3-L1前脂肪细胞的分化过程,以对分化早期的抑制作用最强。RT-PCR结果表明,AM-CHS能明显降低脂肪细胞PPARγ、C/EBPα和SREBP-1c mRNA的表达。结论海地瓜AM-CHS能明显抑制3T3-L1前脂肪细胞的增殖和分化,其作用机制与下调分化相关基因PPARγ、C/EBPα和SREBP-1c的表达有关。     

原代培养的人皮下和网膜前脂肪细胞分化特性比较

目的探讨原代培养的人皮下和网膜前脂肪细胞在体外以无血清培养基诱导分化条件下细胞特性的差别。方法选择8例行择期电切开手术的健康成年女性腹部皮下和网膜分离前脂肪细胞,进行原代培养。细胞在无血清培养基诱导分化的条件下体外培养14d。观察分化后不同部位来源细胞的细胞内脂质含量和前脂肪细胞分化标志物——甘油-3-磷酸脱氢酶的活性。细胞的胰岛素敏感性通过葡萄糖消耗试验进行测定。结果诱导分化后,人皮下和网膜前脂肪细胞的胰岛素敏感性指标葡萄糖消耗量和细胞晚期分化指标G3PDH活性差异均无统计学意义（P〉0．05）。网膜来源的前脂肪细胞分化后脂质含量指标油红O高于皮下来源细胞（t=2．506,P=0．025）。结论在同等分化条件下,网膜前脂肪细胞较之皮下来源细胞的脂肪含量增加,提示前脂肪细胞的分化存在部位特异性。     

Verapamil inhibits 3T3-L1 preadipocyte differentiation

Objective: To investigate the effect of the calcium channel blocker verapamil on adipocyte differentiation and its mechanism of action. Methods: Preadipocytes from 3T3-L1 strain mouse embryos were cultured and differentiated into matured adipocytes in vitro. Verapamil was added to the culture medium in the concentration of 30 μmol/L on Day 0. Cell differentiation was determined by Oil Red O staining and marker gene mRNA expression was evaluated and compared by RT-PCR. The fluo-3/AM probe and laser scanning confocal microscopy were used to measure intracellular calcium concentrations. Results: ①The differentiation rate of 3T3-L1 preadipocytes exposed to verapamil was lower than that of untreated cells. ②Verapamil promoted the retention of pref-1 gene expression. Lipoprotein lipase expression in the verapamil group was significantly lower than that in the control group on Day 4, Day 6 and Day 8 (P < 0.05) and resistin expression was significantly lower than that in the control group on Day 6, Day 8 and Day 10 (P < 0.05). Fatty acid synthase expression in the verapamil group was significantly lower than that in the control group from Day 2 (P < 0.05). ③ Intracellular concentrations of calcium [Ca2+]i in the verapamil group were significantly decreased compared with those in the control group on Day 2, Day 4 and Day 6 (P < 0.05), while there was no obvious difference between the two groups on Day 0 (P > 0.05). Conclusion: In 3T3-L1 preadipocytes verapamil significantly reduced adipocyte differentiation, down-regulated the mRNA expression of three marker genes for adipocytes differentiation, and prolonged the mRNA expression of an inhibitor of differentiation. The inhibitory effect of verapamil on differentiation may involve its role as a blocker of calcium influx in adipocytes.     

Cold adaptation modulates Ca<Superscript>2+</Superscript> signaling in brown preadipocytes

One-week cold exposure of mice led to a 2-fold increase in the density of α₁-adrenoceptors in brown adipose tissue. The density of α₁-adrenoceptors returned to normal after adaptation to cold for 2 weeks. The reduced Ca²⁺ signaling in stem cells of brown fat activated via β-adrenoceptors and cAMP was transformed into the Ca²⁺-system induced by α₁-adrenoceptors and similar to that in mature brown adipocytes. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 7, pp. 59–62, July, 2004     

Cold Adaptation Modulates Ca2+ Signaling in Brown Preadipocytes

One-week cold exposure of mice led to a 2-fold increase in the density of alpha1-adrenoceptors in brown adipose tissue. The density of alpha1-adrenoceptors returned to normal after adaptation to cold for 2 weeks. The reduced Ca2+ signaling in stem cells of brown fat activated via beta-adrenoceptors and cAMP was transformed into the Ca2+-system induced by alpha1-adrenoceptors and similar to that in mature brown adipocytes.     

油酸诱导SW872前脂肪细胞分化的作用

目的探讨油酸对SW872前脂肪细胞的诱导分化作用,为体外研究脂肪细胞功能及其相关疾病建立细胞模型。方法体外培养,0.6 mmol/L油酸诱导SW872前脂肪细胞分化,光学显微镜观察SW872前脂肪细胞形态的变化,油红O染色观察胞浆中脂滴的聚集,化学比色法测定细胞中三酰甘油(TG)总量,RT-PCR方法检测不同分化时间点转录因子过氧化物酶体增殖物激活受体-γ2(PPAR-γ2)与CAAT/增强子结合蛋白-α(C/EBP-α)mRNA的时序性表达。结果1.油酸诱导分化24 h时SW872前脂肪细胞胞体由小变大,形态由梭形变为圆形,胞浆中出现细小脂滴;诱导48 h时细胞体积进一步变大,几乎所有细胞形态变圆,胞浆中脂滴明显增多;诱导分化72 h时细胞呈戒环状,胞浆脂滴含量更多,油红O染色胞浆中可见丰富的脂肪染色。2.油酸诱导分化24 h时,细胞中TG总量增多;诱导分化48 h时TG总量是分化前8.5倍;诱导分化72 h时TG总量是分化前14倍(P<0.01)。3.油酸诱导分化24 h时PPAR-γ2与C/EBP-αmRNA表达轻度升高;诱导分化48 h时PPAR-γ2与C/EBP-αmRNA表达明显升高,分别是诱导分化前的10.23倍和12.91倍;诱导分化72 h时PPAR-γ2与C/EBP-αmRNA表达进一步升高,分别是诱导分化前的14.15倍和14.82倍(P均<0.01)。结论油酸刺激72 h能促进SW872前脂肪细胞中TG的合成与积聚,可诱导SW872前脂肪细胞中转录因子PPAR-γ2与C/EBP-αmRNA时序性表达,成功诱导SW872前脂肪细胞分化为成熟脂肪细胞。     

以PPARγ2为靶点的传统中药细胞学筛选方法的建立和应用

目的构建含人PPARγ2基因启动子的荧光素酶表达质粒,通过建立稳定转染该质粒的细胞系,建立传统中药细胞学筛选方法。方法首先以p GL3-Basic-Luc和p GL3-Enhancer-Luc为载体构建含不同长度人PPARγ2基因启动子序列的荧光素酶表达质粒。脂质体转染,建立稳定转染上述质粒的3T3-L1细胞系。选取红花和茜草等28种可能具有减肥作用的中药制备成中药水溶性提取物(ECMH),观察不同浓度ECMH对3T3-L1细胞中荧光素酶表达的影响。结果 p GL3-Enhancer-PPARγ2 625 bp-Luc质粒稳定转染的细胞荧光素酶表达最高,是本底的200倍左右。故采用此细胞系进行传统中药筛选,红花ECMH在10、100和1 000μg/m L时均可使3T3-L1细胞中荧光素酶的表达明显增加,分别为对照组的1.63倍、1.90倍和2.30倍(P0.05)。在10~1 000μg/m L荷叶、茜草ECMH也均能促进3T3-L1细胞中荧光素酶的表达,在浓度为1 000μg/m L时荷叶和茜草对3T3-L1细胞中荧光素酶的表达作用最强,分别为对照组的2.03倍(P0.01)和2.00倍(P0.01)。结论成功构建p GL3-Enhancer-PPARγ2625 bp-Luc质粒,并建立稳定转染的3T3-L1细胞系。红花、荷叶和茜草的ECMH能明显促进3T3-L1细胞中人PPARγ2基因启动子的活性,它们可能成为未来潜在的减肥药物。     

贝那普利、替米沙坦对人前脂肪细胞脂联素表达的影响

目的探讨贝那普利、替米沙坦对体外原代培养的人网膜和皮下来源的前脂肪细胞脂联素(APN)表达的影响。方法自12例行电切开腹部手术的健康成年女性腹部皮下和网膜分离前脂肪细胞,分为3组,即无干预正常对照组(NC组)、血管紧张素转换酶抑制剂类药物贝那普利组(ACEI组)和血管紧张素Ⅱ受体拮抗剂类药物替米沙坦组(ARB组),诱导分化共14 d。放射免疫法测定各组APN mRNA表达水平。结果与NC组比较,ACEI组、ARB组体外原代培养的人网膜和皮下前脂肪细胞中APN mRNA表达明显增强。结论贝那普利、替米沙坦可促进网膜来源的前脂肪细胞的分化,在以腹型肥胖为特征的代谢综合征干预方面可能具有广泛的应用前景。     

Lipogenic and mitogenic effects of insulin during conversion of Ob17 cells to adipose-like cells

Chronic exposure to insulin of confluent cells of a preadipocyte clonal line (Ob17) leads to an acceleration of their development into adipose cells. The short-term effects of insulin have been examined by the stimulation of [14C] alpha-aminoisobutyrate uptake and the long-term effects by the increase in the activity levels of several lipogenic enzymes and in the intracellular triacylglycerol content. These metabolic effects of insulin occur within a physiological range of concentrations (EC50 congruent to 1 nM). As compared to insulin, dose-response curves obtained with proinsulin on these parameters show at least a 10-fold decrease in sensitivity of the cells. In contrast, the growth-promoting effects of both insulin and proinsulin occur at supraphysiological concentrations (EC50 greater than 300 nM). This mitogenic response is likely mediated through binding to receptors of insulin-like growth factors. Our data demonstrate that long-term effects of insulin on lipid synthesis can be dissociated from its effect on cell growth. Therefore the Ob17 cell line should be a useful model to study the role of insulin in the regulation of lipid synthesis in adipose cells.     

基因重组融合蛋白hNPY对小鼠前脂肪细胞增殖和分化影响的实验研究

目的：前脂肪细胞是一类具有增殖和向脂肪细胞分化潜力的特异化的前体细胞,如能找到可促进前脂肪细胞增殖和分化的因子或药物,并在脂肪组织移植的同时使用,则有希望提高脂肪组织的移植效果,本实验探索一种新的人体肥胖关联基因和外周脂肪细胞激动剂一基因重组融合蛋白hNPY对小鼠3T3-L1前脂肪细胞增殖和分化的影响及其分子调控机制。方法：采用基因工程技术设计hNPY基因上下游序列,经过PCR反应合成hNPY的cDNA后与pET28a＋载体重组,再将已构建好、并经测序确认无误的重组质粒pET28a—NPY转导至大肠杆菌BL21（DE3）,再由IPTG诱导表达hNPY融合蛋白、并进行纯化;然后,将体外培养的小鼠3T3-L1前脂肪细胞经由3-异丁基-1-甲基黄嘌呤、胰岛素和地塞米松进行联合诱导;诱导2d后,再将此细胞分为三组,即空白对照组（未加任何诱导剂组）、经典诱导组（胰岛素诱导）和实验干预组（hNPY融合蛋白干预）,其中,实验干预组再按照hNPY融合蛋白浓度不同又分为高、中、低三个浓度组（10^-8mol／L、10^-19mol／L和10^-9 mol／L）。分别于细胞培养的第7d和第12d用相差显微镜观察各组细胞的形态学变化,再于细胞培养的第12d用油红O染色观察脂肪细胞的分化程度;同时,采用MTT法检测该细胞的增殖状况;采用Westernblot法检测脂肪细胞分化相关基因过氧化物体增殖剂活化受体-γ（PPAR-γ）、CAAT／增强子结合蛋白-a（C／EBP-a）蛋白的表达水平。结果：低浓度（10^-10 mol／L）的hNPY融合蛋白,无明显促进小鼠3T3-L1前脂肪细胞增殖和分化的作用效果;中浓度（10^-9 mol／L）的hNPY融合蛋白,可有效促进小鼠3T3-L1前脂肪细胞增殖及细胞数量增多;而高浓度（10^-8 mol／L）的hNPY融合蛋白,不仅能明显促进小鼠3T3-L1前脂肪细胞的细胞增殖和分化,且能显著提高该细胞C／EBPa和PPARγ的表达水平、而明显降低INSIG-2的表达。结论：高浓度（10^-8mol／L）的基因重组融合蛋白hNPY能够明显促进小鼠3T3-L1前脂肪细胞的增殖和分化,其促进3T3-L1细胞增殖和分化的分子调控机制很可能与上调PPARγ、C／EBPa表达和降低INSIG-2表达水平有关,这提示：hNPY作为脂肪细胞膜上受体NPYR的有效促进剂或激动剂,未来很可能成为人体外周脂肪细胞一个新的作用靶点。