诱导SW872前脂肪细胞分化的最优方法探讨

目的探讨诱导SW872脂肪细胞分化的最优方法。方法根据不同的分化诱导刺激分为6组:①对照组:无分化刺激,仅有DMEM/F12培养基;②胰岛素组:含2 mg/L Insulin;③1-甲基3-异丁基黄嘌呤组:含0.5 mmol/L IBMX;④促酰化蛋白组:含50 mg/L ASP;⑤激素鸡尾酒(胰岛素 1-甲基3-异丁基黄嘌呤 地塞米松组:含2 mg/L insulin 0.5 mmol/L IBMX 1.0μmol/L DEX;⑥油酸(oleic acid)组:含0.2 mg/L oleic acid。通过形态学观察、油红染色、测定细胞甘油三酯总量的方法。结果多组分化刺激中,油酸组刺激可在24 h内诱导SW872细胞分化,而且分化均匀,分化率高,分化后形成的脂肪细胞形态典型;而且油酸组促进SW872细胞分化过程中细胞内甘油三酯的积累。结论油酸是诱导SW872细胞分化的最佳方法,该方法的建立和统一,为进一步利用SW872细胞进行脂代谢、脂肪细胞功能的研究奠定了基础。     

促酰化蛋白诱导3T3-F442A前脂肪细胞分化的研究

目的：探讨新型脂源性激素促酰化蛋白（ASP）是否具有诱导前脂肪细胞分化的作用。方法： 以3T3-F442A前脂肪细胞为研究对象，通过形态学观察、油红染色测定脂肪细胞分化率，测定脂肪细胞甘油三酯合成率和甘油三酯总量，采用［3H］-胸腺嘧啶掺入法，反映ASP诱导3T3-F442A前脂肪细胞分化过程中克隆增殖的情况，并与经典的诱导分化剂胰岛素比较。结果： (1)单独的ASP刺激，即可诱导3T3-F442A 前脂肪细胞向成熟脂肪细胞的形态转变，且分化率较高，与胰岛素刺激3T3-F442A 前脂肪细胞分化相比，无显著差异（P>0.05）。(2)ASP促进3T3-F442A前脂肪细胞的甘油三酯合成，并增加细胞甘油三酯的总量，均明显高于对照组(P<0.05)，而与胰岛素组相比无显著差异（P>0.05）。(3)分化诱导24 h，ASP组［3H］-胸腺嘧啶掺入率是对照组的223%（P<0.01），胰岛素组［3H］-胸腺嘧啶掺入是对照组的589%（P<0.01）。结论： 新型的脂源性激素ASP具有诱导前脂肪细胞分化为成熟脂肪细胞的生物学作用。     

大鼠骨髓间充质干细胞分离培养及向脂肪细胞分化的实验研究

目的探讨体外大鼠骨髓间充质干细胞(MSCs)的分离培养及向脂肪细胞的分化潜能。方法从大鼠骨髓中获得间充质干细胞,体外培养传代。通过地塞米松、胰岛素等诱导MSCs向脂肪细胞分化,采用苏丹Ⅳ染色鉴定。结果诱导培养4d后,细胞胞浆内开始出现细小脂滴,12 d后在可观察到大量细胞由长梭形变为圆形或多边形,胞浆内形成高折光性的脂滴,苏丹Ⅳ脂肪染色后显示克隆中心的细胞胞浆内大量的颗粒状红色脂滴形成。细胞爬片显示约有60%骨髓间充质干细胞分化为脂肪细胞。结论大鼠骨髓间充质干细胞能进行体外分离培养并能诱导分化为脂肪细胞。     

地塞米松促进胎儿主动脉血管CD105+间充质干细胞向脂肪细胞分化

目的:研究来自胎儿血管壁内的CD₁₀₅⁺细胞是否具有间充质干细胞的特性,地塞米松是否促进其向脂肪细胞分化。方法:免疫组化检测CD105阳性的细胞在胎儿主动脉分布,分离主动脉血管的成纤维样细胞,流式细胞仪检测细胞免疫表型,并接种在脂肪分化和成骨分化的诱导培养液中培养,油红O和VonKossa染色及透射电镜鉴定脂滴和钙化基质沉淀的形成。结果:CD105阳性的细胞分布在主动脉血管内膜的内皮细胞,部分中膜和外膜。分离到的细胞CD105、CD106、CD29、CD44阳性,CD34、CD31、CD11a、CD11b、HLA-DR为阴性。油红O和VonKossa染色分别显示脂滴和钙化基质形成。电镜下诱导的脂肪细胞胞浆中可见有包膜脂滴,诱导的成骨细胞胞浆内外电子密度高的钙盐沉积。诱导液中无地塞米松,未见含大脂滴的脂肪细胞。结论:分离到主动脉壁CD₁₀₅⁺细胞具有间充质干细胞的特性,并且地塞米松促进其向脂肪细胞分化,提示血管内的细胞可以向脂肪分化可能与动脉粥样硬化的病理发生过程可能相关。     

代谢相关药物对3T3-L1脂肪细胞促酰化蛋白分泌的影响

目的:建立使用3T3-L1脂肪细胞评价药物影响促酰化蛋白(ASP)分泌的细胞模型和测定ASP分泌的ELISA方法,观察代谢相关药物二甲双胍、罗格列酮钠及立莫那班对ASP分泌的影响及机制,以及与补体C3、非酯化脂肪酸(NE-FA)释放、甘油三酯总量(TG mass)、脂肪酸摄取量的关系。方法:以3T3-L1前脂肪细胞为实验对象,诱导细胞分化,分别加入乳糜微粒、二甲双胍、罗格列酮钠及立莫那班作用48 h。采用ELISA法测定ASP、C3含量,使用酶标比色法测定NEFA含量,脂肪细胞FA摄取速度在荧光酶标仪进行动力学方法测量,采用分光光度法测定TG含量,考马斯亮蓝染料结合法测定细胞总蛋白。结果:乳糜微粒刺激ASP分泌(达411%±133%P<0.05);罗格列酮钠和立莫那班抑制ASP产生(-53%～-85%,P<0.05),同时抑制前体蛋白C3分泌(-37%～-65%,P<0.05);二甲双胍抑制ASP分泌(-54%～-100%,P<0.05),对前体蛋白C3分泌无影响;二甲双胍降低TG含量(达-60%,P<0.05)和FA摄取速度(达-75%,P<0.05)。结论:成功建立了评价药物影响促酰化蛋白(ASP)分泌的3T3-L1前脂肪细胞模型,并建立了测定ASP分泌的ELISA方法。     

无血清原代培养人前脂肪细胞并诱导分化

目的无血清原代培养人前脂肪细胞并诱导其分化为成熟脂肪细胞。方法采用胶原酶消化法分离并原代培养人前脂肪细胞,通过对细胞形态学的观察、油红O染色,以及脂肪细胞标志性酶G-3-PDH活性的测定对细胞进行鉴定。结果摸索出无血清培养并诱导人前脂肪细胞分化为成熟脂肪细胞的条件。在无血清的基础培养基中前脂肪细胞能够维持增殖。无血清分化培养基培养4d后细胞形态逐渐变圆,并出现球性脂滴,脂滴的数量逐渐增多至分化培养的第21天到达顶峰。结论在无血清培养的状态下成功诱导前脂肪细胞向脂肪细胞的分化,以作为激素或细胞因子对前脂肪细胞增殖或分化影响的研究基础。     

脂肪酸诱导脂肪细胞促酰化蛋白抵抗及机制研究

目的:观察不同浓度单不饱和脂肪酸(油酸)和饱和脂肪酸(棕榈酸)对3T3-L1(前)脂肪细胞葡萄糖转运的影响,探讨高游离脂肪酸(FFA)负荷在促酰化蛋白(ASP)抵抗形成中的意义,及FFA诱导的3T3-L1(前)脂肪细胞ASP抵抗的机制。方法:体外培养3T3-L1细胞,诱导细胞分化,用不同浓度FFA作用于3T3-L1(前)脂肪细胞,孵育过夜后收获细胞,采用2-脱氧-[3H]-D-葡萄糖掺入法,观察3T3-L1成熟脂肪细胞和前脂肪细胞基础状态和ASP刺激状态的葡萄糖摄取率;采用Western blotting法检测基础状态和ASP刺激的鸟苷酸结合蛋白alpha-q/11(Gαq/11),鸟苷酸结合蛋白beta(Gβ),磷酸化蛋白激酶Calpha(p-PKCα)和磷酸化蛋白激酶Czeta(p-PKCζ)蛋白表达。结果:ASP刺激后,3T3-L1成熟脂肪细胞和前脂肪细胞葡萄糖摄取率分别是基础状态的1.98倍(P0.01)和2.87倍(P0.01)。低浓度FFA不影响ASP刺激的葡萄糖转运;而1.0mmol/L时油酸组和棕榈酸组ASP刺激的成熟脂肪细胞葡萄糖摄取率分别减少47%(P0.05)和34%(P0.05),前脂肪细胞葡萄糖摄取率分别减少43%(P0.05)和62%(P0.01)。1.0mmol/L油酸和棕榈酸抑制成熟脂肪细胞基础状态和ASP刺激的Gβ、Gαq/11、p-PKCα和p-PKCζ蛋白表达,油酸组ASP刺激的蛋白表达分别减少了47%Gβ(P0.01),44%Gαq/11(P0.05)、39%p-PKCα(P0.05)和20%p-PKCζ(P0.05);棕榈酸组也可观察到类似现象(P0.05或P0.01)。在前脂肪细胞,油酸仅抑制ASP刺激的p-PKCα和p-PKCζ(均P0.05)蛋白表达;而棕榈酸下调上述4种信号蛋白的表达(P0.05或P0.01)。结论:油酸或棕榈酸抑制3T3-L1成熟脂肪细胞和前脂肪细胞ASP刺激的葡萄糖转运,证明FFA诱导脂肪细胞产生胰岛素抵抗状态下同时存在ASP抵抗。FFA诱导的ASP抵抗的发生机制与其干扰ASP-C5L2信号转导途径有关。ASP抵抗参与了"脂毒性"-胰岛素抵抗/肥胖症的病理生理过程。     

促酰化蛋白诱导的前脂肪细胞分化过程中转录因子表达的时序性研究

目的：观察促酰化蛋白（ASP）诱导3T3-L1前脂肪细胞的分化过程，转录因子PPARγ、C/EBPδ、C/EBPα mRNA表达的强度及时序性。 方法： 以3T3-L1前脂肪细胞为实验对象，用ASP代替经典激素鸡尾酒诱导刺激中的胰岛素，即促酰化蛋白、1-甲基-3-异丁基黄嘌呤和地塞米松（ASP+IBMX+DEX）诱导3T3-L1前脂肪细胞分化，分别在诱导分化1 d、2 d、4 d、6 d、8 d收获细胞，采用RT-PCR法检测ASP诱导3T3-L1前脂肪细胞分化过程中转录因子PPARγ、C/EBPδ、C/EBPα mRNA表达的情况。 结果： PPARγ mRNA在诱导分化1 d时有低水平表达，在诱导分化过程中表达逐步升高，在终末分化阶段仍保持高水平表达。C/EBPδ mRNA在诱导分化1 d时有中等水平表达，在诱导分化2 d时表达水平最高，诱导分化4 d时表达明显减少，在诱导分化6 d和8 d，检测不到C/EBPδ mRNA的表达。C/EBPα mRNA在诱导分化1 d仅有低水平表达，在诱导分化过程中表达逐步升高，在终末分化阶段仍保持高水平表达。IBMX+DEX诱导前脂肪细胞分化过程中，PPARγ、C/EBPδ和C/EBPα mRNA分化早期也有一定升高，但明显低于ASP诱导的转录因子的表达。 结论： ASP对转录因子C/EBPδ、C/EBPα和PPARγ表达的时序性影响，可能是ASP诱导前脂肪细胞分化的重要分子机制之一。     

前脂肪细胞分化为成熟脂肪细胞后的再增殖

用经典的的激素鸡尾酒诱导法诱导3T3-L1前脂肪细胞分化，观察并比较诱导分化过程中3T3-L1细胞的形态学变化；流式细胞仪分析细胞周期的构成细胞增殖的情况。结果发现诱导分化第4天，3T3-L1细胞中出现脂滴，此时可见较多细胞具有双核；诱导分化第8天，90％的3T3-L1细胞分化，胞浆中含有大量的脂滴，脂滴聚集于核周，形成典型的“戒环样”结构，此时仍有许多含有大量脂滴的细胞具有双核，并观察到正在分裂成为两个细胞的脂肪细胞；流式细胞仪分析的结果显示，给予分化刺激后第4天，第8天时，脂肪细胞仍处于增殖期。说明来源于3T3-L1前脂肪细胞的成熟脂肪细胞仍具有分裂增殖的能力。     

促酰化蛋白通过PLC信号途径调控脂滴相关蛋白TIP47的表达

目的 研究在3T3－L1脂肪细胞诱导分化过程中促酰化蛋白（ASP）对脂滴相关蛋白TIP47表达的影响,及阻断细胞PLC信号途径后此影响的变化。方法 (1)对诱导分化过程中的3T3－L1脂肪细胞分别给予ASP、U73122及U73122和ASP处理,并设立相应空白对照;(2)RT-PCR检测细胞中TIP47 mRNA的表达,Western blot检测细胞中TIP47蛋白的表达。结果 (1) ASP对3T3－L1脂肪细胞中TIP47 mRNA和蛋白表达有显著的上调作用;(2)PLC信号途径阻断剂U73122对其有显著的下调作用;(3) U73122和ASP处理后脂肪细胞中TIP47 mRNA和蛋白表达水平较仅ASP处理的脂肪细胞有显著降低,而较仅U73122处理的脂肪细胞有明显增高。 结论 PLC信号途径参与ASP调节TIP47表达的信号转导,从分子水平深化了对ASP成脂作用的认识,为肥胖症的认识及防治开拓新的思路。     

Fine structural studies on white adipocyte differentiation

The differentiation of mammalian white adipocytes from prenatal through early postnatal periods was studied by light and electron microscopy in C57BL mice. Anatomical regions chosen for this study were the epididymal, mesometrial, mesenteric and inguinal fat pads. In each of these regions, adipocytes differentiated from fibroblast-like cells (preadipocytes) characterized by an ovoid nucleus, profiles of rough endoplasmic reticulum, microtubules, microfilaments, spherical mitochondria, and small multiple lipid inclusions. Preadipocytes of the inguinal fat pad were first observed prior to birth (17–19 days), whereas, in the other anatomical sites, these cells were not observed until one to three days postnatally. As differentiation proceeded, and as the adipocytes assumed a spherical shape, there was a progressive decrease in the amount of rough endoplasmic reticulum and microfilaments concomitant with transient glycogen storage and an increase in the size of lipid droplets. Mature unilocular adipocytes were observed in the inguinal fat pads at three days of age. On the other hand, these cells did not appear until seven days after birth in the epididymal fat pad, mesometrium and mesentery. Regardless of the anatomical region studied, the differentiation of preadipocytes to adipocytes proceeded similarly. Preadipocytes could not be distinguished from fibroblasts morphologically within the fat depots studied. Adipocytes at the mid-stages of differentiation and in all regions studied occasionally exhibited close intercellular contacts of varying morphology.     

Leptin-dependent toll-like receptor expression and responsiveness in preadipocytes and adipocytes

Leptin, an adipokine mainly produced by adipocytes, has been well characterized with regard to its regulatory function on immune cells. Thus the question occurred of how adipocytes and preadipocytes interact with the immune system and whether or not this communication is regulated by leptin. With the present study we evaluated the Toll-like receptor (TLR) expression and TLR ligand-specific activation of murine preadipocytes and adipocytes in the presence [wild type (WT), 3T3L1] or absence of leptin (ob/ob) or leptin signaling (db/db). The ob/ob as well as db/db adipocytes and preadipocytes were characterized by a significant up-regulation of TLR1 to -9 expression when compared with WT cells. In WT preadipocytes the TLR responsiveness increased during maturation to adipocytes; however, stimulation of ob/ob and db/db cells resulted in a 10- to 20-fold higher interleukin-6 production. Signaling studies revealed, in addition to the increased TLR expression, alterations in the phosphoinositide 3 kinase signaling cascade in ob/ob and db/db cells as an explanation for this increased responsiveness. In conclusion, the present study indicates the expression and responsiveness of TLR1 to -9 in murine preadipocytes as well as adipocytes, both of which are strongly regulated by the adipokine leptin. In summary, these data further emphasize the role of fat tissue in the immune system.     

In vivo differentiation of brown adipocytes in adult mice: An electron microscopic study

The differentiation of brown adipocyte precursor cells was studied in interscapular brown adipose tissue of adult mice by electron microscopy. Different stages of cell differentiation were characterized in situ. Previous autoradiographic studies suggested that interstitial cells represent the precursor cells of fully differentiated brown adipocytes. The present observations provide morphological evidence for a progressive differentiation of interstitial stem cells into mature brown adipocytes. Four typical stages of development were identified: (1) interstitial cells, (2) protoadipocytes, (3) preadipocytes, and (4) mature brown adipocytes. Interstitial stem cells were small spindle shaped cells, situated between brown adipocytes and characterized by a high nuclear-cytoplasmic ratio, the scarcity of organelles, and the absence of lipid inclusions. Protoadipocytes resembled interstitial cells except that they contained a few tiny lipid droplets in their cytoplasm. Preadipocytes had a larger cytoplasm enclosing many mitochondria and lipid droplets; the smooth endoplasmic reticulum was well developed surrounding the lipid droplets, and was closely associated with the mitochondria. Preadipocytes had the typical structure of growing cells, developing long cytoplasmic processes between and around blood capillaries. Mature brown adipocytes represented the final stage of differentiation. Almost all their cellular volume was occupied by lipid droplets and numerous mitochondria with very dense cristae. Brown adipocytes were also characterized by a tight association with blood capillaries, as expected from metabolically active cells requiring oxygen and substrates. These observations provide direct ultrastructural evidence for a progressive differentiation of interstitial cells into brown adipocytes with a continuum of intermediate cellular types.     

积雪草酸改善小鼠脂肪细胞胰岛素抵抗的机制研究

 目的： 观察番石榴叶三萜化合物积雪草酸对小鼠3T3-L1前脂肪细胞增殖、分化以及胰岛素抵抗脂肪细胞糖脂代谢的影响并探讨其作用机制。方法：MTT法检测药物对3T3-L1前脂肪细胞增殖的影响;油红O染色法观察药物对其分化的影响。地塞米松诱导建立脂肪细胞胰岛素抵抗模型,药物干预后采用葡萄糖氧化酶法检测培养液中葡萄糖消耗量;比色法检测游离脂肪酸浓度;ELISA法检测脂联素水平;Western blotting法检测过氧化物酶体增殖物激活受体γ（PPARγ）和蛋白酪氨酸磷酸酶1B(PTP1B)蛋白表达的变化。结果：与溶媒对照组相比,积雪草酸在10~100 μmol/L时能显著促进3T3-L1前脂肪细胞增殖,但明显抑制其分化（P<0.05或P<0.01）;在30和100 μmol/L时,无论是基础状态还是胰岛素刺激状态,均能显著增加胰岛素抵抗脂肪细胞葡萄糖的消耗,减少游离脂肪酸的产生（P<0.05）;其对胰岛素抵抗脂肪细胞的脂联素分泌和PPARγ蛋白表达无明显影响（P>0.05）,但能显著下调PTP1B蛋白的表达（P<0.05或P<0.01）。结论：积雪草酸能显著改善脂肪细胞胰岛素抵抗,增加胰岛素抵抗脂肪细胞葡萄糖的消耗和减少游离脂肪酸的产生,其机制可能是其下调胰岛素信号转导的负性调节因子PTP1B的表达,增强胰岛素信号转导,从而改善胰岛素抵抗。     

Src family kinases suppress differentiation of brown adipocytes and browning of white adipocytes

Brown adipocytes and beige adipocytes can expend energy, generate heat, and increase whole‐body energy expenditure. The detailed mechanisms of adipogenesis and thermogenesis of these cells are still obscure. Here, we show that Src family kinases (SFKs) regulate both brown adipogenesis and browning of white adipocytes. To identify factors involved in brown adipogenesis, we first examined the effect of several chemical inhibitors on the differentiation of brown preadipocytes isolated from mouse brown adipose tissue (BAT) and found that treatment with PP2, the specific inhibitor of SFKs, promoted the differentiation. Another inhibitor of SFKs, PP1, also promoted the brown adipogenesis, whereas an inactive analogue of PP2, PP3, did not. Moreover, over‐expression of C‐terminal Src kinase (CSK), the negative regulator of SFKs, also promoted brown adipogenesis. Next, we examined the effect of inhibition of SFKs on the differentiation of white preadipocytes isolated from white adipose tissue (WAT). Our results showed that either PP2 treatment or CSK‐over‐expression generated Ucp1‐positive beige adipocytes, thus inducing browning of white adipocytes. Finally, our analysis showed that the expression levels and activity of SFKs in WAT were much higher than in BAT. These results taken together suggest that SFKs regulate differentiation and browning of fat cells in vivo.     

枸骨叶水提物对小鼠肥胖的预防作用及对脂肪分化的影响

目的:研究枸骨叶水提物(ICAE)对高脂饮食(HFD)小鼠肥胖的预防作用及对脂肪分化的影响.方法:本研究采用HFD诱导小鼠肥胖,同时灌胃给予ICAE,以奥利司他(orlistat)为阳性对照药。39只昆明雄性小鼠分成4组,包括对照组(n=10)、肥胖模型组(n=9)、orlistat治疗组(n=10)和ICAE治疗组(n=10)。以体重、腹内和皮下脂肪含量、肝重以及血清甘油三酯(TG)和总胆固醇(TC)水平为指标,观察ICAE对肥胖的预防作用;在实验第5周,连续5 d监测ICAE对小鼠24 h平均摄食量的影响;HE染色观察ICAE对脂肪组织的影响。分离和培养大鼠附睾来源的前脂肪细胞,尼罗红染色观察ICAE对分化脂肪细胞内脂滴形态的影响,Western blot法检测ICAE对细胞内过氧化物酶体增殖物激活受体γ(PPARγ)、脂滴包被蛋白1(Plin1)及激素敏感性脂肪酶(HSL)蛋白表达的影响。结果:ICAE可以显著抑制HFD引起的小鼠体重、腹内和皮下脂肪含量以及肝重的增加(P<0.01),并且显著降低血清TC和TG水平(P<0.01),但是对摄食量无显著影响;HE染色显示...     

Two alternative procedures for isolating adipofibroblasts from sheep skeletal muscle

Methods to isolate cells used in the study of adipocyte differentiation are lengthy, potentially damaging to the cells collected, and usually result in a mixed group of cells which are difficult to define clearly. Additionally, much work done on the differentiation of fibroblasts to preadipocytes or preadipocytes to adipocytes has relied on the use of populations of cells which are either embryonic in origin or from genetically unique animals. We therefore report two simple and rapid protocols for obtaining relatively pure populations of preadipocytes from perimuscular fat and from intramuscular fat depots of normal sheep skeletal muscle. In the first procedure, a finely minced preparation of perimuscular adipose tissue is placed directly into flasks for ceiling culture. During the second procedure, free-floating adipocytes, resulting from the enzymatic preparation of satellite cells from skeletal muscle, are placed into ceiling culture. Cells from both isolation procedures attach, grow, and are later harvested for use. These cells demonstrate proliferation and differentiation abilities of normal preadipocytes. Cell populations may be expanded for use in cloning pure populations of adipocytes or used directly in studies to identify mechanisms of adipocyte development and intercellular communication with myogenic cells.