脂肪细胞型脂肪酸结合蛋白的研究进展

脂肪细胞型脂肪酸结合蛋白（adipocyte fatty acid binding protein,AFABP/aP2）作为脂肪酸结合蛋白（FABPS）超家族成员之一,广泛存在于各种正常的组织细胞中,参与脂肪酸贮存,运输与降解等过程。近年来,对脂肪细胞型脂肪酸结合蛋白的研究已成为热点,本文就其主要特征及其与各类疾病的关系作一简要综述。     

动物FABP基因家族研究进展及育种应用探讨

脂肪酸结合蛋白家族(FABPs)是脂质结合蛋白超家族成员,它们广泛存在于哺乳动物的小肠、肝、心、脑、骨骼肌等多种细胞内。在调节细胞内长链脂肪酸(LCFA)的摄取、转运和代谢等生理活动发挥着重要的作用。本研究对几种常见的脂肪酸结合蛋白,如心脏型脂肪酸结合蛋白(H-FABP)、脂肪细胞型脂肪酸结合蛋白(A-FABP)、肠型脂肪酸结合蛋白(I-FABP)基因的基因多态性、在动物育种上的应用等相关研究进展进行了阐述,为利用FABPs基因改良和提高畜产品品质提供参考。     

糖尿病和动脉粥样硬化的潜在靶标——FABP4（aP2）

脂肪细胞型脂肪酸结合蛋白（A-FABP／FABP4／aP2／ALBP）作为脂肪酸结合蛋白家族中的一员,在脂肪细胞和巨噬细胞中高表达。在鼠及人的肥胖个体中FABP4表达均增加。FABP4基因缺陷可改善胰岛素抵抗,并抑制动脉粥样硬化的发生发展。FABP4抑制剂减小了动物体内动脉硬化斑块的大小且提高了胰岛素敏感性。FABP4已经成为治疗糖尿病和动脉粥样硬化的重要潜在靶标。     

肝型脂肪酸结合蛋白研究进展

肝型脂肪酸结合蛋白(liver-type fatty acid binding protein,L-FABP,FABPI)是脂肪酸结合蛋白家族的成员之一,主要在肝脏、小肠、肾脏及胰腺等组织细胞中有表达.研究发现,L-FABP与脂肪酸的摄取、转运、代谢调节有关.近年研究表明,肝型脂肪酸结合蛋白(L-FABP)与肿瘤、肾脏疾病、脂肪肝、肥胖、糖尿病等多种疾病的发生发展密切相关.本文就肝型脂肪酸结合蛋白的分子结构、功能以及与疾病的关系作一综述.     

克隆用于干癣病态分析的脂肪酸结合蛋白的cDNA

新泻大学医学部教授小野辉夫等小组从小鼠皮肤中分离出新的脂肪酸结合蛋白(C-FABP),并克隆了cDNA。C-FABP与人干癣病表皮细胞大量表达的脂肪酸结合蛋白(PA-FABP)的同源性高达81.5％。C-FABP的表达可能与干癣病有某种关系。在大阪召开的第67届日本生化学会上发表了该项成果。 得到的C-FABP的cDNA编码了135个氨基酸,C-FABP是分子量约15000的蛋白。目前已得知FABP家族有心肌型、脂肪细胞型、髓磷脂型等多种,它们与这次新分离的C-FABP的同源性分别为48％、52.6％、54.1％。C-FABP参与静电性结合,含有在FABP家族中保守性强的精氨酸残基。但含     

过表达RBP4抑制体外培养的猪前体脂肪细胞分化

为研究视黄醇结合蛋白4(retinol binding protein 4,RBP4)对猪前体脂肪细胞分化的影响,实验构建了RBP4重组腺病毒表达载体,包装并感染猪前体细胞,采用油红O染色和Real-time PCR等方法,检测了过表达RBP4对成脂分化的作用. 研究结果显示,重组腺病毒RBP4载体构建成功,转染猪前体脂肪细胞后,使RBP4的mRNA水平和蛋白水平分别增加了约400倍和20倍. 过表达RBP4能减少脂肪细胞的脂质积累,降低成脂关键基因过氧化物酶体增生物激活受体γ (peroxisome proliferator-activated receptor gamma, PPARγ)和脂肪酸结合蛋白2 (adipocyte protein 2, aP2)的表达. 结果表明,RBP4对猪前体脂肪细胞分化有抑制作用,为进一步研究RBP4对猪前体脂肪细胞分化的作用机制奠定基础.     

游离脂肪酸受体的结构、分布及功能

游离脂肪酸的生理功能及其与某些疾病的相关性长期以来受到人们的关注。由于特异性膜受体一直未被发现．关于其分子机制的认识无法深入。最近的研究表明,长链脂肪酸是孤儿型G蛋白偶联受体GPR40的配基．而短链脂肪酸则是孤儿型G蛋白偶联受体GPR4l和GPR43的配基。体外实验显示,长链脂肪酸通过GPR40增强胰岛B细胞的分泌功能;短链脂肪酸经GPR41刺激脂肪细胞中瘦蛋白(1eptin)的产生。GPR43在白细胞活化过程中发挥一定的作用。作为潜在的药物作用靶点,游离脂肪酸特异性受体为寻找治疗代谢性疾病的新手段指明了的方向。     

TNF-α影响胰岛素对原代培养大鼠脂肪细胞增殖及生脂基因的转录表达

采用RTPCR、MTT比色法和油红O染色提取法,分别测定外源TNFα、胰岛素对原代培养大鼠前体脂肪细胞增殖及脂肪生成和碳水化合物反应元件结合蛋白(ChREBP)、固醇调控元件结合蛋白(SREBP)1c、脂肪酸合酶(FAS)及乙酰辅酶A羧化酶(ACC)1基因转录表达的影响。结果表明,TNFα可有效抑制胰岛素对原代培养大鼠前体脂肪细胞增殖的促进作用,并通过抑制胰岛素对转录因子SREBP1c和脂肪酸合酶FAS及ACC1基因转录表达的促进作用,减少脂肪酸的生物合成,抑制成熟脂肪细胞的脂肪生成,证明TNFα是动物脂肪形成的有效抑制因子。此外,TNFα下调ChREBPmRNA表达,但胰岛素在低糖条件下对其表达没有明显影响     

烟碱型乙酰胆碱受体介导脂肪组织褐变

哺乳动物有三种脂肪细胞:白色脂肪细胞(white adipocyte)、褐色脂肪细胞(brown adipocyte)、米色脂肪细胞(beige adipocyte)。白色脂肪细胞主要储存甘油三酯、并分泌脂肪因子(adipokines);褐色脂肪细胞,可利用葡萄糖和脂肪酸经“非寒战产热”(non-shivering thermogenesis)为机体提供热量;褐色脂肪细胞是人类婴儿期的重要热量来源,但却在成年期退化。     

BAMBI通过促进ERK1/2磷酸化抑制猪前体脂肪细胞分化

为了研究BAMBI在猪前体脂肪细胞分化过程中的作用,构建了BAMBI慢病毒干扰载体,包装并感染猪前体脂肪细胞,采用油红O染色、油红O提取比色法检测猪前体脂肪细胞分化情况,采用Real-time qPCR、Western blotting检测成脂标志基因mRNA以及蛋白水平表达的变化情况。结果表明,BAMBI慢病毒干扰载体感染前体脂肪细胞后显著降低了BAMBI的表达,shRNA2干扰效率最高,达到了60%以上,干扰BAMBI后能增加猪脂肪细胞的脂质积累,增加了成脂标志基因过氧化物酶体增殖物激活受体γ(Peroxisome proliferator-activated receptorγ,PPARγ)和脂肪酸结合蛋白2(Adipocyte protein 2,ap2)的表达。此外,干扰BAMBI后ERK1/2的磷酸化水平减少了。这些结果表明,BAMBI可能通过促进ERK1/2的磷酸化抑制脂肪细胞分化。     

Relationship between fatty acid binding proteins,acetyl-CoA formation and fatty acid synthesis in developing human placenta

The relationship between fatty acid binding proteins, ATP citrate lyase activity and fatty acid synthesis in developing human placenta has been studied. Fatty acid binding proteins reverse the inhibitory efect of palmitoyl-CoA and oleate on ATP citrate lyase and fatty acid synthesis. In the absence of these inhibitors fatty acid binding proteins activate ATP citrate lyase and stimulate [ 1-¹⁴ C] acetate incorporation into placental fatty acids indicating binding of endogenous inhibitors by these proteins. Thus these proteins regulate the supply of acetyl-CoA as well as the synthesis of fatty acids from that substrates. As gestation proceeds and more lipids are required by the developing placenta fatty acid binding protein content, activity of ATP citrate lyase and rate of fatty acid synthesis increase indicating a cause and efect relationship between the demand of lipids and supply of precursor fatty acids during human placental development.     

Relationship between glycerol-3-phosphate dehydrogenase,fatty acid synthase and fatty acid binding proteins in developing human placenta

The activities of the enzymes glycerol-3-phosphate dehydrogenase and fatty acid synthase are inhibited by palmitoyl-coenzyme A and oleate. The two isoforms of fatty acid binding proteins (PI 6.9 and PI 5.4) enhance the activities of glycerol-3-phosphate dehydrogenase and fatty acid synthase in the absence of palmitoyl-coenzyme A or oleate and also protect them against palmitoyl-coenzyme A or oleate inhibition. Levels of fatty acid binding proteins, the activities of the enzymes fatty acid synthase and glycerol-3-phosphate dehydrogenase increase with gestation showing a peak at term. However, the activity of fatty acid synthase showed the same trend up to the 30th week of gestation and then declined slightly at term. With the advancement of pregnancy when more lipids are required for the developing placenta, fatty acid binding proteins supply more fatty acids and glycerol-3-phosphate for the synthesis of lipids. Thus a correlation exists between glycerol-3-phosphate dehydrogenase, fatty acid synthase and fatty acid binding proteins in developing human placenta.     

Study on fatty acid binding by proteins in yeast. Dissimilar results in Saccharomyces cerevisiae and Yarrowia lipolytica.

1. The presence of soluble proteins with fatty acid binding activity was investigated in cell-free extracts from Saccharomyces cerevisiae and Yarrowia lipolytica cultures. 2. No significant fatty acid binding by proteins was detected in S. cerevisiae, even when grown on a fatty acid-rich medium, thus indicating that such proteins are not essential to fatty acid metabolism. 3. An inducible fatty acid binding protein (K0.5 = 3-4 microM) was found in Y. lipolytica which had grown on a minimal medium with palmitate as the sole source of carbon and energy. 4. The relative molecular mass of this protein was 100,000 as inferred from Sephacryl S-200 gel filtration.     

Potent and selective biphenyl azole inhibitors of adipocyte fatty acid binding protein (aFABP)

Herein we report the first disclosure of biphenyl azoles that are nanomolar binders of adipocyte fatty acid binding protein (aFABP or aP2) with up to thousand-fold selectivity against muscle fatty acid binding protein and epidermal fatty acid binding protein. In addition a new radio-ligand to determine binding against the three fatty acid binding proteins was also synthesized.     

The role of fatty acid binding proteins in metabolic syndrome and atherosclerosis

PURPOSE OF REVIEW: The global prevalence of obesity is increasing epidemically. Obesity causes an array of health problems, reduces life expectancy, and costs over US dollar 100 billion annually. More than a quarter of the population suffers from an aggregation of co-morbidities, including obesity, atherosclerosis, insulin resistance, dyslipidemias, coagulopathies, hypertension, and a pro-inflammatory state known as the metabolic syndrome. Patients with metabolic syndrome have high risk of atherosclerosis as well as type 2 diabetes and other health problems. Like obesity, atherosclerosis has very limited therapeutic options. RECENT FINDINGS: Fatty acid binding proteins integrate metabolic and immune responses and link the inflammatory and lipid-mediated pathways that are critical in the metabolic syndrome. This review will highlight recent studies on fatty acid binding protein-deficient models and several fatty acid binding protein-mediated pathways specifically modified in macrophages, cells that are paramount to the initiation and persistence of cardiovascular lesions. SUMMARY: Adipocyte/macrophage fatty acid binding proteins, aP2 and mal1, act at the interface of metabolic and inflammatory pathways. These fatty acid binding proteins are involved in the formation of atherosclerosis predominantly through the direct modification of macrophage cholesterol trafficking and inflammatory responses. In addition to atherosclerosis, these fatty acid binding proteins also exert a dramatic impact on obesity, insulin resistance, type 2 diabetes and fatty liver disease. The creation of pharmacological agents to modify fatty acid binding protein function will provide tissue or cell-type-specific control of these lipid signaling pathways, inflammatory responses, atherosclerosis, and the other components of the metabolic syndrome, therefore offering a new class of multi-indication therapeutic agents.     

Interaction of fatty acids with recombinant rat intestinal and liver fatty acid-binding proteins

Intestinal enterocytes contain two homologous fatty acid-binding proteins, intestinal fatty acid-binding protein (I-FABP)2 and liver fatty acid-binding protein (L-FABP). Since the functional basis for this multiplicity is not known, the fatty acid-binding specificity of recombinant forms of both rat I-FABP and rat L-FABP was examined. A systematic comparative analysis of the 18 carbon chain length fatty acid binding parameters, using both radiolabeled (stearic, oleic, and linoleic) and fluorescent (trans-parinaric and cis-parinaric) fatty acids, was undertaken. Results obtained with a classical Lipidex-1000 binding assay, which requires separation of bound from free fatty acid, were confirmed with a fluorescent fatty acid-binding assay not requiring separation of bound and unbound ligand. Depending on the nature of the fatty acid ligand, I-FABP bound fatty acid had dissociation constants between 0.2 and 3.1 microM and a consistent 1:1 molar ratio. The dissociation constants for L-FABP bound fatty acids ranged between 0.9 and 2.6 microM and the protein bound up to 2 mol fatty acid per mole of protein. Both fatty acid-binding proteins exhibited relatively higher affinity for unsaturated fatty acids as compared to saturated fatty acids of the same chain length. cis-Parinaric acid or trans-parinaric acid (each containing four double bonds) bound to L-FABP and I-FABP were displaced in a competitive manner by non-fluorescent fatty acid. Hill plots of the binding of cis- and trans- parinaric acid to L-FABP showed that the binding affinities of the two sites were very similar and did not exhibit cooperativity. The lack of fluorescence self-quenching upon binding 2 mol of either trans- or cis-parinaric acid/mol L-FABP is consistent with the presence of two binding sites with dissimilar orientation in the L-FABP. Thus, the difference in binding capacity between I-FABP and L-FABP predicts a structurally different binding site or sites.     

Binding of acyl-CoA to liver fatty acid binding protein: effect on acyl-CoA synthesis

The ability of purified rat liver and heart fatty acid binding proteins to bind oleoyl-CoA and modulate acyl-CoA synthesis by microsomal membranes was investigated. Using binding assays employing either Lipidex 1000 or multilamellar liposomes to sequester unbound ligand, rat liver but not rat heart fatty acid binding protein was shown to bind radiolabeled acyl CoA. Binding studies suggest that liver fatty acid binding protein has a single binding site acyl-CoA which is separate from the two binding sites for fatty acids. Experiments were then performed to determine how binding may influence acyl-CoA metabolism by liver microsomes or heart sarcoplasmic reticulum. Using liposomes as fatty acid donors, liver fatty acid binding protein stimulated acyl-CoA production, whereas that from heart did not stimulate production over control values. 14C-labeled fatty acid-fatty acid binding protein complexes were prepared, incubated with membranes, and acyl-CoA synthetase activity was determined. Up to 70% of the fatty acid could be converted to acyl-CoA in the presence of liver fatty acid binding protein but in the presence of heart fatty acid binding protein, only 45% of the fatty acid was converted. Liver but not heart fatty acid binding protein bound the acyl-CoA formed and removed it from the membranes. The amount of product formed was not changed by additional membrane, enzyme cofactors, or incubation time. Additional liver fatty acid binding protein was the only factor found that stimulated product formation. Acyl-CoA hydrolase activity was also shown in the absence of ATP and CoA. These studies suggest that liver fatty acid binding protein can increase the amount of acyl-CoA by binding this ligand, thereby removing it from the membrane and possibly aiding transport within the cell.     

Identification of two lipid binding proteins from liver of Gallus domesticus

1. Two low molecular weight (approximately 14,000 Da) proteins exhibiting lipid binding activity were purified from liver cytosol and identified as non-specific lipid binding protein (ns-LTP) and fatty acid binding protein (L-FABP). 2. Ligand binding assays indicated that ns-LTP exhibited greater binding activity for cholesterol and little binding of fatty acids. Conversely, L-FABP had higher relative binding activity for fatty acids but did not bind cholesterol. 3. Amino acid composition and pI data supported the identification of the chicken liver lipid binding proteins as L-FABP and ns-LTP. 4. Polyclonal antisera was prepared against each of the liver lipid binding proteins and monospecificity verified using Western blot analysis.