Moreno-Navarrete José María, Escoté Xavier, Ortega Francisco, Camps Marta, Ricart Wifredo, Zorzano Antonio, Vendrell Joan, Vidal-Puig Antonio, Fernández-Real José Manuel
Section of Diabetes, Endocrinology and Nutrition, Hospital of Girona 'Dr Josep Trueta', Carretera de França s/n, 17007, Girona, Spain.
Institut d'Investigació Biomèdica de Girona (IdIBGi), Girona, Spain.
Diabetologia. 2015 Oct;58(10):2424-34. doi: 10.1007/s00125-015-3692-7. Epub 2015 Jul 23.
AIMS/HYPOTHESIS: Lipopolysaccharide (LPS) binding protein (LBP) is a novel 65 kDa adipokine, linked to adipose tissue (AT) inflammation, obesity and insulin resistance, that inhibits adipocyte differentiation. Here, we investigated the molecular mechanisms behind these detrimental effects on adipogenesis through whole-genome transcriptomics and in vitro experiments.
Permanent and transient knockdown (KD) and co-culture experiments were performed in 3T3-L1 and 3T3-F442A cell lines during adipocyte differentiation. Microarray gene expression was performed using Genechip Affymetrix technology and validated by real-time PCR.
LBP KD of 3T3-L1 cells led to a potentiated adipocyte differentiation with a dose-response relationship; genes involved in mitochondrial biogenesis, fatty acid metabolism and peroxisome proliferator-activated receptor γ (PPAR-γ) action were dramatically upregulated in parallel to increased insulin signalling. Cells with LBP KD became refractory to proinflammatory cytokines and other inflammatory stimuli (LPS and palmitate). This phenotype, mediated through disrupted nuclear factor κB (NFκB) signalling, was reversed by a soluble factor present in a co-culture with native cells and by exogenous LBP. Double-silencing of LBP and toll-like receptor 4 (TLR4) again rendered these cells insensitive to co-culture, LBP and inflammatory factors.
CONCLUSIONS/INTERPRETATION: In summary, LBP is a proinflammatory soluble adipokine that acts as a brake for adipogenesis, strengthening the negative effects of palmitate and LPS on adipocyte differentiation.
目的/假设：脂多糖（LPS）结合蛋白（LBP）是一种新的65 kDa脂肪因子，与脂肪组织（AT）炎症、肥胖和胰岛素抵抗有关，可抑制脂肪细胞分化。在此，我们通过全基因组转录组学和体外实验研究了这些对脂肪生成产生有害影响背后的分子机制。
在脂肪细胞分化过程中，对3T3-L1和3T3-F442A细胞系进行了永久性和瞬时敲低（KD）以及共培养实验。使用基因芯片Affymetrix技术进行微阵列基因表达分析，并通过实时PCR进行验证。
3T3-L1细胞的LBP敲低导致脂肪细胞分化增强，呈剂量反应关系；参与线粒体生物合成、脂肪酸代谢和过氧化物酶体增殖物激活受体γ（PPAR-γ）作用的基因与胰岛素信号增加同时显著上调。LBP敲低的细胞对促炎细胞因子和其他炎症刺激（LPS和棕榈酸）变得不敏感。这种通过破坏核因子κB（NFκB）信号传导介导的表型，被与天然细胞共培养中存在的一种可溶性因子和外源性LBP所逆转。LBP和Toll样受体4（TLR4）的双重沉默再次使这些细胞对共培养、LBP和炎症因子不敏感。
结论/解读：总之，LBP是一种促炎可溶性脂肪因子，它作为脂肪生成的制动器，强化了棕榈酸和LPS对脂肪细胞分化的负面影响。
