目的:脂肪组织是一种高度通用的系统,其中脂肪细胞中的线粒体在主动组织重塑过程中发生显着变化。BCL2/腺病毒E1B19kDa蛋白相互作用蛋白3(BNIP3)是线粒体蛋白和已知的线粒体质量调节剂。在这项研究中,我们研究了BNIP3在脂肪细胞中的作用,特别是在过氧化物酶体增殖物激活受体γ(PPARγ)诱导的脂肪组织重塑条件下。
方法:体外评价BNIP3在3T3-L1脂肪细胞中的表达,饲喂高脂肪饮食的C57BL/6小鼠和db/db小鼠体内。罗格列酮治疗后,在BNIP3敲低脂肪细胞中研究了线粒体生物能量学。通过启动子测定和电泳迁移率变化测定(EMSA)表征了推定的过氧化物酶体增殖激素反应元件(PPRE)。
结果:蛋白BNIP3在棕色脂肪组织中的含量高于白色脂肪组织。此外,BNIP3表达通过3T3-L1前脂肪细胞分化上调,饥饿和罗格列酮治疗。相反,在与胰岛素抵抗相关的各种条件下,脂肪细胞中的BNIP3表达降低。通过罗格列酮处理恢复了BNIP3的这种下调。BNIP3在脂肪细胞中的敲除抑制罗格列酮诱导的线粒体生物合成和功能,部分由5'AMP激活蛋白激酶(AMPK)-过氧化物酶体增殖物激活受体γ介导,共激活因子1α(PGC1α)信号通路。罗格列酮处理增加了报告基因测定中Bnip3的转录水平,并且通过EMSA证明了Bnip3启动子中PPRE位点的存在。
结论:蛋白质BNIP3有助于改善暴露于罗格列酮时发生的线粒体生物能学。它可能是在胰岛素抵抗条件下恢复线粒体功能障碍的新治疗靶标。
OBJECTIVE: Adipose tissue is a highly versatile system in which mitochondria in adipocytes undergo significant changes during active tissue remodelling. BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) is a mitochondrial protein and a known mitochondrial quality regulator. In this study, we investigated the role of BNIP3 in adipocytes, specifically under conditions of peroxisome proliferator-activated receptor-γ (PPARγ)-induced adipose tissue remodelling.
METHODS: The expression of BNIP3 was evaluated in 3T3-L1 adipocytes in vitro, C57BL/6 mice fed a high-fat diet and db/db mice in vivo. Mitochondrial bioenergetics was investigated in BNIP3-knockdown adipocytes after rosiglitazone treatment. A putative peroxisome proliferator hormone responsive element (
PPRE) was characterised by promoter assay and electrophoretic mobility shift assay (EMSA).
RESULTS: The protein BNIP3 was more abundant in brown adipose tissue than white adipose tissue. Furthermore, BNIP3 expression was upregulated by 3T3-L1 pre-adipocyte differentiation, starvation and rosiglitazone treatment. Conversely, BNIP3 expression in adipocytes decreased under various conditions associated with insulin resistance. This downregulation of BNIP3 was restored by rosiglitazone treatment. Knockdown of BNIP3 in adipocytes inhibited rosiglitazone-induced mitochondrial biogenesis and function, partially mediated by the 5\' AMP-activated protein kinase (AMPK)-peroxisome proliferator-activated receptor γ, co-activator 1 α (PGC1α) signalling pathway. Rosiglitazone treatment increased the transcription level of Bnip3 in the reporter assay and the presence of the
PPRE site in the Bnip3 promoter was demonstrated by EMSA.
CONCLUSIONS: The protein BNIP3 contributes to the improvement of mitochondrial bioenergetics that occurs on exposure to rosiglitazone. It may be a novel therapeutic target for restoring mitochondrial dysfunction under insulin-resistant conditions.