Identification of LRP16 as a Negative Regulator of Insulin Action and Adipogenesis in 3T3-L1 Adipocytes
Identification of LRP16 as a Negative Regulator of Insulin Action and Adipogenesis in 3T3-L1 Adipocytes
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DOI：
10.1055/s-0032-1331215
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发表时间：
2013-02
影响因子：
2.2
通讯作者：
L. Zang;B. Xue;Zhao-hui Lü;X. Li;Guoqing Yang;Qing-hua Guo;J. Ba;Xiao-man Zou;J. Dou;Juming Lu;C-Y Pan;Yiming Mu
中科院分区：
文献类型：
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作者：
L. Zang;B. Xue;Zhao-hui Lü;X. Li;Guoqing Yang;Qing-hua Guo;J. Ba;Xiao-man Zou;J. Dou;Juming Lu;C-Y Pan;Yiming Mu
摘要 白血病相关蛋白16（LRP16）是本实验室首次从急性髓系白血病细胞中克隆出来的。在本研究中，我们试图使用LRP16耗尽且过度表达的3T3-L1细胞来研究LRP16在胰岛素作用和敏感性中的作用。 LRP16 沉默导致肿瘤坏死因子-α (TNF-α) 的表达和分泌减少，同时过氧化物酶体增殖物激活受体-γ (PPAR-γ) 的表达增加。此外，LRP16耗竭促进了胰岛素诱导的葡萄糖摄取和3T3-L1细胞的脂肪细胞分化。相反，LRP16 过表达会增加 TNF-α 分泌，抑制葡萄糖摄取，并减弱 3T3-L1 细胞分化。与相应的对照细胞相比，胰岛素受体底物 1 (IRS-1)、磷脂酰肌醇 3-激酶 (PI3-K) 和 Akt 的磷酸化水平在 LRP16 缺陷的 3T3-L1 细胞中增加，相反，在 LRP16 过表达的 3T3-L1 细胞中减少。此外，LRP16 过表达提高了哺乳动物雷帕霉素靶点 (mTOR) 的磷酸化水平。使用 mTOR 特异性抑制剂雷帕霉素进行预处理，可防止 LRP16 过表达细胞中 TNF-α 升高和 PPAR-γ 降低，并恢复 IRS-1、PI3-K 和 Akt 的磷酸化。我们的数据共同表明，LRP16 在 3T3-L1 脂肪细胞中充当胰岛素作用和脂肪生成的负调节因子，这涉及 mTOR 信号通路的激活。
Abstract Leukemia related protein 16 (LRP16) was first cloned from acute myeloid leukemia cells in our laboratory. In the present study, we sought to investigate the role of LRP16 in insulin action and sensitivity, using LRP16-depleted and -overexpressing 3T3-L1 cells. LRP16 silencing resulted in a reduction of the expression and secretion of tumor necrosis factor-alpha (TNF-α) and a concomitant increase in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ). Moreover, LRP16 depletion promoted insulin-induced glucose uptake and adipocyte differentiation of 3T3-L1 cells. In contrast, LRP16 overexpression increased TNF-α secretion, suppressed glucose uptake, and attenuated 3T3-L1 cell differentiation. The phosphorylation levels of insulin receptor substrate 1 (IRS-1), phosphatidylinositide 3-kinase (PI3-K), and Akt were increased in LRP16-deficient 3T3-L1 cells, and conversely, diminished in LRP16-overexpressing 3T3-L1 cells, when compared to the corresponding control cells. Additionally, LRP16 overexpression raised the phosphorylation level of mammalian target of rapamycin (mTOR). The pretreatment with rapamycin, a specific inhibitor of mTOR, prevented the TNF-α elevation and PPAR-γ reduction and restored the phosphorylation of IRS-1, PI3-K, and Akt in LRP16-overexpressing cells. Our data collectively indicate that LRP16 acts as a negative regulator of insulin action and adipogenesis in 3T3-L1 adipocytes, which involves the activation of the mTOR signaling pathway.