Suppression of PPAR-γ attenuates insulin-stimulated glucose uptake by affecting both GLUT1 and GLUT4 in 3T3-L1 adipocytes
Suppression of PPAR-γ attenuates insulin-stimulated glucose uptake by affecting both GLUT1 and GLUT4 in 3T3-L1 adipocytes
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DOI：
10.1152/ajpendo.00695.2006
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发表时间：
2007-07-01
影响因子：
5.1
通讯作者：
Olefsky, Jerrold M.
中科院分区：
文献类型：
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作者：
Liao, Wei;Nguyen, M. T. Audrey;Olefsky, Jerrold M.
过氧化物酶体增殖物激活受体-y (PPAR-,y) 在调节胰岛素敏感性和葡萄糖稳态中发挥着关键作用。在这项研究中，我们鉴定了高效的小干扰RNA (siRNA) 序列，并使用慢病毒短发夹RNA 和siRNA 电穿孔来消除3T3-L1 脂肪细胞中的PPAR-gamma，以阐明其在脂肪生成和胰岛素信号传导中的作用。我们发现，PPAR-gamma 敲低可阻止脂肪细胞分化，但在细胞发生脂肪形成后，敲低并不是维持脂肪细胞分化状态所必需的。我们进一步证明，PPAR-gamma 抑制减少了胰岛素刺激的葡萄糖摄取，而不影响脂肪细胞中的早期胰岛素信号传导步骤。使用双重 siRNA 策略，我们发现 PPAR-gamma 缺失的这种效应是由 GLUT4 和 GLUT1 介导的。有趣的是，PPAR-γ 耗尽的细胞对 TNF-α 刺激表现出增强的炎症反应，这与内源性 PPAR-γ 的慢性抗炎作用一致。总之，1) PPAR-gamma 对于脂肪细胞分化过程至关重要，但对于维持分化状态的必要性较低，2) PPAR-,y 支持正常的胰岛素刺激的葡萄糖转运，3) 内源性 PPAR-gamma 可能在抑制 3T3-L1 细胞的炎症途径中发挥作用。
Peroxisome proliferator-activated receptor-y (PPAR-,y) plays a critical role in regulating insulin sensitivity and glucose homeostasis. In this study, we identified highly efficient small interfering RNA (siRNA) sequences and used lentiviral short hairpin RNA and electroporation of siRNAs to deplete PPAR-gamma from 3T3-L1 adipocytes to elucidate its role in adipogenesis and insulin signaling. We show that PPAR-gamma knockdown prevented adipocyte differentiation but was not required for maintenance of the adipocyte differentiation state after the cells had undergone adipogenesis. We further demonstrate that PPAR-gamma suppression reduced insulin-stimulated glucose uptake without affecting the early insulin signaling steps in the adipocytes. Using dual siRNA strategies, we show that this effect of PPAR-gamma deletion was mediated by both GLUT4 and GLUT1. Interestingly, PPAR-gamma-depleted cells displayed enhanced inflammatory responses to TNF-alpha- stimulation, consistent with a chronic anti-inflammatory effect of endogenous PPAR-gamma. In summary, 1) PPAR-gamma is essential for the process of adipocyte differentiation but is less necessary for maintenance of the differentiated state, 2) PPAR-,y supports normal insulin-stimulated glucose transport, and 3) endogenous PPAR-gamma may play a role in suppression of the inflammatory pathway in 3T3-L1 cells.