Tiam1 mediates Rac1 activation and contraction-induced glucose uptake in skeletal muscle cells
Tiam1 mediates Rac1 activation and contraction-induced glucose uptake in skeletal muscle cells
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Tiam1 介导骨骼肌细胞中 Rac1 激活和收缩诱导的葡萄糖摄取。
DOI：
10.1096/fj.202001312r
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发表时间：
2020-11-22
期刊：
影响因子：
4.8
通讯作者：
Niu, Wenyan
中科院分区：
文献类型：
--
作者：
Yue, Yingying;Zhang, Chang;Niu, Wenyan
收缩刺激的骨骼肌葡萄糖摄取需要Rac 1，但其激活的分子机制尚未完全了解。采用跑台运动诱导C57 BL/6小鼠后肢骨骼肌在体收缩和电脉冲刺激诱导C2 C12肌管在体收缩。AMPK或Rac 1特异性GEF Tiam 1的蛋白水平或活性通过激活剂、抑制剂、siRNA介导的敲除和腺病毒介导的表达来操纵。通过下拉试验和免疫印迹检测活化的Rac 1。使用2-NBD-葡萄糖荧光类似物测量葡萄糖摄取。电脉冲刺激收缩或跑台运动以AMPK依赖的方式上调骨骼肌中Tiam 1的表达。Axin 1 siRNA介导的敲低通过收缩减少AMPK激活和Tiam 1蛋白表达的上调。Tiam 1 siRNA介导的敲低减少了收缩诱导的Rac 1激活、GLUT 4易位和葡萄糖摄取。收缩增加Tiam 1基因表达和通过AMPK的Tiam 1蛋白的丝氨酸磷酸化。这些发现表明Tiam 1是AMPK-Tiam 1-Rac 1信号通路的一部分，该通路介导骨骼肌细胞和组织中收缩刺激的葡萄糖摄取。
Contraction-stimulated glucose uptake in skeletal muscle requires Rac1, but the molecular mechanism of its activation is not fully understood. Treadmill running was applied to induce C57BL/6 mouse hind limb skeletal muscle contraction in vivo and electrical pulse stimulation contracted C2C12 myotube cultures in vitro. The protein levels or activities of AMPK or the Rac1-specific GEF, Tiam1, were manipulated by activators, inhibitors, siRNA-mediated knockdown, and adenovirus-mediated expression. Activated Rac1 was detected by a pull-down assay and immunoblotting. Glucose uptake was measured using the 2-NBD-glucose fluorescent analog. Electrical pulse stimulated contraction or treadmill exercise upregulated the expression of Tiam1 in skeletal muscle in an AMPK-dependent manner. Axin1 siRNA-mediated knockdown diminished AMPK activation and upregulation of Tiam1 protein expression by contraction. Tiam1 siRNA-mediated knockdown diminished contraction-induced Rac1 activation, GLUT4 translocation, and glucose uptake. Contraction increased Tiam1 gene expression and serine phosphorylation of Tiam1 protein via AMPK. These findings suggest Tiam1 is part of an AMPK-Tiam1-Rac1 signaling pathway that mediates contraction-stimulated glucose uptake in skeletal muscle cells and tissue.