Bouzid Tasneem, Kim Eunju, Riehl Brandon D, Yang Ruiguo, Saraswathi Viswanathan, Kim Jason K, Lim Jung Yul
Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
Bioengineering (Basel). 2024 Dec 16;11(12):1279. doi: 10.3390/bioengineering11121279.
Adipose tissue in vivo is physiologically exposed to compound mechanical loading due to bodyweight bearing, posture, and motion. The capability of adipocytes to sense and respond to mechanical loading milieus to influence metabolic functions may provide a new insight into obesity and metabolic diseases such as type 2 diabetes (T2D). Here, we evidenced physiological mechanical loading control of adipocyte insulin signaling cascades. We exposed differentiated 3T3-L1 adipocytes to mechanical stretching and assessed key markers of insulin signaling, AKT activation, and GLUT4 translocation, required for glucose uptake. We showed that cyclic stretch loading at 5% strain and 1 Hz frequency increases AKT phosphorylation and GLUT4 translocation to the plasma membrane by approximately two-fold increases compared to unstretched controls for both markers as assessed by immunoblotting ( < 0.05). These results indicate that cyclic stretching activates insulin signaling and GLUT4 trafficking in adipocytes. In the mechanosensing mechanism study, focal adhesion kinase (FAK) inhibitor (FAK14) and RhoA kinase (ROCK) inhibitor (Y-27632) impaired actin cytoskeleton structural formation and significantly suppressed the stretch induction of AKT phosphorylation in adipocytes ( < 0.001). This suggests the regulatory role of focal adhesion and cytoskeletal mechanosensing in adipocyte insulin signaling under stretch loading. Our finding on the impact of mechanical stretch loading on key insulin signaling effectors in differentiated adipocytes and the mediatory role of focal adhesion and cytoskeleton mechanosensors is the first of its kind to our knowledge. This may suggest a therapeutic potential of mechanical loading cue in improving conditions of obesity and T2D. For instance, cyclic mechanical stretch loading of adipose tissue could be explored as a tool to improve insulin sensitivity in patients with obesity and T2D, and the mediatory mechanosensors such as FAK and ROCK may be targeted to further invigorate stretch-induced insulin signaling activation.
在体内,脂肪组织因体重支撑、姿势和运动而在生理上受到复合机械负荷的作用。脂肪细胞感知并响应机械负荷环境以影响代谢功能的能力,可能为肥胖症和2型糖尿病(T2D)等代谢性疾病提供新的见解。在此,我们证明了生理机械负荷对脂肪细胞胰岛素信号级联反应的控制作用。我们将分化的3T3-L1脂肪细胞置于机械拉伸环境中,并评估了胰岛素信号传导、AKT激活和葡萄糖摄取所需的GLUT4转位的关键标志物。我们发现,与未拉伸的对照组相比,以5%的应变和1 Hz的频率进行循环拉伸负荷,通过免疫印迹法评估,两种标志物的AKT磷酸化和GLUT4向质膜的转位均增加了约两倍(P<0.05)。这些结果表明,循环拉伸可激活脂肪细胞中的胰岛素信号传导和GLUT4转运。在机械传感机制研究中,粘着斑激酶(FAK)抑制剂(FAK14)和RhoA激酶(ROCK)抑制剂(Y-27632)损害了肌动蛋白细胞骨架结构的形成,并显著抑制了脂肪细胞中AKT磷酸化的拉伸诱导作用(P<0.001)。这表明粘着斑和细胞骨架机械传感在拉伸负荷下对脂肪细胞胰岛素信号传导具有调节作用。据我们所知,我们关于机械拉伸负荷对分化脂肪细胞中关键胰岛素信号效应器的影响以及粘着斑和细胞骨架机械传感器的介导作用的发现尚属首次。这可能表明机械负荷线索在改善肥胖症和T2D病情方面具有治疗潜力。例如,可以探索对脂肪组织进行循环机械拉伸负荷,作为改善肥胖症和T2D患者胰岛素敏感性的一种手段,并且可以靶向诸如FAK和ROCK等介导性机械传感器,以进一步增强拉伸诱导的胰岛素信号激活。