Tuberous Sclerosis Complex 2 (TSC2) Regulates Cell Migration and Polarity through Activation of CDC42 and RAC1
Tuberous Sclerosis Complex 2 (TSC2) Regulates Cell Migration and Polarity through Activation of CDC42 and RAC1
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DOI：
10.1074/jbc.m109.096917
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发表时间：
2010-08-06
影响因子：
4.8
通讯作者：
Gao, Tianyan
中科院分区：
文献类型：
--
作者：
Larson, Yan;Liu, Jianyu;Gao, Tianyan
磷脂酰肌醇3-激酶（PI 3 K）/AKT通路在调节细胞运动中起重要作用。TSC 2是AKT的下游靶标，是通过抑制mTOR（雷帕霉素的哺乳动物靶标）的活性来负控制细胞增殖和蛋白质翻译的核心参与者。然而，TSC 2在调节细胞迁移中的功能仍不清楚。在这里，我们表明，TSC 2在控制细胞的扩散，极性和迁移中起着至关重要的作用。TSC 2缺陷的成纤维细胞在用胰岛素样生长因子-1刺激后扩散和改变肌动蛋白细胞骨架的能力受损。利用划痕诱导极化实验，我们证明TSC 2（（-/-））成纤维细胞与野生型细胞相比，向伤口极化较差。类似地，结肠癌细胞中TSC 2表达的敲低导致细胞运动性的显著降低。在功能上，在TSC 2敲除的成纤维细胞和TSC 2敲减的癌细胞中，CDC 42-和RAC 1-GT α的活化大大降低。此外，激活p110 α突变体的过表达或短期雷帕霉素处理挽救了TSC 2（（-/-））成纤维细胞中的细胞极化缺陷。同时，CDC 42和RAC 1的活化增加。通过将TSC 2重新引入到TSC 2（（-/-））成纤维细胞中来逆转细胞迁移和CDC 42和RAC 1活化的缺陷。总之，我们确定了一个新的作用，TSC 2控制细胞极性和迁移通过调节CDC 42和RAC 1激活。
The phosphatidylinositol 3-kinase (PI3K)/AKT pathway plays important roles in regulating cell motility. TSC2, a downstream target of AKT, is a central player in negatively controlling cell proliferation and protein translation through suppressing the activity of mTOR (mammalian target of rapamycin). However, the function of TSC2 in regulating cell migration remains unclear. Here, we show that TSC2 plays a critical role in the control of cell spreading, polarity, and migration. TSC2-deficient fibroblast cells were impaired in their ability to spread and alter actin cytoskeleton upon stimulation with insulin-like growth factor-1. Using scratch-induced polarization assay, we demonstrate that TSC2((-/-)) fibroblast cells polarized poorly toward the wound compared with wild-type cells. Similarly, knockdown of TSC2 expression in colon cancer cells resulted in a marked decrease in cell motility. Functionally, the activation of CDC42-and RAC1-GTPase was largely reduced in TSC2 knock-out fibroblast and TSC2 knockdown cancer cells. Furthermore, overexpression of an activating p110 alpha mutant or short term rapamycin treatment rescued the cell polarization defect in TSC2((-/-)) fibroblast cells. Concurrently, the activation of CDC42 and RAC1 increased. The defect in cell migration and CDC42 and RAC1 activation was reversed by reintroducing TSC2 back into TSC2((-/-)) fibroblast cells. Taken together, we identified a novel role of TSC2 in controlling cell polarity and migration by regulating CDC42 and RAC1 activation.