Contribution of caveolin-1α and Akt to TNF-α-induced cell death
Contribution of caveolin-1α and Akt to TNF-α-induced cell death
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DOI：
10.1152/ajplung.00293.2003
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发表时间：
2004-07-01
影响因子：
4.9
通讯作者：
Hasegawa, K
中科院分区：
文献类型：
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作者：
Ono, K;Iwanaga, Y;Hasegawa, K
我们使用逆转录病毒插入介导的随机突变从L929细胞中产生肿瘤坏死因子-α(TNF-α)抗性株。利用这种方法，我们发现小窝蛋白-1α在肿瘤坏死因子-α诱导的L929细胞死亡中是必需的。在异位重组小窝蛋白-1α/β表达后，恢复了对肿瘤坏死因子-α的敏感性，证实了在肿瘤坏死因子-α诱导的细胞死亡中需要小窝蛋白-1α。该突变株对H_2O_2和星形孢子素也有抗性，但对氯硝胺没有抗性。已知的是，HepG2细胞缺乏内源性小窝蛋白。稳定表达小窝蛋白-1α/β基因的HepG2细胞对肿瘤坏死因子-α的敏感性明显高于亲代细胞和空载体细胞。与其广泛报道的抗凋亡作用相反，Akt活性的升高似乎在使表达小窝蛋白-1的细胞对肿瘤坏死因子-α增敏方面具有重要作用，因为用磷脂酰肌醇3-激酶(PI3K)抑制剂LY-294002或Wortmannin预处理细胞完全阻断了PI3K的激活，并显著提高了经肿瘤坏死因子-α处理的L929细胞的存活。经PI3K抑制剂和肿瘤坏死因子-α处理后，小窝蛋白-1α正常和缺陷细胞L929的存活率相当。稳定表达小凹蛋白-1α/β或-β的HepG2细胞和转染空载体的亲本细胞也得到了类似的结果。综上所述，我们的结果表明，小窝蛋白-1α通过激活PI3K/Akt信号通路优先增强L929细胞对肿瘤坏死因子-α的敏感性。
We used retrovirus insertion-mediated random mutagenesis to generate tumor necrosis factor-alpha (TNF-alpha)-resistant lines from L929 cells. Using this approach, we discovered that caveolin-1alpha is required for TNF-alpha-induced cell death in L929 cells. The need for caveolin-1alpha in TNF-alpha-induced cell death was confirmed by the restoration of sensitivity to TNF-alpha after ectopic reconstitution of caveolin-1alpha/beta expression. This caveolin-1alpha-mutated line was also resistant to H2O2 and staurosporine, but not to lonidamine. HepG2 cells are known to lack endogenous caveolins. HepG2 cells stably transfected with caveolin-1alpha/beta were found to be much more sensitive to TNF-alpha than either parental cells transfected with caveolin-1alpha or parental cells transfected with an empty vector. In contrast to its extensively documented antiapoptotic effect, the elevated activity of Akt appears to be important in sensitizing caveolin-1-expressing cells to TNF-alpha, since pretreatment of cells with the phosphatidylinositide 3-kinase (PI3K) inhibitor LY-294002 or wortmannin completely blocked PI3K activation and markedly improved the survival of TNF-alpha-treated L929 cells. The survival rates of caveolin-1alpha-normal and caveolin-1alpha-deficient L929 cells were comparable after treatment with PI3K inhibitor and TNF-alpha. Similar results were obtained with HepG2 cells that stably expressed caveolin-1alpha/beta or -beta and parental cells transfected with an empty vector. In summary, our results indicate that caveolin-1alpha preferentially sensitizes L929 cells to TNF-alpha through the activation of a PI3K/Akt signaling pathway.