Increased resistance to apoptosis in cells overexpressing thymosin beta four:: A role for focal adhesion kinase pp125FAK
Increased resistance to apoptosis in cells overexpressing thymosin beta four:: A role for focal adhesion kinase pp125FAK
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DOI：
10.3109/15419060009015002
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发表时间：
2000-01-01
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影响因子：
--
通讯作者：
Nachmias, VT
中科院分区：
文献类型：
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作者：
Niu, M;Nachmias, VT
失去对底物的粘附性本身可以诱导上皮细胞凋亡，但在成纤维细胞中不会。为了验证即使在成纤维细胞中，粘附也能传递抑制细胞凋亡的信号，我们利用了在过度表达胸腺酶β 4的NIH3T3细胞系中观察到的对基质的粘附性大大增加的观点。我们用紫外线（UV）或肿瘤坏死因子α (TNF α)处理过表达（OE）和载体对照线。当细胞在基质上时，黏附程度越高的OE细胞对两种处理诱导的凋亡的抵抗力是载体对照的2倍。相比之下，当细胞在悬浮状态下用任何一种药物处理时，OE细胞和载体对照之间的抗性差异消失。因此，细胞凋亡抵抗的增强依赖于粘附。OE细胞中bcl-2含量与对照组无明显差异。pp(125)FAK与抗凋亡之间的联系已经在成纤维细胞的原代培养中得到证实。T β(4)过表达细胞的pp (125)FAK比对照高1.4倍，贴壁OE细胞的激酶磷酸化程度比载体对照高2倍。当细胞处于悬浮状态时，pp(125)FAK的磷酸化水平明显降低。此外，与载体对照相比，OE贴壁细胞中与pp(125)FAK相关的paxillin是载体对照的两倍，但悬浮细胞中也没有这种差异。我们的研究结果支持了成纤维细胞中粘附依赖pp(125)FAK-paxillin信号通路抑制损伤诱导的细胞凋亡的概念。
Loss of adherence to substrate can, by itself, induce apoptosis (anoikis) in epithelial cells, but does not do so in fibroblasts. To test the idea that adherence transmits signals that inhibit apoptosis even in fibroblasts, we took advantage of the greatly increased adherence to the substratum observed in NIH3T3 cell lines that overexpress thymosin beta four. We treated overexpressing (OE) and vector control lines with either ultraviolet light (UV) or tumor necrosis factor alpha (TNF alpha). When the cells were on a substratum, the more adherent OE cells were 2-fold more resistant to apoptosis induced by either treatment than vector controls. In contrast, when the cells were treated with either agent while in suspension, the difference in resistance between OE cells and vector controls was lost. Thus the increased resistance to apoptosis was dependent on adherence. There was no difference in the content of bcl-2 in the OE cells vs the controls. A connection between pp(125)FAK and resistance to apoptosis has been previously shown in primary cultures of fibroblasts. The T beta(4) Overexpressing cells have similar to 1.4x more pp (125)FAK than the controls, and the kinase is similar to 2-fold more phosphorylated in adherent OE cells than in the vector controls. The phosphorylation of pp(125)FAK decreased strikingly when the cells were put into suspension. In addition, twice as much paxillin associated with pp(125)FAK in OE adherent cells as in vector controls, but this difference was also lost in suspended cells. Our results support the concept of an adherence dependent pp(125)FAK-paxillin signalling pathway in fibroblasts that inhibits damage-induced apoptosis.