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Bak/Bax与mTOR信号之间的相互作用调节辐射诱导的自噬。

Crosstalk between Bak/Bax and mTOR signaling regulates radiation-induced autophagy.

作者信息

Moretti Luigi, Attia Albert, Kim Kwang Woon, Lu Bo

机构信息

Department of Radiation Oncology, Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-5671, USA.

出版信息

Autophagy. 2007 Mar-Apr;3(2):142-4. doi: 10.4161/auto.3607. Epub 2007 Mar 20.

Abstract

Bax and Bak, act as a gateway for caspase-mediated cell death. mTOR, an Akt downstream effector, plays a critical role in cell proliferation, growth and survival. The inhibition of mTOR induces autophagy, whereas apoptosis is a minor cell death mechanism in irradiated solid tumors. We explored possible alternative pathways for cell death induced by radiation in Bax/Bak-/- double knockout (DKO) MEF cells and wild-type cells, and we compared the cell survival: the Bax/Bak-/- cells were more radiosensitive than the wild-type cells. The irradiated cells displayed an increase in the pro-autophagic proteins ATG5-ATG12 and Beclin-1. These results are surprising in the fact that the inhibition of apoptosis resulted in increasing radiosensitivity; indicating that perhaps autophagy is the cornerstone in the cell radiation sensitivity regulation. Furthermore, irradiation upregulates autophagic programmed cell death in cells that are unable to undergo Bax/Bak-mediated apoptosis. We hypothesize the presence of a phosphatase-possibly PTEN, an Akt/mTOR negative regulator that can be inhibited by Bax/Bak. This fits with our hypothesis of Bax/Bak as a downregulator of autophagy. We are currently conducting experiments to explore the relationship between apoptosis and autophagy. Future directions in research include strategies targeting Bax/Bak in cancer xenografts and exploring novel radiosensitizers targeting autophagy pathways.

摘要

Bax和Bak作为半胱天冬酶介导的细胞死亡的通道。mTOR是Akt的下游效应器,在细胞增殖、生长和存活中起关键作用。mTOR的抑制诱导自噬,而凋亡是辐射后的实体瘤中次要的细胞死亡机制。我们在Bax/Bak基因双敲除(DKO)的小鼠胚胎成纤维细胞(MEF)和野生型细胞中探索了辐射诱导细胞死亡的可能替代途径,并比较了细胞存活率:Bax/Bak基因双敲除细胞比野生型细胞对辐射更敏感。受辐射的细胞中促自噬蛋白ATG5-ATG12和Beclin-1有所增加。这些结果令人惊讶,因为凋亡的抑制导致了辐射敏感性的增加;这表明自噬可能是细胞辐射敏感性调节的基石。此外,辐射上调了无法经历Bax/Bak介导的凋亡的细胞中的自噬程序性细胞死亡。我们推测存在一种磷酸酶——可能是PTEN,一种可被Bax/Bak抑制的Akt/mTOR负调节因子。这与我们关于Bax/Bak作为自噬下调因子的假设相符。我们目前正在进行实验以探索凋亡与自噬之间的关系。未来的研究方向包括在癌症异种移植中靶向Bax/Bak的策略,以及探索靶向自噬途径的新型放射增敏剂。

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