Holcik M, Sonenberg N, Korneluk R G
Solange Gauthier Karsh Molecular Genetics Laboratory, Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, ON, K1H 8L1, Ottawa, Canada.
Trends Genet. 2000 Oct;16(10):469-73. doi: 10.1016/s0168-9525(00)02106-5.
The majority of cellular stresses lead to the inhibition of cap-dependent translation. Some mRNAs, however, are translated by a cap-independent mechanism, mediated by ribosome binding to internal ribosome entry site (IRES) elements located in the 5' untranslated region. Interestingly, IRES elements are found in the mRNAs of several survival factors, oncogenes and proteins crucially involved in the control of apoptosis. These mRNAs are translated under a variety of stress conditions, including hypoxia, serum deprivation, irradiation and apoptosis. Thus, IRES-mediated translational control might have evolved to regulate cellular responses in acute but transient stress conditions that would otherwise lead to cell death.
大多数细胞应激会导致帽依赖性翻译受到抑制。然而，一些mRNA是通过不依赖帽的机制进行翻译的，该机制由核糖体与位于5'非翻译区的内部核糖体进入位点（IRES）元件结合介导。有趣的是，在几种生存因子、癌基因和对细胞凋亡控制至关重要的蛋白质的mRNA中发现了IRES元件。这些mRNA在多种应激条件下进行翻译，包括缺氧、血清剥夺、辐射和细胞凋亡。因此，IRES介导的翻译控制可能已经进化，以调节急性但短暂应激条件下的细胞反应，否则这些应激条件会导致细胞死亡。
