Adler V, Fuchs S Y, Kim J, Kraft A, King M P, Pelling J, Ronai Z
Molecular Carcinogenesis Program, American Health Foundation, Valhalla, New York 10595, USA.
Cell Growth Differ. 1995 Nov;6(11):1437-46.
jun-NH2-terminal kinase (JNK) belongs to a family of protein kinases that phosphorylates c-Jun, ATF2, and Elk1 in response to various forms of stress including UV irradiation and heat shock. Although in previous studies we have demonstrated the importance of membrane components for JNK activation by UV irradiation, here we have elucidated the role of DNA damage in this response. We show that in vitro-irradiated or sonicated DNA that is added to proteins prepared from UV-treated cells can further induce JNK activation in a dose-dependent manner. When compared with UV-B (300 nm), UV-C (254 nm), which is better absorbed by the DNA, is significantly more potent in activating JNK. Furthermore, when wavelengths lower than 300 nm were filtered out, UV-B was no longer able to activate JNK. With the aid of melanoma and fibroblast cells, which exhibit different resistances to irradiation and require different UV doses to generate the same number of DNA lesions, we demonstrate that above a threshold level of 0.45 lesions and up to 0.75 lesions per 1875 bp, the degree of JNK activation correlates with the amount of lesions induced by UV-C irradiation. Finally, to explore the role of nuclear and mitochondrial DNA (mtDNA) in mediating JNK activation after UV irradiation, we have used cells that lacks mtDNA. Although the lack of mtDNA did not impair the ability of UV to activate JNK, when enucleated, these cells had lost the ability to activate JNK in response to UV irradiation. Overall, our results suggest that DNA damage in the nuclear compartment is an essential component that acts in concert with membrane-anchored proteins to mediate c-Jun phosphorylation by JNK.
JNK氨基末端激酶（JNK）属于蛋白激酶家族，可响应包括紫外线照射和热休克在内的各种应激形式，使c-Jun、ATF2和Elk1磷酸化。尽管在之前的研究中我们已经证明了膜成分对于紫外线照射激活JNK的重要性，但在此我们阐明了DNA损伤在这种反应中的作用。我们发现，添加到紫外线处理细胞制备的蛋白质中的体外照射或超声处理的DNA能够以剂量依赖的方式进一步诱导JNK激活。与UV-B（300nm）相比，DNA对其吸收更好的UV-C（254nm）在激活JNK方面的效力显著更高。此外，当滤除低于300nm的波长时，UV-B不再能够激活JNK。借助对辐射表现出不同抗性且需要不同紫外线剂量才能产生相同数量DNA损伤的黑色素瘤细胞和成纤维细胞，我们证明，在每1875bp有0.45个损伤至0.75个损伤的阈值水平以上，JNK激活程度与UV-C照射诱导的损伤量相关。最后，为了探究核DNA和线粒体DNA（mtDNA）在紫外线照射后介导JNK激活中的作用，我们使用了缺乏mtDNA的细胞。尽管缺乏mtDNA并未损害紫外线激活JNK的能力，但去核后，这些细胞失去了对紫外线照射激活JNK的能力。总体而言，我们的结果表明，核区室中的DNA损伤是一个重要组成部分，它与膜锚定蛋白协同作用，介导JNK对c-Jun的磷酸化。
