Honglu Liu, Huanyi Fu, Chunhong Yu, Na Zhang, Canhua Huang, Lu Lv, Chunhong Hu, Fang Chen, Zhiqiang Xiao, Zhuohua Zhang, Huasong Lu, Kai Yuan
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引用次数: 0
Abstract
Lesions on the DNA template can impact transcription via distinct regulatory pathways. Ionizing radiation (IR) as the mainstay modality for many malignancies elicits most of the cytotoxicity by inducing a variety of DNA damages in the genome. How the IR treatment alters the transcription cycle and whether it contributes to the development of radioresistance remain poorly understood. Here, we report an increase in the paused RNA polymerase II (RNAPII), as indicated by the phosphorylation at serine 5 residue of its C-terminal domain, in recurrent nasopharyngeal carcinoma (NPC) patient samples after IR treatment and cultured NPC cells developing IR resistance. Reducing the pool of paused RNAPII by either inhibiting TFIIH-associated CDK7 or stimulating the positive transcription elongation factor b, a CDK9-CycT1 heterodimer, attenuates IR resistance of NPC cells. Interestingly, the poly(ADP-ribosyl)ation of CycT1, which disrupts its phase separation, is elevated in the IR-resistant cells. Mutation of the major poly(ADP-ribosyl)ation sites of CycT1 decreases RNAPII pausing and restores IR sensitivity. Genome-wide chromatin immunoprecipitation followed by sequencing analyses reveal that several genes involved in radiation response and cell cycle control are subject to the regulation imposed by the paused RNAPII. Particularly, we identify the NIMA-related kinase NEK7 under such regulation as a new radioresistance factor, whose downregulation results in the increased chromosome instability, enabling the development of IR resistance. Overall, our results highlight a novel link between the alteration in the transcription cycle and the acquisition of IR resistance, opening up new opportunities to increase the efficacy of radiotherapy and thwart radioresistance in NPC.
期刊介绍:
The Journal of Molecular Cell Biology ( JMCB ) is a full open access, peer-reviewed online journal interested in inter-disciplinary studies at the cross-sections between molecular and cell biology as well as other disciplines of life sciences. The broad scope of JMCB reflects the merging of these life science disciplines such as stem cell research, signaling, genetics, epigenetics, genomics, development, immunology, cancer biology, molecular pathogenesis, neuroscience, and systems biology. The journal will publish primary research papers with findings of unusual significance and broad scientific interest. Review articles, letters and commentary on timely issues are also welcome.
JMCB features an outstanding Editorial Board, which will serve as scientific advisors to the journal and provide strategic guidance for the development of the journal. By selecting only the best papers for publication, JMCB will provide a first rate publishing forum for scientists all over the world.