Identification And Preliminary Study Of LncRNAs In Response To DNA Damage

Maintenance of the integrity of genome is critical to the survival and propagation of all organisms.DNA lesions can be caused by a variety of exogenous and endogenous factors,such as metabolism of cells,ultraviolet?UV?radiation and ionizing radiation?IR?,and so on.In order to maintain the integrity of genomic DNA,the organisms have evolved an evolutionarily conserved DNA damage response?DDR?system,which involves multiple processes:sense DNA damage,transduce DNA damage signals,promote DNA damage repair,activate cell cycle checkpoints,and induce apoptosis when damage is unrepaired^[1].DDR has a extensive impact on multiple cellular processes.To ensure sufficient time to complete efficient DNA repair,cell cycle checkpoints are activated to start cell cycle arrest,which allows time for DNA repair.Simultaneously,DDR activates some key genes transcription program,which involved in DNA repair and cell cycle regulation.Recent studies have demonstrated that not only these protein-coding genes,non-coding RNAs are also required for DNA damage response^[1-3],long non coding RNA?lncRNA?are defined as RNA molecules with more than 200 nucleotides.Most lncRNAs are transcribed by RNA polymerase II,they are lowly expresse,poorly conserve,and having cell type-specific expression.Mechanistically,when DNA is damaged,the DDR related lncRNA is regulated at the transcriptional level,post-transcriptional level and RNA degradation level.In parallel,lncRNAs can directly regulate cellular processes by altering expression of their targeting genes involved in DDR,lncRNAs can regulate transcription of DDR relevant genes as signal,decoy,guide,and scaffold.In recent years,although numerous research have been made to illuminate the role of lncRNAs in genome maintenance,many key questions remain to be answered including how lncRNAs participate in DNA damage response.We have got 43 lncRNA knockout Drosophila from Professor Gao at Tsinghua University.We investigated survival rate and number of chromosome breaks after irradiation to detect the DNA damage sensitivity of these lncRNA knockout flies.Totally 12 lncRNA knockout flies were found sensitive to irradiatioin.To systemiclly identify lncRNAs involved into DNA damage response,we used high-throughput sequencing under the conditions of w¹¹¹⁸ NP vs IR,NP e2f1^07172/i2 vs w¹¹¹⁸,IR e2f1^07172/i2 vs w¹¹¹⁸,NP p53^5A-1-4 vs w¹¹¹⁸,IR p53^5A-1-4 vs w¹¹¹⁸ and obtained 242differentially expressed lncRNAs.Furthermore,the CR43356 knockout fly is differentially expressed shown by RNA sequencing.Interestingly,CR43356 knockout fly is highly sensitive to irradiation.By searching the information in FlyBase,we found that CR43356 is mainly expressed in the wing disc of the third stage larva of Drosophila,In order to explore the mechanism of CR43356 involved in DNA damage response,we detected apoptosis and G2/M checkpoint in CR43356 knockout mutant.The results showed that CR43356 was involved in the apoptosis regulation process in the DNA damage response.