Functions Of Long Non-coding RNAs As Competitive Endogenous RNAs During Reprogramming

In recent years,lots of studies have reported pervasive transcription across 70-90% of the human genome.However,surprisingly,less than 2% of the total human genome encodes protein-coding genes,which suggests that non-coding RNAs?nc RNAs?represent most of the transcriptome.Numerous studies have documented the existence of nc RNAs and the mechanisms of their roles in regulating gene expression.Long noncoding RNAs?lnc RNAs?can modulate gene expression as competing endogenous RNAs?ce RNAs?via sponging micro RNAs?miRNAs?.However,the extent and functional consequences of ce RNAs in diverse cellular context still need to be proven.In this study,we ami to investigate the effect of ce RNA crosstalk on somatic cell reprogramming.Exogenous expression of pluripotent transcription factors leads to cell fate conversion,and produce pluripotent stem cells.In 2006,Yamanaka et al.reprogrammed mouse embryonic fibroblasts?MEFs?to pluripotent stem cells by Oct4,Sox2,Klf4 and c-Myc?OSKM?,and termed these pluripotent stem cells as ?induced pluripotent stem cells?i PSCs??.In our study,we use a doxycycline inducible expression of Yamanaka four factors to generate i PSCs from MEFs,we found the miRNAs from MEFs remained highly expressed from day 0 to day 6 after doxycycline induction;unexpectedly,many genes targeted by these miRNAs were actually up-regulated;meanwhile,long intergenic noncoding RNAs?linc RNAs?and circular RNAs?circ RNAs?which have complementary binding sites with the miRNAs were highly expressed,indicating linc RNAs and circ RNAs?linc/circ RNAs?may serve as sponges for miRNAs to block their activities during reprogramming.Furthermore,we found mmu-mi R-21a-3p,mmu-mi R-421-3p,mmu-mi R-497a-5p and mmu-mi R-532-3p could efficiently down-regulate Oct4 expression at high concentrations.Intriguingly,the knockdown of the linc/circ RNAs?ENSMUSG00000092341,mmu_circ₀0006895 and mmu_circ₀0000319?sponging the miRNAs targeting Oct4 m RNA resulted in down-regulation of exogenous Oct4 expression,decrease of reprogramming efficiency,and low-grade chimera forming i PSCs.We concluded that,?1?The expression of MEFs derived miRNAs were not decreased over the course of reprogramming,but decreased in i PSCs;?2?The lnc RNAs ENSMUSG00000092341,mmu_circ₀0006895 and mmu_circ₀0000319 can function as Oct4-miRNAs sponges to sustain high expression of exogenous Oct4 during reprogramming;?3?The lnc RNAs ENSMUSG00000092341,mmu_circ₀0006895 and mmu_circ₀0000319 can function as Oct4-miRNAs sponges to maintain the reprogramming efficiency and the quality of i PSCs;?4?Lnc RNAs can function as ce RNAs to regulate cellular reprogramming.