Expression Change Of MicroRNA Under ER Stress And The Function And Possible Mechanism

MicroRNA,a class of small non-coding RNAs with a length of about 22nt,usually down-regulate mRNAs by base pairing with the 3’UTR region of target mRNAs.MicroRNAs are involved in multiple kinds of cellular stress responses,among which we are interested in is endoplasmic reticulum stress(ER Stress).ER stress triggered by misfolded or overloaded proteins in the endoplasmic reticulum is a condition that cells have to deal with during certain physiological circumstances.Reports about roles of specific microRNAs in ER stress are coming out recently,although systematic evaluation of changes of microRNA in ER stressed cells has been missing.Here we found that microRNA expressing profiles demonstrated profound changes under ER Stress in Hela and HEK293 cells through RNA deep-sequencing.Main microRNA processing factors showed no significant changes in ER Stressed cells,which suggested that the expressional variation may not be caused by changes in microRNA processing pathwany but by other unknown factors.We further on one hand investigate that some microRNAs showing changes under ER Stress,such as miR-423-5p,miR-221-3p and miR-452-5p,may function as regulators in response to ER Stress by targeting their targets p21 and CDKN1B involved in apoptosis and cell cycle progression.On the other hand,we tried to explore the mechanism of microRNA changes under ER Stress.We discovered a dead-box protein called DDX3X,which interacts with Ago2 and may play a new role in microRNA biogenesis.