Regulation of ER stress responses by microRNAs

MicroRNAs (miRNAs) have been shown to be critically involved in control of cell survival and cell death decisions. The main function of miRNAs is to direct posttranscriptional regulation of gene expression, typically by binding to 3' UTR of cognate mRNAs and inhibiting their translation and/or stability. Hundreds of miRNAs, many of them evolutionarily conserved, have been identified in mammals, but their physiological functions are just beginning to be elucidated. Endoplasmic Reticulum (ER) stress has been associated with a wide range of diseases, including neurodegeneration, stroke, bipolar disorder, cardiac disease, cancer and diabetes. Although the Unfolded Protein Response (UPR) is primarily pro-survival, in the event of prolonged or severe ER stress that is not resolved, the UPR switches to initiation of apoptosis. Here we have discussed the role of miRNAs in determining cell fate during conditions of ER stress. This chapter will provide novel insights into regulation of UPR signaling by miRNAs.