No abstract

Micro-RNAs typically function at the level of post-transcriptional gene silencing within the cytoplasm; however increasing evidence suggests that they may also function in nuclear, Argonaut containing complexes, to directly repress target gene transcription. We have investigated the role of micro-RNAs in mediating endoplasmic reticulum (ER) stress responses. ER stress triggers the activation of three signaling molecules: Ire-1α/β, PERK and ATF6 whose function is to facilitate adaption to the ensuing stress. We demonstrate that PERK induces miR-211, which in turn attenuates stress-dependent expression of the pro-apoptotic transcription factor chop/gadd153. MiR-211 directly targets the proximal chop/gadd153 promoter where it increases histone methylation and represses chop expression. Maximal chop accumulation ultimately correlates with miR-211 down regulation. Our data suggests a model where PERK-dependent miR-211 induction prevents premature chop accumulation and thereby provides a window of opportunity for the cell to re-establish homeostasis prior to apoptotic commitment.