IRE1-mediated miRNA maturation in macrophage phosphoinositide signaling.

Endoplasmic reticulum (ER) stress signaling has long been associated with various pathological states in particular with the development of diseases with an underlying inflammation, such as diabetes, liver or cardiovascular dysfunctions, and cancer. ER stress signaling is mediated by three stress sensors. The most evolutionarily conserved one, the inositol-requiring enzyme 1 alpha (IRE1), transduces most of the signals through an endoribonuclease (RNase) activity toward RNAs including mRNAs and microRNAs (miRNAs). By exploring phosphoinositide signaling in human macrophages, Hamid and colleagues discovered a novel function of IRE1 RNase that through the cleavage of pre-miR-2317 generates a mature miR-2317 independently of the canonical Dicer endonuclease to yield specific biological outcomes (Hamid et al, 2020).