Mechanisms and physiological functions of ER-phagy

The endoplasmic reticulum (ER) is the largest cellular organelle that undergoes constant turnover upon diverse functional demands and cellular signals. Removal of nonfunctional or superfluous subdomains is balanced by the parallel expansion and formation of ER membranes, leading to the dynamic exchange of ER components. In recent years, selective autophagy of the ER, termed ER-phagy, has emerged as a predominant process involved in ER degradation and maintenance of ER homeostasis. Identification of multiple ER-phagy receptors, many with additional ER-shaping functions, paved the way for our molecular understanding of ER turnover in different cells and organs. In this review, we describe the molecular principles underling the physiological functions of ER-phagy in maintaining ER homeostasis via receptor-mediated macroautophagy and elaborate current focus points of the field.