Fig. 3

Regulation of autophagy by ER stress. Four major signaling pathways, including IRE1α, ATF6, PERK and Ca²⁺-related pathways implicated in ER stress-triggered autophagy. Among those pathways, UPR is triggered by the activation of the above three protein sensors (IRE1α, ATF6 and PERK) and regulates the transcription of autophagy genes and/or the function of autophagy protein. The release of Ca²⁺ from ER can activate autophagy via Ca²⁺/CaMKKβ/AMPK and PKCθ pathways. Dashed arrows indicate that the effect is multistep