Signal Transduction Regulation of Autophagy

As a major stress-responsive catabolic pathway, autophagy communicates with a variety of signal transduction pathways ranging from proliferative signaling, metabolic pathways, cell death pathways, and multiple cellular stresses. As such, autophagy needs to be able to integrate diverse signaling events and respond to various complex biological conditions in a highly orchestrated manner. Mechanistically, while the molecular basis underlying the function of the core autophagy machinery has been relatively well established, how does autophagy pathway sense diverse upstream signaling pathways? How does autophagy contribute to the eventual biological outcomes of these signaling pathways? Is there any feedback regulation from autophagy to the upstream signaling pathways? And what governs signal transduction within the core autophagy pathway? This chapter discusses the current understanding of these questions. Particularly, an emphasis is placed on the role of the Atg1/ULK1 complex in sensing the upstream nutrient/energy signaling and relaying the upstream signaling to downstream autophagy machinery.