Regulation of autophagy: modulation of the size and number of autophagosomes.

Autophagy as a conserved degradation and recycling process in eukaryotic cells, occurs constitutively, but is induced by stress. A fine regulation of autophagy in space, time, and intensity is critical for maintaining normal energy homeostasis and metabolism, and to allow for its therapeutic modulation in various autophagy-related human diseases. Autophagy activity is regulated in both transcriptional and post-translational manners. In this review, we summarize the cytosolic regulation of autophagy via its molecular machinery, and nuclear regulation by transcription factors. Specifically, we consider Ume6-ATG8 and Pho23-ATG9 transcriptional regulation in detail, as examples of how nuclear transcription factors and cytosolic machinery cooperate to determine autophagosome size and number, which are the two main mechanistic factors through which autophagy activity is regulated.