ATG7(2) Interacts With Metabolic Proteins and Regulates Central Energy Metabolism

Macroautophagy/autophagy is a catabolic process that targets a wide variety of cellular components including proteins, lipids, damaged organelles, and pathogens. The autophagy protein ATG7 is involved in autophagy initiation by facilitating the lipidation of LC3/GABARAPs at the growing autophagosomal membrane. ATG7 is important for normal cellular homeostasis as well as diseased state such as tumor initiation and progression in various tumors. A short isoform of ATG7, termed ATG7(2) in contrast to the full-length ATG7(1), is unable to perform the characterized ATG7 mediated autophagy lipidation activity. In this study, we found that ATG7(1) and ATG7(2) are not correlated in expression in human tissues. They have different patterns of expression indicating that these isoforms are involved in diverse cellular mechanisms. To address the functional role of the short ATG7(2) isoform, we performed mass spectrometry analysis of the protein interactome of ATG7(1) and ATG7(2). This revealed that whereas ATG7(1) interacts with the autophagy machinery, ATG7(2) interacts with key glycolysis and mitochondrial membrane proteins. Functional experiments showed that ATG7(2) expression mediates a decrease in glycolytic activity, opposite to the effects mediated by ATG7(1) expression. These findings suggest a molecular switch between main catabolic processes through isoform dependent expression of a key autophagy gene.