pbio.3003523.t001 -

Mitochondrial function and dynamics are essential for maintaining cellular homeostasis and overall health. Disruptions in these processes can contribute to various diseases, including cancer. The Hippo signaling pathway, a key regulator of tissue growth, plays a central role in cancer through its main effector YAP, known as Yki in Drosophila. In this model organism, Yki upregulation drives benign tissue overgrowth in imaginal discs. Our research demonstrates that the conserved metabolic regulator dPGC1 restricts Yki-driven tissue hyperplasia and helps maintain epithelial integrity in vivo. Combined Yki upregulation and dPGC1 depletion results in tumors characterized by enlarged mitochondria and the upregulation of genes promoting mitochondrial fusion, a condition that is both necessary and sufficient for Yki-driven oncogenic growth. We further demonstrate that mitochondrial enlargement is associated with increased levels of the cell cycle regulator Cyclin E, which plays a critical role in tumor development. These findings identify dPGC1 as a context-dependent tumor suppressor that coordinates mitochondrial dynamics and cell cycle regulation in response to oncogene activation, with implications for understanding cancer development in humans.