Nutrient/TOR signaling controls adipose mitochondrial transcription factor A (TFAM) to regulate organismal growth in Drosophila.

Animals must adapt their growth to fluctuations in nutrient availability to ensure proper development. While nutrient-sensing tissues coordinate organismal growth through interorgan signaling, the metabolic changes within these tissues that mediate whole-body growth control remain poorly understood. Using Drosophila larvae, we show that TOR (target of rapamycin), a conserved nutrient-sensing kinase, controls developmental growth through regulation of the mitochondrial genome transcription factor TFAM, which controls mitochondrial bioenergetic capacity. We find that nutrient/TOR signaling post-transcriptionally suppresses TFAM protein levels. Furthermore, we find that TOR regulation of TFAM in the larval fat body, a key nutrient-sensing tissue, controls developmental growth. These findings establish a molecular mechanism linking nutrient-sensing pathways to mitochondrial metabolism, revealing how environmental nutrient availability coordinates organismal growth through tissue-specific metabolic control.