α-Ketoglutarate couples cellular metabolism to developmental growth via hydroxylation-dependent degradation of Yorkie

The evolutionarily conserved Hippo signaling pathway, essential for development and tissue homeostasis, is intimately linked to cellular metabolism. While cellular α-ketoglutarate (α-KG) levels fluctuate with metabolic state, the functional significance of these fluctuations for development remains poorly defined. Here, this study uncovers an evolutionarily conserved mechanism whereby α-KG directly regulates Hippo signaling activity during development. We demonstrate that elevated α-KG promotes the degradation of Yki, the key Hippo pathway effector in Drosophila, in a concentration-dependent manner. Mechanistically, α-KG drives PH4αEFB-mediated prolyl hydroxylation of specific proline residues in Yki, thereby targeting it for ubiquitination and proteasomal degradation. Critically, mutation of these hydroxylation sites of Yki abolishes its sensitivity to α-KG, resulting in Yki protein hyperstabilization, aberrant activation of Hippo targets, and organ overgrowth in Drosophila. Overall, these findings establish α-KG as a central metabolic regulator of Hippo activity, thereby coupling metabolic status to developmental growth control.