Compartmentalized glycolysis powers ATP production in primary cilia and engages mitochondria via the phosphoenolpyruvate cycle

Primary cilia are antenna-like sensory and signaling organelles present on most mammalian cells, including glucose-sensing pancreatic {beta}-cells. Here, we show that the local energetic demands of primary cilia require the ATP-producing enzyme pyruvate kinase, with loss of PKm1, but not PKm2, impairing ciliary glycolytic flux. While the entire glycolytic machinery localizes to cilia, our data indicate that mitochondria are a critical source of phosphoenolpyruvate (PEP), the high-energy glycolytic intermediate that drives the pyruvate kinase reaction. Abolishing PCK2, the mitochondrial enzyme that generates PEP, prevents cilia from sensing not only glucose but also the amino acids glutamine and leucine. Finally, by mislocalizing glycolysis, we demonstrate that primary cilia can utilize ATP generated within the cell body when glucose is limiting. These findings indicate that primary cilia, while possessing the capacity for local ATP generation, leverage a ciliary-mitochondrial signaling axis to meet their bioenergetic needs.