Insulin signaling couples growth and early maturation to cholesterol intake in Drosophila

• Published in: Current biology Vol. 32; no. 7; pp. 1548 - 1562.e6
• Main Authors: Texada, Michael J., Lassen, Mette, Pedersen, Lisa H., Koyama, Takashi, Malita, Alina, Rewitz, Kim
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 11.04.2022
• Subjects: Adipose; Animals; Cholesterol; Developmental timing; Drosophila; Drosophila melanogaster - metabolism; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Ecdysone; Glia; Insulin - metabolism; Larva; Mammals; NPC1; Nutrients; Nutrition; Pediatric Obesity; Steroids - metabolism; TOR; Adipose; Nutrition; NPC1; TOR; Nutrients; Ecdysone; Glia; Developmental timing
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2022.02.021

Nutrition is one of the most important influences on growth and the timing of maturational transitions including mammalian puberty and insect metamorphosis. Childhood obesity is associated with precocious puberty, but the assessment mechanism that links body fat to early maturation is unknown. During development, the intake of nutrients promotes signaling through insulin-like systems that govern the growth of cells and tissues and also regulates the timely production of the steroid hormones that initiate the juvenile-adult transition. We show here that the dietary lipid cholesterol, which is required as a component of cell membranes and as a substrate for steroid biosynthesis, also governs body growth and maturation in Drosophila via promoting the expression and release of insulin-like peptides. This nutritional input acts via the nutrient sensor TOR, which is regulated by the Niemann-Pick-type-C 1 (Npc1) cholesterol transporter, in the glia of the blood-brain barrier and cells of the adipose tissue to remotely drive systemic insulin signaling and body growth. Furthermore, increasing intracellular cholesterol levels in the steroid-producing prothoracic gland strongly promotes endoreduplication, leading to an accelerated attainment of a nutritional checkpoint that normally ensures that animals do not initiate maturation prematurely. These findings, therefore, show that a Npc1-TOR signaling system couples the sensing of the lipid cholesterol with cellular and systemic growth control and maturational timing, which may help explain both the link between cholesterol and cancer as well as the connection between body fat (obesity) and early puberty. •Dietary cholesterol promotes developmental growth and leads to early maturation•Insulin signaling couples cholesterol intake with systemic growth•Npc1-TOR couples cholesterol with insulin signaling via glial and fat-tissue relays•Cholesterol sensing affects a nutritional checkpoint that prevents early maturation Cholesterol is necessary for normal physiology, but its overabundance contributes to disease. Texada et al. report that dietary cholesterol activates mTOR in Drosophila adipose-/hepatic-like cells and blood-brain-barrier glia, which remotely upregulate systemic insulin-like signaling, a finding that may have implications for health.