| Summary: | Summary: In Drosophila, ecdysone hormone levels determine the timing of larval development. Its production is regulated by the stereotypical rise in prothoracicotropic hormone (PTTH) levels. Additionally, ecdysone levels can also be modulated by nutrition (specifically by amino acids) through their action on Drosophila insulin-like peptides (Dilps). Moreover, in glia, amino-acid-sensitive production of Dilps regulates brain development. In this work, we describe the function of an SLC7 amino acid transporter, Sobremesa (Sbm). Larvae with reduced Sbm levels in glia remain in third instar for an additional 24 hr. These larvae show reduced brain growth with increased body size but do not show reduction in insulin signaling or production. Interestingly, Sbm downregulation in glia leads to reduced Ecdysone production and a surprising delay in the rise of PTTH levels. Our work highlights Sbm as a modulator of both brain development and the timing of larval development via an amino-acid-sensitive and Dilp-independent function of glia. : Galagovsky et al. reveal a molecular and cellular pathway linking metabolism to developmental growth control. This pathway governs body and nervous system growth timing and involves an amino acid transporter expressed in glia. Keywords: amino acid transporter, glia, nervous system, tissue growth, development, insulin, PTTH, ecdysone, feeding, Drosophila
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