title: Growth-Blocking Peptides As Nutrition-Sensitive Signals for Insulin Secretion and Body Size Regulation.
abstract: In Drosophila, the fat body, functionally equivalent to the mammalian liver and adipocytes, plays a central role in regulating systemic growth in response to nutrition. The fat body senses intracellular amino acids through Target of Rapamycin (TOR) signaling, and produces an unidentified humoral factor(s) to regulate insulin-like peptide (ILP) synthesis and/or secretion in the insulin-producing cells. Here, we find that two peptides, Growth-Blocking Peptide (GBP1) and CG11395 (GBP2), are produced in the fat body in response to amino acids and TOR signaling. Reducing the expression of GBP1 and GBP2 (GBPs) specifically in the fat body results in smaller body size due to reduced growth rate. In addition, we found that GBPs stimulate ILP secretion from the insulin-producing cells, either directly or indirectly, thereby increasing insulin and insulin-like growth factor signaling activity throughout the body. Our findings fill an important gap in our understanding of how the fat body transmits nutritional information to the insulin producing cells to control body size.
authors.affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors.forename: Takashi
authors.initials: T
authors.lastname: Koyama
authors.affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal.|School of Biological Sciences, Monash University, Clayton, Victoria, Australia.
authors.forename: Christen K
authors.initials: CK
authors.lastname: Mirth
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D049628:Body Size; D001921:Brain / Q000378:metabolism; D046508:Culture Techniques; D016207:Cytokines / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000502:physiology*; D005216:Fat Body / Q000378:metabolism*; D005260:Female; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D013002:Somatomedins / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D016207:Cytokines; D029721:Drosophila Proteins; D007328:Insulin; D013002:Somatomedins; C000602870:growth-blocking peptide, Drosophila; D058570:TOR Serine-Threonine Kinases