title: Identification, evolution and expression of an insulin-like peptide in the cephalochordate Branchiostoma lanceolatum.
abstract: Insulin is one of the most studied proteins since it is central to the regulation of carbohydrate and fat metabolism in vertebrates and its expression and release are disturbed in diabetes, the most frequent human metabolic disease worldwide. However, the evolution of the function of the insulin protein family is still unclear. In this study, we present a phylogenetic and developmental analysis of the Insulin Like Peptide (ILP) in the cephalochordate amphioxus. We identified an ILP in the European amphioxus Branchiostoma lanceolatum that displays structural characteristics of both vertebrate insulin and Insulin-like Growth Factors (IGFs). Our phylogenetic analysis revealed that amphioxus ILP represents the sister group of both vertebrate insulin and IGF proteins. We also characterized both temporal and spatial expression of ILP in amphioxus. We show that ilp is highly expressed in endoderm and paraxial mesoderm during development, and mainly expressed in the gut of both the developing embryo and adult. We hypothesize that ILP has critical implications in both developmental processes and metabolism and could display IGF- and insulin-like functions in amphioxus supporting the idea of a common ancestral protein.
authors.affiliation: Molecular Zoology Team, Institut de Génomique Fonctionnelle de Lyon, École Normale Supérieure de Lyon, CNRS, Université Lyon, Lyon, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Lecroisey
authors.affiliation: CNRS, UMR 7232, BIOM, Observatoire Océanologique, F-66650 Banyuls/Mer, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Pétillon
authors.affiliation: CNRS, UMR 7232, BIOM, Observatoire Océanologique, F-66650 Banyuls/Mer, France.
authors.forename: Hector
authors.initials: H
authors.lastname: Escriva
authors.affiliation: Institute of Metabolic Physiology, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Lammert
authors.affiliation: Molecular Zoology Team, Institut de Génomique Fonctionnelle de Lyon, École Normale Supérieure de Lyon, CNRS, Université Lyon, Lyon, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Laudet
mesh_terms: D000818:Animals; D064174:Cephalochordata / Q000235:genetics / Q000378:metabolism*; D004707:Endoderm / Q000378:metabolism; D019143:Evolution, Molecular; D007328:Insulin / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008648:Mesoderm / Q000378:metabolism; D010455:Peptides / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D010802:Phylogeny; D013002:Somatomedins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D007328:Insulin; D010455:Peptides; D013002:Somatomedins