title: Retinoid metabolism in invertebrates: when evolution meets endocrine disruption.
abstract: Recent genomic and biochemical evidence in invertebrate species pushes back the origin of the retinoid metabolic and signaling modules to the last common ancestor of all bilaterians. However, the evolution of retinoid pathways are far from fully understood. In the majority of non-chordate invertebrate lineages, the ongoing functional characterization of retinoid-related genes (metabolism and signaling pathways), as well as the characterization of the endogenous retinoid content (precursors and active retinoids), is still incomplete. Despite limited, the available data supports the presence of biologically active retinoid pathways in invertebrates. Yet, the mechanisms controlling the spatial and temporal distribution of retinoids as well as their physiological significance share similarities and differences with vertebrates. For instance, retinol storage in the form of retinyl esters, a key feature for the maintenance of retinoid homeostatic balance in vertebrates, was only recently demonstrated in some mollusk species, suggesting that such ability is older than previously anticipated. In contrast, the enzymatic repertoire involved in this process is probably unlike that of vertebrates. The suggested ancestry of active retinoid pathways implies that many more metazoan species might be potential targets for endocrine disrupting chemicals. Here, we review the current knowledge about the occurrence and functionality of retinoid metabolic and signaling pathways in invertebrate lineages, paying special attention to the evolutionary origin of retinoid storage mechanisms. Additionally, we summarize existing information on the endocrine disruption of invertebrate retinoid modules by environmental chemicals. Research priorities in the field are highlighted.
authors.affiliation: CIMAR/CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; ICBAS - Institute of Biomedical Sciences Abel Salazar, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal. Electronic address: iandre@ciimar.up.pt.
authors.forename: A
authors.initials: A
authors.lastname: André
authors.affiliation: CIMAR/CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal. Electronic address: rruivo@ciimar.up.pt.
authors.forename: R
authors.initials: R
authors.lastname: Ruivo
authors.affiliation: Laboratorio de Fisioloxía Animal, Facultade de Bioloxía, Universidade de Vigo, 36310 Vigo, Spain. Electronic address: manuelgesto@uvigo.es.
authors.forename: M
authors.initials: M
authors.lastname: Gesto
authors.affiliation: CIMAR/CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; FCUP - Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal. Electronic address: filipe.castro@ciimar.up.pt.
authors.forename: L Filipe C
authors.initials: LF
authors.lastname: Castro
authors.affiliation: CIMAR/CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; FCUP - Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal. Electronic address: santos@ciimar.up.pt.
authors.forename: M M
authors.initials: MM
authors.lastname: Santos
mesh_terms: D000818:Animals; D005075:Biological Evolution; D052244:Endocrine Disruptors / Q000378:metabolism*; D007448:Invertebrates / Q000378:metabolism*; D012176:Retinoids / Q000378:metabolism*; D015398:Signal Transduction; D014714:Vertebrates / Q000378:metabolism
chemical_list: D052244:Endocrine Disruptors; D012176:Retinoids
keywords: Endocrine disruption; Evolution; Invertebrates; Retinoid pathways