Meeting Abstract

P3.61  Thursday, Jan. 6  Ancestral neurotrophins and the evolution of the ‘neurotrophic signaling’ in Eumetazoa LAURI, A.*; TOMER, R.; ARENDT, D.; EMBL; EMBL; EMBL lauri@embl.de

Since the first neurotrophic factor was discovered more then 20 years ago, findings emerging from the study and these fascinating molecules have deeply influenced the field of developmental biology and neuroscience. Neurotrophic factors and their receptors have a crucial role in the development of the nervous system in vertebrates; controlling processes such as axonal path-finding and neuronal outgrowth. Outside vertebrates recent studies have shown the presence of similar molecules in several deuterostomes.Currently no data are available on the gene expression and the function of these molecules outside vertebrates, with the exception of the amphioxus AmphyTrk, expressed in ectodermal sensory cells and in the Hatschek’s pit (homologous to the adenohypophysis). In Platynereis dumerilii (a representative member of the protostomes) we show the presence of highly conserved prototypical molecules of the neurotrophic signaling (PduNt , Trk , p75 ), their expression and preliminary indications on their ‘invertebrate-ancestral’ function.This, together with recent data from arthropods, indicate that neurotrophic signaling, and likley its involvement in the ancestral neural network patterning, already existed at the protostome /deuterostome split, and it is not a key innovation of the vertebrates as previously hypothesized. Intriguingly, an additional paralog family has been found in Ecdysozoa.Members of this specific family (Spz) differ from the canonical molecules and their role is unknown; but it is unlikely that they act via the canonical pathway. This family is not present in lophotrocopzoa (the group to which Platyneris dumerilii belongs to), or in deuterostomes, and probably originated at some point in the protostomes from an ancestral Neurotrphin molecule, PduNt like.