le réseau de la biologie du développpement à Sorbonne Université
Exploratory Collaborative Projects & Master 2
Project coordinated by Hector Escriva Collaboratif PLUS
1) Laboratoire de Biologie Intégrative des Organismes marins (UMR 7232 , OOB)
2) Laboratoire de Biologie du Développement de Villefranche sur Mer (UMR 7009, OOV)
3) Centro Andaluz de Biología del Desarrollo (CSIC/ Universidad Pablo de Olavide, Sevilla, Espagne)
The three participants of this PECP are part of the consortium that sequenced, assembled and analyzed the complete genome of amphioxus Mediterranean Branchiostoma lanceolatum. In this context, we established the first known Epigenome of a Cephalochordate. For this, the involvement of the Spanish partner in this project PECP, Jose Luis Gomez Skarmeta, an international expert of Epigenomics, was essential.
This PECP project is led to the continuation of the work of Epigenomics but in a functional context. Thus, both SU partners Michael Schubert and Hector Escriva, have collaborated in the past to study the role of retinoic acid in embryonic development control amphioxus (see PNAS 2004 101: 10320; Development 2005, 1:61), and here they want to study the changes produced by Epigenomic activation and / or repression of retinoic acid signal during development of amphioxus. The technique we use is ATAC-seq, a technique mastered by the Spanish partner that has already reported positive results in wild amphioxus embryos in 2014. This technique (see Nat Methods 2013, 10: 1213) provides a simple and fast technique to highlight on a limited number of cells the open chromatin with a resolution of one nucleotide, which allows the study of active or inactive enhancers at any given time of development.
During the nesting season of amphioxus this year 2015 (May-July) we have prepared wild samples and treated retinoic acid and AR antagonists for the study by ATACseq. These samples will be sequenced (Hiseq2500) this season and the generated data will be studied during the year 2016.
This project allowed us to fund the travel and accommodation of OOV and Spanish partners to OOB or in vivo experiments on amphioxus embryos were performed, and the costs of the project.
Project coordinated by Michael Schubert Collaboratif Master 2
1) Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV, UMR 7009)
2) Laboratoire de Biologie du Développement (LBD, Campus Jussieu UMR 7622)
Retinoic acid (RA) is a diffusible molecule underlying genetic regulation involved in the control of many processes during development in vertebrates, including the regulation of cell differentiation or that of homeostasis. RA exerts its biological function by binding to heterodimers composed of two nuclear receptors, RAR (Retinoic Acid Receptor) and RXR (Retinoid X Receptor). These receptors possess DNA-binding domains that can interact with specific sequences located in the regulatory regions of targeted pathway genes, sequences commonly referred to as "RA Response Elements" or RARE.
During this project, we propose a comparative analysis of transcriptomic data obtained in Xenopus and Amphioxus to identify the target genes of the RA signaling during embryogenesis of a vertebrate (Xenopus) and a invertebrate chordate (Amphioxus). Together these results will establish not only the identity, but also the level of conservation of the target genes of the retinoid signaling in the evolution of chordates.
Project coordinated by Hervé Tostivint Collaboratif
Caractérisation de l’urotensine II (UII) et de son récepteur chez l’amphioxus Branchiostoma lanceolatum
1) Développement et évolution des systèmes neurosécréteurs (MNHN, CNRS, UMR 7221, Paris)
2) Evolution et développement des Chordés (Sorbonne Université, CNRS, UMR 7232, BIOM, Observatoire Océanologique de Banyuls sur Mer)
Neuropeptides are important actors of neuronal communication that essentially can be grouped in the form of multigene families. Many neuropeptides families known in vertebrates have also members in "invertebrates", suggesting that they have a very ancient origin and existed in the common ancestor of all bilaterian.
The work we do is focused on the study of the family of a peptide called urotensin II (UII). The existence of peptide family UII is well documented among all vertebrates but is still controversial in other metazoan groups.
Our project aims to investigate the UII and its receptor in amphioxus, a species belonging to the group cephalochordates considered evolutionarily very close to that of vertebrates. A preliminary study has led us to identify in the genome of amphioxus structurally related sequences with those of the UII and its receptor. Our goal will be to characterize the corresponding genes and search their functions during development of amphioxus.
Project coordinated by Jennifer Croce Collaboratif
Towards the identification of an ancestral Wnt function
1) Evolution of Intercellular Signaling in Development , Laboratoire de Biologie du Développement (UMR7009 CNRS‐Sorbonne Université)
2) Induction and Differentiation during Vertebrate Embryonic Development, Biologie du Développement (UMR7622 CNRS-Sorbonne Université)
Wnt genes encode secreted glycoprotein ligands that to date have been reported in animals from all metazoan phyla, ranging from sponges to vertebrates, while they have yet to be found in other living organisms (i.e. unicellular entities and plants). In planulozoans (which encompass both bilaterians and cnidarians), at least ten wnt genes have been reported in most genomes investigated so far, and their related proteins have been described as key regulators of numerous developmental processes, including primary body axis establishment and convergent-extension movements during gastrulation and neurulation. In contrast, in non-planulozoans (i.e. sponges, placozoans and ctenophores), the overall number of wnt genes reported is usually smaller (between three and four) and a developmental function for their corresponding proteins has yet to be ascertained. The goal of our project is to trace the evolutionary history of the wnt genes in metazoans, i.e. to determine their origin and a model for their diversification throughout the metazoan kingdom, as well as to examine the ancestral biological function of this family of ligands.
Seminars & Conferences
Project coordinated by Benoit Perthame Séminaire intra réseau
Mathematical modeling in developmental biology
2) SBR et UMR 8227 (Catherine BOYEN)
Since the seminal work of Alan Turing in 1952, mathematical models are used to explain pattern formation during development. Turing shows that morphogens reacting with short range activation combined with long range inhibition is a possible mechanism for generating boundaries. The french flag model of L. Wolpert (1968) is based on the idea that some positional information comes from a morphogen, diffused from one extremity of the developing organism, and determines cell differentiation. A. Prochiantz, B. Perthame, C. Quininao and J. Touboul show that short range diffusion of a homeoprotein in a morphogen gradient is able to select a precise boundary within a bistable dynamics thus determinig precisely the cell fate.
This topic is part of a larger initiative of the Laboratoire Jacques-Louis Lions (UFR de mathématiques) to use mathematical models where spatial distribution and dynamics play a central role in life sciences.
Project coordinated by Nicolas Robert Conférence
The wnt cradle: on the evolution of wnt repertoires in metazoans
at the "Developmental Biology of Sea Urchins XXIII Conference"
WNTs are secreted proteins that upon binding to transmembrane receptors (e.g. FRIZZLED) are able to trigger several intracellular signaling cascades, which play crucial roles during embryogenesis. It has to be highlighted that WNT proteins are a metazoan exclusivity and phylogenetic analyses have grouped them into several subfamilies. In planulozoans (bilaterians and cnidarians), thirteen distinct WNT subfamilies have been defined. Outside of planulozoans (i.e. sponges, ctenophores, placozoans), most species investigated so far have been shown to exhibit a smaller wnt catalog, with only three to four wnt genes, raising the question of the origin and the diversification of the wnt subfamilies in metazoans. Here, using a combination of molecular phylogenetic approaches, wnt cluster analyses and investigations of wnt synteny (between human, sponge and placozoan loci), we were able to assess the wnt catalogs of various metazoans taxa and to propose a model for to the origin, expansion, and dispersion of the metazoan wnt subfamilies