@article {7996, title = {Molecular and physiological characterization of a crustacean cardioactive signaling system in a lophotrochozoan - the Pacific oyster (Crassostrea gigas): a role in reproduction and salinity acclimation.}, journal = {J Exp Biol}, volume = {224}, year = {2021}, month = {2021 May 15}, abstract = {

The crustacean cardioactive peptide (CCAP) is an important neuropeptide involved in the regulation of a variety of physiological processes in arthropods. Although this family of peptides has an ancestral origin, its function remains poorly understood among protostome species - apart from arthropods. We functionally characterized three G protein-coupled receptors (GPCRs) in the oyster Crassostrea gigas, phylogenetically related to ecdysozoan CCAP receptors (CCAPRs) and to chordate neuropeptide S receptors (NPSRs). Cragi-CCAPR1 and Cragi-CCAPR2 were specifically activated by the Cragi-CCAP1 and Cragi-CCAP2 peptides, respectively, both derived from the same CCAP precursor. In contrast, Cragi-CCAPR3 was only partially activated by CCAP1 and CCAP2 at high concentrations. The Cragi-CCAPR1 and Cragi-CCAPR2 genes were expressed in various adult tissues. They are both most expressed in the gills, while Cragi-CCAPR3 is mainly expressed in the visceral ganglia (VG). Cragi-CCAP precursor transcripts are higher in the VG, the labial palps and the gills. Receptor and ligand-encoding transcripts are more abundantly expressed in the gonads in the first stages of gametogenesis, while the Cragi-CCAP precursor is upregulated in the VG in the last stages of gametogenesis. This suggests a role of the CCAP signaling system in the regulation of reproductive processes. A role in water and ionic regulation is also supported considering the differential expression of the CCAP signaling components in oysters exposed to brackish water.

}, issn = {1477-9145}, doi = {10.1242/jeb.241588}, author = {R{\'e}alis-Doyelle, Emilie and Julie Schwartz and Marie-Pierre Dubos and Pascal Favrel} } @article {6796, title = {Characterization of an evolutionarily conserved calcitonin signalling system in a lophotrochozoan, the Pacific oyster (Crassostrea gigas) }, journal = {The Journal of Experimental Biology}, volume = {222}, year = {2019}, month = {Jan-07-2019}, pages = {jeb201319}, issn = {0022-0949}, doi = {10.1242/jeb.201319}, url = {http://jeb.biologists.org/lookup/doi/10.1242/jeb.201319}, author = {Julie Schwartz and R{\'e}alis-Doyelle, Emilie and Marie-Pierre Dubos and Lefranc, Benjamin and Leprince, J{\'e}r{\^o}me and Pascal Favrel} } @article {6116, title = {Characterization of an evolutionarily conserved calcitonin signalling system in a lophotrochozoan, the Pacific oyster ().}, journal = {J Exp Biol}, volume = {222}, year = {2019}, month = {2019 Jul 05}, abstract = {

In Protostoma, the diuretic hormone 31 (DH31) signalling system was long considered as the orthologue of the chordate calcitonin (CT) signalling system. Using the Pacific oyster () transcriptomic database GigaTON, we characterized seven G-protein-coupled receptors (GPCRs) named Cragi-CTR1-7 and phylogenetically related to chordate CT receptors (CTRs) and to protostome DH31 receptors. Two CT precursors (Cragi-CTP1 and Cragi-CTP2) containing two CT-type peptides and encoded by two distinct genes with a similar organization were also characterized. These oyster neuropeptides (Cragi-CT1/2) exhibit the two N-terminal paired cysteine residues and, except CTP2-derived peptide (Cragi-CTP2dp), show the C-terminal proline-amide motif typical of deuterostome CT-type peptides. All mature Cragi-CTs except Cragi-CTP2dp were detected in visceral ganglion extracts using mass spectrometry. Cell-based assays revealed that the previously characterized oyster receptors Cg-CT-R and Cragi-CTR2 were specifically activated by Cragi-CT1b and Cragi-CT2, respectively. This activation does not require the co-expression of receptor activity-modifying proteins (RAMPs). Thus, oyster CT signalling appears functionally more closely related to vertebrate CT/CTR signalling than to calcitonin gene-related peptide/calcitonin receptor-like receptor (CGRP/CLR) signalling. Gene expression profiles in different adult tissues and in oysters acclimated to brackish water suggest the potential implication of both Cg-CT-R/Cragi-CT1b and Cragi-CTR2/Cragi-CT2 in water and ionic regulations, although with apparently opposite effects. The present study represents the first comprehensive characterization of a functional CT-type signalling system in a protostome and provides evidence for its evolutionarily ancient origin and its early role in osmotic homeostasis.

}, issn = {1477-9145}, doi = {10.1242/jeb.201319}, author = {Julie Schwartz and R{\'e}alis-Doyelle, Emilie and Marie-Pierre Dubos and Lefranc, Benjamin and Leprince, J{\'e}r{\^o}me and Pascal Favrel} } @article {5564, title = {Characterization of a tachykinin signalling system in the bivalve mollusc Crassostrea gigas}, journal = {General and Comparative Endocrinology}, volume = {266}, year = {2018}, pages = {110-118}, type = {regular}, abstract = {

Although tachykinin-like neuropeptides have been identified in molluscs more than two decades ago, knowledge on their function and signalling has so far remained largely elusive. We developed a cell-based assay to address the functionality of the tachykinin G-protein coupled receptor (Cragi-TKR) in the oyster Crassostrea gigas. The oyster tachykinin neuropeptides that are derived from the tachykinin precursor gene Cragi-TK activate the Cragi-TKR in nanomolar concentrations. Receptor activation is sensitive to Ala-substitution of critical Cragi-TK amino acid residues. The Cragi-TKR gene is expressed in a variety of tissues, albeit at higher levels in the visceral ganglia (VG) of the nervous system. Fluctuations of Cragi-TKR expression is in line with a role for TK signalling in C. gigas reproduction. The expression level of the Cragi-TK gene in the VG depends on the nutritional status of the oyster, suggesting a role for TK signalling in the complex regulation of feeding in C. gigas.

}, doi = {https://doi.org/10.1016/j.ygcen.2018.05.003}, author = {Marie-Pierre Dubos and Sven Zels and Julie Schwartz and Jeremy Pasquier and Liliane Schoofs and Pascal Favrel} } @article {5707, title = {Emergence of a cholecystokinin/sulfakinin signalling system in Lophotrochozoa}, journal = {Scientific Reports}, volume = {8}, year = {2018}, month = {11/2018}, pages = {16424}, abstract = {Chordate gastrin/cholecystokinin (G/CCK) and ecdysozoan sulfakinin (SK) signalling systems represent divergent evolutionary scenarios of a common ancestral signalling system. The present article investigates for the first time the evolution of the CCK/SK signalling system in a member of the Lophotrochozoa, the second clade of protostome animals. We identified two G protein-coupled receptors (GPCR) in the oyster\ Crassostrea gigas\ (Mollusca), phylogenetically related to chordate CCK receptors (CCKR) and to ecdysozoan sulfakinin receptors (SKR). These receptors, Cragi-CCKR1 and Cragi-CCKR2, were characterised functionally using a cell-based assay. We identified di- and mono-sulphated forms of oyster Cragi-CCK1 (pEGAWDY(SO3H)DY(SO3H)GLGGGRF-NH2) as the potent endogenous agonists for these receptors. The Cragi-CCK genes were expressed in the visceral ganglia of the nervous system. The Cragi-CCKR1 gene was expressed in a variety of tissues, while Cragi-CCKR2 gene expression was more restricted to nervous tissues. An\ in vitro\ bioassay revealed that different forms of Cragi-CCK1 decreased the frequency of the spontaneous contractions of oyster hindgut. Expression analyses in oysters with contrasted nutritional statuses or in the course of their reproductive cycle highlighted the plausible role of Cragi-CCK signalling in the regulation of feeding and its possible involvement in the coordination of nutrition and energy storage in the gonad. This study confirms the early origin of the CCK/SK signalling system from the common bilaterian ancestor and delivers new insights into its structural and functional evolution in the lophotrochozoan lineage.}, doi = {doi.org/10.1038/s41598-018-34700-4}, url = {https://www.nature.com/articles/s41598-018-34700-4}, author = {Julie Schwartz and Marie-Pierre Dubos and Jeremy Pasquier and C{\'e}line Zatylny-Gaudin and Pascal Favrel} }