@article {9514, title = {Structural and functional characterization of an egg-laying hormone signaling system in a lophotrochozoan - The pacific oyster (Crassostrea gigas).}, journal = {Gen Comp Endocrinol}, volume = {346}, year = {2023}, month = {2023 Nov 28}, pages = {114417}, abstract = {

The egg-laying hormones (ELHs) of gastropod mollusks were characterized more than forty years ago. Yet, they have remained little explored in other mollusks. To gain insights into the functionality of the ELH signaling system in a bivalve mollusk - the oyster Crassostrea gigas, this study investigates the processing of its ELH precursor (Cragi-ELH) by mass spectrometry. Some of the ELH mature peptides identified in this study were subsequently investigated by nuclear magnetic resonance and shown to adopt an extended alpha-helix structure in a micellar medium mimicking the plasma membrane. To further characterize the ELH signaling system in C. gigas, a G protein-coupled receptor phylogenetically related to ecdysozoan diuretic hormone DH44 and corticotropin-releasing hormone (CRH) receptors named Cragi-ELHR was also characterized functionally and shown to be specifically activated by the two predicted mature ELH peptides and their N-terminal fragments. Both Cragi-ELH and Cragi-ELHR encoding genes were mostly expressed in the visceral ganglia (VG). Cragi-ELH expression was significantly increased in the VG of both fully mature male and female oysters at the spawning stage. When the oysters were submitted to a nutritional or hyposaline stress, no change in the expression of the ligand or receptor genes was recorded, except for Cragi-ELHR only during a mild acclimation episode to brackish water. These results suggest a role of Cragi-ELH signaling in the regulation of reproduction but not in mediating the stress response in our experimental conditions.

}, issn = {1095-6840}, doi = {10.1016/j.ygcen.2023.114417}, author = {Favrel, P and Dubos, M P and Bernay, B and Pasquier, J and Schwartz, J and Lefranc, B and Mouret, L and Rivi{\`e}re, G and Leprince, J and Bondon, A} } @article {5421, title = {Eel Kisspeptins: identification, functional activity, and inhibition on both pituitary LH and GnRH receptor expression}, journal = {Frontiers in Endocrinology}, volume = {8}, year = {2018}, pages = {353}, abstract = {

The European eel (Anguilla anguilla) presents a blockade of sexual maturation at a prepubertal stage due to a deficient production of gonadotropins. We previously initiated, in the eel, the investigation of the kisspeptin system, one of the major gatekeepers of puberty in mammals, and we predicted the sequence of two Kiss genes. In the present study, we cloned and sequenced Kiss1 and Kiss2 cDNAs from the eel brain. The tissue distributions of Kiss1 and Kiss2 transcripts, as investigated by quantitative real-time PCR, showed that both genes are primarily expressed in the eel brain and pituitary. The two 10-residue long sequences characteristic of kisspeptin, eel Kp1(10) and Kp2(10), as well as two longer sequences, predicted as mature peptides, eel Kp1(15) and Kp2(12), were synthesized and functionally analyzed. Using rat Kiss1 receptor-transfected Chinese hamster ovary cells, we found that the four synthesized eel peptides were able to induce [Ca2+]i responses, indicating their ability to bind mammalian KissR-1 and to activate second messenger pathways. In primary culture of eel pituitary cells, all four peptides were able to specifically and dose-dependently inhibit lhβ expression, without any effect on fshβ, confirming our previous data with heterologous kisspeptins. Furthermore, in this eel in vitro system, all four peptides inhibited the expression of the type 2 GnRH receptor (gnrh-r2). Our data revealed a dual inhibitory effect of homologous kisspeptins on both pituitary lhβ and gnrh-r2 expression in the European eel.

}, doi = {10.3389/fendo.2017.00353}, author = {Pasquier, J and Anne-Gaelle Lafont and Florian, D and Lefranc, B and Dubessy, C and Moreno-Herrera, A and Vaudry, H and Leprince, J and Sylvie Dufour and Karine Rousseau} }