Differential Regulation of the Expression of the Two Thyrotropin Beta Subunit Paralogs by Salmon Pituitary Cells In Vitro

• Published in: Frontiers in Endocrinology
• Main Authors: Fleming, Mitchell, Maugars, Gersende, Martin, Patrick, Dufour, Sylvie, Rousseau, Karine
• Other Authors: Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Conservatoire National du Saumon Sauvage (CNSS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: tshb paralogs; gh; thyroid hormones; cortisol; IGF1; CRH; Salmo salar; pituitary cells in vitro; [SDV]Life Sciences [q-bio]; [SDE]Environmental Sciences; Atlantic salmon
• Online Access: https://hal.archives-ouvertes.fr/hal-03065703; https://hal.archives-ouvertes.fr/hal-03065703/document; https://hal.archives-ouvertes.fr/hal-03065703/file/Fleming2020fendo-11-603538.pdf; https://doi.org/10.3389/fendo.2020.603538

International audience We recently characterized two paralogs of the thyrotropin (TSH) beta subunit in Atlantic salmon, tshba and tshbb, issued from teleost-specific whole genome duplication. The transcript expression of tshbb, but not of tshba, peaks at the time of smoltification, which revealed a specific involvement of tshbb paralog in this metamorphic event. Tshba and tshbb are expressed by distinct pituitary cells in salmon, likely related to TSH cells from the pars distalis and pars tuberalis, respectively, in mammals and birds. The present study aimed at investigating the neuroendocrine and endocrine factors potentially involved in the differential regulation of tshba and tshbb paralogs, using primary cultures of Atlantic salmon pituitary cells. The effects of various neurohormones and endocrine factors potentially involved in the control of development, growth, and metabolism were tested. Transcript levels of tshba and tshbb were measured by qPCR, as well as those of growth hormone (gh), for comparison and validation. Corticotropin-releasing hormone (CRH) stimulated tshba transcript levels in agreement with its potential role in the thyrotropic axis in teleosts, but had no effect on tshbb paralog, while it also stimulated gh transcript levels. Thyrotropin-releasing hormone (TRH) had no effect on neither tshb paralogs nor gh. Somatostatin (SRIH) had no effects on both tshb paralogs, while it exerted a canonical inhibitory effect on gh transcript levels. Thyroid hormones [triiodothyronine (T3) and thyroxine (T4)] inhibited transcript levels of both tshb paralogs, as well as gh, but with a much stronger effect on tshba than on tshbb and gh. Conversely, cortisol had a stronger inhibitory effect on tshbb than tshba, while no effect on gh. Remarkably, insulin-like growth factor 1 (IGF1) dose-dependently stimulated tshbb transcript levels, while it had no effect on tshba, and a classical inhibitory effect on gh. This study provides the first data on the neuroendocrine factors involved in the differential ...