AUTHOR=Perera Erick , Román-Padilla Javier , Hidalgo-Pérez Juan Antonio , Huesa-Cerdán Rubén , Yúfera Manuel , Mancera Juan Miguel , Martos-Sitcha Juan Antonio , Martínez-Rodríguez Gonzalo , Ortiz-Delgado Juan Bosco , Navarro-Guillén Carmen , Rodriguez-Casariego Javier A. 

TITLE=Tissue explants as tools for studying the epigenetic modulation of the GH-IGF-I axis in farmed fish

JOURNAL=Frontiers in Physiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1410660

DOI=10.3389/fphys.2024.1410660

ISSN=1664-042X

ABSTRACT=<p>Somatic growth in vertebrates is mainly controlled by the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. The role of epigenetic mechanisms in regulating this axis in fish is far from being understood. This work aimed to optimize and evaluate the use of short-term culture of pituitary and liver explants from a farmed fish, the gilthead seabream <italic>Sparus aurata</italic>, for studying epigenetic mechanisms involved in GH/IGF-I axis regulation. Our results on viability, structure, proliferation, and functionality of explants support their use in short-term assays. Pituitary explants showed no variation in <italic>gh</italic> expression after exposure to the DNA methylation inhibitor decitabine (5-Aza-2′-deoxycytidine; DAC), despite responding to DAC by changing <italic>dnmt3bb</italic> and <italic>tet1</italic> expression, and TET activity, producing an increase in overall DNA hydroxymethylation. Conversely, in liver explants, DAC had no effects on <italic>dnmt</italic><sub><italic>s</italic></sub> and <italic>tet</italic><sub><italic>s</italic></sub> expression or activity, but modified the expression of genes from the GH-IGF-I axis. In particular, the expression of <italic>igfbp2a</italic> was increased and that of <italic>igfbp4</italic>, <italic>ghri</italic> and <italic>ghrii</italic> was decreased by DAC as well as by genistein, which is suggestive of impaired growth. While incubation of liver explants with S-adenosylmethionine (SAM) produced no clear effects, it is proposed that nutrients must ensure the methylation milieu within the liver in the fish to sustain proper growth, which need further <italic>in vivo</italic> verification. Pituitary and liver explants from <italic>S. aurata</italic> can be further used as described herein for the screening of inhibitors or activators of epigenetic regulators, as well as for assessing epigenetic mechanisms behind GH-IGF-I variation in farmed fish.</p>