AUTHOR=Paul Bidisha , Dockery Rejenae , Valverde Valery M. , Buchholz Daniel R. 

TITLE=Characterization of a novel corticosterone response gene in Xenopus tropicalis tadpole tails

JOURNAL=Frontiers in Endocrinology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2023.1121002

DOI=10.3389/fendo.2023.1121002

ISSN=1664-2392

ABSTRACT=<p>Corticosteroids are critical for development and for mediating stress responses across diverse vertebrate taxa. Study of frog metamorphosis has made significant breakthroughs in our understanding of corticosteroid signaling during development in non-mammalian vertebrate species. However, lack of adequate corticosterone (CORT) response genes in tadpoles make identification and quantification of CORT responses challenging. Here, we characterized a CORT-response gene <italic>frzb</italic> (frizzled related protein) previously identified in <italic>Xenopus tropicalis</italic> tadpole tail skin by an RNA-seq study. We validated the RNA-seq results that CORT and not thyroid hormone induces <italic>frzb</italic> in the tails using quantitative PCR. Further, maximum <italic>frzb</italic> expression was achieved by 100-250 nM CORT within 12-24 hours. <italic>frzb</italic> is not significantly induced in the liver and brain in response to 100 nM CORT. We also found no change in <italic>frzb</italic> expression across natural metamorphosis when endogenous CORT levels peak. Surprisingly, <italic>frzb</italic> is only induced by CORT in <italic>X. tropicalis</italic> tails and not in <italic>Xenopus laevis</italic> tails. The exact downstream function of increased <italic>frzb</italic> expression in tails in response to CORT is not known, but the specificity of hormone response and its high mRNA expression levels in the tail render <italic>frzb</italic> a useful marker of exogenous CORT-response independent of thyroid hormone for exogenous hormone treatments and <italic>in-vivo</italic> endocrine disruption studies.</p>