Differential effects of 3,5-T2 and T3 on the gill regeneration and metamorphosis of the Ambystoma mexicanum (axolotl)
Por:
Lazcano, I., Olvera, A., Pech-Pool, S. M., Sachs, L., Buisine, N., Orozco, A.
Publicada:
10 jul 2023
Categoría:
Endocrinology, diabetes and metabolism
Resumen:
Thyroid hormones (THs) regulate tissue remodeling processes during
early- and post-embryonic stages in vertebrates. The Mexican axolotl
(Ambystoma mexicanum) is a neotenic species that has lost the ability to
undergo metamorphosis; however, it can be artificially induced by
exogenous administration of thyroxine (T4) and 3,3 &
PRIME;,5-triiodo-L-thyronine (T3). Another TH derivative with
demonstrative biological effects in fish and mammals is
3,5-diiodo-L-thyronine (3,5-T2). Because the effects of this bioactive
TH remains unexplored in other vertebrates, we hypothesized that it
could be biologically active in amphibians and, therefore, could induce
metamorphosis in axolotl. We performed a 3,5-T2 treatment by immersion
and observed that the secondary gills were retracted, similar to the
onset stage phenotype; however, tissue regeneration was observed after
treatment withdrawal. In contrast, T4 and T3 immersion equimolar
treatments as well as a four-fold increase in 3,5-T2 concentration
triggered complete metamorphosis. To identify the possible molecular
mechanisms that could explain the contrasting reversible or irreversible
effects of 3,5-T2 and T3 upon gill retraction, we performed a
transcriptomic analysis of differential expression genes in the gills of
control, 3,5-T2-treated, and T3-treated axolotls. We found that both THs
modify gene expression patterns. T3 regulates 10 times more genes than
3,5-T2, suggesting that the latter has a lower affinity for TH receptors
(TRs) or that these hormones could act through different TR isoforms.
However, both TH treatments regulated different gene sets known to
participate in tissue development and cell cycle processes. In
conclusion, 3,5-T2 is a bioactive iodothyronine that promoted partial
gill retraction but induced full metamorphosis in higher concentrations.
Differential effects on gill retraction after 3,5,-T2 or T3 treatment
could be explained by the activation of different clusters of genes
related with apoptosis, regeneration, and proliferation; in addition,
these effects could be initially mediated by TRs that are expressed in
gills. This study showed, for the first time, the 3,5,-T2 bioactivity in
a neotenic amphibian.
Filiaciones:
Lazcano, I.:
Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
Olvera, A.:
Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
Pech-Pool, S. M.:
Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
Sachs, L.:
UMR PhyMA CNRS, Muséum National d’Histoire Naturelle, Paris, France
Buisine, N.:
UMR PhyMA CNRS, Muséum National d’Histoire Naturelle, Paris, France
Orozco, A.:
Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
Escuela Nacional de Estudios Superiores, Unidad Juriquilla, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
Green Published, gold, All Open Access; Gold
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