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Amphibian metamorphosis represents a dramatic example of post-embryonic development. In the anuran Xenopus laevis frog, this process involves extensive changes to larval tissues, structures, and physiology to produce its adult form. As a long-standing model to study tissue remodeling, both amphibian metamorphosis and mammalian development are under the control of thyroid hormone. Successful remodeling though, also requires precise temporospatial regulation of immune activation. Yet there is much to learn about the immune components linked to metamorphosis. In turn, granulocytes are a class of innate immune cells recently touted for their participation in processes beyond classical immune defenses, including in pathological and non-pathological tissue remodeling. In this manuscript, we explore the roles of granulocytes in perhaps the most conspicuous anuran metamorphic event: tadpole tail reabsorption. We characterize granulocyte infiltration into the tail as metamorphosis progresses. Although some granulocyte subpopulations exist in both Xenopus and mammals, our previous work has identified additional Xenopus-specific populations. Thus, here we further explored subpopulation dynamics through distinct stages of natural metamorphosis, their likely roles during this process, and their relationship with thyroid hormone. As endocrine disruptors continue to threaten species across the animal kingdom, the work described here offers much-needed insight into immune contributions to endocrine-linked development.
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Characterization of a novel corticosterone response gene in Xenopus tropicalis tadpole tails
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 genefrzb(frizzled related protein) previously identified inXenopus tropicalistadpole tail skin by an RNA-seq study. We validated the RNA-seq results that CORT and not thyroid hormone inducesfrzbin the tails using quantitative PCR. Further, maximumfrzbexpression was achieved by 100-250 nM CORT within 12-24 hours.frzbis not significantly induced in the liver and brain in response to 100 nM CORT. We also found no change infrzbexpression across natural metamorphosis when endogenous CORT levels peak. Surprisingly,frzbis only induced by CORT inX. tropicalistails and not inXenopus laevistails. The exact downstream function of increasedfrzbexpression in tails in response to CORT is not known, but the specificity of hormone response and its high mRNA expression levels in the tail renderfrzba useful marker of exogenous CORT-response independent of thyroid hormone for exogenous hormone treatments andin-vivoendocrine disruption studies.
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- Award ID(s):
- 2035732
- PAR ID:
- 10485481
- Publisher / Repository:
- Endocrine Society
- Date Published:
- Journal Name:
- Frontiers in Endocrinology
- Volume:
- 14
- ISSN:
- 1664-2392
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fendo.2023.1121002
