Tissue-specific regulation of type III iodothyronine 5-deiodinase gene expression mediates the effects of prolactin and growth hormone in Xenopus metamorphosis.
Prolactin (PRL) and growth hormone (GH) are known to be able to act as antimetamorphic hormones. From investigations of how PRL inhibits Xenopus tail regression in vitro, it was found that the both hormones could, in addition to their known antimetamorphic actions, upregulate mRNA expression of type III iodothyronine 5-deiodinase (5D), an enzyme that inactivates thyroid hormones (TH). Conversely, both PRL and GH were found to downregulate 5D mRNA expression in the liver. Blockage by PRL of TH-induced tail regression in organ culture was released by treatment with iopanoic acid (IOP, an inhibitor of 5D activity). The IOP-released tail regression displayed a unique morphology of the larger fins retained on the regressing tails, consistent with the finding that mRNA for both PRL receptor and 5D were enriched in the fin. The results suggest that the metamorphosis-modulating actions of PRL and GH are mediated, at least partially, by tissue-specific regulation of 5D mRNA expression.
Shintani
Noriyuki
N
Developmental Biology Laboratory, Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima 739-8521, Japan.
Nohira
Takashi
T
Hikosaka
Akira
A
Kawahara
Akira
A
D000818:Animals; D015536:Down-Regulation; D018507:Gene Expression Regulation, Developmental; D013006:Growth Hormone / Q000378:metabolism*; D007453:Iodide Peroxidase / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D008099:Liver / Q000187:drug effects; D009928:Organ Specificity / Q000502:physiology; D036361:Peptide Hormones / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism* / Q000494:pharmacology; D013623:Tail / Q000187:drug effects; D037042:Thyroid Hormone Receptors beta / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation; D014981:Xenopus / Q000196:embryology*
D036361:Peptide Hormones; D037042:Thyroid Hormone Receptors beta; D011388:Prolactin; D013006:Growth Hormone; C117274:iodothyronine deiodinase type III; D007453:Iodide Peroxidase