RRC ID 31780
Author Nakajima K, Fujimoto K, Yaoita Y.
Title Regulation of thyroid hormone sensitivity by differential expression of the thyroid hormone receptor during Xenopus metamorphosis.
Journal Genes Cells
Abstract During amphibian metamorphosis, a series of dynamic changes occur in a predetermined order. Hind limb morphogenesis begins in response to low levels of thyroid hormone (TH) in early prometamorphosis, but tail muscle cell death is delayed until climax, when TH levels are high. It takes about 20 days for tadpoles to grow from early prometamorphosis to climax. To study the molecular basis of the timing of tissue-specific transformations, we introduced thyroid hormone receptor (TR) expression constructs into tail muscle cells of Xenopus tadpoles. The TR-transfected tail muscle cells died upon exposure to a low level of thyroxine (T4). This cell death was suggested to be mediated by type 2 iodothyronine deiodinase (D2) that converts T4 to T3-the more active form of TH. D2 mRNA was induced in the TR-overexpressing cells by low levels of TH. D2 promoter contains a TH-response element (TRE) with a lower affinity for TR. These results show that the TR transfection confers the ability to respond to physiological concentrations of TH at early prometamorphosis to tail muscle cells through D2 activity and promotes TH signaling. We propose the positive feedback loop model to amplify the cell's ability to respond to low levels of T4.
Volume 17(8)
Pages 645-59
Published 2012-8
DOI 10.1111/j.1365-2443.2012.01614.x
PMID 22686326
MeSH Animals Cell Death Electrophoretic Mobility Shift Assay Feedback, Physiological Gene Expression Regulation, Developmental* Green Fluorescent Proteins / genetics Green Fluorescent Proteins / metabolism Hindlimb / metabolism Iodide Peroxidase / metabolism Larva / genetics Larva / growth & development Metamorphosis, Biological* Microinjections Muscle Cells / cytology Muscle Cells / drug effects Muscle Cells / metabolism Promoter Regions, Genetic RNA, Messenger / genetics RNA, Messenger / metabolism Receptors, Thyroid Hormone / drug effects Receptors, Thyroid Hormone / metabolism* Signal Transduction Tail / cytology Tail / metabolism Thyroxine / metabolism Thyroxine / pharmacology* Time Factors Transcriptome Transfection Triiodothyronine / metabolism Xenopus laevis / genetics Xenopus laevis / growth & development
IF 2.048
Times Cited 15
Xenopus tropicalis Ivory Coast line