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XB-ART-14014
Dev Biol November 1, 1998; 203 (1): 12-23.
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The expression pattern of thyroid hormone response genes in the tadpole tail identifies multiple resorption programs.

Berry DL , Schwartzman RA , Brown DD .


Abstract
Expression of genes up-regulated by thyroid hormone (TH) during amphibian tail resorption was localized by in situ hybridization. The constitutive thyroid hormone receptor (TRalpha) and its heterodimeric partners (RXRalpha and RXRbeta) are expressed ubiquitously in the resorbing tail. A group of early response genes, including those encoding transcription factors, are expressed at greatest levels within tissues whose cells attempt to grow and differentiate in the tail, but eventually succumb to the resorption program. The TH-inducible TR isoform, TRbeta, is expressed ubiquitously in the tail, but especially high in fibroblasts. Similarly, a group of delayed response genes including two proteolytic enzymes that appear to execute the tail resorption program, is expressed specifically in fibroblasts that line and surround the notochord and lie beneath the epidermal lamella (subepidermal fibroblasts). During active tail resorption these fibroblasts invade their neighboring epidermal and notochord lamellae as part of the resorption process. Expression analysis implicates the single layer of invasive subepidermal fibroblasts as crucial in tail resorption. Stromelysin-3 is up-regulated by TH with early kinetics, and is expressed most actively in fibroblasts within the tail fins. None of the proteases are expressed in the tadpole epidermis, which will be replaced entirely during metamorphosis. While very few TH response genes are expressed in tadpole muscle, many are activated in fibroblasts that surround muscle and could induce muscle cell death by proteolysis of the extracellular matrix. These distinct localization patterns suggest that the common fate of all cell types within the tail is the result of multiple genetic programs.

PubMed ID: 9806769
Article link: Dev Biol


Species referenced: Xenopus laevis
Genes referenced: crhbp dio3 dpepe fap fn1 fosl2 hhipl2 itga11 klf9 krt78.6 mamdc2 mmp11 mmp13l paaf1 rxra rxrb tfcp2 thibz thra thrb tra


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