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Although thyroid hormone (TH) plays a significant role in vertebrate neural development, the molecular basis of TH action on the brain is poorly understood. Using polymerase chain reaction-based subtractive hybridization we isolated 34 cDNAs for TH-regulated genes in the diencephalon of Xenopus tadpoles. Northern blots verified that the mRNAs are regulated(More)
The current review focuses on the molecular mechanisms and developmental roles of thyroid hormone receptors (TRs) in gene regulation and metamorphosis in Xenopus laevis and discusses implications for TR function in vertebrate development and diversity. Questions addressed are: (1) what are the molecular mechanisms of gene regulation by TR, (2) what are the(More)
The hedgehog family of proteins have been implicated as important signaling molecules in establishing cell positional information and tissue patterning. Here we present the cloning and characterization of a hedgehog homologue from Xenopus laevis similar to the sonic class of vertebrate hedgehog genes. We isolated Xenopus hedgehog (Xhh) from a subtractive(More)
Based on conserved expression patterns, three members of the GATA family of transcriptional regulatory proteins, GATA-4, -5, and -6, are thought to be involved in the regulation of cardiogenesis and gut development. Functions for these factors are known in the heart, but relatively little is understood regarding their possible roles in the regulation of(More)
Intestinal development in anurans is a biphasic process. The embryogenesis of intestine resembles that in higher vertebrates. The subsequent remodeling process during metamorphosis to produce an adult organ is controlled by TH. Recent progress in studying TH action and its application to amphibian metamorphosis has provided considerable insights into the(More)
A fascinating feature of thyroid hormone (T3) receptors (TR) is that they constitutively bind to promoter regions of T3-response genes, providing dual functions. In the presence of T3, TR activates T3-inducible genes, while unliganded TR represses these same genes. Although this dual function model is well demonstrated at the molecular level, few studies(More)
  • Yun-Bo Shi
  • 2009
Thyroid hormone (TH) receptor (TR) plays critical roles in vertebrate development. Transcription studies have shown that TR activates or represses TH-inducible genes by recruiting coactivators or corepressors in the presence or absence of TH, respectively. However, the developmental roles of these TR cofactors remain largely unexplored. Frog metamorphosis(More)
Tissue culture transfection and in vitro biochemical studies have suggested that heterodimers of thyroid hormone receptors (TRs) and 9-cis retinoic acid receptors (RXRs) are the likely in vivo complexes that mediate the biological effects of thyroid hormone, 3,5,3'-triiodothyronine (T3). However, direct in vivo evidence for such a hypothesis has been(More)
The total dependence of amphibian metamorphosis on thyroid hormone (T(3)) provides a unique vertebrate model for studying the molecular mechanism of T(3) receptor (TR) function in vivo. In vitro transcription and developmental expression studies have led to a dual function model for TR in amphibian development, i.e., TRs act as transcriptional repressors in(More)