Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract??? Thyroid hormone (T3) is important for adult organ function and vertebrate development, particularly during the postembryonic period when many organs develop/mature into their adult forms. Amphibian metamorphosis is totally dependent on T3 and can be easily manipulated, thus offering a unique opportunity for studying how T3 controls postembryonic development in vertebrates. Numerous early studies have demonstrated that T3 affects frog metamorphosis through T3 receptor (TR)-mediated regulation of T3 response genes, where TR forms a heterodimer with RXR (9-cis retinoic acid receptor) and binds to T3 response elements (TREs) in T3 response genes to regulate their expression. We have previously identified many candidate direct T3 response genes in Xenopus tropicalis tadpoleintestine. Among them is the proto-oncogene Ski, which encodes a nuclear protein with complex function in regulating cell fate. We show here that Ski is upregulated in the intestine and tail of premetamorphic tadpoles upon T3 treatment and its expression peaks at stage 62, the climax of metamorphosis. We have further discovered a putative TRE in the first exon that can bind to TR/RXR in vitro and mediate T3 regulation of the promoter in vivo. These data demonstrate that Ski is activated by T3 through TR binding to a TRE in the first exon during Xenopus tropicalis metamorphosis, implicating a role of Ski in regulating cell fate during metamorphosis.
Fig. 1. Ski expression peaks at the climax of metamorphosis during natural frog metamorphosis. Genomic DNA-free total RNAs were extracted from the intestine and tail of X. tropicalis tadpoles at indicated stages and subjected to qRT-PCR analysis with primers specific for Ski as well as the control gene EF1α, respectively. Ski expression was normalized to that of EF1α and presented as mean + standard error of the mean (S.E.M), relative to the level at stage 56 in the organs, which was set to 1. Statistical analysis was done with ordinary-one-way ANOVA. *: p < 0.05.
Fig. 2. Ski expression is upregulated by T3 in X. tropicalis tadpoles. Premetamorphic X. tropicalis tadpoles at stage 54 were treated with or without T3 for 2 days and subjected to total RNA extraction from the intestine and tail, respectively. cDNAs were made from the total RNAs and subjected to qRT-PCR analysis for Ski and EF1α expression, respectively. Ski expression was normalized to that of EF1α and presented as mean + standard error of the mean (S.E.M), relative to the level at stage 54 in the organs, which was set to 1. Student t-test was used to determine the significance of T3 regulation. *: p < 0.05.
Fig. 3. TR binds to the putative TRE within the first exon of the Ski gene in vitro. (A) Schematic diagram of putative TREs in X. tropicalis Ski gene with the first (E1) and the last (E7) exons shown as clear boxes. (B) Sequences of the putative TREs in comparison with the sequences of consensus TRE and the TRE of Xenopus laevis TRβA gene (TRβA TRE). The numbers indicate the locations relative to the transcriptional start site of Ski gene (identified based on the 5′-end of cDNA sequence and denoted as + 1). Mutant versions of Ski TREs (Ski mTRE1/2, mutated nucleotides are underlined) were used for studies below. Bold letters indicate TRE half sites. E1: exon 1; E7: exon 7. (C)/(D) The putative Ski TRE2 compete efficiently against the TRβA TRE for binding to TR/RXR heterodimer in gel shift assay. The labeled double stranded TRβA TRE, used as the probe, was mixed with in vitro translated TR/RXR heterodimers in the presence or absence of 4x, 20x, or 100x of unlabeled wild type (C) or mutant (D) Ski TREs as indicated. The reaction mixtures were analyzed by Electrophoretic (or gel) Mobility Shift Assay (EMSA). The locations of TR/RXR bound probes (TR/RXR-probe complex) and unbound probes (Free probe) are indicated with arrows. Note that the labeled probe binding to the TR/RXR was competed away efficiently by the unlabeled TRβA TRE (C, lanes 3–5) and that Ski TRE2 also had strong competition (C, lanes 9–11) while Ski TRE1 had little competition (C, lanes 6–8). Neither one of the mutant Ski TREs had noticeable competition (D).
Fig. 4. The TRE2 but not TRE1 of X. tropicalis Ski gene mediates transcriptional regulation by T3 in vivo. (A) Schematic diagram of firefly luciferase reporter constructs containing the wild type putative Ski TRE1 (Ski-TRE1) or a mutant TRE1 (Ski-mTRE1) generated through PCR-mediated cloning to bring the putative Ski TRE1 or its mutant closer to the transcription start site (This was done because TREs located far from the start site do not activate the promoter effectively (Wong et al., 1997)). The Ski-basic has a truncated promoter region lacking the TRE1 or TRE2. (B) The Ski-TRE1 promoter is not activated by liganded TR in frog oocytes. The Ski-basic, Ski-TRE1 or Ski-mTRE1 promoter construct was co-injected with the control Renilla luciferase construct phRG-TK into the nucleus of Xenopus laevis oocytes with prior cytoplasmic injection of GFP mRNA or Xenopus tropicalis TRα and RXRβ mRNAs. The oocytes were incubated at 18 °C overnight in the absence or presence of 100 nM T3 and then lysed for dual luciferase assay. The relative activities of the firefly luciferase to Renilla luciferase were plotted as a measure of the reporter promoter activity. Error bars indicate S.E.M. Note that none of the reporters, including the one with wild type TRE1, was regulated by TR in the oocytes. (C) Schematic diagram of firefly luciferase reporter constructs containing the putative Ski TRE2 (Ski-TRE2) or a mutant TRE2 (Ski-mTRE2). (D) The Ski-TRE2 promoter is strongly activated by liganded TR in frog oocytes. The Ski-TRE2 or Ski-mTRE2 promoter construct was co-injected with the control Renilla luciferase construct phRG-TK into the nucleus of Xenopus laevis oocytes with prior cytoplasmic injection of GFP mRNA or Xenopus tropicalis TRα and RXRβ mRNAs. Oocytes were treated and analyzed as in (B). Error bars indicate S.E.M. Note that the wild type TRE2-containing reporter was activated by T3 only in the presence of TR/RXR and that the mutations in the Ski TRE2 abolished this activation. Statistical analysis was done with ordinary-one-way ANOVA. *: p < 0.05.
Bagamasbad,
A role for basic transcription element-binding protein 1 (BTEB1) in the autoinduction of thyroid hormone receptor beta.
2008, Pubmed,
Xenbase
Bagamasbad,
A role for basic transcription element-binding protein 1 (BTEB1) in the autoinduction of thyroid hormone receptor beta.
2008,
Pubmed
,
Xenbase
Bonnon,
c-Ski in health and disease.
2012,
Pubmed
Bravou,
TGF-beta repressors SnoN and Ski are implicated in human colorectal carcinogenesis.
2009,
Pubmed
Brown,
Amphibian metamorphosis.
2007,
Pubmed
,
Xenbase
Buchholz,
A dominant-negative thyroid hormone receptor blocks amphibian metamorphosis by retaining corepressors at target genes.
2003,
Pubmed
,
Xenbase
Buchholz,
Molecular and developmental analyses of thyroid hormone receptor function in Xenopus laevis, the African clawed frog.
2006,
Pubmed
,
Xenbase
Buchholz,
Dual function model revised by thyroid hormone receptor alpha knockout frogs.
2018,
Pubmed
,
Xenbase
Buchholz,
Transgenic analysis reveals that thyroid hormone receptor is sufficient to mediate the thyroid hormone signal in frog metamorphosis.
2004,
Pubmed
,
Xenbase
Buess,
Amplification of SKI is a prognostic marker in early colorectal cancer.
2004,
Pubmed
Chen,
SKI knockdown inhibits human melanoma tumor growth in vivo.
2009,
Pubmed
Choi,
Growth, Development, and Intestinal Remodeling Occurs in the Absence of Thyroid Hormone Receptor α in Tadpoles of Xenopus tropicalis.
2017,
Pubmed
,
Xenbase
Choi,
Unliganded thyroid hormone receptor α regulates developmental timing via gene repression in Xenopus tropicalis.
2015,
Pubmed
,
Xenbase
Colmenares,
The ski oncogene induces muscle differentiation in quail embryo cells.
1989,
Pubmed
Das,
Identification of direct thyroid hormone response genes reveals the earliest gene regulation programs during frog metamorphosis.
2009,
Pubmed
,
Xenbase
Denver,
Thyroid hormone receptor subtype specificity for hormone-dependent neurogenesis in Xenopus laevis.
2009,
Pubmed
,
Xenbase
Fu,
Sperm associated antigen 7 is activated by T3 during Xenopus tropicalis metamorphosis via a thyroid hormone response element within the first intron.
2022,
Pubmed
,
Xenbase
Fu,
Genome-wide identification of thyroid hormone receptor targets in the remodeling intestine during Xenopus tropicalis metamorphosis.
2017,
Pubmed
,
Xenbase
Fukuchi,
Increased expression of c-Ski as a co-repressor in transforming growth factor-beta signaling correlates with progression of esophageal squamous cell carcinoma.
2004,
Pubmed
Grimaldi,
Mechanisms of thyroid hormone receptor action during development: lessons from amphibian studies.
2013,
Pubmed
,
Xenbase
Heider,
Ski promotes tumor growth through abrogation of transforming growth factor-beta signaling in pancreatic cancer.
2007,
Pubmed
Heimeier,
Studies on Xenopus laevis intestine reveal biological pathways underlying vertebrate gut adaptation from embryo to adult.
2010,
Pubmed
,
Xenbase
Li,
The cellular and molecular mechanisms of tissue repair and regeneration as revealed by studies in Xenopus.
2016,
Pubmed
,
Xenbase
Li,
Unique sequence, ski, in Sloan-Kettering avian retroviruses with properties of a new cell-derived oncogene.
1986,
Pubmed
Luo,
Ski and SnoN: negative regulators of TGF-beta signaling.
2004,
Pubmed
Marshall,
Stage-dependent cardiac regeneration in Xenopus is regulated by thyroid hormone availability.
2019,
Pubmed
,
Xenbase
Nakajima,
A unique role of thyroid hormone receptor β in regulating notochord resorption during Xenopus metamorphosis.
2019,
Pubmed
,
Xenbase
Nakajima,
Thyroid Hormone Receptor α- and β-Knockout Xenopus tropicalis Tadpoles Reveal Subtype-Specific Roles During Development.
2018,
Pubmed
,
Xenbase
Nakajima,
Dual mechanisms governing muscle cell death in tadpole tail during amphibian metamorphosis.
2003,
Pubmed
,
Xenbase
Nomura,
Ski is a component of the histone deacetylase complex required for transcriptional repression by Mad and thyroid hormone receptor.
1999,
Pubmed
Puzianowska-Kuznicka,
Both thyroid hormone and 9-cis retinoic acid receptors are required to efficiently mediate the effects of thyroid hormone on embryonic development and specific gene regulation in Xenopus laevis.
1997,
Pubmed
,
Xenbase
Ranjan,
Transcriptional repression of Xenopus TR beta gene is mediated by a thyroid hormone response element located near the start site.
1994,
Pubmed
,
Xenbase
Sachs,
Unliganded thyroid hormone receptor function: amphibian metamorphosis got TALENs.
2015,
Pubmed
,
Xenbase
Sachs,
Dual functions of thyroid hormone receptors during Xenopus development.
2000,
Pubmed
,
Xenbase
Sachs,
Targeted chromatin binding and histone acetylation in vivo by thyroid hormone receptor during amphibian development.
2000,
Pubmed
,
Xenbase
Sakane,
Functional analysis of thyroid hormone receptor beta in Xenopus tropicalis founders using CRISPR-Cas.
2018,
Pubmed
,
Xenbase
Sandelin,
Prediction of nuclear hormone receptor response elements.
2005,
Pubmed
Schreiber,
Diverse developmental programs of Xenopus laevis metamorphosis are inhibited by a dominant negative thyroid hormone receptor.
2001,
Pubmed
,
Xenbase
Schreiber,
Cell-cell interactions during remodeling of the intestine at metamorphosis in Xenopus laevis.
2009,
Pubmed
,
Xenbase
Shi,
Molecular biology of amphibian metamorphosis A new approach to an old problem.
1994,
Pubmed
Shi,
Dual functions of thyroid hormone receptors in vertebrate development: the roles of histone-modifying cofactor complexes.
2009,
Pubmed
,
Xenbase
Shi,
Biphasic intestinal development in amphibians: embryogenesis and remodeling during metamorphosis.
1996,
Pubmed
,
Xenbase
Shi,
Life Without Thyroid Hormone Receptor.
2021,
Pubmed
,
Xenbase
Shi,
Thyroid hormone receptor actions on transcription in amphibia: The roles of histone modification and chromatin disruption.
2012,
Pubmed
Shibata,
Knocking out histone methyltransferase PRMT1 leads to stalled tadpole development and lethality in Xenopus tropicalis.
2020,
Pubmed
,
Xenbase
Shibata,
Thyroid Hormone Receptor Is Essential for Larval Epithelial Apoptosis and Adult Epithelial Stem Cell Development but Not Adult Intestinal Morphogenesis during Xenopus tropicalis Metamorphosis.
2021,
Pubmed
,
Xenbase
Stavnezer,
Generation of transforming viruses in cultures of chicken fibroblasts infected with an avian leukosis virus.
1981,
Pubmed
Sun,
Expression profiling of intestinal tissues implicates tissue-specific genes and pathways essential for thyroid hormone-induced adult stem cell development.
2013,
Pubmed
,
Xenbase
Sun,
Interaction of the Ski oncoprotein with Smad3 regulates TGF-beta signaling.
1999,
Pubmed
Tanizaki,
Analysis of Thyroid Hormone Receptor α-Knockout Tadpoles Reveals That the Activation of Cell Cycle Program Is Involved in Thyroid Hormone-Induced Larval Epithelial Cell Death and Adult Intestinal Stem Cell Development During Xenopus tropicalis Metamorphosis.
2021,
Pubmed
,
Xenbase
Tanizaki,
Thyroid Hormone Receptor α Controls the Hind Limb Metamorphosis by Regulating Cell Proliferation and Wnt Signaling Pathways in Xenopus tropicalis.
2022,
Pubmed
,
Xenbase
Tanizaki,
Thyroid hormone receptor α controls larval intestinal epithelial cell death by regulating the CDK1 pathway.
2022,
Pubmed
,
Xenbase
Tata,
Gene expression during metamorphosis: an ideal model for post-embryonic development.
1993,
Pubmed
Tecalco-Cruz,
Transcriptional cofactors Ski and SnoN are major regulators of the TGF-β/Smad signaling pathway in health and disease.
2018,
Pubmed
Theohari,
Differential effect of the expression of TGF-β pathway inhibitors, Smad-7 and Ski, on invasive breast carcinomas: relation to biologic behavior.
2012,
Pubmed
Tokitou,
Viral ski inhibits retinoblastoma protein (Rb)-mediated transcriptional repression in a dominant negative fashion.
1999,
Pubmed
Wang,
c-Ski activates cancer-associated fibroblasts to regulate breast cancer cell invasion.
2013,
Pubmed
Wang,
Evolutionary divergence in tail regeneration between Xenopus laevis and Xenopus tropicalis.
2021,
Pubmed
Wang,
Developmental regulation and function of thyroid hormone receptors and 9-cis retinoic acid receptors during Xenopus tropicalis metamorphosis.
2008,
Pubmed
,
Xenbase
Wen,
Unliganded thyroid hormone receptor α controls developmental timing in Xenopus tropicalis.
2015,
Pubmed
,
Xenbase
Wen,
Regulation of growth rate and developmental timing by Xenopus thyroid hormone receptor α.
2016,
Pubmed
,
Xenbase
Wen,
Thyroid Hormone Receptor α Controls Developmental Timing and Regulates the Rate and Coordination of Tissue-Specific Metamorphosis in Xenopus tropicalis.
2017,
Pubmed
,
Xenbase
Wong,
Transcription from the thyroid hormone-dependent promoter of the Xenopus laevis thyroid hormone receptor betaA gene requires a novel upstream element and the initiator, but not a TATA Box.
1998,
Pubmed
,
Xenbase
Wong,
Coordinated regulation of and transcriptional activation by Xenopus thyroid hormone and retinoid X receptors.
1995,
Pubmed
,
Xenbase
Wong,
Determinants of chromatin disruption and transcriptional regulation instigated by the thyroid hormone receptor: hormone-regulated chromatin disruption is not sufficient for transcriptional activation.
1997,
Pubmed
,
Xenbase
Yen,
Unliganded TRs regulate growth and developmental timing during early embryogenesis: evidence for a dual function mechanism of TR action.
2015,
Pubmed
,
Xenbase
