Autoinduction of thyroid hormone receptor during metamorphosis is reproduced in Xenopus XTC-2 cells

Machuca, Irma; Tata, Jamshed R.

doi:10.1016/0303-7207(92)90238-2

Cited by 44 publications

(16 citation statements)

References 25 publications

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“…4). We transfected the myoblastic XTC cell line (Machuca and Tata, 1992) with Bax to induce apoptosis, and abrogation of cell death was investigated by cotransfection of the dominant-negative alone (DN9) or fused to RFP (DN9-RFP). As in previous experiments (Sachs et al, 1997), a luciferase-expressing plasmid was cotransfected with the test plasmids, and luciferase activity measured in cell extracts as an indicator of cell survival.…”

Section: Expression Of a Dominantnegative Form Of Caspase 9 Counteracmentioning

confidence: 99%

Apoptosis of tail muscle during amphibian metamorphosis involves a caspase 9-dependent mechanism

et al. 2005

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The climax of amphibian metamorphosis is marked by thyroid hormone-dependent tadpole tail resorption, implicating apoptosis of multiple cell types, including epidermal cells, fibroblasts, nerve cells, and muscles. The molecular cascades leading to and coordinating the death of different cell types are not fully elucidated. It is known that the mitochondrial pathway, and in particular the Bax and XR11 genes, regulates the balance between apoptosis and survival in muscle. However, the down-stream factors modulated by changes in mitochondrial permeability have not been studied in a functional context. To investigate further the mitochondrial-dependent pathway, we analyzed the regulation and the role of caspase 9 in Xenopus tadpoles. We report that caspase 9 mRNA is expressed in the tail before metamorphosis and increases before and during climax. Similarly, at the protein level, the production of active forms of caspase 9 increases in muscle tissue as metamorphosis progresses. To assess the functional role of caspase 9, we designed a dominant-negative protein. Overexpression of this dominant-negative abrogates both Bax-induced cell death in vitro and muscle apoptosis in vivo during natural metamorphosis. These findings consolidate a model of metamorphic muscle death that directly implicates the mitochondrial pathway and the apoptosome. Developmental Dynamics 233:76 -87, 2005.

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Section: Expression Of a Dominantnegative Form Of Caspase 9 Counteracmentioning

confidence: 99%

Apoptosis of tail muscle during amphibian metamorphosis involves a caspase 9-dependent mechanism

et al. 2005

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“…After climax, the amounts of both isoforms of receptor transcripts decrease and return to basal levels (Baker and Tata 1990;Kawahara et al 1991). It is noteworthy that TR␤ expression is upregulated by thyroid hormones (Kanamori and Brown 1992;Machuca and Tata 1992;Ulisse et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Thyroid Hormone Receptor Genes of Neotenic Amphibians

et al. 1997

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Since thyroid hormones play a pivotal role in amphibian metamorphosis we used PCR to amplify DNA fragments corresponding to a portion of the ligand-binding domain of the thyroid hormone receptor (TR) genes in several neotenic amphibians: the obligatory neotenic members of the family Proteidea the mudpuppy Necturus maculosus and Proteus anguinus as well as two members of the facultative neotenic Ambystoma genus: the axolotl Ambystoma mexicanum and the tiger salamander Ambystoma tigrinum. In addition, we looked for TR genes in the genome of an apode Typhlonectes compressicaudus. TR genes were found in all these species including the obligatory neotenic ones. The PCR fragments obtained encompass both the C and E domains and correspond to alpha and beta genes. Their sequences appear to be normal, suggesting that there is no acceleration of evolutionary rates in the TR genes of neotenic amphibians. This result is not surprising for Ambystomatidae, which are known to respond to T3 (3,3',5-triiodothyronine) but is not in agreement with biochemical and biological data showing that Proteidea cannot respond to thyroid hormones. Interestingly, by RT-PCR analysis we observed a high expression levels of TRalpha in gills, intestine, and muscles of Necturus as well as in the liver of Ambystoma mexicanum, whereas TRbeta expression was only detected in Ambystoma mexicanum but not in Necturus. Such a differential expression pattern of TRalpha and TRbeta may explain the neoteny in Proteidea. The cloning of thyroid-hormone-receptor gene fragments from these species will allow the molecular study of their failure to undergo metamorphosis.

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“…5). A similar observation has been reported for Kr cells, which is a clonal line of A6 and, therefore, may be identical to XLA cells (10). A sensitive PCR quantification (11) Proc.…”

Section: Resultsmentioning

confidence: 53%

Cultured cells as a model for amphibian metamorphosis.

Kanamori

Brown

1993

Proc. Natl. Acad. Sci. U.S.A.

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Gene expression screens have been applied to a cultured cell line of Xenopus laevis, XL-177, to isolate genes that are up- and down-regulated in the first 8 h after thyroid hormone (TH) induction. At least 14 up-regulated genes were isolated from TH-induced cells grown in the presence or absence of cycloheximide, an inhibitor of protein synthesis. These genes respond directly to TH as demonstrated by the resistance of up-regulation to protein synthesis inhibition in the cultured cells or in tadpoles. Kinetics of mRNA accumulation after TH induction is similar for these genes, including those that are superinduced by cycloheximide. Their mRNAs start to be up-regulated several hours after TH treatment and reach maximum levels between 8 and 16 h. These genes show up-regulation in one or more tadpole organs in response to exogenous TH. Only a few minimally down-regulated genes were identified. Fourteen of the 20 genes that were found to be up-regulated by TH in tadpole tail are also up-regulated in XL-177 cells. Their up-regulation falls into the same two kinetic patterns in the cultured cells as it does in tadpole tail. Another cell line of X. laevis, XLA, is greatly reduced in its ability to up-regulate the same genes isolated from XL-177 cells and tadpole tails in response to TH. Thus these cell lines make up a model system to examine the interactions of gene expression triggered by TH during amphibian metamorphosis.

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Autoinduction of thyroid hormone receptor during metamorphosis is reproduced in Xenopus XTC-2 cells

Cited by 44 publications

References 25 publications

Apoptosis of tail muscle during amphibian metamorphosis involves a caspase 9-dependent mechanism

Apoptosis of tail muscle during amphibian metamorphosis involves a caspase 9-dependent mechanism

Thyroid Hormone Receptor Genes of Neotenic Amphibians

Cultured cells as a model for amphibian metamorphosis.

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