Autoinduction of nuclear receptor genes and its significance

Tata, Jamshed R.; Baker, Betty S.; Machuca, Irma; Rabelo, Élida Mara Leite; Yamauchi, Kiyoshi

doi:10.1016/0960-0760(93)90286-6

Cited by 111 publications

(40 citation statements)

References 36 publications

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“…In fact, TR␤ transcript and protein was reported to be detected in the tail as well as the other tissues at an early phase of metamorphosis (Kawahara et al 1991;Fairclough & Tata 1997). High level TR␤ expression is thought to be caused by 'autoinduction mechanism', as the liganded TR␤ promotes its own gene expression (for review, Tata et al 1993). Establishment of autoinduction of the TR␤ gene in the process of thyroid hormone-dependent upregulation may be responsible for substantial metamorphic change.…”

Section: Discussionmentioning

confidence: 99%

Role of type III iodothyronine 5‐deiodinase gene expression in temporal regulation of Xenopus metamorphosis

1999

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To elucidate the role of type III iodothyronine 5-deiodinase (5-D) in the temporal regulation of amphibian metamorphosis, the regulation of gene expression of 5-D and thyroid hormone receptor ␤ (TR␤) in organs of Xenopus laevis was investigated. High levels of TR␤ mRNA in the respective organs were observed at the times of their major morphological changes. Expression of the 5-D gene was highly regulated among the organs during metamorphosis, including up-regulation in the tail and down-regulation in the liver. The tail and liver expressed 5-D gene before their metamorphic changes. These precocious expressions correlated with the lower responsiveness to exogenously added triiodo-L-thyronine (T3) for inducing a high level of TR␤ mRNA expression. However, the same organs responded to lower doses of T3 to regulate 5-D gene expression as seen in spontaneous metamorphosis. The induction of 5-D gene expression was considerably delayed in the intestine, even at an excess dose of T3. Thus, the two genes in a given organ appeared to respond to T3 either with different dose dependencies or with different timetables. The results obtained are also discussed in respect to recent findings in Rana catesbeiana.

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Section: Discussionmentioning

confidence: 99%

Role of type III iodothyronine 5‐deiodinase gene expression in temporal regulation of Xenopus metamorphosis

1999

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“…Levels of triiodothyronine (T 3 ) and thyroxine (T 4 ; red lines) were estimated from data by Gancedo et al (1997) for stages 37/38 -52 and extrapolated for earlier stages. Data for T 3 levels at stages 53-57 are from Tata et al (1993); all other data on T 3 and T 4 levels are from Leloup and Buscaglia (1977). The exact time course of generation rates of sensory neurons, motor neurons, and interneurons (where the latter term is used in a wide sense, i.e., including second-order sensory neurons and other projection neurons) is not know, but rough approximations are possible by compiling data from various sources.…”

Section: Introductionmentioning

confidence: 99%

Thyroid hormone promotes neurogenesis in the Xenopus spinal cord

Schlosser

Koyano-Nakagawa

Kintner

2002

Developmental Dynamics

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Three phases of neurogenesis can be recognized during Xenopus spinal cord development. An early peak during gastrulation/ neurulation is followed by a phase of low level neurogenesis throughout the remaining embryonic stages and a later peak at early larval stages. We show here that several genes known to be essential for early neurogenesis (X-NGNR-1, XNeuroD, XMyT1, X-Delta-1) are also expressed during later phases of neurogenesis in the spinal cord, suggesting that they are involved in regulating spinal neurogenesis at later stages. However, additional neuronal determination genes may be important during larval stages, because X-NGNR-1 shows only scant expression in the spinal cord during larval stages. Thyroid hormone treatment of early larvae promotes neurogenesis in the spinal cord, where thyroid hormone receptor xTR␣ is expressed from early larval stages onward and results in precocious up-regulation of XNeuroD, XMyT1, and N-Tubulin expression. Similarly, thyroid hormone treatments of Xenopus embryos, which were coinjected with xTR␣ and the retinoid X receptor xRXR␣, repeatedly resulted in increased numbers of neurons, whereas unliganded receptors repressed neurogenesis. Our findings show that thyroid hormones are sufficient to up-regulate neurogenesis in the Xenopus spinal cord.

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“…More precisely, TRa is expressed very early, even before TH synthesis, whereas TRb expression is controlled by and thus correlates with TH levels [ (Kawahara et al, 1991), review in (Buchholz et al, 2006)]. This peak of TRb expression at the onset of metamorphosis is particularly important, because it transmits the signal of the peak of TH: as TRb is one of its own target genes, the peak of TH production activates a positive loop of TRb production and activation characteristic of the metamorphosis climax (Tata et al, 1993).…”

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confidence: 99%

The history of a developmental stage: Metamorphosis in chordates

Paris

Laudet

2008

Genesis

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Summary: Metamorphosis displays a striking diversity in chordates, a deuterostome phylum that comprises vertebrates, urochordates (tunicates), and cephalochordates (amphioxus). In anuran amphibians, the tadpole loses its tail, develops limbs, and undergoes profound changes at the behavioral, physiological, biochemical, and ecological levels. In ascidian tunicates, the tail is lost and the head tissues are drastically remodeled into the adult animal, whereas in amphioxus, the highly asymmetric larva transforms into a relatively symmetric adult. This wide diversity has led to the proposal that metamorphosis evolved several times independently in the different chordate lineages during evolution. However, the molecular mechanisms involved in metamorphosis are largely unknown outside amphibians and teleost fishes, in which metamorphosis is regulated by the thyroid hormones (TH) T 3 and T 4 binding to their receptors (thyroid hormone receptors). In this review, we compare metamorphosis in chordates and then propose a unifying definition of the larva-to-adult transition, based on the conservation of the role of THs and some of their derivatives as the main regulators of metamorphosis. According to this definition, all chordates (if not, all deuterostomes) have a homologous metamorphosis stage during their postembryonic development. The intensity and the nature of the morphological remodeling varies extensively among taxa, from drastic remodeling like in some ascidians or amphibians to more subtle events, as in mammals. genesis 46:657-672,

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Autoinduction of nuclear receptor genes and its significance

Cited by 111 publications

References 36 publications

Role of type III iodothyronine 5‐deiodinase gene expression in temporal regulation of Xenopus metamorphosis

Role of type III iodothyronine 5‐deiodinase gene expression in temporal regulation of Xenopus metamorphosis

Thyroid hormone promotes neurogenesis in the Xenopus spinal cord

The history of a developmental stage: Metamorphosis in chordates

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