MINIREVIEWS
Cell Research (1998)8:259-272
© 1998 SIBS, CAS All rights reserved 1001-0602/98
Amphibian metamorphosis as a model for studying the developmental
actions of thyroid hormone.
Tata JR.
National Institute for Medical Research, London, U.K.
The thyroid hormones L-thyroxine and triiodo-L-thyronine have profound effects
on postembryonic development of most vertebrates. Analysis of their action
in mammals is vitiated by the exposure of the developing foetus to a number
of maternal factors which do not allow one to specifically define the role
of thyroid hormone (TH) or that of other hormones and factors that modulate
its action. Amphibian metamorphosis is obligatorily dependent on TH which
can initiate all the diverse physiological manifestations of this postembryonic
developmental process (morphogenesis, cell death, re-structuring, etc.)
in free-living embryos and larvae of most anurans. This article will first
describe the salient features of metamorphosis and its control by TH and
other hormones. Emphasis will be laid on the key role played by TH receptor
(TR), in particular the phenomenon of TR gene autoinduction, in initiating
the developmental action of TH. Finally, it will be argued that the findings
on the control of amphibian metamorphosis enhance our understanding of the
regulation of postembryonic development by TH in other vertebrate species.
Keywords : Thyroid
hormone, metamorphosis, postenbryonic development, thyroid hormone receptor,
autoinduction. |
