- 作者: Yun-Bo Shi; Atsuko Ishizuya-Oka
- 作者服務機構: a Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, Bethesda, Md., USA;; b Department of Anatomy, Dokkyo University School of Medicine, Mibu, Tochigi, Japan
- 中文摘要: --
- 英文摘要: The thyroid hormone (T3)-dependent amphibian metamorphosis involves degeneration of larval tissues through programmed cell death (apoptosis) and concurrent proliferation and differentiation of adult cell types. As the mediators of the causative effects of T3 on metamorphosis, both thyroid hormone receptor (TR) α and β genes have been found to be expressed in different tissues during this process. In particular, the Xenopus TRβ genes have been shown to be regulated by T3 at the transcriptional level and their expression correlates with organ-specific metamorphosis. We demonstrate here by in situ hybridization that the Xenopus TRβ genes are regulated in a cell-type specific manner that correlates with tissue transformation. In particular, they are found to be expressed in the larval intestinal epithelial cells prior to their apop-totic degeneration and in the proliferating cells of the adult epithelium, connective tissue, and muscles. However, they are repressed again upon the differentiation of these adult cells. These results implicate that TRβ participates both in inducing apoptosis and stimulating cell proliferation during development.
- 中文關鍵字: --
- 英文關鍵字: Thyroid hormone receptor; Xenopus laevis; Metamorphosis; Apoptosis; Cell proliferation