Thyroid gland development and function in the zebrafish model

Abstract

Thyroid development has been intensively studied in the mouse, where it closely recapitulates the human situation. Despite the lack of a compact thyroid gland, the zebrafish thyroid tissue originates from the pharyngeal endoderm and the main genes involved in its patterning and early development are conserved between zebrafish and mammals. In recent years, the zebrafish has become a powerful model not only for the developmental biology studies, but also for large-scale genetic analyses and drug screenings, mostly thanks to the ease with which its embryos can be manipulated and to its translucent body, which allows in vivo imaging. In this review we will provide an overview of the current knowledge of thyroid gland origin and differentiation in the zebrafish. Moreover, we will consider the action of thyroid hormones and some aspects related to endocrine disruptors.

Exposure to DE-71 alters thyroid hormone levels and gene transcription in the hypothalamic–pituitary–thyroid axis of zebrafish larvae

“…In zebrafish, the slc5a5 gene (encoding a sodium/iodide symporter) is expressed in the thyroid and its product is responsible for iodine uptake from the bloodstream (Porazzi et al, 2009). In the present study, the transcription of slc5a5 and TG genes was significantly upregulated.…”

“…Environmental chemicals that interfere with TH synthesis have attracted great attention in recent studies (e.g., Boas et al, 2006;Zoeller et al, 2007a,b;Lema et al, 2008;Richardson et al, 2008;Li et al, 2009;Porazzi et al, 2009;Morgado et al, 2009;Szabo et al, 2009). We developed a model in which zebrafish embryos were exposed to DE-71 until 14 dpf and evaluated the embryos for TH disruption.…”

“…In our study, the mRNA expression of Pax8 and Nkx2.1a was noted to be significantly upregulated; Pax8 was expressed up to 7 dpf. Pax8 protein is essential for the late differentiation of the follicular cells (Wendl et al, 2002) and the transcription factor Nkx2.1 (or TTF1) plays an essential role in thyroid development in zebrafish (Wendl et al, 2002;Porazzi et al, 2009). The upregulation of the transcription of Pax8 and Nkx2.1 genes suggests that DE-71 induces gene expression and may promote the growth of the thyroid primordium to compensate for reduced TH levels.…”

Animal models of medullary thyroid cancer: state of the art and view to the future

“…Although mammalian C cells are located in the thyroid interfollicular spaces, fish C cells form the ultimobranchial bodies, an independent organ that does not fuse with the thyroid. In zebrafish, starting from 60 h after fertilisation, ultimobranchial bodies are organised in two groups of cells on either side of the heart, in this way, C cells are not in contact with thyroid follicles (Porazzi et al 2009). Thus, zebrafish could help us in understanding if extracellular matrix components, produced by thyroid epithelial, are necessary to the emergence of the MTC phenotype, as previously hypothesised in humans (Lekmine et al 1999).…”

Morphogenetics of early thyroid development

“…Finally, current views on the causes of TD in human patients and some aspects of embryonic stem (ES) cells will be briefly considered. For recent comprehensive reviews on thyroid morphogenesis in the most important animal models (mice, chicken, and zebrafish), see Porazzi et al (2009) andNilsson (2010).…”