Mutational Analysis of Endothelin Receptor b1 (rose) during Neural Crest and Pigment Pattern Development in the Zebrafish Danio rerio

Abstract

Pigment patterns of fishes are a tractable system for studying the genetic and cellular bases for postembryonic phenotypes. In the zebrafish Danio rerio, neural crest-derived pigment cells generate different pigment patterns during different phases of the life cycle. Whereas early larvae exhibit simple stripes of melanocytes and silver iridophores in a background of yellow xanthophores, this pigment pattern is transformed at metamorphosis into that of the adult, comprising a series of dark melanocyte and iridophore stripes, alternating with light stripes of iridophores and xanthophores. Although several genes have been identified in D. rerio that contribute to the development of both early larval and adult pigment patterns, comparatively little is known about genes that are essential for pattern formation during just one or the other life cycle phase. In this study, we identify the gene responsible for the rose mutant phenotype in D. rerio. rose mutants have wild-type early larval pigment patterns, but fail to develop normal numbers of melanocytes and iridophores during pigment pattern metamorphosis and exhibit a disrupted pattern of these cells. We show that rose corresponds to endothelin receptor b1 (ednrb1), an orthologue of amniote Ednrb genes that have long been studied for their roles in neural crest and pigment cell development. Furthermore, we demonstrate that D. rerio ednrb1 is expressed both during pigment pattern metamorphosis and during embryogenesis, and cells of melanocyte, iridophore, and xanthophore lineages all express this gene. These analyses suggest a phylogenetic conservation of roles for Ednrb signaling in the development of amniote and teleost pigment cell precursors. As murine Ednrb is essential for the development of all neural crest derived melanocytes, and D. rerio ednrb1 is required only by a subset of adult melanocytes and iridophores, these analyses also reveal variation among vertebrates in the cellular requirements for Ednrb signaling, and suggest alternative models for the cellular and genetic bases of pigment pattern metamorphosis in D. rerio.

Molecular Characterization of Two Endothelin Pathways in East African Cichlid Fishes

“…1). This is in agreement with previously described endothelin functions: EdnrB1/EdnrB2 duplicates and Edn3 are known to be involved in pigmentation in a range of vertebrates including zebrafish (e.g., Parichy et al 2000;Pla and Larue 2003); whereas a correlation between Edn1, EdnrA duplicates and the pharyngeal bone development has been uncovered in zebrafish (Kimmel et al 2003;Pla and Larue 2003).…”

“…1), which is in concordance with the wide range of functions known for the endothelin family members. Most studied and described functions of the endothelin system are related to the blood pressure regulation functions of Edn1 in adult vertebrates (e.g., Yanagisawa et al 1988) and the functions during early development of neural crest derivatives (e.g., Miller et al 2000;Parichy et al 2000). Yet, the endothelin system is not limited to vasoconstriction or early development, since several neural crest derivatives such as pigmentation and the (dentition on the cichlids') pharyngeal jaws are produced and maintained throughout adulthood.…”

“…Photographs taken by M. Muschick, A. Theis, and C. Heule. Pathways based on, e.g., Bonano et al 2008;McGill et al 2002;Parichy 2000;Pla and Larue 2003;Rawls et al 2001;Slack 2001;Yanagisawa et al 2003 itself-an evolutionary innovation of the vertebrate clade (e.g., Gans and Northcutt 1983;Shimeld and Holland 2000). Neural crest cells originate in the neural folds, and migrate away from the neural tube to form a wide variety of cell types across the whole body including neuron cells, pigment cells, craniofacial bones, Schwann cells, and smooth muscle cells (Chung et al 2009;Slack 2001).…”

“…Endothelin 1 was discovered in 1988 as vasoconstrictor by Yanagisawa et al (1988). Later, more members of this gene family were found and their functions annotated, so it is now evident that the endothelin system is involved in the formation of craniofacial structures, enteric ganglion neurons, pigmentation, and vasoconstriction in both mouse (Baynash et al 1994;Clouthier et al 1998;Hosoda et al 1994;Kurihara et al 1994;Ozeki et al 2004;Yanagisawa et al 1988) and zebrafish (Miller et al 2000;Parichy et al 2000). The active gene product of the endothelin genes is only 21 amino acids long and obtained via two steps of cleaving from the inactive precursors preproendothelin and big endothelin, respectively (Masaki 2004).…”

Toxicological and melanin synthesis effects of Polygonum multiflorum root extracts on zebrafish embryos and human melanocytes

“…Effects of Polygonum multiflorum on zebrafish and human melanocytes been used as an ideal model for study of melanin formation and dispersion (Parichy et al, 2000;Rawls et al, 2001). So far, there have been limited studies focusing on the evaluation of toxicological and melanin synthesis effects of PM in vitro as well as in vivo.…”