|Title||Ephrin-mediated restriction of ERK1/2 activity delimits the number of pigment cells in the Ciona CNS.|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Haupaix, N, Abitua, PB, Sirour, C, Yasuo, H, Levine, M, Hudson, C|
|Date Published||2014 Oct 1|
|Keywords||Animals, Biological Evolution, Blastula, Body Patterning, Cell Division, Cell Lineage, Central Nervous System, Ciona intestinalis, Embryo, Nonmammalian, Ephrins, Extracellular Signal-Regulated MAP Kinases, Melanocytes, Neural Crest, Pigmentation, Receptors, Eph Family, Stem Cells|
Recent evidence suggests that ascidian pigment cells are related to neural crest-derived melanocytes of vertebrates. Using live-imaging, we determine a revised cell lineage of the pigment cells in Ciona intestinalis embryos. The neural precursors undergo successive rounds of anterior-posterior (A-P) oriented cell divisions, starting at the blastula 64-cell stage. A previously unrecognized fourth A-P oriented cell division in the pigment cell lineage leads to the generation of the post-mitotic pigment cell precursors. We provide evidence that MEK/ERK signals are required for pigment cell specification until approximately 30min after the final cell division has taken place. Following each of the four A-P oriented cell divisions, ERK1/2 is differentially activated in the posterior sister cells, into which the pigment cell lineage segregates. Eph/ephrin signals are critical during the third A-P oriented cell division to spatially restrict ERK1/2 activation to the posterior daughter cell. Targeted inhibition of Eph/ephrin signals results in, at neurula stages, anterior expansion of both ERK1/2 activation and a pigment cell lineage marker and subsequently, at larval stages, supernumerary pigment cells. We discuss the implications of these findings with respect to the evolution of the vertebrate neural crest.
|Alternate Journal||Dev. Biol.|