Three calcium-sensitive genes, fus, brd3 and wdr5, are highly expressed in neural and renal territories during amphibian development

Abstract

Numerous Ca2+ signaling events have been associated with early development of vertebrate embryo, from fertilization to organogenesis. In Xenopus laevis, Ca2+ signals are key regulators in the earliest steps of the nervous system development. If neural determination is one of the best-characterized examples of the role of Ca2+ during embryogenesis, increasing literature supports a determining role of organogenesis and differentiation. In blastula the cells of the presumptive ectoderm (animal caps) are pluripotent and can be induced toward neural fate with an intracellular increase of free Ca2+ triggered by caffeine. To identify genes that are transcribed early upon Ca2+ stimuli and involved in neural determination, we have constructed a subtractive cDNA library between neuralized and non-neuralized animal caps. Here we present the expression pattern of three new Ca2+-sensitive genes: fus (fused in sarcoma), brd3 (bromodomain containing 3) and wdr5 (WD repeat domain 5) as they all represent potential regulators of the transcriptional machinery. Using in situ hybridization we illustrated the spatial expression pattern of fus, brd3 and wdr5 during early developmental stages of Xenopus embryos. Strikingly, their domains of expression are not restricted to neural territories. They all share a specific expression throughout renal organogenesis which has been found to rely also on Ca2+ signaling. This therefore highlights the key function of Ca2+ target genes in specific territories during early development. We propose that Ca2+ signaling through modulation of fus, brd3 and wdr5 expressions can control the transcription machinery to achieve proper embryogenesis. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.