Ancient Evolutionary Origin of the Neural Crest Gene Regulatory Network

Division of Biology 139-74, California Institute of Technology, Pasadena, CA 91125, USA.
Developmental Cell (Impact Factor: 9.71). 10/2007; 13(3):405-20. DOI: 10.1016/j.devcel.2007.08.005
Source: PubMed


The vertebrate neural crest migrates from its origin, the neural plate border, to form diverse derivatives. We previously hypothesized that a neural crest gene regulatory network (NC-GRN) guides neural crest formation. Here, we investigate when during evolution this hypothetical network emerged by analyzing neural crest formation in lamprey, a basal extant vertebrate. We identify 50 NC-GRN homologs and use morpholinos to demonstrate a critical role for eight transcriptional regulators. The results reveal conservation in deployment of upstream factors, suggesting that proximal portions of the network arose early in vertebrate evolution and have been conserved for >500 million years. We found biphasic expression of neural crest specifiers and differences in deployment of some specifiers and effectors expected to confer species-specific properties. By testing the collective expression and function of neural crest genes in a single, basal vertebrate, we reveal the ground state of the NC-GRN and resolve ambiguities between model organisms.

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Available from: Tatjana Sauka-Spengler, Feb 02, 2014
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    • "RNAi can be adapted as a tool to investigate the roles of specific genes, has provided important insight into developmental mechanisms and disease (Alvarez-Garcia and Miska 2005), and has recently been shown to be functional during lamprey development (Heath et al. 2014). Morpholino delivery has been accomplished by microinjection into individual embryos (McCauley and Bronner-Fraser 2006, Sauka-Spengler et al. 2007, Lakiza et al. 2011), whereas small interfering (si)RNA uptake has also been accomplished through feeding directly to larval lampreys (Heath et al. 2014). A recent advance in the ability to target genes for knockdown has been the adaptation of CRISPR/Cas technology to delete gene sequences of interest from diverse model organisms (Cong et al. 2013). "
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    ABSTRACT: Lampreys, one of the two surviving groups of ancient vertebrates, have become important models for study in diverse fields of biology. Lampreys (of which there are approximately 40 species) are being studied, for example, (a) to control pest sea lamprey in the North American Great Lakes and to restore declining populations of native species elsewhere; (b) in biomedical research, focusing particularly on the regenerative capability of lampreys; and (c) by developmental biologists studying the evolution of key vertebrate characters. Although a lack of genetic resources has hindered research on the mechanisms regulating many aspects of lamprey life history and development, formerly intractable questions are now amenable to investigation following the recent publication of the sea lamprey genome. Here, we provide an overview of the ways in which genomic tools are currently being deployed to tackle diverse research questions and suggest several areas that may benefit from the availability of the sea lamprey genome.
    Full-text · Article · Oct 2015 · BioScience
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    • "For linearised plasmid injection, the pm3285_cfos_EGFP plasmid, consisting of the lamprey homolog of CNE 3285 cloned into the pGW_cfosEGFP vector, was linearised with KpnI (NEB), purified with a Qiagen PCR purification kit and eluted in distilled water. Lamprey embryos were obtained as described previously [6] and injected with approximately 2–3 nl of linearised plasmid at a concentration of 100 ngμl−1 during the first cell division. Circular plasmid injection was performed at a concentration of 50 ngµl−1. "
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    ABSTRACT: The sea lamprey is an important model organism for investigating the evolutionary origins of vertebrates. As more vertebrate genome sequences are obtained, evolutionary developmental biologists are becoming increasingly able to identify putative gene regulatory elements across the breadth of the vertebrate taxa. The identification of these regions makes it possible to address how changes at the genomic level have led to changes in developmental gene regulatory networks and ultimately to the evolution of morphological diversity. Comparative genomics approaches using sea lamprey have already predicted a number of such regulatory elements in the lamprey genome. Functional characterisation of these sequences and other similar elements requires efficient reporter assays in lamprey. In this report, we describe the development of a transient transgenesis method for lamprey embryos. Focusing on conserved non-coding elements (CNEs), we use this method to investigate their functional conservation across the vertebrate subphylum. We find instances of both functional conservation and lineage-specific functional evolution of CNEs across vertebrates, emphasising the utility of functionally testing homologous CNEs in their host species.
    Full-text · Article · Jan 2014 · PLoS ONE
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    • "The neural crest gene regulatory network is conserved among vertebrates, including cyclostomes [15,33]. As one could expect for a conserved regulatory network, some of its parts are present in other chordate groups, i.e., tunicates and cephalochordates [15,34,35]. "
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    ABSTRACT: Background The vertebrate head is a highly derived trait with a heavy concentration of sophisticated sensory organs that allow complex behaviour in this lineage. The head sensory structures arise during vertebrate development from cranial placodes and the neural crest. It is generally thought that derivatives of these ectodermal embryonic tissues played a central role in the evolutionary transition at the onset of vertebrates. Despite the obvious importance of head sensory organs for vertebrate biology, their evolutionary history is still uncertain. Results To give a fresh perspective on the adaptive history of the vertebrate head sensory organs, we applied genomic phylostratigraphy to large-scale in situ expression data of the developing zebrafish Danio rerio. Contrary to traditional predictions, we found that dominant adaptive signals in the analyzed sensory structures largely precede the evolutionary advent of vertebrates. The leading adaptive signals at the bilaterian-chordate transition suggested that the visual system was the first sensory structure to evolve. The olfactory, vestibuloauditory, and lateral line sensory organs displayed a strong link with the urochordate-vertebrate ancestor. The only structures that qualified as genuine vertebrate innovations were the neural crest derivatives, trigeminal ganglion and adenohypophysis. We also found evidence that the cranial placodes evolved before the neural crest despite their proposed embryological relatedness. Conclusions Taken together, our findings reveal pre-vertebrate roots and a stepwise adaptive history of the vertebrate sensory systems. This study also underscores that large genomic and expression datasets are rich sources of macroevolutionary information that can be recovered by phylostratigraphic mining.
    Full-text · Article · Apr 2013 · Frontiers in Zoology
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