A Sea Cucumber Homolog of the Mouse T-Brain-1 is Expressed in the Invaginated Cells of the Early Gastrula in Holothuria leucospilota.

Maruyama, Yoshihiko K.

doi:10.2108/zsj.17.383

Cited by 8 publications

(9 citation statements)

References 23 publications

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“…The cooption of tbr to skeletogenic function is a derived feature of the echinoids: endomesodermal expression of tbr is the pleisiomorphic state in deuterostomes. This pleisiomorphy is shown in the endomesodermal transcription pattern of tbrain orthologs in the sea star and in a holothurian, as well as in a hemichordate, amphioxus, and many vertebrates (6,(26)(27)(28).…”

Section: Delta-n Repression Of Mesoderm Specification In Sea Starsmentioning

confidence: 97%

Evolutionary plasticity of developmental gene regulatory network architecture

Hinman

Davidson

2007

Proc. Natl. Acad. Sci. U.S.A.

147

140

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Sea stars and sea urchins evolved from a last common ancestor that lived at the end of the Cambrian, approximately half a billion years ago. In a previous comparative study of the gene regulatory networks (GRNs) that embody the genomic program for embryogenesis in these animals, we discovered an almost perfectly conserved five-gene network subcircuit required for endoderm specification. We show here that the GRN structure upstream and downstream of the conserved network kernel has, by contrast, diverged extensively. Mesoderm specification is accomplished quite differently; the Delta-Notch signaling system is used in radically distinct ways; and various regulatory genes have been coopted to different functions. The conservation of the conserved kernel is thus the more remarkable. The results indicate types of network linkage subject to evolutionary change. An emergent theme is that subcircuit design may be preserved even while the identity of genes performing given roles changes because of alteration in their cis-regulatory control systems.

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Section: Delta-n Repression Of Mesoderm Specification In Sea Starsmentioning

confidence: 97%

Evolutionary plasticity of developmental gene regulatory network architecture

Hinman

Davidson

2007

Proc. Natl. Acad. Sci. U.S.A.

147

140

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“…In basal deuterostomes, the T-Brain expression was observed only in invaginating archenteron of starfish (Shoguchi et al, 2000) and sea cucumber (Maruyama, 2000) embryos, whereas hemichordate cognate was also expressed in apical sensory organ of early tornaria larvae (Tagawa et al, 2000). So far, the T-Brain genes have not been studied in protostomes, an outgroup of deuterostomes that develops through similar ciliary larva using a set of homologous molecules (e.g., Arendt et al, 2001), so that we cannot determine whether the expression of the T-Brain in the apical sensory organ displays an ancestral state or not.…”

Section: Molecular Phylogeny Of T-brain Subfamily Genes and Comparisomentioning

confidence: 99%

“…To date, T-Brain subfamily genes have been isolated not only from vertebrates but also from nonchordate deuterostomes, including a hemichordate (Tagawa et al, 2000) and echinoderms (Maruyama, 2000;Shoguchi et al, 2000). In vertebrates, T-Brain subfamily genes can be subdivided into a Tbr1 class and an Eomesodermin (Tbr2) class.…”

Section: Molecular Phylogeny Of T-brain Subfamily Genes and Comparisomentioning

confidence: 99%

“…Since T-Brain family genes have been isolated from nonchordate deuterostomes (e.g., Maruyama, 2000;Shoguchi et al, 2000;Tagawa et al, 2000), a large part of understanding the origin of such novelty may come down to addressing the history of the modification of developmental programs. It is therefore of interest to compare the T-Brain expression across deuterostome phyla in order to gain an insight into the origin and evolution of the vertebrate brain.…”

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confidence: 99%

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Amphi‐Eomes/Tbr1: an amphioxus cognate of vertebrate Eomesodermin and T‐Brain1 genes whose expression reveals evolutionarily distinct domain in amphioxus development

et al. 2002

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A cDNA for a novel T-box containing gene was isolated from the amphioxus Branchiostoma belcheri. A molecular phylogenetic tree constructed from the deduced amino acid sequence of the isolated cDNA indicates that this gene belongs to the T-Brain subfamily. In situ hybridization reveals that the expression is first detected in the invaginating archenteron at the early gastrula stage and this expression is down-regulated at the neurula stage. In early larvae, the expression appears again and transcripts are detected exclusively in the pre-oral pit (wheel organHatschek's pit of the adult). In contrast to the vertebrate counterparts, no transcripts are detected in the brain vesicle or nerve cord throughout the development. These results are interpreted to mean that a role of T-Brain products in vertebrate forebrain development was acquired after the amphioxus was split from the lineage leading to the vertebrates. On the other hand, comparison of the tissue-specific expression domain of T-Brain genes and other genes between amphioxus and vertebrates revealed that the pre-oral pit of amphioxus has several molecular features which are comparable to those of the vertebrate olfactory and hypophyseal placode.

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“…Yet these roles, and the circuitry underlying them, are evolutionarily derived traits, since only modern sea urchins precociously segregate a SM lineage. In the sister group to the echinoids, the sea cucumbers, tbr is expressed in the developing endomesoderm (Maruyama, 2000). This is the pleisiomorphic function of the tbr gene in embryogenesis, since it is also expressed in endomesoderm in the more distant sea star outgroup (Hinman and Davidson, 2007; Hinman et al, 2003; Shoguchi et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

The cis-regulatory system of the tbrain gene: Alternative use of multiple modules to promote skeletogenic expression in the sea urchin embryo

Wahl

Hahn

Gora

et al. 2009

Developmental Biology

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The genomic cis-regulatory systems controlling regulatory gene expression usually include multiple modules. The regulatory output of such systems at any given time depends on which module is directing the function of the basal transcription apparatus, and ultimately on the transcription factor inputs into that module. Here we examine regulation of the S. purpuratus tbrain gene, a required activator of the skeletogenic specification state in the lineage descendant from the embryo micromeres. Alternate cis-regulatory modules were found to convey skeletogenic expression in reporter constructs. To determine their relative developmental functions in context, we made use of recombineered BAC constructs containing a GFP reporter, and of derivatives from which specific modules had been deleted. The outputs of the various constructs were observed spatially by GFP fluorescence and quantitatively over time by QPCR. In the context of the complete genomic locus, early skeletogenic expression is controlled by an intron enhancer plus a proximal region containing a HesC site as predicted from network analysis. From ingression onward, however, a dedicated distal module utilizing positive Ets1/2 inputs contributes to definitive expression in the skeletogenic mesenchyme. This module also mediates a newly-discovered negative Erg input which excludes non-skeletogenic mesodermal expression.

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A Sea Cucumber Homolog of the Mouse T-Brain-1 is Expressed in the Invaginated Cells of the Early Gastrula in Holothuria leucospilota.

Cited by 8 publications

References 23 publications

Evolutionary plasticity of developmental gene regulatory network architecture

Evolutionary plasticity of developmental gene regulatory network architecture

Amphi‐Eomes/Tbr1: an amphioxus cognate of vertebrate Eomesodermin and T‐Brain1 genes whose expression reveals evolutionarily distinct domain in amphioxus development

The cis-regulatory system of the tbrain gene: Alternative use of multiple modules to promote skeletogenic expression in the sea urchin embryo

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