Role of the
            <i>Xlim-1</i>
            and
            <i>Xbra</i>
            genes in anteroposterior patterning of neural tissue by the head and trunk organizer

Taira, Masanori; Saint-Jeannet, Jean Pierre; Dawid, Igor B.

doi:10.1073/pnas.94.3.895

Cited by 51 publications

(38 citation statements)

References 56 publications

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“…The gene Xbra is an early response gene to mesoderm induction and is expressed in a deep ring around the blastopore (39,40). Similarly, a ring of Xlim1-positive cells was detected around the X. laevis blastopore (14,41). The major difference is the unequal expression of Xlim1 in the dorsal side, whereas Xbra was expressed in a uniform ring (14,40).…”

Section: Discussionmentioning

confidence: 92%

“…Expression of Bra and Lim1 in the presumptive prospective mesoderm of G. riobambae and C. machalilla are separated in time, whereas the expression of Xlim1 and Xbra coincide in the X. laevis early gastrula (41). In fact, a deep ring of Bra-positive cells was first detected in the late gastrula of these frogs, whereas, in X. laevis, the Xbra-positive ring is visible from the onset of gastrulation (4,20,39,40).…”

Section: Discussionmentioning

confidence: 97%

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A comparative analysis of frog early development

Pino

Venegas-Ferrín

Romero‐Carvajal

et al. 2007

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

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The current understanding of Xenopus laevis development provides a comparative background for the analysis of frog developmental modes. Our analysis of development in various frogs reveals that the mode of gastrulation is associated with developmental rate and is unrelated to egg size. In the gastrula of the rapidly developing embryos of the foam-nesting frogs Engystomops coloradorum and Engystomops randi, archenteron and notochord elongation overlapped with involution at the blastopore lip, as in X. laevis embryos. In embryos of dendrobatid frogs and in the frog without tadpoles Eleutherodactylus coqui, which develop somewhat more slowly than X. laevis, involution and archenteron elongation concomitantly occurred during gastrulation; whereas elongation of the notochord and, therefore, dorsal convergence and extension, occurred in the postgastrula. In contrast, in the slow developing embryos of the marsupial frog Gastrotheca riobambae, only involution occurred during gastrulation. The processes of archenteron and notochord elongation and convergence and extension were postgastrulation events. We produced an Ab against the homeodomain protein Lim1 from X. laevis as a tool for the comparative analysis of development. By the expression of Lim1, we were able to identify the dorsal side of the G. riobambae early gastrula, which otherwise was difficult to detect. Moreover, the Lim1 expression in the dorsal lip of the blastopore and notochord differed among the studied frogs, indicating variation in the timing of developmental events. The variation encountered gives evidence of the modular character of frog gastrulation.Brachyury ͉ Gastrotheca ͉ Lim1

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 97%

A comparative analysis of frog early development

Pino

Venegas-Ferrín

Romero‐Carvajal

et al. 2007

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

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“…Additional evidence of the posteriorizing activity of FGF comes from the findings by Taira et al (1997) that the embryonic FGF-inducible gene X bra Isaacs et al, 1994) can posteriorize the anterior neural tissue induced by the activated form of the organizer homeobox gene X lim-1 (Taira et al, 1994). Thus, although FGF alone does not initiate neurogenesis, it may work in concert with neural inducers to induce posterior neural tissue.…”

Section: Fgf Is Required For Neural Induction and Posteriorizationmentioning

confidence: 96%

Studies on the Role of Fibroblast Growth Factor Signaling in Neurogenesis Using Conjugated/Aged Animal Caps and Dorsal Ectoderm-Grafted Embryos

Kim

Taira

et al. 1997

J. Neurosci.

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Basic fibroblast growth factor (bFGF) has been shown to induce neural fate in dissociated animal cap (AC) cells or in AC explants cultured in low calcium and magnesium concentrations. However, long-term disclosure of the cap may cause diffusion of the secreted molecule bone morphogenetic protein 4 (BMP-4), a neural inhibitor present in the AC. This may contribute to the subsequent neurogenesis induced by bFGF. Here we used conjugated and aged blastula AC to avoid diffusion of endogenous molecules from the AC. Unlike noggin, bFGF failed to induce neural tissue in this system. However, it enhanced neuralization elicited by a dominant negative BMP receptor (DN-BR) that inhibits the BMP-4 signaling. Posterior neural markers were turned on by bFGF in AC expressing DN-BR or chordin. Blocking the endogenous FGF signal with a dominant negative FGF receptor (XFD) mainly inhibited development of posterior neural tissue in neuralized ACs. These in vitro studies were confirmed in vivo in embryos grafted with XFD-expressing ACs in the place of neuroectoderm. Expression of some regional neural markers was inhibited, although markers for muscle and posterior notochord were still detectable in the grafted embryos, suggesting that XFD specifically affected neurogenesis but not the dorsal mesoderm. The use of these in vitro and in vivo model systems provides new evidence that FGF, although unable to initiate neurogenesis on its own, is required for neural induction as well as for posteriorization.

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“…1A). The second group, which included BRACHYURY [24,25] and CXCR4 [26], was upregulated by either Activin A or LiCl (Fig. 1B).…”

Section: Tgfb and Wnt Pathways Induce Differentiating Hescs To Expresmentioning

confidence: 99%

Molecular and Functional Characterizations of Gastrula Organizer Cells Derived from Human Embryonic Stem Cells

et al. 2011

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The Spemann-Mangold organizer is the structure that provides the signals, which initiate pattern formation in the developing vertebrate embryo, affecting the main body axes. Very little is known about axial induction in the gastrulating human embryo, as research is hindered by obvious ethical restrictions. Human embryonic stem cells (hESCs) are pluripotent cells derived from the pregastrula embryo that can differentiate in culture following a program similar to normal embryonic development but without pattern formation. Here, we show that in hESC-derived embryoid bodies, we can induce differentiation of cells that harbor markers and characteristics of the gastrula-organizer. Moreover, genetic labeling of these cells enabled their purification, and the discovery of a comprehensive set of their secreted proteins, cell surface receptors, and nuclear factors characteristic of the organizer. Remarkably, transplantation of cell populations enriched for the putative human organizer into frog embryos induced a secondary axis. Our research demonstrates that the human organizer can be induced in vitro and paves the way for the study of pattern formation and the initial regulation of body axis establishment in humans.

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Role of the Xlim-1 and Xbra genes in anteroposterior patterning of neural tissue by the head and trunk organizer

Cited by 51 publications

References 56 publications

A comparative analysis of frog early development

A comparative analysis of frog early development

Studies on the Role of Fibroblast Growth Factor Signaling in Neurogenesis Using Conjugated/Aged Animal Caps and Dorsal Ectoderm-Grafted Embryos

Molecular and Functional Characterizations of Gastrula Organizer Cells Derived from Human Embryonic Stem Cells

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