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Ventx factors function as Nanog-like guardians of developmental potential in Xenopus.

Scerbo P, Girardot F, Vivien C, Markov GV, Luxardi G, Demeneix B, Kodjabachian L, Coen L - PLoS ONE (2012)

Bottom Line: Joint over-expression of Xenopus ventx1.2 and ventx2.1-b (ventx1/2) counteracts lineage commitment towards both dorsal and ventral fates and prevents msx1-induced ventralization.Furthermore, ventx1/2 inactivation leads to down-regulation of the multipotency marker oct91 and to premature differentiation of blastula cells.We conclude that during Xenopus development ventx1/2 activity, reminiscent of that of Nanog in mammalian embryos, controls the switch of early embryonic cells from uncommitted to committed states.

View Article: PubMed Central - PubMed

Affiliation: Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris, France.

ABSTRACT
Vertebrate development requires progressive commitment of embryonic cells into specific lineages through a continuum of signals that play off differentiation versus multipotency. In mammals, Nanog is a key transcription factor that maintains cellular pluripotency by controlling competence to respond to differentiation cues. Nanog orthologs are known in most vertebrates examined to date, but absent from the Anuran amphibian Xenopus. Interestingly, in silico analyses and literature scanning reveal that basal vertebrate ventral homeobox (ventxs) and mammalian Nanog factors share extensive structural, evolutionary and functional properties. Here, we reassess the role of ventx activity in Xenopus laevis embryos and demonstrate that they play an unanticipated role as guardians of high developmental potential during early development. Joint over-expression of Xenopus ventx1.2 and ventx2.1-b (ventx1/2) counteracts lineage commitment towards both dorsal and ventral fates and prevents msx1-induced ventralization. Furthermore, ventx1/2 inactivation leads to down-regulation of the multipotency marker oct91 and to premature differentiation of blastula cells. Finally, supporting the key role of ventx1/2 in the control of developmental potential during development, mouse Nanog (mNanog) expression specifically rescues embryonic axis formation in ventx1/2 deficient embryos. We conclude that during Xenopus development ventx1/2 activity, reminiscent of that of Nanog in mammalian embryos, controls the switch of early embryonic cells from uncommitted to committed states.

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ventx1/2 overexpression prevents multiple lineage commitment.(A) NF2-embryos were injected twice in one blastomere, either with msx1 mRNAs (0.6 ng/blastomere), ventx1/2 mRNAs (1 ng/blastomere), mNanog mRNA (0,3 ng/blastomere), or with water for control; fldx was used as a lineage tracer. WISH with a k81a1 probe were performed at stage NF10.5 (left panels, animal views, dorsal side to the top). The progeny of the injected blastomere was revealed by fluorescence; white arrows indicate the injected side (right panels). (B) Sixteen-cell stage embryos (NF5) were injected in one AB4 blastomere with msx1 mRNA (0.15 ng), ventx1/2 mRNAs (0.5 ng), mNanog mRNA (0.15 ng), or water, collected at stage NF10.5 and processed for WISH with a k81a1 probe (animal views). Black stripped lines mark the border between injected and uninjected domains. (C) NF2-embryos were injected twice in one blastomere with msx1 mRNA (5 ng/blastomere), ventx1/2 mRNAs (5 ng/blastomere), ventx1/2+msx1 mRNAs (5 ng +5 ng/blastomere), or with water. WISH with a myf5 probe were performed at stage NF10.5; black arrowheads point to myf5-expressing territories (left panels, ventral views, dorsal side to the top). The progeny of the injected blastomere was revealed by fldx fluorescence; white arrows point to the injected side (right panels).
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pone-0036855-g003: ventx1/2 overexpression prevents multiple lineage commitment.(A) NF2-embryos were injected twice in one blastomere, either with msx1 mRNAs (0.6 ng/blastomere), ventx1/2 mRNAs (1 ng/blastomere), mNanog mRNA (0,3 ng/blastomere), or with water for control; fldx was used as a lineage tracer. WISH with a k81a1 probe were performed at stage NF10.5 (left panels, animal views, dorsal side to the top). The progeny of the injected blastomere was revealed by fluorescence; white arrows indicate the injected side (right panels). (B) Sixteen-cell stage embryos (NF5) were injected in one AB4 blastomere with msx1 mRNA (0.15 ng), ventx1/2 mRNAs (0.5 ng), mNanog mRNA (0.15 ng), or water, collected at stage NF10.5 and processed for WISH with a k81a1 probe (animal views). Black stripped lines mark the border between injected and uninjected domains. (C) NF2-embryos were injected twice in one blastomere with msx1 mRNA (5 ng/blastomere), ventx1/2 mRNAs (5 ng/blastomere), ventx1/2+msx1 mRNAs (5 ng +5 ng/blastomere), or with water. WISH with a myf5 probe were performed at stage NF10.5; black arrowheads point to myf5-expressing territories (left panels, ventral views, dorsal side to the top). The progeny of the injected blastomere was revealed by fldx fluorescence; white arrows point to the injected side (right panels).

Mentions: To evaluate the above hypothesis, we focused on epidermal differentiation, which is known to require Msx1 function [52]. We injected msx1, ventx1/2 or mNanog mRNAs either unilaterally, in one blastomere of 2-cell stage embryos (NF2, Fig. 3A) or at the 16-cell stage (NF5, Fig. 3B) in one AB4 blastomere fated to give rise only to epidermis. Both mNanog and ventx1/2 repressed expression of the committed ectoderm marker k81a1 in comparable fashion at NF10.5, whereas msx1 had no effect on epidermal differentiation. This result indicates that ventx1/2, unlike msx1, do not favour, but rather impede epidermal differentiation.


Ventx factors function as Nanog-like guardians of developmental potential in Xenopus.

Scerbo P, Girardot F, Vivien C, Markov GV, Luxardi G, Demeneix B, Kodjabachian L, Coen L - PLoS ONE (2012)

ventx1/2 overexpression prevents multiple lineage commitment.(A) NF2-embryos were injected twice in one blastomere, either with msx1 mRNAs (0.6 ng/blastomere), ventx1/2 mRNAs (1 ng/blastomere), mNanog mRNA (0,3 ng/blastomere), or with water for control; fldx was used as a lineage tracer. WISH with a k81a1 probe were performed at stage NF10.5 (left panels, animal views, dorsal side to the top). The progeny of the injected blastomere was revealed by fluorescence; white arrows indicate the injected side (right panels). (B) Sixteen-cell stage embryos (NF5) were injected in one AB4 blastomere with msx1 mRNA (0.15 ng), ventx1/2 mRNAs (0.5 ng), mNanog mRNA (0.15 ng), or water, collected at stage NF10.5 and processed for WISH with a k81a1 probe (animal views). Black stripped lines mark the border between injected and uninjected domains. (C) NF2-embryos were injected twice in one blastomere with msx1 mRNA (5 ng/blastomere), ventx1/2 mRNAs (5 ng/blastomere), ventx1/2+msx1 mRNAs (5 ng +5 ng/blastomere), or with water. WISH with a myf5 probe were performed at stage NF10.5; black arrowheads point to myf5-expressing territories (left panels, ventral views, dorsal side to the top). The progeny of the injected blastomere was revealed by fldx fluorescence; white arrows point to the injected side (right panels).
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Related In: Results  -  Collection

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pone-0036855-g003: ventx1/2 overexpression prevents multiple lineage commitment.(A) NF2-embryos were injected twice in one blastomere, either with msx1 mRNAs (0.6 ng/blastomere), ventx1/2 mRNAs (1 ng/blastomere), mNanog mRNA (0,3 ng/blastomere), or with water for control; fldx was used as a lineage tracer. WISH with a k81a1 probe were performed at stage NF10.5 (left panels, animal views, dorsal side to the top). The progeny of the injected blastomere was revealed by fluorescence; white arrows indicate the injected side (right panels). (B) Sixteen-cell stage embryos (NF5) were injected in one AB4 blastomere with msx1 mRNA (0.15 ng), ventx1/2 mRNAs (0.5 ng), mNanog mRNA (0.15 ng), or water, collected at stage NF10.5 and processed for WISH with a k81a1 probe (animal views). Black stripped lines mark the border between injected and uninjected domains. (C) NF2-embryos were injected twice in one blastomere with msx1 mRNA (5 ng/blastomere), ventx1/2 mRNAs (5 ng/blastomere), ventx1/2+msx1 mRNAs (5 ng +5 ng/blastomere), or with water. WISH with a myf5 probe were performed at stage NF10.5; black arrowheads point to myf5-expressing territories (left panels, ventral views, dorsal side to the top). The progeny of the injected blastomere was revealed by fldx fluorescence; white arrows point to the injected side (right panels).
Mentions: To evaluate the above hypothesis, we focused on epidermal differentiation, which is known to require Msx1 function [52]. We injected msx1, ventx1/2 or mNanog mRNAs either unilaterally, in one blastomere of 2-cell stage embryos (NF2, Fig. 3A) or at the 16-cell stage (NF5, Fig. 3B) in one AB4 blastomere fated to give rise only to epidermis. Both mNanog and ventx1/2 repressed expression of the committed ectoderm marker k81a1 in comparable fashion at NF10.5, whereas msx1 had no effect on epidermal differentiation. This result indicates that ventx1/2, unlike msx1, do not favour, but rather impede epidermal differentiation.

Bottom Line: Joint over-expression of Xenopus ventx1.2 and ventx2.1-b (ventx1/2) counteracts lineage commitment towards both dorsal and ventral fates and prevents msx1-induced ventralization.Furthermore, ventx1/2 inactivation leads to down-regulation of the multipotency marker oct91 and to premature differentiation of blastula cells.We conclude that during Xenopus development ventx1/2 activity, reminiscent of that of Nanog in mammalian embryos, controls the switch of early embryonic cells from uncommitted to committed states.

View Article: PubMed Central - PubMed

Affiliation: Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris, France.

ABSTRACT
Vertebrate development requires progressive commitment of embryonic cells into specific lineages through a continuum of signals that play off differentiation versus multipotency. In mammals, Nanog is a key transcription factor that maintains cellular pluripotency by controlling competence to respond to differentiation cues. Nanog orthologs are known in most vertebrates examined to date, but absent from the Anuran amphibian Xenopus. Interestingly, in silico analyses and literature scanning reveal that basal vertebrate ventral homeobox (ventxs) and mammalian Nanog factors share extensive structural, evolutionary and functional properties. Here, we reassess the role of ventx activity in Xenopus laevis embryos and demonstrate that they play an unanticipated role as guardians of high developmental potential during early development. Joint over-expression of Xenopus ventx1.2 and ventx2.1-b (ventx1/2) counteracts lineage commitment towards both dorsal and ventral fates and prevents msx1-induced ventralization. Furthermore, ventx1/2 inactivation leads to down-regulation of the multipotency marker oct91 and to premature differentiation of blastula cells. Finally, supporting the key role of ventx1/2 in the control of developmental potential during development, mouse Nanog (mNanog) expression specifically rescues embryonic axis formation in ventx1/2 deficient embryos. We conclude that during Xenopus development ventx1/2 activity, reminiscent of that of Nanog in mammalian embryos, controls the switch of early embryonic cells from uncommitted to committed states.

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