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Neural crest cells organize the eye via TGF-β and canonical Wnt signalling.

Grocott T, Johnson S, Bailey AP, Streit A - Nat Commun (2011)

Bottom Line: In vertebrates, the lens and retina arise from different embryonic tissues raising the question of how they are aligned to form a functional eye.Here we show, using the chick as a model system, that neural crest-derived transforming growth factor-βs activate both Smad3 and canonical Wnt signalling in the adjacent ectoderm to position the lens next to the retina.They do so by controlling Pax6 activity: although Smad3 may inhibit Pax6 protein function, its sustained downregulation requires transcriptional repression by Wnt-initiated β-catenin.

View Article: PubMed Central - PubMed

Affiliation: Department of Craniofacial Development, King's College London, Guy's Campus, London SE1 9RT, UK.

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TGF-β represses lens formation.(a–c) Presumptive lens ectoderm (PLE) was electroporated with expression vector encoding green fluorescent protein (GFP): (a) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (b) GFP and δ-crystallin staining only; (c) δ-crystallin staining only. (d–f) PLE was electroporated with expression vector encoding constitutively active Smad3+GFP: (d) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (e) GFP and δ-crystallin staining only; (f) δ-crystallin staining only. (g–k) PLE explants were cultured in vitro and assayed for pre-placodal (Six1, Eya2) or lens (Pax6, L-Maf, δ-crystallin) gene expression: (g) Six1; (h) Eya2; (i) Pax6; (j) L-Maf; and (k) δ-crystallin. (l–p) PLE explants were cultured in the presence of Activin A and assayed for pre-placodal or lens gene expression: (l) Six1; (m) Eya2; (n) Pax6; (o) L-Maf; and (p) δ-crystallin. (q) Model for lens inhibition by TGF-β signalling. (r–t) PLE explants were cultured alone or in combination with Activin A or SB431542 and assayed for δ-crystallin gene expression: (r) PLE alone; (s) PLE+Activin A; and (t) PLE+Activin A+SB431542. (u–w) PLE explants were cultured alone or in combination with neural crest cells (NCC) or SB431542 and assayed for δ-crystallin gene expression: (u) PLE alone; (v) PLE+NCC; and (w) PLE+NCC+SB431542. Scale bars: a, 50 μm for panels a–f, g, 50 μm for panels g–p, r–w.
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f1: TGF-β represses lens formation.(a–c) Presumptive lens ectoderm (PLE) was electroporated with expression vector encoding green fluorescent protein (GFP): (a) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (b) GFP and δ-crystallin staining only; (c) δ-crystallin staining only. (d–f) PLE was electroporated with expression vector encoding constitutively active Smad3+GFP: (d) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (e) GFP and δ-crystallin staining only; (f) δ-crystallin staining only. (g–k) PLE explants were cultured in vitro and assayed for pre-placodal (Six1, Eya2) or lens (Pax6, L-Maf, δ-crystallin) gene expression: (g) Six1; (h) Eya2; (i) Pax6; (j) L-Maf; and (k) δ-crystallin. (l–p) PLE explants were cultured in the presence of Activin A and assayed for pre-placodal or lens gene expression: (l) Six1; (m) Eya2; (n) Pax6; (o) L-Maf; and (p) δ-crystallin. (q) Model for lens inhibition by TGF-β signalling. (r–t) PLE explants were cultured alone or in combination with Activin A or SB431542 and assayed for δ-crystallin gene expression: (r) PLE alone; (s) PLE+Activin A; and (t) PLE+Activin A+SB431542. (u–w) PLE explants were cultured alone or in combination with neural crest cells (NCC) or SB431542 and assayed for δ-crystallin gene expression: (u) PLE alone; (v) PLE+NCC; and (w) PLE+NCC+SB431542. Scale bars: a, 50 μm for panels a–f, g, 50 μm for panels g–p, r–w.

Mentions: To assess whether activated Smad3 suppresses lens fate in vivo, we electroporated constitutively active Smad3 (ref. 16) into the presumptive lens ectoderm (PLE). Although control green fluorescent protein-expressing cells were incorporated into the lens and express the lens marker δ-crystallin (Fig. 1a–c; 3/3 lenses), constitutively active Smad3-expressing cells were excluded from the lens and did not express δ-crystallin (Fig. 1d–f; 0/5 lenses). Together, the above results suggest that TGF-βs prevent lens formation at inappropriate positions.


Neural crest cells organize the eye via TGF-β and canonical Wnt signalling.

Grocott T, Johnson S, Bailey AP, Streit A - Nat Commun (2011)

TGF-β represses lens formation.(a–c) Presumptive lens ectoderm (PLE) was electroporated with expression vector encoding green fluorescent protein (GFP): (a) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (b) GFP and δ-crystallin staining only; (c) δ-crystallin staining only. (d–f) PLE was electroporated with expression vector encoding constitutively active Smad3+GFP: (d) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (e) GFP and δ-crystallin staining only; (f) δ-crystallin staining only. (g–k) PLE explants were cultured in vitro and assayed for pre-placodal (Six1, Eya2) or lens (Pax6, L-Maf, δ-crystallin) gene expression: (g) Six1; (h) Eya2; (i) Pax6; (j) L-Maf; and (k) δ-crystallin. (l–p) PLE explants were cultured in the presence of Activin A and assayed for pre-placodal or lens gene expression: (l) Six1; (m) Eya2; (n) Pax6; (o) L-Maf; and (p) δ-crystallin. (q) Model for lens inhibition by TGF-β signalling. (r–t) PLE explants were cultured alone or in combination with Activin A or SB431542 and assayed for δ-crystallin gene expression: (r) PLE alone; (s) PLE+Activin A; and (t) PLE+Activin A+SB431542. (u–w) PLE explants were cultured alone or in combination with neural crest cells (NCC) or SB431542 and assayed for δ-crystallin gene expression: (u) PLE alone; (v) PLE+NCC; and (w) PLE+NCC+SB431542. Scale bars: a, 50 μm for panels a–f, g, 50 μm for panels g–p, r–w.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3104559&req=5

f1: TGF-β represses lens formation.(a–c) Presumptive lens ectoderm (PLE) was electroporated with expression vector encoding green fluorescent protein (GFP): (a) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (b) GFP and δ-crystallin staining only; (c) δ-crystallin staining only. (d–f) PLE was electroporated with expression vector encoding constitutively active Smad3+GFP: (d) GFP-expressing cells (green) counterstained for δ-crystallin (magenta) and cell nuclei (grey); (e) GFP and δ-crystallin staining only; (f) δ-crystallin staining only. (g–k) PLE explants were cultured in vitro and assayed for pre-placodal (Six1, Eya2) or lens (Pax6, L-Maf, δ-crystallin) gene expression: (g) Six1; (h) Eya2; (i) Pax6; (j) L-Maf; and (k) δ-crystallin. (l–p) PLE explants were cultured in the presence of Activin A and assayed for pre-placodal or lens gene expression: (l) Six1; (m) Eya2; (n) Pax6; (o) L-Maf; and (p) δ-crystallin. (q) Model for lens inhibition by TGF-β signalling. (r–t) PLE explants were cultured alone or in combination with Activin A or SB431542 and assayed for δ-crystallin gene expression: (r) PLE alone; (s) PLE+Activin A; and (t) PLE+Activin A+SB431542. (u–w) PLE explants were cultured alone or in combination with neural crest cells (NCC) or SB431542 and assayed for δ-crystallin gene expression: (u) PLE alone; (v) PLE+NCC; and (w) PLE+NCC+SB431542. Scale bars: a, 50 μm for panels a–f, g, 50 μm for panels g–p, r–w.
Mentions: To assess whether activated Smad3 suppresses lens fate in vivo, we electroporated constitutively active Smad3 (ref. 16) into the presumptive lens ectoderm (PLE). Although control green fluorescent protein-expressing cells were incorporated into the lens and express the lens marker δ-crystallin (Fig. 1a–c; 3/3 lenses), constitutively active Smad3-expressing cells were excluded from the lens and did not express δ-crystallin (Fig. 1d–f; 0/5 lenses). Together, the above results suggest that TGF-βs prevent lens formation at inappropriate positions.

Bottom Line: In vertebrates, the lens and retina arise from different embryonic tissues raising the question of how they are aligned to form a functional eye.Here we show, using the chick as a model system, that neural crest-derived transforming growth factor-βs activate both Smad3 and canonical Wnt signalling in the adjacent ectoderm to position the lens next to the retina.They do so by controlling Pax6 activity: although Smad3 may inhibit Pax6 protein function, its sustained downregulation requires transcriptional repression by Wnt-initiated β-catenin.

View Article: PubMed Central - PubMed

Affiliation: Department of Craniofacial Development, King's College London, Guy's Campus, London SE1 9RT, UK.

Show MeSH
Related in: MedlinePlus