- Title
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Cell Identity Switching Regulated by Retinoic Acid Signaling Maintains Homogeneous Segments in the Hindbrain
- Authors
- Addison, M., Xu, Q., Cayuso, J., Wilkinson, D.G.
- Source
- Full text @ Dev. Cell
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Analysis of ephA4 mutant embryos (A, B): An ephA4 mutant has disrupted sharpening of the r2/r3, r3/r4 and r5/r6 borders. MO-mediated knockdown disrupts ephA4 function since the same phenotype occurs in ephA4 morphant embryos (Cooke et al., 2005; Terriente et al., 2012). |
Analysis of egr2 knockdown embryos (A-H): Knockdown of egr2a and egr2b results in loss of egr2b expression in r3 and severe reduction of expression in r5* at 17 hpf (E) compared to control embryos (A). Following loss of r3 territory, the flanking segments still express hox genes that mark r2 (hoxa2) and r4 (hoxb1 plus hoxa2): compare controls (B-D) with egr2 knockdown embryos (F-H). A-C and E-G are single in situ hybridizations, and D, H are double in situ hybridizations, as indicated. Scale bar: 50 μm. |
cyp26c1 mutant embryos have ectopic egr2-expressing cells (A-D): Expression of egr2 was analyzed in cyp26c1 mutant embryos. Ectopic egr2-expressing cells were observed in r2 and r4 (arrowheads), as seen in morphants (Fig.6B). That this phenotype occurs following inactivation of cyp26c1 alone suggests that RA levels in r2 and r4 are altered sufficiently to disrupt identity switching. Scale bar: 50 μm. |
hoxb1 knockdown does not alter cyp26b1 or cyp26c1 expression (A-H): hoxb1a and hoxb1b were knocked down and expression of cyp26b1 and cyp26c1 analyzed. While knockdown of hoxb1 increases the size of r3 at the expense of r4, cyp26b1 is still highly expressed in r4 at 13 hpf (B) and 15 hpf (E), as in control embryos (A, E). Similarly, cyp26c1 is still expressed in r4 of hoxb1 morphants at 13 hpf (D) and 15 hpf (H), as in control embryos (C, G). Embryos in are flat-mounted with anterior to the top. Scale bars: 50 μm. |
Reprinted from Developmental Cell, 45, Addison, M., Xu, Q., Cayuso, J., Wilkinson, D.G., Cell Identity Switching Regulated by Retinoic Acid Signaling Maintains Homogeneous Segments in the Hindbrain, 606-620.e3, Copyright (2018) with permission from Elsevier. Full text @ Dev. Cell