QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 3 August 2006
doi: 10.1242/dev.02523

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chazaud, C. Articles by Rossant, J. Search for Related Content PubMed PubMed Citation Articles by Chazaud, C. Articles by Rossant, J. Social Bookmarking                         What's this?

Disruption of early proximodistal patterning and AVE formation in Apc mutants

Claire Chazaud^1,*, and Janet Rossant^1,2

¹ Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.
² Department of Molecular and Medical Genetics, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.

View larger version (108K): [in a new window]   Fig. 1. Morphology and ß-catenin expression in ApcMin/Min embryos. (A-E) Bright-field images of wild-type and mutant embryos at 5.75 (A-C) and 4.75 (D,E) dpc embryos. (F-J) Immunohistochemistry of ß-catenin (red) with YOYO-1 nuclear staining (green) (bottom panels) in 5.75 (F,G) and 4.75 dpc embryos (H-J). Arrowheads indicate nuclei of visceral endoderm cells. Co-expression of ß-catenin and nuclear stain is apparent in the epiblast and visceral endoderm at 5.75 dpc and in the epiblast and PrE at 4.75 dpc. Nuclear ß-catenin is not obviously seen in the trophoblast lineage. Ep, epiblast; ExE, extraembryonic ectoderm; PA, proamniotic cavity; VE, visceral endoderm; PrE, primitive endoderm.

View larger version (101K): [in a new window]   Fig. 2. Ectopic T expression in ApcMin/Min epiblast, detected by in situ hybridization with T and Oct4. (A-C) Ectopic expression of T in the entire epiblast at 5.75 dpc. Wild-type and mutant VE differ in thickness (arrowheads). (C) Only T probe was hybridized. (D-G) T and Oct-4 expression in wild-type and mutant embryos at 4.75 and 3.75 dpc. The arrowhead indicates the unlabelled PrE. Ep, epiblast; ICM, inner cell mass; Oct4, blue: T, red.

View larger version (152K): [in a new window]   Fig. 3. Expression of primitive streak and AVE markers in wild-type and ApcMin/Min embryos. In situ hybridization in 4.75 (A), and 5.5 (B-L) dpc embryos. Double labeling with T and (A) Pem, (B) Gsc or (C) Hex. (D-H) Single labeling of Eomes (D), Otx2 (E), Fgf8 (F), Lhx1 (G), Cer1 (H), Snai1 (I), cripto (J), Nodal (K) and Foxa2 (L). The arrowhead in D indicates a labeled epiblast cell. Ep, epiblast; PE, parietal endoderm; ExE, extraembryonic ectoderm.

View larger version (99K): [in a new window]   Fig. 4. Chimeric analysis of ApcMin/Min mutants. (A) T (red) and EGFP (green) in situ hybridization on chimeras with low epiblast contribution from wild-type YFP-labeled ES cells in ApcMin/Min mutant embryos at 5.5 dpc. (B-D) Chimeras with high epiblast contributions from wild-type ES cells in wild-type and ApcMin/Min mutant embryos. Chimeras (5.5-6.0 dpc) were hybridized with probes against EGFP (B,C, green) and (in red) Hex/Bmp4 (marks the ExE; B), Gsc or Cer1 alone (C,D). The arrowheads indicate boundaries of the DVE/AVE.

View larger version (77K): [in a new window]   Fig. 5. Asymmetric expression of molecular markers. (A,B) Immunohistochemistry of ß-catenin (red) and E-cadherin (blue, B only) on 4.5 dpc embryos. B is a magnified right lateral view of A. The arrowheads indicate the trophoblast expressing ß-catenin throughout the cell. (C) In situ hybridization of Hex and Pem at 4.5 dpc. Arrowheads indicate the enhanced expression of Hex and Pem. (D)In situ hybridization of Hex (red) and Oct4 (blue) at 4.75 dpc. (E-H) Embryo (4.5 dpc) labeled with ß-catenin antibody (green), with propidium iodide for nuclei (red) and with Hex probe (blue). E and F are at the same z section, whereas H is in a different plane of the same embryo. G is an overlay of E,F,H. The arrowheads indicate the same trophoblast cell bearing nuclear ß-catenin. The arrow in G,H indicates the enhanced expression of Hex. (I,J) In situ hybridization of Lefty1 (red) and immunolocalisation of Dab-2 (green) at 4.5 dpc. (K) In situ hybridization of Lefty1 (red) and immunolocalisation of Dab-2 (green) at 4.75-5.0 dpc. The arrowhead indicates the center of Dab-2-expressing cells. Ep, epiblast; Tr, trophectoderm.

View larger version (30K): [in a new window]   Fig. 6. Representation of signaling events in early egg cylinder. Wild-type (A), ApcMin/Min mutants (B) and chimeras with mutant extraembryonic lineages and wild-type epiblast (C). (A) (1) ExE induces proximodistal axis in epiblast and PrE/VE. (2) Through Nodal, epiblast induces the DVE that is restricted distally by Lefty1 and Cer1. (3) DVE distalizes the epiblast by restricting Nodal, cripto and later mesendoderm markers proximally. (4) DVE moves to the anterior side to become AVE. (5) Mesendoderm (T) is induced proximally and afterwards gastrulation movements begin on the posterior side. (B) In ApcMin/Min mutants, the epiblast is unable to induce the DVE (2). T is not restricted proximally but is induced throughout the epiblast (5). The embryo is proximalized. (C) In chimeras, the extraembryonic tissues ExE and VE (or both) are unable to set up the proximodistal axis (1). Without distal pole, the DVE (Gsc, Hex) is induced throughout the PrE (2). DVE represses mesendoderm induction (3) in the whole epiblast. The embryo is distalized. D, distal; P, proximal.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter