spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online 17 July 2008
doi: 10.1242/dev.018341

Development 135, 2797-2805 (2008)
Published by The Company of Biologists 2008
This Article
Right arrow Summary Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplementary Material
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Related articles in Development
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Michon, F.
Right arrow Articles by Dhouailly, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Michon, F.
Right arrow Articles by Dhouailly, D.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

BMP2 and BMP7 play antagonistic roles in feather induction

Frederic Michon1, Loïc Forest2,*, Elodie Collomb1, Jacques Demongeot2 and Danielle Dhouailly1,{dagger}

1 Equipe Ontogenèse et Cellules Souches du Tégument, Centre de Recherche INSERM UJF - U823, Institut Albert Bonniot, Site Santé, La Tronche, BP170, 38042 Grenoble Cedex 9, France.
2 Laboratoire de Techniques de l'Imagerie, de la Modélisation et de la Cognition UMR CNRS 5525, Institut d'Informatique et de Mathématiques Appliquées de Grenoble, Faculté de Médecine, 38706 La Tronche, Cedex, France.


Figure 1
View larger version (92K):
[in this window]
[in a new window]

  		Fig. 1. The expression of BMP pathway factors during feather primordium formation. (A-D) The left and right femoral tract of the same HH30 embryo were compared; the numbers correspond to the order of appearance of the rows. The second row (R2) had only two feather primordia expressing BMP2 (A), whereas five expressed BMP7 (B). The additional primordia are indicated with red arrows and those also expressing BMP2 with black arrows. The distal border (yellow arrow), which preceded the appearance of R3, delimited the femoral and zeugopodial tracts and already expressed BMP7 (B) but not BMP2 (A). In another embryo, R4 expressed BMP2 on the left side (C, arrow), whereas follistatin was expressed only in three rows on the right (D). The continuous line (D, arrow), contiguous to R3, is the distal border of the tract, which expressed follistatin and not BMP2. (E-G) ID gene expression in the dorsal tract of HH30 embryos, analyzed by in situ hybridization with RNA probes. (E) There was a decrease of ID1 expression from the newly formed (black arrow) to the older primordia (red arrow). (F) ID3 transcripts showed stable expression in all the primordia. (G) ID4 expression exhibited early expression in the entire primordia (black arrow), and later expression restricted to a peripheral ring (red arrow). Scale bars: in A-D, 1000 µm; in E-G, 800 µm.

 

Figure 2
View larger version (15K):
[in this window]
[in a new window]

  		Fig. 2. Comparative effects of BMP2 and BMP7 on dermal fibroblast cytokinesis. A freshly dissociated dermal cell suspension was added to a cell culture insert and basic medium placed on the other side of the 8 µm pore membrane. Two types of control were performed: first, basic media with or without FBS; and second, basic media with or without FBS, with FGF2. The first control allowed a normalization of the cell migration measurement (50.1% and 100%), the second, the validation of the chemotactic effect with FGF2 (60.8% and 110.9%). BMP7 had an even stronger chemotactic effect (70.1% and 122.3%). Perturbation of fibroblast migration was clearly shown with BMP2 (38.1% and 81.6%). The chemotaxis obtained with BMP7 decreased with the addition of BMP2 (51.2% and 98.2%). The migration was evaluated in triplicate by a fluorescent method. P<0.05 by Student's t-test. BMP2 and BMP7, 0.5 µg/ml; FGF2, 0.33 µg/ml.

 

Figure 3
View larger version (129K):
[in this window]
[in a new window]

  		Fig. 3. The Fibronectin exon EIIIA was involved in dermal organization. (A,B) Chick embryo dorsal skin. (A) At HH29+, EIIIA was expressed in the periphery (red arrow) of the first feather primordia, as well as in two ribbons on either side of the first row (black arrows). (B) At HH30, the EIIIA transcripts were expressed in the periphery of primordia and in two ribbons (black arrows) on either side of feather rows, although there was a slight decrease of its expression in the three first rows (red arrow). (C,D) BMP2 and EIIIA expression in the left and right femoral tract of the same HH30 embryo. Five feather primordia of the fourth row (R4) expressed BMP2 (C), whereas two no longer expressed EIIIA in the corresponding right row (D). The additional primordia are indicated with red arrows and those no longer expressing EIIIA with black arrows. The R3, expressing the EIIIA domain (arrow) has started to form close to the distal border line. Scale bars: 800 µm in A,B; 1000 µm in C,D.

 

Figure 4
View larger version (25K):
[in this window]
[in a new window]

  		Fig. 4. The regulation of EIIIA and {alpha}4 integrin expression. (A,B) EIIIA expression in dermal fibroblasts cultured in hanging drops for 24, 48 or 72 hours. RT-PCR for Actin, total Fibronectin and the EIIIA exon were performed. Fibronectin expression was normalized to Actin expression. There was a small decrease in Fibronectin expression between t0 (100%) and t48 (92.8%), and, a noticeable decrease at t72 (64.1%; A). EIIIA expression was normalized to Fibronectin expression. During the same time-lapse, the portion of Fibronectin-expressing cells containing the EIIIA exon decreased from 59.4% to 24.3% (B). (C,D) Cells were placed in adherent culture with or without BMP2 and BMP7 (0.5 µg/ml) for 20 hours. Then RT-PCR to detect EIIIA and integrin {alpha}4 expression was performed. The portion of Fibronectin-expressing cells containing the EIIIA exon decreased with BMP2 treatment, from 61.1% to 34.4%, whereas BMP7 treatment led to a slight decrease, 53.1% (C). BMP2 treatment led to an increase of {alpha}4 integrin expression, from 100% to 125.29%, whereas BMP7 induced only a non-significant increase (105.5%; D).

 

Figure 5
View larger version (55K):
[in this window]
[in a new window]

  		Fig. 5. Sequential appearance and patterning of spots with mathematical simulation. (A) The resolution of the model led to the formation of a primary migrating cell midline. (B) The redistribution of these cells, via chemotaxis, led to the formation of spots, whereas laterally, new cells started to migrate. (C) The lateral expansion of the pattern was due to migrating cells under both chemotaxis and arresting factors. (D) At the end of the simulation, the hexagonal pattern occurred all over the modeled domain. Cell density is represented in false colors.

 

Figure 6
View larger version (35K):
[in this window]
[in a new window]

  		Fig. 6. The progressive increase of the cell density correlated successively with the formation of an apterium, a semi-apterium and a pteryla. (A) The pteryla was characterized by a regular pattern. (B,C) The decrease of cell density (q) to 0.2 (B) and 0.12 (C) led, respectively, to an irregular pattern at the boundary of the pteryla and the semi-apteria. (D) The switch from spot formation to a glabrous region implicated only a small difference in cell density (q=0.12 versus q=0.11).

 

Figure 7
View larger version (91K):
[in this window]
[in a new window]

  		Fig. 7. The over-activation of chemoattraction led to similar results with mathematical simulation and organotypic culture. (A-C) Simulation of a local pulse of activator led to the formation of an accumulation of cells, surrounded by a ring of inhibition. The size of this ring was proportional to the activator concentration. (D-F) Patterns resulting from the local application of BMP7-coated beads. The maximal area of inhibition (red circle) was obtained with the maximal concentration of BMP7. pu(x,0)=c*exp(-(x2+(y-0.5)2)*500) with c=4, 8 or 24. Scale bars: 250 µm.

 

Figure 8
View larger version (56K):
[in this window]
[in a new window]

  		Fig. 8. Model of dermal condensation formation in dorsal chick embryo skin. The chronological events from dense dermis to stabilized dermal condensation require a molecular dialogue both inter- and intra-tissular in the skin (see the text). Note that the placodes are larger and earlier than the dermal condensations (Dhouailly, 1984Go). This model took into account only the BMP genes, as well as a few other important genes among those expressed in embryonic skin.

 

Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?



© The Company of Biologists Ltd 2008