Abstract
To determine the role of Bone morphogenetic protein (BMP) signaling in murine limb development in vivo, the keratin 14 promoter was used to drive expression of the BMP antagonist Noggin in transgenic mice. Phosphorylation and nuclear translocation of Smad1/5 were dramatically reduced in limbs of the transgenic animals, confirming the inhibition of BMP signaling. These mice developed extensive limb soft tissue syndactyly and postaxial polydactyly. Apoptosis in the developing limb necrotic zones was reduced with incomplete regression of the interdigital tissue. The postaxial extra digit is also consistent with a role for BMPs in regulating apoptosis. Furthermore, there was persistent expression of Fgf8, suggesting a delay in the regression of the AER. However, Msx1 and Msx2 expression was unchanged in these transgenic mice, implying that induction of these genes is not essential for mediating BMP-induced interdigital apoptosis in mice. These abnormalities were rescued by coexpressing BMP4 under the same promoter in double transgenic mice, suggesting that the limb abnormalities are a direct effect of inhibiting BMP signaling.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 108-120 |
| Number of pages | 13 |
| Journal | Developmental Biology |
| Volume | 249 |
| Issue number | 1 |
| DOIs | |
| State | Published - 2002 |
Funding
We thank Dr. Lee A. Niswander and Dr. Henry M. Kronenberg for helpful discussions and comments on the manuscript. We are also grateful to Dr. Frank Macaluso for help with the scanning EM and the transgenic facility of Albert Einstein College of Medicine for transgene injections. We thank Drs. Elaine Fuchs for the K14-promoter plasmid; A. P. McMahon, Gail R. Martin, Cory Abate-Shen, Mario R. Capecchi, and Denis Duboule for probes; Dr. Aris Economides and Regeneron pharmaceuticals for the Noggin antibody; Dr. Perry Bickel for the GDI antibody; and Dr. Peter ten Dijke for p-Smad1/5 antibody. The monoclonal antibody, 4G1, against Msx1/2 was obtained from the Developmental Studies Hybridoma Bank developed under the auspices of the NICHD and maintained by The University of Iowa, Department of Biological Sciences, Iowa City, IA 52242. This work was supported by grants from the NIH (RO1 NS20013 and RO1 NS20778) (to J.A.K.), and by the Davee Foundation and the Feinberg Clinical Neuroscience Institute. The work was also supported by NIH Grants (RO1 CA70896, RO1 CA75503 and RO1 CA86072) (to R.G.P.) and awards from the Susan G. Komen Breast Cancer Foundation and Breast Cancer Alliance Inc. R.G.P. is a Monique Weill-Caulier and Irma T. Hirschl Scholar.
Keywords
- Apoptosis
- BMP
- FGF8
- Hox
- Keratin 14
- Limb development
- Msx
- Noggin
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology
- Developmental Biology