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Two different network topologies yield bistability in models of mesoderm and anterior mesendoderm specification in amphibians.
- Source :
-
Journal of theoretical biology [J Theor Biol] 2014 Jul 21; Vol. 353, pp. 67-77. Date of Electronic Publication: 2014 Mar 17. - Publication Year :
- 2014
-
Abstract
- Understanding the Gene Regulatory Networks (GRNs) that underlie development is a major question for systems biology. The establishment of the germ layers is amongst the earliest events of development and has been characterised in numerous model systems. The establishment of the mesoderm is best characterised in the frog Xenopus laevis and has been well studied both experimentally and mathematically. However, the Xenopus network has significant differences from that in mouse and humans, including the presence of multiple copies of two key genes in the network, Mix and Nodal. The axolotl, a urodele amphibian, provides a model with all the benefits of amphibian embryology but crucially only a single Mix and Nodal gene required for the specification of the mesoderm. Remarkably, the number of genes within the network is not the only difference. The interaction between Mix and Brachyury, two transcription factors involved in the establishment of the endoderm and mesoderm respectively, is not conserved. While Mix represses Brachyury in Xenopus, it activates Brachyury in axolotl. Thus, whilst the topology of the networks in the two species differs, both are able to form mesoderm and endoderm in vivo. Based on current knowledge of the structure of the mesendoderm GRN we develop deterministic models that describe the time evolution of transcription factors in a single axolotl cell and compare numerical simulations with previous results from Xenopus. The models are shown to have stable steady states corresponding to mesoderm and anterior mesendoderm, with the in vitro model showing how the concentration of Activin can determine cell fate, while the in vivo model shows that β-catenin concentration can determine cell fate. Moreover, our analysis suggests that additional components must be important in the axolotl network in the specification of the full range of tissues.<br /> (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Subjects :
- Ambystoma mexicanum embryology
Ambystoma mexicanum genetics
Animals
Numerical Analysis, Computer-Assisted
Time Factors
Xenopus embryology
Xenopus genetics
Amphibians embryology
Amphibians genetics
Body Patterning genetics
Endoderm embryology
Gene Regulatory Networks
Mesoderm embryology
Models, Genetic
Subjects
Details
- Language :
- English
- ISSN :
- 1095-8541
- Volume :
- 353
- Database :
- MEDLINE
- Journal :
- Journal of theoretical biology
- Publication Type :
- Academic Journal
- Accession number :
- 24650939
- Full Text :
- https://doi.org/10.1016/j.jtbi.2014.03.015