Mesp1 and Mesp2 are homologous basic helix-loop-helix (bHLH) transcription factors that are co-expressed in the anterior presomitic mesoderm (PSM) just prior to somite formation. Analysis of possible functional redundancy of Mesp1 and Mesp2 has been prevented by the early developmental arrest of Mesp1/Mesp2 double–null embryos. Here we performed chimera analysis, using either Mesp2-null cells or Mesp1/Mesp2 double–null cells, to clarify (1)possible functional redundancy and the relative contributions of both Mesp1 and Mesp2 to somitogenesis and (2) the level of cell autonomy of Mesp functions for several aspects of somitogenesis. Both Mesp2-null and Mesp1/Mesp2 double–null cells failed to form initial segment borders or to acquire rostral properties, confirming that the contribution of Mesp1 is minor during these events. By contrast, Mesp1/Mesp2 double–null cells contributed to neither epithelial somite nor dermomyotome formation, whereas Mesp2-null cells partially contributed to incomplete somites and the dermomyotome. This indicates that Mesp1 has a significant role in the epithelialization of somitic mesoderm. We found that the roles of the Mesp genes in epithelialization and in the establishment of rostral properties are cell autonomous. However, we also show that epithelial somite formation, with normal rostro-caudal patterning, by wild-type cells was severely disrupted by the presence of Mesp mutant cells, demonstrating non-cell autonomous effects and supporting our previous hypothesis that Mesp2 is responsible for the rostro-caudal patterning process itself in the anterior PSM, via cellular interaction.
Differential contributions of Mesp1 and Mesp2 to the epithelialization and rostro-caudal patterning of somites
Yu Takahashi, Satoshi Kitajima, Tohru Inoue, Jun Kanno, Yumiko Saga; Differential contributions of Mesp1 and Mesp2 to the epithelialization and rostro-caudal patterning of somites. Development 15 February 2005; 132 (4): 787–796. doi: https://doi.org/10.1242/dev.01597
Download citation file:
Sign in
Client Account
Sign in via your institution
Sign in via ShibbolethAdvertisement
History of our journals

As our publisher, The Company of Biologists, turns 100 years old, read about Development’s journey and highlights from some its first issues, and explore the history of each of our sister journals: Journal of Cell Science, Journal of Experimental Biology, Disease Models & Mechanisms and Biology Open.
Call for papers – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues

Development invites you to submit your latest research to our upcoming special issue – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues. This issue will be coordinated by Guest Editors Meritxell Huch (Max Planck Institute of Molecular Cell Biology and Genetics, Germany) and Mansi Srivastava (Harvard University and Museum of Comparative Zoology, USA), working alongside our team of academic Editors. Submit your articles by 15 May 2025.
A case for broadening our view of mechanism in developmental biology

In this Perspective, B. Duygu Özpolat and colleagues survey researchers on their views on what it takes to infer mechanism in developmental biology. They examine what factors shape our idea of what we mean by ‘mechanism’ and suggest a path forward that embraces a broad outlook on the diversity of studies that advance knowledge in our field.
In preprints
Did you know that Development publishes perspectives on recent preprints? These articles help our readers navigate the ever-growing preprint literature. We welcome proposals for ‘In preprints’ articles, so please do get in touch if you’d like to contribute.