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Dynamic expression and essential functions of Hes7 in somite segmentation
Y Bessho1, R Sakata, S Komatsu
1Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan.
Genes & Development
|October 20, 2001
Summary
The Hes7 gene controls cyclic gene expression, which is crucial for proper somite segmentation and the development of vertebrae and ribs in mice. Loss of Hes7 disrupts this process, leading to severe developmental disorganization.
Area of Science:
- Developmental biology
- Genetics
- Molecular biology
Background:
- The Hes7 gene, a basic helix-loop-helix (bHLH) protein, functions as a transcriptional repressor.
- Hes7 is considered a potential effector in the Notch signaling pathway, which is vital for embryonic development.
Purpose of the Study:
- To investigate the role of Hes7 in regulating gene expression oscillations.
- To determine the necessity of Hes7 for somite segmentation and anterior-posterior polarity.
- To elucidate the relationship between Hes7, lunatic fringe, and the Notch pathway during somitogenesis.
Main Methods:
- Analysis of Hes7 gene expression patterns in the presomitic mesoderm (PSM).
- Phenotypic analysis of Hes7-null mutant mice to assess somite segmentation and polarity.
- Examination of Notch pathway components and lunatic fringe expression in wild-type and mutant PSM.
Main Results:
- Hes7 expression was found to oscillate in 2-hour cycles within the PSM.
- Hes7-null mice exhibited defects in somite segmentation and disrupted anterior-posterior polarity.
- The expression of lunatic fringe, an oscillator and Notch modulator, became continuous in Hes7-null PSM, while Notch and its ligands remained largely unaffected.
Conclusions:
- Hes7 plays a critical role in controlling the cyclic expression of lunatic fringe.
- Hes7 is essential for the precise segmentation of somites and the establishment of embryonic polarity.
- Disruption of Hes7 function leads to severe disorganization of somite derivatives, including vertebrae and ribs.