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1: Genes Dev. 2003 Jun 15;17(12):1451-6. Epub 2003 Jun 3.
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Periodic repression by the bHLH factor Hes7 is an essential mechanism for the somite segmentation clock.

Bessho Y, Hirata H, Masamizu Y, Kageyama R.

Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan. ybessho@virus.kyoto-u.ac.jp

Hes7, a bHLH gene essential for somitogenesis, displays cyclic expression of mRNA in the presomitic mesoderm (PSM). Here, we show that Hes7 protein is also expressed in a dynamic manner, which depends on proteasome-mediated degradation. Spatial comparison revealed that Hes7 and Lunatic fringe (Lfng) transcription occurs in the Hes7 protein-negative domains. Furthermore, Hes7 and Lfng transcription is constitutively up-regulated in the absence of Hes7 protein and down-regulated by stabilization of Hes7 protein. Thus, periodic repression by Hes7 protein is critical for the cyclic transcription of Hes7 and Lfng, and this negative feedback represents a molecular basis for the segmentation clock.

Publication Types:
PMID: 12783854 [PubMed - indexed for MEDLINE]

PMCID: PMC196074