Hes7, a basic helix-loop-helix (bHLH)-type repressor gene, is regulated by Notch and expressed in the presomitic mesoderm [6]. It is a key segmentation clock gene that controls the periodic formation of somites, which are crucial for the proper development of the vertebrae [1]. Somitogenesis, regulated by the oscillatory expression of Hes7, is associated with the Fgf and Notch signaling pathways [2].

Mouse models have provided significant insights into Hes7 function. In knock-in mice where Hes7 3'UTR was disrupted, proper splicing was affected, leading to reduced Hes7 protein levels, damped oscillation, and improper periodic somite segmentation, demonstrating the importance of 3'UTR for normal Hes7 function [5]. Mice expressing mutant Hes7 with a longer half-life showed severely disorganized somite segmentation and oscillatory expression after a few normal cycles, highlighting the essential role of Hes7 protein instability for sustained oscillation and its function as a segmentation clock [7]. Additionally, Fgf4 mutants, which display vertebral defects, show that Fgf4 maintains Hes7 levels and normal oscillatory patterns, indicating a genetic synergy between Hes7 and Fgf4 [4].

In conclusion, Hes7 is essential for the somite segmentation clock during vertebrate development. Mouse models, including those with disrupted 3'UTR or altered protein stability, have revealed its role in normal somitogenesis. Understanding Hes7 function is relevant to human congenital spine diseases, such as spondylocostal dysostosis 4, caused by HES7 variants, emphasizing the importance of Hes7-related research for disease understanding [3].