Peripheral Clocks

Winding a Two-Hour Clock

Science's STKE  29 Oct 2002:
Vol. 2002, Issue 156, pp. tw396-TW396
DOI: 10.1126/stke.2002.156.tw396

The reiterated structures of the vertebrate axial skeleton and muscles are derived from the metameric structure of somites. Messenger RNAs (mRNAs) of Notch signaling molecules, such as Hes1, oscillate in 2-hour cycles during somite segmentation. However, the molecular mechanism of such oscillation remains unknown. Hirata et al. now describe the oscillation of Hes1 mRNA and protein in cultured cells after serum treatment. This oscillation requires Hes1 protein synthesis and degradation and relies on the negative autoregulation of Hes1 mRNA synthesis by Hes1 protein. Hence, this work indicates that Hes1 represents a 2-hour-cycle clock gene. Furthermore, because Hes1 oscillation occurs in many cell types, this clock may apply to several biological processes as well as to somite segmentation.

H. Hirata, S. Yoshiura, T. Ohtsuka, Y. Bessho, T. Harada, K. Yoshikawa, R. Kageyama, Oscillatory expression of the bHLH factor Hes1 regulated by a negative feedback loop. Science 298, 840-843 (2002). [Abstract] [Full Text]