biostudies-literatureUnknown22(18)Kim WThe number of vertebrae is defined strictly for a given species and depends on the number of somites, which are the earliest metameric structures that form in development. Somites are formed by sequential segmentation. The periodicity of somite segmentation is orchestrated by the synchronous oscillation of gene expression in the presomitic mesoderm (PSM), termed the "somite segmentation clock," in which Notch signaling plays a crucial role. Here we show that the clock period is sensitive to Notch activity, which is fine-tuned by its feedback regulator, Notch-regulated ankyrin repeat protein (Nrarp), and that Nrarp is essential for forming the proper number and morphology of axial skeleton components. Null-mutant mice for Nrarp have fewer vertebrae and have defective morphologies. Notch actMolecular biology of the cell3541-9https://www.ebi.ac.uk/biostudies/studies/S-EPMC3172277biostudies-literatureThe period of the somite segmentation clock is sensitive to Notch activity.PMC3172277Sakumura YKim WOba SBessho YKohno KIshibashi MTamada KYamao MTakumi TIshii SMatsui TfalseThe period of the somite segmentation clock is sensitive to Notch activity.The number of vertebrae is defined strictly for a given species and depends on the number of somites, which are the earliest metameric structures that form in development. Somites are formed by sequential segmentation. The periodicity of somite segmentation is orchestrated by the synchronous oscillation of gene expression in the presomitic mesoderm (PSM), termed the "somite segmentation clock," in which Notch signaling plays a crucial role. Here we show that the clock period is sensitive to Notch activity, which is fine-tuned by its feedback regulator, Notch-regulated ankyrin repeat protein (Nrarp), and that Nrarp is essential for forming the proper number and morphology of axial skeleton components. Null-mutant mice for Nrarp have fewer vertebrae and have defective morphologies. Notch act2011-01-01T00:00:00Z2011 Sep2026-07-15T08:35:41.584Z2026-07-02T03:09:06.893ZS-EPMC31722772179539110.1091/mbc.E11-02-0139