Notch signalling is required for cyclic expression of the hairy-like gene HES1 in the presomitic mesoderm.
Somitic segmentation provides the framework on which the segmental pattern of the vertebrae, some muscles and the peripheral nervous system is established. Recent evidence indicates that a molecular oscillator, the 'segmentation clock', operates in the presomitic mesoderm (PSM) to direct periodic expression of c-hairy1 and lunatic fringe (l-fng). Here, we report the identification and characterisation of a second avian hairy-related gene, c-hairy2, which also cycles in the PSM and whose sequence is closely related to the mammalian HES1 gene, a downstream target of Notch signalling in vertebrates. We show that HES1 mRNA is also expressed in a cyclic fashion in the mouse PSM, similar to that observed for c-hairy1 and c-hairy2 in the chick. In HES1 mutant mouse embryos, the periodic expression of l-fng is maintained, suggesting that HES1 is not a critical component of the oscillator mechanism. In contrast, dynamic HES1 expression is lost in mice mutant for Delta1, which are defective for Notch signalling. These results suggest that Notch signalling is required for hairy-like genes cyclic expression in the PSM.
Jouve
C
C
Laboratoire de génétique et de physiologie du développement (LGPD), Developmental Biology Institute of Marseille (IBDM), Campus de Luminy, Case 907, France.
Palmeirim
I
I
Henrique
D
D
Beckers
J
J
Gossler
A
A
Ish-Horowicz
D
D
Pourquié
O
O
D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001683:Biological Clocks / Q000235:genetics; D019521:Body Patterning / Q000235:genetics; D002642:Chick Embryo; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008648:Mesoderm / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D019170:Somites / Q000378:metabolism; D000072056:Transcription Factor HES-1
D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D017931:DNA Primers; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009124:Muscle Proteins; D011506:Proteins; D012333:RNA, Messenger; D051880:Receptors, Notch; D000072056:Transcription Factor HES-1; C489734:Hes1 protein, mouse; C064045:delta protein; C109424:hairy1 protein, Gallus gallus