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Asymmetric localization of Numb in the chick somite and the influence of myogenic signals
- Publication Year :
- 2006
-
Abstract
- Whereas Notch signaling is known to play an essential role in the formation of somites, its role during later stages of somite maturation is less well understood. Here, we examine the signals and transcription factors that control the expression of the Notch antagonist, Numb, during somite maturation in the chick embryo. Numb mRNA is present in the epithelial somite and is increased in expression in the forming myotome. Numb protein displays a very specific subcellular localization and dynamic expression during somite maturation. Numb protein is asymmetrically localized in a cortical crescent on the basal side of dividing cells in the dorsomedial lip of the dermomyotome and is subsequently uniformly distributed throughout differentiated myotomal cells. Treatment of somites with either the combination of Wnt-3a and Shh, or ectodermal signals plus noggin, both of which induce somitic myogenesis, did not significantly affect Numb transcript levels but did lead to a dramatic increase in the levels of Numb protein, which was uniformly distributed throughout the cytoplasm of the resultant myotubes. Forced expression of MyoD in somites similarly induced high levels of Numb protein throughout the cytoplasm, without affecting Numb mRNA levels. We also found that signals that promote somitic myogenesis or forced MyoD expression induced expression of the Notch ligand, Serrate-2. Our findings suggest that Notch signals are specifically repressed in the myotome and that asymmetric expression of Numb in dividing cells of the dorsomedial lip of the dermomyotome may modulate whether these cells continue to divide or differentiate into myotomal cells.
- Subjects :
- animal structures
Transcription, Genetic
Notch signaling pathway
Dermomyotome
Chick Embryo
Biology
MyoD
Muscle Development
Article
Wnt3 Protein
MyoD Protein
Myotome
medicine
Animals
Hedgehog Proteins
RNA, Messenger
Receptors, Notch
Myogenesis
Membrane Proteins
Cell Differentiation
Cell biology
Wnt Proteins
Somite
medicine.anatomical_structure
Biochemistry
Somites
embryonic structures
NUMB
Trans-Activators
Carrier Proteins
hormones, hormone substitutes, and hormone antagonists
Developmental Biology
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....d15ed2cfed5753f6fe2386e7dd77d5da