N-cadherin/catenin-mediated morphoregulation of somite formation.
Somitogenesis during early stages in the chick and mouse embryo was examined in relation to N-cadherin-mediated adhesion. Previous studies indicated that N-cadherin localizes to the somite regions during their formation. Those observations were extended to include a spatiotemporal immunohistochemical analyses of beta-catenin and alpha-catenin, as well as a more detailed study of N-cadherin, during segmentation, compaction, and compartmentalization of the somite. N-cadherin and the catenins appear early within the segmental plate and are expressed as small patch-like foci throughout this tissue. The small foci of immunostaining coalesce into larger clusters of N-cadherin/catenin-expressing regions. The clusters subsequently coalesce into a region of centrally localized cells that express N-cadherin/catenins at their apical surfaces. The multiple clusters are spaced wide apart in the anterior segmental plates that form the first 6 somite pairs, as contrasted to segmental plates that form somites 7 and beyond. To examine the functional significance of N-cadherin, segmental plates were exposed to antibodies that perturb N-cadherin-mediated adhesion in the chick embryo. The multiple, anomalous somites that result in these experiments indicate that each N-cadherin/catenin-expressing cluster can give rise to a somitic structure. beta-Catenin involvement in somitogenesis suggests a role for Wnt-mediated signaling. Embryos treated with LiCl also show induction of similar anomalous somites indicating further the possibility that Wnt-mediated signaling may be involved in the clustering event. It is suggested that beta-catenin serves to initiate the adhesion process which is spread then by N-cadherin. Later during compartmentalization, N-cadherin/catenins remain expressed by the myotome compartment. Taken together, these results suggest that the Ca2+-dependent cell adhesion molecule N-cadherin and the intracellular catenins are important in segmentation and formation of the somite and myotome compartment. It is proposed that the N-cadherin-mediated adhesion process may serve as a common, evolutionarily conserved, link in the differentiation pathways of skeletal and cardiac muscle.
Department of Cell Biology, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA. linaskkk@umdnj.edu
K K
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Linask
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Ludwig
M D
MD
Han
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Liu
G L
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Radice
K A
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Knudsen
D000818:Animals; D000911:Antibodies, Monoclonal; D015820:Cadherins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D002642:Chick Embryo; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000502:physiology*; D018021:Lithium Chloride / Q000494:pharmacology; D051379:Mice; D009154:Mutation; D019170:Somites / Q000737:chemistry / Q000166:cytology*; D015534:Trans-Activators; D051178:alpha Catenin; D051176:beta Catenin
D000911:Antibodies, Monoclonal; C495267:CTNNB1 protein, mouse; D015820:Cadherins; C495272:Ctnna1 protein, mouse; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051178:alpha Catenin; D051176:beta Catenin; D018021:Lithium Chloride