Asymmetric distribution of dynamic calcium signals in the node of mouse embryo during left-right axis formation.
In the node of mouse embryo, rotational movements of cilia generate an external liquid flow known as nodal flow, which determines left-right asymmetric gene expression. How nodal flow is converted into asymmetric gene expression is still controversial, but the increase of Ca(2+) levels in endodermal cells to the left of the node has been proposed to play a role. However, Ca(2+) signals inside the node itself have not yet been described. By our optimized Ca(2+) imaging method, we were able to observe dynamic Ca(2+) signals in the node in live mouse embryos. Pharmacological disruption of Ca(2+) signals did not affect ciliary movements or nodal flow, but did alter the expression patterns of the Nodal and Cerl-2 genes. Quantitative analyses of Ca(2+) signal frequencies and distributions showed that during left-right axis establishment, formerly symmetric Ca(2+) signals became biased to the left side. In iv/iv mutant embryos that showed randomized laterality due to ciliary immotility, Ca(2+) signals were found to be variously left-sided, right-sided, or bilateral, and thus symmetric on average. In Pkd2 mutant embryos, which lacked polycystin-2, a Ca(2+)-permeable cation channel necessary for left-right axis formation, the Ca(2+) signal frequency was lower than in wild-type embryos. Our data support a model in which dynamic Ca(2+) signals in the node are involved in left-right patterning.
Laboratory for Spatiotemporal Regulations, National Institute for Basic Biology, Japan.
Daisuke
D
Takao
Tomomi
T
Nemoto
Takaya
T
Abe
Hiroshi
H
Kiyonari
Hiroko
H
Kajiura-Kobayashi
Hidetaka
H
Shiratori
Shigenori
S
Nonaka
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D002923:Cilia / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D055457:Nodal Protein / Q000378:metabolism; D020897:Organizers, Embryonic / Q000196:embryology* / Q000378:metabolism; D050396:TRPP Cation Channels / Q000235:genetics
D036341:Intercellular Signaling Peptides and Proteins; D055457:Nodal Protein; D050396:TRPP Cation Channels; C119003:Dte protein, mouse; C526008:Nodal protein, mouse