Left-right patterning of the mouse lateral plate requires nodal produced in the node.
Initial determination of left-right (L-R) polarity in mammalian embryos takes place in the node. However, it is not known how asymmetric signals are generated in the node and transferred to the lateral plate mesoderm (LPM). Mice homozygous for a hypomorphic Nodal allele (Nodal(neo)) were generated and found to exhibit L-R defects, including right isomerism. Although the mutant embryos express Nodal at gastrulation stages, the subsequent expression of this gene in the node and left LPM is lost. A transgene that conferred Nodal expression specifically in the node rescued the L-R defects of the Nodal(neo/neo) embryos. Conversely, ectopic expression of the Nodal inhibitor Lefty2 in the node of Nodal(neo/+) embryos resulted in a phenotype similar to that of the Nodal(neo/neo) mutant. These results indicate that Nodal produced in the node is required for expression of Nodal and other left side-specific genes in the LPM.
Saijoh
Yukio
Y
Developmental Genetics Group, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Osaka 565-0871, Suita, Japan. saijoh@fbs.osaka-u.ac.jp
Oki
Shinya
S
Ohishi
Sachiko
S
Hamada
Hiroshi
H
D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D007763:Lac Operon; D055458:Left-Right Determination Factors; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D008954:Models, Biological; D055457:Nodal Protein; D010641:Phenotype; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000235:genetics*
D055458:Left-Right Determination Factors; D055457:Nodal Protein; C526008:Nodal protein, mouse; D016212:Transforming Growth Factor beta