Mesodermal subdivision along the mediolateral axis in chicken controlled by different concentrations of BMP-4.
Molecular mechanisms by which the mesoderm is subdivided along the mediolateral axis in early chicken embryos have been studied. When the presomitic mesoderm (medial mesoderm) was transplanted into the lateral plate, the graft was transformed into lateral plate tissue, indicating that the primitive somite was not fully committed and that the lateral plate has a cue for mesodermal lateralization. Since the lateral plate expresses a high level of BMP-4 mRNA, a member of the TGF-beta family, we hypothesized that it is the molecule responsible for the lateralization of the somite. To test this, we transplanted COS cells producing BMP-4 into the presomitic region. Those cells locally prevented the presomitic cells from differentiating into somites, converting them instead into lateral plate mesoderm, which was revealed by expression of cytokeratin mRNA, a marker for the lateral plate. The effect was dependent on the level of effective BMP-4: with a high level of BMP-4, the somite was transformed completely to lateral plate; with a low level, the somite formed but was occupied by the lateral somitic component expressing cSim 1, a marker for the lateral somite. These results suggest that different thresholds of effective BMP-4 determine distinct subtypes of the mesoderm as a lateralizer during early development.
Tonegawa
A
A
Department of Bioscience, Kitasato University, Sagamihara, Japan.
Funayama
N
N
Ueno
N
N
Takahashi
Y
Y
D000818:Animals; D019521:Body Patterning / Q000502:physiology; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000502:physiology*; D019556:COS Cells; D002454:Cell Differentiation; D002465:Cell Movement / Q000502:physiology; D002642:Chick Embryo; D002678:Chimera; D003370:Coturnix; D004268:DNA-Binding Proteins / Q000235:genetics; D005775:Gastrula / Q000502:physiology*; D007633:Keratins / Q000235:genetics; D008648:Mesoderm / Q000166:cytology* / Q000502:physiology / Q000637:transplantation; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins / Q000235:genetics; D014157:Transcription Factors; D014162:Transfection
C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; C068686:Pax3 protein, mouse; D007633:Keratins