TGF beta in murine morphogenetic processes: the early embryo and cardiogenesis.
The tissue distribution of TGF beta-1 RNA was examined within whole mouse embryos from implantation to 10.5 days gestational age and, in the developing heart, up to 8 days postpartum. The earliest high level expression of TGF beta-1 RNA is at 7.0 days postcoitum (p.c.) in the cardiac mesoderm. At 8.0 days gestational age, cardiac TGF beta-1 RNA expression is limited to endocardial cells. By 9.5 days p.c., this expression pattern becomes regionalized to those cells that overlie cardiac cushion tissue. High TGF beta-1 RNA levels continue to persist in endothelial cells of the heart valves until approximately one week postpartum. The TGF beta-1 RNA distribution was compared with the extracellular distributions of polypeptides for TGF beta and J1/tenascin. As previously reported, endothelial expression of TGF beta-1 RNA is correlated with mesenchymal expression of TGF beta polypeptide, suggesting a paracrine mode of action for this growth factor in cardiac development. Minor discrepancies in the distributions of TGF beta-1 RNA and the extracellular form of the TGF beta polypeptide suggest that translational or post-translational control of protein levels occurs and/or the possibility that the antibody used may also recognise other members of the TGF beta polypeptide family. A correlation between endothelial TGF beta-1 expression and distribution of J1/tenascin in the mesenchyme gives further support to the proposition that the biological effects of TGF beta-1 may, in part, be mediated by J1/tenascin.
Duncan Guthrie Institute of Medical Genetics, University of Glasgow, Yorkhill, UK.
R J
RJ
Akhurst
S A
SA
Lehnert
A
A
Faissner
E
E
Duffie
D000818:Animals; D002448:Cell Adhesion; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D015342:DNA Probes; D005260:Female; D005775:Gastrula / Q000378:metabolism; D006321:Heart / Q000196:embryology*; D006351:Heart Valves / Q000196:embryology / Q000378:metabolism; D008297:Male; D051379:Mice; D009024:Morphogenesis; D009206:Myocardium / Q000378:metabolism; D009389:Neovascularization, Pathologic; D012333:RNA, Messenger / Q000378:metabolism; D019063:Tenascin; D015291:Transforming Growth Factors / Q000378:metabolism*
D015816:Cell Adhesion Molecules, Neuronal; D015342:DNA Probes; D012333:RNA, Messenger; D019063:Tenascin; D015291:Transforming Growth Factors