The role of TGF-βs in mammalian development and neoplasia

To date, three mammalian TGF-beta isoforms have been identified, each encoded by different genetic loci. Through each is very similar in primary amino acid structure, there are clear differences both in the mature bioactive peptide region and in the latency-associated peptide, which could potentially confer differential biological specificity. As one route to investigate differential biological function in vivo we have used gene specific probes for in situ hybridization studies to examine the distribution of RNA transcripts during mammalian embryogenesis. Mouse embryos from 6 to 14.5 gestational age and human embryos from 32 to 57 days post-fertilization have been probed. A general conclusion from these studies is that each TGF-beta gene has a distinct, through overlapping, pattern of transcript distribution and that this pattern, in most cases, is conserved between mouse and man. We have focused on the biological function the TGF-betas play in certain epithelia and in cardiogenesis, which will be discussed in this presentation