PDGF-BB AND TGF-ALPHA RESCUE GASTRULATION, SPICULOGENESIS, AND LPS1 EXPRESSION IN COLLAGEN-DISRUPTED EMBRYOS OF THE SEA-URCHIN GENUS LYTECHINUS

Development and LpS1 transcription in Lytechinus embryos are arrested at the mesenchyme blastula stage when collagen deposition is inhibited by the lathyrytic agent beta-aminopropionitrile (BAPN) or by proline analogs. We found that human recombinant platelet derived growth factor-BB (PDGF-BB) and transforming growth factor cr (TGF-cr) synergistically rescue collagen disrupted/developmentally arrested L. pictus and L. variegatus embryos so that development and RNA accumulation of LpS1 proceed. In addition, nonspecific antagonists of PDGF block gastrulation and LpS1 RNA accumulation. The embryos recover and LpS1 RNA accumulation resumes when the antagonists are removed. These data suggest that a growth factor mediated pathway, associated with the ECM, is required for sea urchin gastrulation, spiculogenesis, and LpS1 gene activation.