PDGF-B: the Missing Piece in the Mosaic of PDGF Family Role in Craniofacial Development

BACKGROUND: The PDGF family consists of four ligands (PDGF-A to -D) and two tyrosine kinase receptors (PDGFR-α and -β). In vertebrates, PDGF signaling influences cell proliferation, migration, matrix deposition and its up-regulation is implicated in cancer progression. Despite this evidence, the role of each family member during embryogenesis is still incomplete and partially controversial. In particular, study of the role of pdgf signaling during craniofacial development has been focused on pdgf-a, c while the role of pdgf-b is almost unknown due to the lethal phenotypes of pdgf-b null mice. RESULTS: By using a pdgf-b splice-blocking morpholino approach, we highlighted impairment of NCC migration in Xenopus laevis morphants, leading to alteration of NCC derivatives formation, such as cranial nerves and cartilages. We also uncovered a possible link between pdgf-b and the expression of cadherin superfamily members cdh6 and cdh11, which mediate cell-cell adhesion promoting NCC migration. CONCLUSIONS: Our results suggested that pdgf-b signaling is involved in cranial NCC migration and it is required for proper formation of craniofacial NCC derivatives. Taken together, these data unveiled a new role for pdgf-b during vertebrate development, contributing to complete the picture of pdgf signaling role in craniofacial development.