Human PDGFA mRNA

The platelet-derived growth factor (PDGF) family consists of four ligands (PDGF-A, PDGF-B, PDGF-C, PDGF-D) and two tyrosine kinase receptors (PDGFR-α and PDGFR-β). In vertebrates, PDGF signaling affects cell proliferation, migration, and matrix deposition, and its upregulation has been associated with cancer progression. Here, by utilizing a pdgf-b splicing-blocking morpholino approach, researchers reveal impaired neural crest cell (NCC) migration in Xenopus laevis morphants, leading to altered formation of NCC derivatives such as cranial nerves and cartilage. They also uncovered a possible link between pdgf-b and the expression of cadherin superfamily members cdh6 and cdh11, which mediate cell-cell adhesion and promote NCC migration. These data reveal a novel role for PDGF-B during vertebrate development and contribute to a complete understanding of the role of PDGF signaling in craniofacial development.

The researchers reared ddgf-b morphants until the neurula stage and analyzed possible effects on NCCs by whole-mount in situ hybridization (WISH) using specific NCC markers such as twist and sox10. Since injections were performed only on one side, the effects could be easily and reliably distinguished by comparing the injected and uninjected sides. The analysis showed that the formation of the NCC premigratory stream was affected in pdgf-b morphants (Figure 1A, C); the NCC streams appeared to be fused and the onset of migration was delayed. pdgf-b morphants also exhibited alterations in the NCC migration pattern at later stages. Indeed, at the tailbud stage (stage 25), a significant delay in NCC migration was observed on the injected side (Figure 1A, C), whereas in embryos injected with the control morpholino, no effects were detected at either the neurula or tailbud stage (Figure 1A, C). The statistical significance of these results is reported in Figure 1B and Figure 1D. To verify the specificity of pdgf-b MO, the researchers performed functional rescue experiments by co-injecting pdgf-b MO and PDGF-B mRNA and analyzed its effects on NCC migration at the neurula and tail bud stages (Figure 1E, F). The rescued phenotype was observed and confirmed in three different rounds of experiments, but complete functional rescue could not be achieved. The researchers determined the injection dose of PDGF-B mRNA to achieve a reasonable balance between maximum efficacy and minimum side effects.

Figure 1. pdgf-b down-regulation affects NCC migration. (Corsinovi D, et al., 2019)