Expression of periostin during Xenopus laevis embryogenesis.

Periostin (postn) is a secreted, extracellular matrix protein containing an EMI domain as well as four fasciclin I-like (Fas1) domains. Postn protein functions in cell adhesion, cell mobility, cell proliferation and gene regulation. Earlier studies have shown that postn is involved in different developmental processes such as somitogenesis, cardiogenesis and bone formation. Intriguingly, postn seems to be a very good candidate to establish novel therapies against cancer and chronic heart defects. Here we describe for the first time the spatio-temporal expression profile of postn during early development of Xenopus laevis. By semi-quantitative RT-PCR approaches, we demonstrate that postn is maternally expressed. Zygotic expression starts during early gastrulation and increases until stage 40. Whole mount in situ hybridization experiments revealed that postn is detectable in somites, the sensory layer of the epidermis, the roof plate, the notochord, the heart, migrating neural crest cells, cranial ganglia and forming cranial cartilage structures. Our results implicate a role of postn during Xenopus embryogenesis and represent a good starting point for future functional analyses.