Cloning and characterization of the glycoprotein vitronectin in Xenopus laevis development.

LUQUE, M.E.; SERRANO, M.A.; HONORÉ S.M.; SÁNCHEZ, S.S.

Buenos Aires, Argentina

Congreso; 4th International Meeting of the Latin American Society of Developmental Biology (LASDB); 2008

Vitronectin (VN) is a multifunctional cell-adhesive glycoprotein present in animal blood and in extracellular matrix of a variety of animals. VN regulates cell-mediated proteolytic enzyme cascades, including the complement, coagulation and fibrinolytic system. We have shown that this glycoprotein is not only present in the blood of amphibians Bufo arenarum and Xenopus laevis but interestingly is also stored in yolk platelets during oogenesis of both species. The presence of VN in amphibian oocyte may probably be related to the fact that other adhesion-mediating proteins such as fibronectin, laminin and cadherin, participate during morphogenesis. This data suggests that VN may also play a critical role in amphibian development. To determinate if the maternal VN protein participate in gastrulation movements, microinjections of VN antibody were performed into the blastocoelic cavity, and no morphogenetic movements alterations were found.             To analyze the expression of zygotic VN, we identified the complete cDNA sequence of Xenopus laevis VN. In this work we report a 1.46 Kb length transcript for VN. Expression of this glycoprotein was analyzed during development by RT-PCR, whole mount in situ hybridization and inmunohistochemical methods. We detected VN transcripts from stage 28 onward. The spatial expression pattern by in situ hybridization revealed that VN was mainly expressed in heart and foregut. In later stages it was expressed in liver and others foregut derivatives. Inmunohistochemical analysis revealed that VN protein was located in heart, liver, foregut and pronephrics tubules at stages 43 and 47 of Xenopus embryos. Similarly, VN was found in the developing chick heart and was involved in the migration of endocardial cells. Also in avian embryos, VN and Sonic Hedgehog morphogen act synergistically in the induction of motor neurons. However, we have not found VN and Shh colocalization in amphibian embryos. Together, our results suggest that VN may be involved in the later development of Xenopus laevis, but further studies are necessary to determinate its role.