Delcourt, N., Quevedo, C., Nonne, C., Fons, P., O'Brien, D., Loyaux, D., Diez, M., Autelitano, F., Guillemot, J.C., Ferrara, P., Muriana, A., Callol, C., Hérault, J.P., Herbert, J.M., Favre, G., Bono, F. (2015) Targeted Identification of Sialoglycoproteins in Hypoxic Endothelial Cells and Validation in Zebrafish Reveal Roles for Proteins in Angiogenesis. The Journal of biological chemistry. 290(6):3405-17.
The formation of new vessels in the tumor, termed angiogenesis, is essential for primary tumor growth and facilitates tumor invasion and metastasis. Hypoxia has been described as one of trigger of angiogenesis. Indeed, hypoxia, characterized by areas of low oxygen levels, is a hallmark of solid tumors arising from an imbalance between oxygen delivery and consumption. Hypoxic conditions have profound effects on the different components of the tumoral environment. For example, hypoxia is able to activate endothelial cells leading to angiogenesis but also thereby initiate a cascade of reactions involving neutrophils, smooth muscle cells and fibroblasts. In addition, hypoxia directly regulates the expression of many genes for which the role and the importance in the tumoral environment remain to be completely elucidated. In this study, we used a method to selectively label sialo-glycoproteins in order to identify new membrane and secreted proteins involved in the adaptative process of endothelial cells by mass spectrometry-based proteomics. We used an in vitro assay under hypoxic condition in order to observe an increase of protein expression or modifications of glycosylation. Then, the function of the identified proteins was assessed on a vasculogenesis assay in vivo by using a morpholino strategy in zebrafish. Our approach was first validated by the identification of sialo-glycoproteins such as CD105, neuropilin-1 and CLEC14A which have already been described as playing key roles in angiogenesis. Secondly, we identified several new proteins regulated by hypoxia and demonstrated for the first time the pivotal role of GLUT-1, TMEM16F and SDF4 in angiogenesis.