Overexpression of camello, a member of a novel protein family, reduces blastomere adhesion and inhibits gastrulation in Xenopus laevis

Vertebrate gastrulation involves complex coordinated movements of cells and cell layers to establish the axial structures and the general body plan. A dhesion molecules and the components of extracellular matrix were shown to be involved in this process. However, other participating molecules and det ailed mechanisms of the control of gastrulation movements remain largely un known. Here, we describe a novel Xenopus gene camello (Xcml) which is expre ssed in the suprablastoporal zone of gastrulating embryos. Injection of Xcm l RNA into dorsovegetal blastomeres retards or inhibits gastrulation moveme nts. Database searches revealed a family of mammalian mRNAs encoding polype ptides highly similar to Xcml protein. Characteristic features of the camel lo family include the presence of the central hydrophobic domain and the N- acetyltransferase consensus moths in the C-terminal part, as well as functi onal similarity to Xcml revealed by overexpression studies in Xenopus embry os. Xcml expression results in the decrease of cell adhesion as demonstrate d by the microscopic analysis and the blastomere aggregation assay. Cell fr actionation and confocal microscopy data suggest that Xcml protein is local ized in the secretory pathway. We propose that Xcml may fine tune the gastr ulation movements by modifying the cell surface and possibly extracellular matrix proteins passing through the secretory pathway. (C) 2001 Academic Pr ess.