AUTONOMOUS NEURAL AXIS FORMATION BY ECTOPIC EXPRESSION OF THE PROTOONCOGENE C-SKI

The ski oncogene was originally isolated as an avian retroviral gene w ith the ability to induce quail embryonic cells to differentiate into muscle. Mice containing a chicken c-ski transgene exhibit postnatal hy pertrophy of skeletal muscle. Xenopus ski (Xski) protein is maternal a nd present throughout early development. We show that overexpression o f Xski RNA in Xenopus embryos results in the cell-autonomous induction of secondary neural axis formation. Injection of Xski RNA into prospe ctive endodermal cells resulted in the formation of an ectopic neural tube-like structure and cells derived from the injected blastomeres po pulated the spinal cord. Injected Xski RNA was able to induce neural-s pecific gene expression directly in ectodermal explants in the absence of the expression of mesodermal markers. The widespread distribution of ski protein in the early gastrula embryo including the dorsal anima l region supports a role for ski in neural axis formation in vivo. (C) 1997 Academic Press.