The biochemical properties and transforming potential of human Wnt-2 are similar to Wnt-1

Abstract

Wnt-2 is a member of the Wnt gene family that includes the proto-oncogene Wnt-1 (formerly Int-1). Although the predicted protein product of the Wnt-2 gene has only 38% amino acid identity with Wnt-1, it exhibits significant conservation of structural properties, including a hydrophobic signal sequence and invariant spacing and conservation of 22 cysteine residues. We have sought to characterize the biological and biochemical properties of Wnt family members and here present a characterization of Wnt-2 protein and a comparison with Wnt-1. We demonstrate, using both CHO and AtT-20 cells transfected with human Wnt-2 cDNA, that Wnt-2 encodes a 33 kDa protein that is modified by N-linked glycosylation to a 35 kDa species. Secreted Wnt-2 protein was detected in the culture medium only after cells were treated with suramin indicating that, like Wnt-1 protein, Wnt-2 is tightly associated with the cell surface. Expression of Wnt-2 cDNA in the mammary epithelial cell line C57 mg results in loss of density-inhibited growth and induces a transformed phenotype in monolayer culture similar to the effects produced by Wnt-1. These results indicate that Wnt-2 shares several biochemical and biological characteristics with Wnt-1 and suggests that other Wnt family members, by virtue of conserved structural features, may also exhibit similar properties.