CLONING, EXPRESSION AND CHROMOSOMAL LOCALIZATION OF WNT-13, A NOVEL MEMBER OF THE WNT GENE FAMILY

The Wnt genes, encoding structurally-related secreted glycoproteins, a re implicated in mammary carcinogenesis induced by mouse mammary tumor virus, In search of the Wnt gene(s) expressed in human gastric cancer , a WTGC1 cDNA fragment sharing 66.9% amino-acid homology with human a nd mouse Wnt-2 was isolated by degenerate polymerase chain reaction. T he human gene corresponding to WTGC1 was designated as Wnt-13 and over lapping Wnt-13 cDNAs were cloned, Nucleotide sequence analysis indicat ed that the Wnt-13 gene encodes the protein of 372 amino acids, includ ing a signal peptide, two potential N-glycosylation sites and 24 cyste in residues highly conserved among members of the Wnt gene family, The Wnt-13 mRNA of 2.5 kb in size was detected in heart, brain, placenta, lung, prostate, testis, ovary, small intestine and colon of adult hum an and also in brain, lung and kidney of fetal human, Among various ca ncer cell lines, the Wnt-13 mRNA was detected in HeLa (cervical cancer ), MKN28 and MKN74 (gastric cancer), The Wnt-13 gene has been mapped t o human chromosome 1p13, These results suggest that the Wnt-13 gene ma y be involved in normal human development or differentiation as well a s in human carcinogenesis.