EPITHELIAL GALECTIN-3 DURING HUMAN NEPHROGENESIS AND CHILDHOOD CYSTICDISEASES

Galectin-3 is a beta-galactoside-binding protein with putative roles i n development, oncogenesis, and inflammation. Its expression in human nephrogenesis has not been previously reported. This study examines ga lectin-3 expression in early human embryos by Western blot and immunoh istochemistry. This 33-kD protein was detected in the apical domain of distal tubules of the mesonephros and also in the mesonephric duct. I n the metanephros, the adult kidney precursor, galectin-3 was detected in the apical domains of ureteric bud branches, and there was intense expression in fetal medullary and papillary collecting ducts in both the cytoplasm and plasma membranes. Low levels of galectin-3 were dete cted in the cytoplasm of a subset of cells in adult collecting ducts; these were alpha-intercalated cells because they expressed basal band 3 protein. In human multicystic dysplastic kidneys, all diseased epith elia had an embryonic apical expression pattern of galectin-3 and, in addition, all cystic epithelia in autosomal recessive polycystic kidne ys expressed this molecule. It is concluded that galectin-3 is express ed by cells of the mesonephric duct/ureteric bud lineage, and it is sp eculated that the different subcellular locations may be implicated in both the regulation of normal growth and differentiation of this line age, as well as in the pathogenesis of cystic epithelia.