Galectin-3 and polarized growth within collagen gels of wild-type and ricin-resistant MDCK renal epithelial cells

Previous studies (Q. Bao and R. C, Hughes (1995) J, Cell Sci,, 108, 2791-28 00) showed that the beta-galactoside-binding protein, galectin-3, is secret ed onto the basolateral surface domains of Madin-Darby canine kidney MDCK c ells growing as polarized cysts within a collagen gel. The growth and enlar gement of such cysts were shown to be increased significantly when cultured in the presence of antibodies directed against the lectin and were slowed down by addition of exogenous galectin-3. These results suggested a role fo r galectin-3, interacting with appropriately glycosylated surface receptors , as a negative growth regulator in the development of MDCK cysts, a well-k nown model for renal epithelial morphogenesis, In the present report we hav e tested this proposal by use of a ricin-resistant mutant of MDCK cells tha t is unable to transfer galactose residues during biosynthesis of cellular glycoconjugates and hence lacks extracellular receptors for galectin-3. We find that when grown within collagen gels, the mutant cell cysts grow signi ficantly faster than wildtype cell cysts. Furthermore, they form nonspheric al and tubular cysts that are induced in wild-type cell cysts only under th e influence of the morphogen, hepatocyte growth factor (HGF).