title: Galectin-9 trafficking regulates apical-basal polarity in Madin-Darby canine kidney epithelial cells.
abstract: Galectins are unconventionally secreted lectins that participate in the formation of glycoprotein lattices that perform a variety of cell surface functions. Galectins also bind glycosphingolipid headgroups with as yet unclear implications for cellular physiology. We report a specific interaction between galectin-9 and the Forssman glycosphingolipid (FGL) that is important for polarizing Madin-Darby canine kidney epithelial cells. Galectin-9 knockdown leads to a severe loss of epithelial polarity that can be rescued by addition of the recombinant protein. The FGL glycan is identified as the surface receptor that cycles galectin-9 to the Golgi apparatus from which the protein is recycled back to the apical surface. Together our results suggest a model wherein such glycosphingolipid-galectin couples form a circuit between the Golgi apparatus and the cell surface that in an epithelial context facilitates the apical sorting of proteins and lipids.
authors.affiliation: Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
authors.forename: Rashmi
authors.initials: R
authors.lastname: Mishra
authors.forename: Michal
authors.initials: M
authors.lastname: Grzybek
authors.forename: Toshiro
authors.initials: T
authors.lastname: Niki
authors.forename: Mitsuomi
authors.initials: M
authors.lastname: Hirashima
authors.forename: Kai
authors.initials: K
authors.lastname: Simons
mesh_terms: D000818:Animals; D016764:Cell Polarity / Q000502:physiology*; D004285:Dogs; D004847:Epithelial Cells; D037161:Galectins / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D005915:Globosides / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D007668:Kidney / Q000166:cytology; D008565:Membrane Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D021381:Protein Transport / Q000502:physiology; D034622:RNA Interference
chemical_list: D037161:Galectins; D005915:Globosides; D008565:Membrane Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C010163:Forssman glycolipid