Galectin-9 trafficking regulates apical-basal polarity in Madin-Darby canine kidney epithelial cells

Proc Natl Acad Sci U S A. 2010 Oct 12;107(41):17633-8. doi: 10.1073/pnas.1012424107. Epub 2010 Sep 22.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Polarity / physiology*
  • Dogs
  • Epithelial Cells
  • Galectins / genetics
  • Galectins / metabolism*
  • Gene Knockdown Techniques
  • Globosides / metabolism*
  • Golgi Apparatus / metabolism*
  • Green Fluorescent Proteins
  • Kidney / cytology
  • Membrane Proteins / metabolism*
  • Microscopy, Fluorescence
  • Protein Transport / physiology
  • RNA Interference

Substances

  • Galectins
  • Globosides
  • Membrane Proteins
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Forssman glycolipid