title: Galectin-7 modulates the length of the primary cilia and wound repair in polarized kidney epithelial cells.
abstract: Galectins (Gal) are β-galactoside-binding proteins that function in epithelial development and homeostasis. An overlapping role for Gal-3 and Gal-7 in wound repair was reported in stratified epithelia. Although Gal-7 was thought absent in simple epithelia, it was reported in a proteomic analysis of cilia isolated from cultured human airway, and we recently identified Gal-7 transcripts in Madin-Darby canine kidney (MDCK) cells (Poland PA, Rondanino C, Kinlough CL, Heimburg-Molinaro J, Arthur CM, Stowell SR, Smith DF, Hughey RP. J Biol Chem 286: 6780-6790, 2011). We now report that Gal-7 is localized exclusively on the primary cilium of MDCK, LLC-PK(1) (pig kidney), and mpkCCD(c14) (mouse kidney) cells as well as on cilia in the rat renal proximal tubule. Gal-7 is also present on most cilia of multiciliated cells in human airway epithelia primary cultures. Interestingly, exogenous glutathione S-transferase (GST)-Gal-7 bound the MDCK apical plasma membrane as well as the cilium, while the lectin Ulex europeaus agglutinin, with glycan preferences similar to Gal-7, bound the basolateral plasma membrane as well as the cilium. In pull-down assays, β1-integrin isolated from either the basolateral or apical/cilia membranes of MDCK cells was similarly bound by GST-Gal-7. Selective localization of Gal-7 to cilia despite the presence of binding sites on all cell surfaces suggests that intracellular Gal-7 is specifically delivered to cilia rather than simply binding to surface glycoconjugates after generalized secretion. Moreover, depletion of Gal-7 using tetracycline-induced short-hairpin RNA in mpkCCD(c14) cells significantly reduced cilia length and slowed wound healing in a scratch assay. We conclude that Gal-7 is selectively targeted to cilia and plays a key role in surface stabilization of glycoconjugates responsible for integrating cilia function with epithelial repair.
authors.affiliation: Renal-Electrolyte Div., Dept. of Medicine, Univ. of Pittsburgh School of Medicine, PA 15261, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Rondanino
authors.forename: Paul A
authors.initials: PA
authors.lastname: Poland
authors.forename: Carol L
authors.initials: CL
authors.lastname: Kinlough
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Youssef
authors.initials: Y
authors.lastname: Rbaibi
authors.forename: Michael M
authors.initials: MM
authors.lastname: Myerburg
authors.forename: Mohammad M
authors.initials: MM
authors.lastname: Al-bataineh
authors.forename: Ossama B
authors.initials: OB
authors.lastname: Kashlan
authors.forename: Nuria M
authors.initials: NM
authors.lastname: Pastor-Soler
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Hallows
authors.forename: Ora A
authors.initials: OA
authors.lastname: Weisz
authors.forename: Gerard
authors.initials: G
authors.lastname: Apodaca
authors.forename: Rebecca P
authors.initials: RP
authors.lastname: Hughey
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D002923:Cilia / Q000502:physiology* / Q000648:ultrastructure*; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D037161:Galectins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D019012:Integrin beta1 / Q000502:physiology; D007668:Kidney / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D051379:Mice; D018345:Mice, Knockout; D011485:Protein Binding / Q000502:physiology; D051381:Rats; D013552:Swine; D014945:Wound Healing / Q000502:physiology*
chemical_list: D037161:Galectins; D019012:Integrin beta1; C092525:LGALS7 protein, human; C490487:Lgals7 protein, mouse