Polycystin-1 is a microtubule-driven desmosome-associated component in polarized epithelial cells.
In this study, we have analyzed the expression and localization of polycystin-1 in intestinal epithelial cells, a system lacking primary cilia. Polycystin-1 was found to be expressed in the epithelium of the small intestine during development and levels remained elevated in the adult. Dual-labelling indirect immunofluorescence revealed polycystin-1 at sites of cell-cell contact co-localizing with the desmosomes both in situ as well as in polarized Caco-2/15 cells. In unpolarized cultures of Caco-2/15 cells, polycystin-1 was recruited to the cell surface early during initiation of cell junction assembly. In isolated Caco-2/15 cells and HIEC-6 cell cultures, where junctional complexes are absent, polycystin-1 was found predominantly associated with the cytoskeletal elements of the intermediate filaments and microtubule networks. More precisely, polycystin-1 was seen as brightly labelled puncta decorating the keratin-18 positive filaments as well as the beta-tubulin positive microtubules, which was particularly obvious in the lamellipodia. Treatment with the microtubule-disrupting agent, nocodazole, eliminated the microtubule association of polycystin-1 but did not seem to affect its association with keratin or the desmosomes. Taken together these data suggest that polycystin-1 is involved with the establishment of cell-cell junctions in absorptive intestinal epithelial cells and exploits the microtubule-based machinery in order to be transported to the plasma membrane.
Basora
Nuria
N
Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada. Nuria.Basora@USherbrooke.ca
Tétreault
Marie-Pier
MP
Boucher
Marie-Pierre
MP
Herring
Elizabeth
E
Beaulieu
Jean-François
JF
D000328:Adult; D015153:Blotting, Western; D018938:Caco-2 Cells; D002118:Calcium / Q000378:metabolism; D016764:Cell Polarity; D003896:Desmosomes / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D005333:Fetus / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D053538:Keratin-18 / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050396:TRPP Cation Channels / Q000235:genetics / Q000378:metabolism*
D002118:Calcium; D053538:Keratin-18; D012333:RNA, Messenger; D050396:TRPP Cation Channels