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Stem Cells International
Volume 2017, Article ID 9717353, 9 pages
https://doi.org/10.1155/2017/9717353
Research Article

Mesenchymal Stromal Cells Accelerate Epithelial Tight Junction Assembly via the AMP-Activated Protein Kinase Pathway, Independently of Liver Kinase B1

1Groupe Interdisciplinaire de Génoprotéomique Appliquée (GIGA), Cardiovascular Sciences, University of Liège (ULg), Liège, Belgium
2Division of Nephrology, University of Liège Hospital (ULg CHU), Liège, Belgium
3Centre de Recherche en Cancérologie de Marseille, Aix Marseille Université UM105, Institut Paoli Calmettes, UMR7258 CNRS, U1068 INSERM, Cell Polarity, Cell Signalling and Cancer “Equipe Labellisée Ligue Contre le Cancer”, Marseille, France

Correspondence should be addressed to F. Jouret; eb.ca.glu@teruoj.siocnarf

Received 30 March 2017; Accepted 21 May 2017; Published 11 July 2017

Academic Editor: Bruno Christ

Copyright © 2017 P. Rowart et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. Mesenchymal stromal cells (MSC) are fibroblast-like multipotent cells capable of tissue-repair properties. Given the essentiality of tight junctions (TJ) in epithelial integrity, we hypothesized that MSC modulate TJ formation, via the AMP-activated kinase (AMPK) pathway. Liver kinase-β1 (LKB1) and Ca2+-calmodulin-dependent protein kinase kinase (CaMKK) represent the main kinases that activate AMPK. Methods. The in vitro Ca2+ switch from 5 μM to 1.8 mM was performed using epithelial Madin-Darby canine kidney (MDCK) cells cultured alone or cocultured with rat bone marrow-derived MSC or preexposed to MSC-conditioned medium. TJ assembly was measured by assessing ZO-1 relocation to cell-cell contacts. Experiments were conducted using MDCK stably expressing short-hairpin-RNA (shRNA) against LKB1 or luciferase (LUC, as controls). Compound STO-609 (50 μM) was used as CaMKK inhibitor. Results. Following Ca2+ switch, ZO-1 relocation and phosphorylation/activation of AMPK were significantly higher in MDCK/MSC compared to MDCK. No difference in AMPK phosphorylation was observed between LKB1-shRNA and Luc-shRNA MDCK following Ca2+ switch. Conversely, incubation with STO-609 prior to Ca2+ switch prevented AMPK phosphorylation and ZO-1 relocation. MSC-conditioned medium slightly but significantly increased AMPK activation and accelerated TJ-associated distribution of ZO-1 post Ca2+ switch in comparison to regular medium. Conclusions. MSC modulate the assembly of epithelial TJ, via the CaMKK/AMPK pathway independently of LKB1.