title: Nutrient Starvation Decreases Cx43 Levels and Limits Intercellular Communication in Primary Bovine Corneal Endothelial Cells.
abstract: Connexin (Cx) proteins form large conductance channels which function as regulators of communication between neighboring cells via gap junctions and/or hemichannels. Intercellular communication is essential to coordinate cellular responses in tissues and organs, thereby fulfilling an essential role in the spreading of signaling, survival and death processes. Connexin 43 (Cx43), a major connexin isoform in brain and heart, is rapidly turned over. Recent studies implicated that autophagy, a lysosomal degradation pathway induced upon nutrient starvation, mediates connexins, including Cx43, degradation. Here, we examined the impact of nutrient starvation on endogenous Cx43-protein levels and endogenous Cx43-driven intercellular communication in primary bovine corneal endothelial cells (BCECs). Hank's Balanced Salt Solution (HBSS) was used as a starvation condition that induces autophagic flux without impacting the survival of the BCECs. Nutrient starvation of BCECs caused a rapid decline in Cx43-protein levels, both as gap junctions and as hemichannels. The time course of the decline in Cx43-protein levels coincided with the time course of the decline in intercellular communication, assessed as intercellular Ca(2+)-wave propagation in BCECs exposed to a single-cell mechanical stimulus. The decline in Cx43-protein levels, both as gap junctions and as hemichannels, could be prevented by the addition of bafilomycin A1, a lysosomal inhibitor, during the complete nutrient starvation period. Consistent with this, bafilomycin A1 significantly alleviated the decrease in intercellular Ca(2+)-wave propagation. This study further underpins the importance of autophagy as an important degradation pathway for Cx43 proteins during periods of nutrient deprivation, thereby impacting the ability of cells to perform intercellular communication.
authors.affiliation: Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signaling, KU Leuven, Campus Gasthuisberg O/N-I Bus 802, Herestraat 49, 3000, Louvain, Belgium.
authors.forename: Catheleyne
authors.initials: C
authors.lastname: D'hondt
authors.affiliation: Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signaling, KU Leuven, Campus Gasthuisberg O/N-I Bus 802, Herestraat 49, 3000, Louvain, Belgium.
authors.forename: Jegan
authors.initials: J
authors.lastname: Iyyathurai
authors.affiliation: Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signaling, KU Leuven, Campus Gasthuisberg O/N-I Bus 802, Herestraat 49, 3000, Louvain, Belgium.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Welkenhuyzen
authors.affiliation: Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signaling, KU Leuven, Campus Gasthuisberg O/N-I Bus 802, Herestraat 49, 3000, Louvain, Belgium.
authors.forename: Bernard
authors.initials: B
authors.lastname: Himpens
authors.affiliation: Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Physiology Group, Ghent University, 9000, Ghent, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Leybaert
authors.affiliation: Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signaling, KU Leuven, Campus Gasthuisberg O/N-I Bus 802, Herestraat 49, 3000, Louvain, Belgium. geert.bultynck@med.kuleuven.be.
authors.forename: Geert
authors.initials: G
authors.lastname: Bultynck
mesh_terms: D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002450:Cell Communication; D018031:Connexin 43 / Q000378:metabolism*; D017630:Connexins / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D019573:Epithelium, Corneal / Q000378:metabolism*; D017629:Gap Junctions / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D015398:Signal Transduction; D013217:Starvation
chemical_list: D018031:Connexin 43; D017630:Connexins; D018942:Macrolides; C040929:bafilomycin A1; D002118:Calcium
keywords: Autophagy; Connexins; Starvation