Title: Intramolecular loop/tail interactions are essential for connexin 43-hemichannel activity
Authors: Ponsaerts, Raf *
De Vuyst, Elke *
Retamal, Mauricio
D'hondt, Catheleyne
Vermeire, Dieter
Wang, Nan
De Smedt, Humbert
Zimmermann, Pascale
Himpens, Bernard
Vereecke, Johan
Leybaert, Luc
Bultynck, Geert # ×
Issue Date: Jul-2010
Publisher: The Federation of American Societies for Experimental Biology
Series Title: FASEB Journal vol:24 issue:11 pages:4378-4395
Abstract: Connexin-assembled gap junctions (GJs) and hemichannels coordinate intercellular signaling processes. Although the regulation of connexins in GJs has been well characterized, the molecular determinants controlling connexin-hemichannel activity are unresolved. Here we investigated the regulation of Cx43-hemichannel activity by actomyosin contractility and intracellular [Ca(2+)] ([Ca(2+)]i) using plasma membrane-permeable TAT peptides (100 muM) designed to interfere with interactions between the cytoplasmic loop (CL) and carboxy-terminal (CT) in primary bovine corneal endothelial cells and HeLa, C6 glioma, and Xenopus oocytes ectopically expressing Cx43. Peptides corresponding to the last 10 CT aa (TAT-Cx43CT) prevented the inhibition of Cx43-hemichannel activity by contractility/high [Ca(2+)]i, whereas a reverse peptide (TAT-Cx43CTrev) did not. These effects were independent of zonula occludens-1, a cytoskeletal-associated Cx43-binding protein. In contrast, peptides corresponding to CL (TAT-L2) inhibited Cx43-hemichannel responses, whereas a mutant peptide (TAT-L2(H126K/I130N)) did not inhibit. In these assays, TAT-Cx43CT acted as a scaffold for TAT-L2 and vice versa, a finding supported by surface plasmon resonance measurements. Loop/tail interactions appeared essential for Cx43-hemichannel activity, because TAT-Cx43CT restored the activity of nonfunctional hemichannels, consisting of either Cx43 lacking the C-terminal tail (Cx43(M239)) or intact Cx43 ectopically expressed in Xenopus oocytes. We conclude that intramolecular loop/tail interactions control Cx43-hemichannel activity, laying the basis for developing hemichannel-specific blockers.-Ponsaerts, R., De Vuyst, E., Retamal, M., D'hondt, C., Vermeire, D., Wang, N., De Smedt, H., Zimmermann, P., Himpens, B., Vereecke, J., Leybaert, L., Bultynck, G. Intramolecular loop/tail interactions are essential for connexin 43-hemichannel activity.
Description: Luc Leybaert and Geert Bultynck are shared last-author.
ISSN: 0892-6638
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Department of Human Genetics - miscellaneous
Laboratory of Molecular and Cellular Signaling
Department of Cellular and Molecular Medicine - miscellaneous
* (joint) first author
× corresponding author
# (joint) last author

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