title: Hunting for connexin hemichannels.
abstract: Connexin hemichannels (connexons) are building blocks of gap junctions but also function as free unapposed channels, which has become an active field of research. Defining functions of hemichannels and their involvement in any biological event requires ruling out possible participation of other channels that share biophysical and regulatory properties, for example pannexins, CALHM1 and P2X receptors. The lack of specific inhibitors for these channels has become an obstacle in elucidating the role of connexin hemichannels. Several experimental approaches are now available to identify hemichannels at the cell surface and to characterize their electrophysiological, permeability and regulatory properties. The use of connexin knockout/knockdown, and the development of peptides that target intracellular connexin domains and specific antibodies directed to extracellular domains have helped to dissect the role of hemichannels in endogenously expressing systems. Moreover, studies of connexin mutants in exogenous expression systems have provided convincing evidence on hemichannels in the pathogenesis of several human genetic diseases. We here present a brief overview of connexin hemichannels as functional channels and itemize a list of aspects to consider when concluding on their involvement.
authors.affiliation: Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago and Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Valparaíso, Chile. Electronic address: jsaez@bio.puc.cl.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Sáez
authors.affiliation: Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 (Block B - Rm 031), 9000 Ghent, Belgium. Electronic address: Luc.Leybaert@UGent.be.
authors.forename: Luc
authors.initials: L
authors.lastname: Leybaert
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000378:metabolism; D017630:Connexins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D011485:Protein Binding; D058469:Receptors, Purinergic P2X / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D017630:Connexins; C514423:Gap 26 peptide; D008562:Membrane Glycoproteins; D010455:Peptides; D058469:Receptors, Purinergic P2X
keywords: ATP release; Dye uptake; Hemichannel block; Mimetic peptide; Unitary conductance