Authors: JeanClaude Hervé Mickaël Derangeon
Publish Date: 2012/09/01
Volume: 352, Issue: 1, Pages: 21-31
Abstract
Cells of multicellular organisms need to communicate with each other and have evolved various mechanisms for this purpose the most direct and quickest of which is through channels that directly connect the cytoplasms of adjacent cells Such intercellular channels span the two plasma membranes and the intercellular space and result from the docking of two hemichannels These channels are densely packed into plasmamembrane spatial microdomains termed “gap junctions” and allow cells to exchange ions and small molecules directly A hemichannel is a hexameric torus of junctional proteins around an aqueous pore Vertebrates express two families of gapjunction proteins the wellcharacterized connexins and the more recently discovered pannexins the latter being related to invertebrate innexins “invertebrate connexins” Some gapjunctional hemichannels also appear to mediate cellextracellular communication Communicating junctions play crucial roles in the maintenance of homeostasis morphogenesis cell differentiation and growth control in metazoans Gapjunctional channels are not passive conduits as previously long regarded but use “gating” mechanisms to open and close the central pore in response to biological stimuli eg a change in the transjunctional voltage Their permeability is finely tuned by complex mechanisms that have just begun to be identified Given their ubiquity and diversity gap junctions play crucial roles in a plethora of functions and their dysfunctions are involved in a wide range of diseases However the exact mechanisms involved remain poorly understood
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