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Visualization and functional blocking of gap junction hemichannels (connexons) with antibodies against external loop domains in astrocytes
Author(s) -
Hofer Andreas,
Dermietzel Rolf
Publication year - 1998
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(199809)24:1<141::aid-glia13>3.0.co;2-r
Subject(s) - connexon , gap junction , biology , syncytium , connexin , extracellular , microbiology and biotechnology , lucifer yellow , pannexin , neuroscience , astrocyte , biophysics , intracellular , cell , biochemistry , central nervous system
Astrocytes constitute a metabolically and electrically coupled syncytium which is essential for the regulation of ionic homeostasis of the interstitial brain fluid and for coordinating responses to neuronal activities. The structural avenues that couple individual astrocytes are provided by gap junctions which consist of transmembraneous channels that bridge the extracellular space. Each gap junction channel is composed of two hemichannels (connexons) that dock to each other via their extracellular loops. Here we report on the characterization of external loop antibodies that visualize hemichannels in specific plasma membranes of vital astrocytes. Hemichannels were found to be concentrated on cytoplasmic processes and filopodia of subconfluent cells. Specificity of hemichannel‐binding was evaluated by blockage of Lucifer Yellow (LY) dye‐transfer and Ca 2+ transmission, as well as LY uptake under calcium‐deficient conditions. Our data indicate that hemichannels are accessible from the extracytoplasmic side either for direct visualization or functional manipulation. The availability of such a probe will allow in vivo experiments which require selective and/or temporal blocking of gap junctions in animal models. GLIA 24:141–154, 1998. © 1998 Wiley‐Liss, Inc.