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CO 2 ‐dependent opening of connexin 26 and related β connexins
Author(s) -
Huckstepp Robert T. R.,
Eason Robert,
Sachdev Anshu,
Dale Nicholas
Publication year - 2010
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2010.192096
Subject(s) - connexin , extracellular , gap junction , heterologous , hela , heterologous expression , microbiology and biotechnology , intracellular , chemistry , biology , biophysics , biochemistry , in vitro , gene , recombinant dna
We have previously shown connexin mediated CO 2 ‐dependent ATP release from the surface of the medulla oblongata. Given the localization of connexin 26 (Cx26) to the chemosensing areas of the medulla, we have tested in a heterologous expression system (HeLa cells) whether Cx26 may be sensitive to changes in . Cx26 responded to an increase in at constant extracellular pH by opening and to a decrease in by closing. Furthermore, Cx26 was partially activated at a physiological of around 40 mmHg. Cx26 in isolated patches responded to changes in , suggesting direct CO 2 sensitivity of the hemichannel to CO 2 . Heterologous expression of Cx26 in HeLa cells was sufficient to endow them with the capacity to release ATP in a CO 2 ‐sensitive manner. We have examined other heterologously expressed connexins for their ability to respond to changes in . The closely related β connexins Cx30 and Cx32 also displayed sensitivity to changes in , but with slightly different characteristics from Cx26. The more distant Cx43 exhibited CO 2 ‐dependent closing (possibly mediated through intracellular acidification), while Cx36 displayed no CO 2 sensitivity. These surprising findings suggest that connexins may play a hitherto unappreciated variety of signalling roles, and that Cx26 and related β connexins may impart direct sensitivity to CO 2 throughout the brain.