TY - JOUR
T1 - Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca2+ elevation
AU - Wang, Nan
AU - De Bock, Marijke
AU - Antoons, Gudrun
AU - Gadicherla, Ashish K.
AU - Bol, Mélissa
AU - Decrock, Elke
AU - Evans, William Howard
AU - Sipido, Karin R.
AU - Bukauskas, Feliksas F.
AU - Leybaert, Luc
N1 - Publisher Copyright:
© Springer-Verlag Berlin Heidelberg 2012.
PY - 2012/11/1
Y1 - 2012/11/1
N2 - Connexin mimetic peptides (CxMPs), such as Gap26 and Gap27, are known as inhibitors of gap junction channels but evidence is accruing that these peptides also inhibit unapposed/non-junctional hemichannels (HCs) residing in the plasma membrane. We used voltage clamp studies to investigate the effect of Gap26/27 at the single channel level. Such an approach allows unequivocal identification of HC currents by their single channel conductance that is typically~220 pS for Cx43. In HeLa cells stably transfected with Cx43 (HeLa-Cx43), Gap26/27 peptides inhibited Cx43 HC unitary currents over minutes and increased the voltage threshold for HC opening. By contrast, an elevation of intracellular calcium ([Ca2+]i) to 200–500 nM potentiated the unitary HC current activity and lowered the voltage threshold for HC opening. Interestingly, Gap26/27 inhibited the Ca2+-potentiated HC currents and prevented lowering of the voltage threshold for HC opening. Experiments on isolated pig ventricular cardiomyocytes, which display strong endogenous Cx43 expression, demonstrated voltage-activated unitary currents with biophysical properties of Cx43 HCs that were inhibited by small interfering RNA targeting Cx43. As observed in HeLa-Cx43 cells, HC current activity in ventricular cardiomyocytes was potentiated by [Ca2+]i elevation to 500 nM and was inhibited by Gap26/27. Our results indicate that under pathological conditions, when [Ca2+]i is elevated, Cx43 HC opening is promoted in cardiomyocytes and CxMPs counteract this effect.
AB - Connexin mimetic peptides (CxMPs), such as Gap26 and Gap27, are known as inhibitors of gap junction channels but evidence is accruing that these peptides also inhibit unapposed/non-junctional hemichannels (HCs) residing in the plasma membrane. We used voltage clamp studies to investigate the effect of Gap26/27 at the single channel level. Such an approach allows unequivocal identification of HC currents by their single channel conductance that is typically~220 pS for Cx43. In HeLa cells stably transfected with Cx43 (HeLa-Cx43), Gap26/27 peptides inhibited Cx43 HC unitary currents over minutes and increased the voltage threshold for HC opening. By contrast, an elevation of intracellular calcium ([Ca2+]i) to 200–500 nM potentiated the unitary HC current activity and lowered the voltage threshold for HC opening. Interestingly, Gap26/27 inhibited the Ca2+-potentiated HC currents and prevented lowering of the voltage threshold for HC opening. Experiments on isolated pig ventricular cardiomyocytes, which display strong endogenous Cx43 expression, demonstrated voltage-activated unitary currents with biophysical properties of Cx43 HCs that were inhibited by small interfering RNA targeting Cx43. As observed in HeLa-Cx43 cells, HC current activity in ventricular cardiomyocytes was potentiated by [Ca2+]i elevation to 500 nM and was inhibited by Gap26/27. Our results indicate that under pathological conditions, when [Ca2+]i is elevated, Cx43 HC opening is promoted in cardiomyocytes and CxMPs counteract this effect.
KW - Cardiomyocytes
KW - Connexin 43
KW - Connexin hemichannel
KW - Mimetic peptides
KW - Single channel
UR - http://www.scopus.com/inward/record.url?scp=84867644930&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84867644930&partnerID=8YFLogxK
U2 - 10.1007/s00395-012-0304-2
DO - 10.1007/s00395-012-0304-2
M3 - Article
C2 - 23095853
AN - SCOPUS:84867644930
SN - 0300-8428
VL - 107
SP - 17
JO - Basic research in cardiology
JF - Basic research in cardiology
IS - 6
M1 - 304
ER -