Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca 2+ elevation

Nan Wang, Marijke De Bock, Gudrun Antoons, Ashish K. Gadicherla, Mélissa Bol, Elke Decrock, William Howard Evans, Karin R. Sipido, Feliksas F. Bukauskas, Luc Leybaert

Research output: Contribution to journalArticle

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Abstract

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 ([Ca 2+] i) to 200-500 nM potentiated the unitary HC current activity and lowered the voltage threshold for HC opening. Interestingly, Gap26/27 inhibited the Ca 2+-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 [Ca 2+] i elevation to 500 nM and was inhibited by Gap26/27. Our results indicate that under pathological conditions, when [Ca 2+] i is elevated, Cx43 HC opening is promoted in cardiomyocytes and CxMPs counteract this effect.

Original languageEnglish (US)
Pages (from-to)1-17
Number of pages17
JournalBasic Research in Cardiology
Volume107
Issue number6
DOIs
StateAccepted/In press - Nov 2012

Fingerprint

Connexin 43
Connexins
Peptides
Cardiac Myocytes
HeLa Cells
Gap Junctions
Small Interfering RNA
Swine
Cell Membrane
Calcium

Keywords

  • Cardiomyocytes
  • Connexin 43
  • Connexin hemichannel
  • Mimetic peptides
  • Single channel

ASJC Scopus subject areas

  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine
  • Physiology

Cite this

Wang, N., De Bock, M., Antoons, G., Gadicherla, A. K., Bol, M., Decrock, E., ... Leybaert, L. (Accepted/In press). Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca 2+ elevation. Basic Research in Cardiology, 107(6), 1-17. https://doi.org/10.1007/s00395-012-0304-2

Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca 2+ elevation. / Wang, Nan; De Bock, Marijke; Antoons, Gudrun; Gadicherla, Ashish K.; Bol, Mélissa; Decrock, Elke; Evans, William Howard; Sipido, Karin R.; Bukauskas, Feliksas F.; Leybaert, Luc.

In: Basic Research in Cardiology, Vol. 107, No. 6, 11.2012, p. 1-17.

Research output: Contribution to journalArticle

Wang, N, De Bock, M, Antoons, G, Gadicherla, AK, Bol, M, Decrock, E, Evans, WH, Sipido, KR, Bukauskas, FF & Leybaert, L 2012, 'Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca 2+ elevation', Basic Research in Cardiology, vol. 107, no. 6, pp. 1-17. https://doi.org/10.1007/s00395-012-0304-2
Wang, Nan ; De Bock, Marijke ; Antoons, Gudrun ; Gadicherla, Ashish K. ; Bol, Mélissa ; Decrock, Elke ; Evans, William Howard ; Sipido, Karin R. ; Bukauskas, Feliksas F. ; Leybaert, Luc. / Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca 2+ elevation. In: Basic Research in Cardiology. 2012 ; Vol. 107, No. 6. pp. 1-17.
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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

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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 ([Ca 2+] i) to 200-500 nM potentiated the unitary HC current activity and lowered the voltage threshold for HC opening. Interestingly, Gap26/27 inhibited the Ca 2+-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 [Ca 2+] i elevation to 500 nM and was inhibited by Gap26/27. Our results indicate that under pathological conditions, when [Ca 2+] i is elevated, Cx43 HC opening is promoted in cardiomyocytes and CxMPs counteract this effect.

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