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Connexin 43 hemichannels contribute to cytoplasmic Ca2+ oscillations by providing a bimodal Ca2+-dependent Ca2+ entry pathway

Marijke De Bock UGent, Nan Wang UGent, Mélissa Bol UGent, Elke Decrock UGent, Raf Ponsaerts, Geert Bultynck, Gnenviève Dupont and Luc Leybaert UGent (2012) JOURNAL OF BIOLOGICAL CHEMISTRY. 287(15). p.12250-12266
abstract
Many cellular functions are driven by changes in the intracellular Ca2+ concentration ([Ca2+](i)) that are highly organized in time and space. Ca2+ oscillations are particularly important in this respect and are based on positive and negative [Ca2+](i) feedback on inositol 1,4,5-trisphosphate receptors (InsP(3)Rs). Connexin hemichannels are Ca2+-permeable plasma membrane channels that are also controlled by [Ca2+](i). We aimed to investigate how hemichannels may contribute to Ca2+ oscillations. Madin-Darby canine kidney cells expressing connexin-32 (Cx32) and Cx43 were exposed to bradykinin (BK) or ATP to induce Ca2+ oscillations. BK-induced oscillations were rapidly (minutes) and reversibly inhibited by the connexin-mimetic peptides (32)Gap27/(43)Gap26, whereas ATP-induced oscillations were unaffected. Furthermore, these peptides inhibited the BK-triggered release of calcein, a hemichannel-permeable dye. BK-induced oscillations, but not those induced by ATP, were dependent on extracellular Ca2+. Alleviating the negative feedback of [Ca2+](i) on InsP(3)Rs using cytochrome c inhibited BK- and ATP-induced oscillations. Cx32 and Cx43 hemichannels are activated by < 500 nM [Ca2+](i) but inhibited by higher concentrations and CT9 peptide (last 9 amino acids of the Cx43 C terminus) removes this high [Ca2+](i) inhibition. Unlike interfering with the bell-shaped dependence of InsP3Rs to [Ca2+](i), CT9 peptide prevented BK-induced oscillations but not those triggered by ATP. Collectively, these data indicate that connexin hemichannels contribute to BK-induced oscillations by allowing Ca2+ entry during the rising phase of the Ca2+ spikes and by providing an OFF mechanism during the falling phase of the spikes. Hemichannels were not sufficient to ignite oscillations by themselves; however, their contribution was crucial as hemichannel inhibition stopped the oscillations.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
INOSITOL 1, PROTEIN-KINASE-C, 4, 5-TRISPHOSPHATE RECEPTOR, CAPACITATIVE CALCIUM-ENTRY, GAP-JUNCTION CHANNELS, BLOOD-BRAIN-BARRIER, CANINE KIDNEY-CELLS, ATP RELEASE, 2-AMINOETHOXYDIPHENYL BORATE, EXTRACELLULAR CALCIUM, ENDOTHELIAL-CELLS
journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
J. Biol. Chem.
volume
287
issue
15
pages
12250 - 12266
Web of Science type
Article
Web of Science id
000302782200066
JCR category
BIOCHEMISTRY & MOLECULAR BIOLOGY
JCR impact factor
4.651 (2012)
JCR rank
61/288 (2012)
JCR quartile
1 (2012)
ISSN
0021-9258
DOI
10.1074/jbc.M111.299610
language
English
UGent publication?
yes
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
2106360
handle
http://hdl.handle.net/1854/LU-2106360
date created
2012-05-14 20:50:01
date last changed
2012-05-15 09:05:20
@article{2106360,
  abstract     = {Many cellular functions are driven by changes in the intracellular Ca2+ concentration ([Ca2+](i)) that are highly organized in time and space. Ca2+ oscillations are particularly important in this respect and are based on positive and negative [Ca2+](i) feedback on inositol 1,4,5-trisphosphate receptors (InsP(3)Rs). Connexin hemichannels are Ca2+-permeable plasma membrane channels that are also controlled by [Ca2+](i). We aimed to investigate how hemichannels may contribute to Ca2+ oscillations. Madin-Darby canine kidney cells expressing connexin-32 (Cx32) and Cx43 were exposed to bradykinin (BK) or ATP to induce Ca2+ oscillations. BK-induced oscillations were rapidly (minutes) and reversibly inhibited by the connexin-mimetic peptides (32)Gap27/(43)Gap26, whereas ATP-induced oscillations were unaffected. Furthermore, these peptides inhibited the BK-triggered release of calcein, a hemichannel-permeable dye. BK-induced oscillations, but not those induced by ATP, were dependent on extracellular Ca2+. Alleviating the negative feedback of [Ca2+](i) on InsP(3)Rs using cytochrome c inhibited BK- and ATP-induced oscillations. Cx32 and Cx43 hemichannels are activated by {\textlangle} 500 nM [Ca2+](i) but inhibited by higher concentrations and CT9 peptide (last 9 amino acids of the Cx43 C terminus) removes this high [Ca2+](i) inhibition. Unlike interfering with the bell-shaped dependence of InsP3Rs to [Ca2+](i), CT9 peptide prevented BK-induced oscillations but not those triggered by ATP. Collectively, these data indicate that connexin hemichannels contribute to BK-induced oscillations by allowing Ca2+ entry during the rising phase of the Ca2+ spikes and by providing an OFF mechanism during the falling phase of the spikes. Hemichannels were not sufficient to ignite oscillations by themselves; however, their contribution was crucial as hemichannel inhibition stopped the oscillations.},
  author       = {De Bock, Marijke and Wang, Nan and Bol, M{\'e}lissa and Decrock, Elke and Ponsaerts, Raf and Bultynck, Geert and Dupont, Gnenvi{\`e}ve and Leybaert, Luc},
  issn         = {0021-9258},
  journal      = {JOURNAL OF BIOLOGICAL CHEMISTRY},
  keyword      = {INOSITOL 1,PROTEIN-KINASE-C,4,5-TRISPHOSPHATE RECEPTOR,CAPACITATIVE CALCIUM-ENTRY,GAP-JUNCTION CHANNELS,BLOOD-BRAIN-BARRIER,CANINE KIDNEY-CELLS,ATP RELEASE,2-AMINOETHOXYDIPHENYL BORATE,EXTRACELLULAR CALCIUM,ENDOTHELIAL-CELLS},
  language     = {eng},
  number       = {15},
  pages        = {12250--12266},
  title        = {Connexin 43 hemichannels contribute to cytoplasmic Ca2+ oscillations by providing a bimodal Ca2+-dependent Ca2+ entry pathway},
  url          = {http://dx.doi.org/10.1074/jbc.M111.299610},
  volume       = {287},
  year         = {2012},
}

Chicago
De Bock, Marijke, Nan Wang, Mélissa Bol, Elke Decrock, Raf Ponsaerts, Geert Bultynck, Gnenviève Dupont, and Luc Leybaert. 2012. “Connexin 43 Hemichannels Contribute to Cytoplasmic Ca2+ Oscillations by Providing a Bimodal Ca2+-dependent Ca2+ Entry Pathway.” Journal of Biological Chemistry 287 (15): 12250–12266.
APA
De Bock, Marijke, Wang, N., Bol, M., Decrock, E., Ponsaerts, R., Bultynck, G., Dupont, G., et al. (2012). Connexin 43 hemichannels contribute to cytoplasmic Ca2+ oscillations by providing a bimodal Ca2+-dependent Ca2+ entry pathway. JOURNAL OF BIOLOGICAL CHEMISTRY, 287(15), 12250–12266.
Vancouver
1.
De Bock M, Wang N, Bol M, Decrock E, Ponsaerts R, Bultynck G, et al. Connexin 43 hemichannels contribute to cytoplasmic Ca2+ oscillations by providing a bimodal Ca2+-dependent Ca2+ entry pathway. JOURNAL OF BIOLOGICAL CHEMISTRY. 2012;287(15):12250–66.
MLA
De Bock, Marijke, Nan Wang, Mélissa Bol, et al. “Connexin 43 Hemichannels Contribute to Cytoplasmic Ca2+ Oscillations by Providing a Bimodal Ca2+-dependent Ca2+ Entry Pathway.” JOURNAL OF BIOLOGICAL CHEMISTRY 287.15 (2012): 12250–12266. Print.