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The contractile system as a negative regulator of the connexin 43 hemichannel

(2012) BIOLOGY OF THE CELL. 104(7). p.367-377
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Abstract
The molecular mechanisms underlying the regulation of gap junction (GJ) channels based on the 43-kDa connexin isoform (Cx43) have been studied extensively. GJ channels are formed by the docking of opposed hemichannels in adjacent cells. Mounting data indicate that unopposed Cx43 hemichannels are also functional in the plasma membrane. However, our understanding of how Cx43-hemichannel opening and closing is regulated at the molecular level is only poorly understood. Recent work elucidated that actomyosin contractility inhibits potently Cx43 hemichannels. It is known that intracellular Ca2+ exerts a bell-shaped-dependent effect on Cx43-hemichannel opening. While low-intracellular [Ca2+] (<500 nM) provokes opening of the channel, high-intracellular [Ca2+] (> 500 nM) favours closing of the channel. The mechanism underlying this negative regulation of Cx43-hemichannel activity by high-intracellular [Ca2+] seems to be dependent on the activation of the actomyosin contractile system. The activity of Cx43 hemichannels is critically controlled by molecular interactions between the intracellular loop and the C-terminal tail. These interactions are essential for Cx43-hemichannel opening in response to triggers such as cytosolic [Ca2+] rise or external [Ca2+] lowering. In this review, we present the hypothesis that the actomyosin contractile system can function as an important brake mechanism on Cx43-hemichannel opening. By controlling looptail interactions, the contractile system would prevent aberrant or excessive opening of Cx43 hemichannels.
Keywords
CARBOXYL-TERMINUS, CORNEAL ENDOTHELIAL-CELLS, ATP release, ZONULA OCCLUDENS-1, intramolecular interactions, CALCIUM WAVE-PROPAGATION, MYOSIN-II, LIGHT-CHAIN, MEMBRANE PERMEABILIZATION, connexin hemichannel, CYTOPLASMIC LOOP, actomyosin contractility, calcium, GAP-JUNCTION CHANNELS, SCANNING CONFOCAL MICROSCOPY

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Citation

Please use this url to cite or link to this publication:

Chicago
Ponsaerts, Raf, Nan Wang, Bernard Himpens, Luc Leybaert, and Geert Bultynck. 2012. “The Contractile System as a Negative Regulator of the Connexin 43 Hemichannel.” Biology of the Cell 104 (7): 367–377.
APA
Ponsaerts, R., Wang, N., Himpens, B., Leybaert, L., & Bultynck, G. (2012). The contractile system as a negative regulator of the connexin 43 hemichannel. BIOLOGY OF THE CELL, 104(7), 367–377.
Vancouver
1.
Ponsaerts R, Wang N, Himpens B, Leybaert L, Bultynck G. The contractile system as a negative regulator of the connexin 43 hemichannel. BIOLOGY OF THE CELL. 2012;104(7):367–77.
MLA
Ponsaerts, Raf, Nan Wang, Bernard Himpens, et al. “The Contractile System as a Negative Regulator of the Connexin 43 Hemichannel.” BIOLOGY OF THE CELL 104.7 (2012): 367–377. Print.
@article{2106503,
  abstract     = {The molecular mechanisms underlying the regulation of gap junction (GJ) channels based on the 43-kDa connexin isoform (Cx43) have been studied extensively. GJ channels are formed by the docking of opposed hemichannels in adjacent cells. Mounting data indicate that unopposed Cx43 hemichannels are also functional in the plasma membrane. However, our understanding of how Cx43-hemichannel opening and closing is regulated at the molecular level is only poorly understood. Recent work elucidated that actomyosin contractility inhibits potently Cx43 hemichannels. It is known that intracellular Ca2+ exerts a bell-shaped-dependent effect on Cx43-hemichannel opening. While low-intracellular [Ca2+] ({\textlangle}500 nM) provokes opening of the channel, high-intracellular [Ca2+] ({\textrangle} 500 nM) favours closing of the channel. The mechanism underlying this negative regulation of Cx43-hemichannel activity by high-intracellular [Ca2+] seems to be dependent on the activation of the actomyosin contractile system. The activity of Cx43 hemichannels is critically controlled by molecular interactions between the intracellular loop and the C-terminal tail. These interactions are essential for Cx43-hemichannel opening in response to triggers such as cytosolic [Ca2+] rise or external [Ca2+] lowering. In this review, we present the hypothesis that the actomyosin contractile system can function as an important brake mechanism on Cx43-hemichannel opening. By controlling looptail interactions, the contractile system would prevent aberrant or excessive opening of Cx43 hemichannels.},
  author       = {Ponsaerts, Raf and Wang, Nan and Himpens, Bernard and Leybaert, Luc and Bultynck, Geert},
  issn         = {0248-4900},
  journal      = {BIOLOGY OF THE CELL},
  keyword      = {CARBOXYL-TERMINUS,CORNEAL ENDOTHELIAL-CELLS,ATP release,ZONULA OCCLUDENS-1,intramolecular interactions,CALCIUM WAVE-PROPAGATION,MYOSIN-II,LIGHT-CHAIN,MEMBRANE PERMEABILIZATION,connexin hemichannel,CYTOPLASMIC LOOP,actomyosin contractility,calcium,GAP-JUNCTION CHANNELS,SCANNING CONFOCAL MICROSCOPY},
  language     = {eng},
  number       = {7},
  pages        = {367--377},
  title        = {The contractile system as a negative regulator of the connexin 43 hemichannel},
  url          = {http://dx.doi.org/10.1111/boc.201100079},
  volume       = {104},
  year         = {2012},
}

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