Gap-junction coupling can prolong beta-cell burst period by an order of magnitude via phantom bursting

2018 ◽  
Vol 28 (6) ◽  
pp. 063111 ◽  
Author(s):  
Alessandro Loppini ◽  
Morten Gram Pedersen
Keyword(s):  
Beta Cell ◽  
Gap Junction ◽  
Burst Period ◽  
Gap Junction Coupling ◽  
Order Of Magnitude ◽  
Junction Coupling

Investigation of the roles of Ca2+ and InsP3 diffusion in the coordination of Ca2+ signals between connected hepatocytes

2001 ◽  
Vol 114 (11) ◽  
pp. 1999-2007
Author(s):  
Caroline Clair ◽  
Cécile Chalumeau ◽  
Thierry Tordjmann ◽  
Josiane Poggioli ◽  
Christophe Erneux ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Significant Role ◽  
Signaling Molecules ◽  
Rat Hepatocyte ◽  
Inositol 1,4,5 Trisphosphate ◽  
Gap Junction Coupling ◽  
Junction Coupling ◽  
Insp3 Receptor

Glycogenolytic agonists induce coordinated Ca2+ oscillations in multicellular rat hepatocyte systems as well as in the intact liver. The coordination of intercellular Ca2+ signals requires functional gap-junction coupling. The mechanisms ensuring this coordination are not precisely known. We investigated possible roles of Ca2+ or inositol 1,4,5-trisphosphate (InsP3) as a coordinating messengers for Ca2+ spiking among connected hepatocytes. Application of ionomycin or of supra-maximal concentrations of agonists show that Ca2+ does not significantly diffuse between connected hepatocytes, although gap junctions ensure the passage of small signaling molecules, as demonstrated by FRAP experiments. By contrast, coordination of Ca2+ spiking among connected hepatocytes can be favored by a rise in the level of InsP3, via the increase of agonist concentrations, or by a shift in the affinity of InsP3 receptor for InsP3. In the same line, coordination cannot be achieved if the InsP3 is rapidly metabolized by InsP3-phosphatase in one cell of the multiplet. These results demonstrate that even if small amounts of Ca2+ diffuse across gap junctions, they most probably do not play a significant role in inducing a coordinated Ca2+ signal among connected hepatocytes. By contrast, coordination of Ca2+ oscillations is fully dependent on the diffusion of InsP3 between neighboring cells.

Abstract 336: A 14-3-3 Mode-1 Binding Motif Promotes Gap Junction Internalization During Acute Cardiac Ischemia

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
James W Smyth ◽  
Jose M Sanchez ◽  
Samy Lamouille ◽  
Ting-Ting Hong ◽  
Jacob M Vogan ◽  
...  
Keyword(s):  
Gap Junction ◽  
Protein Trafficking ◽  
Connexin 43 ◽  
Electrical Coupling ◽  
Acute Ischemia ◽  
Binding Motif ◽  
Wild Type ◽  
Gap Junction Coupling ◽  
Junction Coupling ◽  
Cell Cell

During each heartbeat, robust cell-cell electrical coupling via connexin 43 (Cx43) gap junctions allows billions of individual cardiomyocytes to contract in synchrony. Cx43 turns over rapidly, and altered Cx43 trafficking during disease contributes to the arrhythmias of sudden cardiac death. The overall phosphorylation status of the Cx43 protein is known to regulate gap junction coupling, but the role of many residue specific phosphorylation events remains unknown. One such residue, Ser373, forms a mode-1 14-3-3 binding motif upon phosphorylation. Given that 14-3-3 proteins are known to regulate protein trafficking, we hypothesized a role for Cx43 Ser373 phosphorylation in regulation of Cx43 gap junction coupling. Using Langendorff-perfused mouse hearts we find robust phosphorylation of Cx43 at Ser373 and Ser368 after 30 min of no-flow ischemia. In human cell lines, a S373A mutation ablated Cx43/14-3-3 complexing and 35 S pulse-chase revealed Cx43 S373A also experiences a longer half-life than wild-type Cx43. Previous reports have implicated phosphorylation of Cx43 Ser368 in PKC mediated Cx43 internalization. We find that upon activation of PKC, the Cx43 S373A mutant undergoes lower and more transient levels of phosphorylation at Ser368 than wild-type Cx43. Consistent with these data, siRNA-mediated ablation of 14-3-3 expression results in enlargement of gap junction plaque formation at cell-cell borders. In conclusion, we propose that phosphorylation of Cx43 Ser373 results in 14-3-3 binding which promotes and maintains phosphorylation of Cx43 Ser368 and the subsequent internalization of gap junction channels. These results identify for the first time a specific role for 14-3-3 proteins in regulation of Cx43 internalization during acute ischemia and contribute to the development of therapies aimed at preserving or enhancing gap junction coupling in the heart.

scholarly journals BAAV Mediated GJB2 Gene Transfer Restores Gap Junction Coupling in Cochlear Organotypic Cultures from Deaf Cx26Sox10Cre Mice

PLoS ONE ◽  
2011 ◽  
Vol 6 (8) ◽  
pp. e23279 ◽  
Author(s):  
Giulia Crispino ◽  
Giovanni Di Pasquale ◽  
Pietro Scimemi ◽  
Laura Rodriguez ◽  
Fabian Galindo Ramirez ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Gap Junction ◽  
Gjb2 Gene ◽  
Organotypic Cultures ◽  
Gap Junction Coupling ◽  
Junction Coupling

scholarly journals Neuronal Gap Junction Coupling Is Regulated by Glutamate and Plays Critical Role in Cell Death during Neuronal Injury

2012 ◽  
Vol 32 (2) ◽  
pp. 713-725 ◽  
Author(s):  
Y. Wang ◽  
J.-H. Song ◽  
J. V. Denisova ◽  
W.-M. Park ◽  
J. D. Fontes ◽  
...  
Keyword(s):  
Cell Death ◽  
Gap Junction ◽  
Critical Role ◽  
Neuronal Injury ◽  
Gap Junction Coupling ◽  
Junction Coupling

scholarly journals Gap Junction Coupling Shapes the Encoding of Light in the Developing Retina

2020 ◽  
Vol 30 (1) ◽  
pp. 185
Author(s):  
Franklin Caval-Holme ◽  
Marla B. Feller
Keyword(s):  
Gap Junction ◽  
Gap Junction Coupling ◽  
Junction Coupling
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