Faculty Opinions recommendation of Gap junction channels exhibit connexin-specific permeability to cyclic nucleotides.

2008 ◽  
Author(s):  
Eric Beyer
Keyword(s):  
Gap Junction ◽  
Cyclic Nucleotides ◽  
Gap Junction Channels ◽  
Specific Permeability

Gap Junction Channels Exhibit Connexin-specific Permeability to Cyclic Nucleotides

2008 ◽  
Vol 181 (2) ◽  
pp. i8-i8
Author(s):  
Giedrius Kanaporis ◽  
Gulistan Mese ◽  
Laima Valiuniene ◽  
Thomas W. White ◽  
Peter R. Brink ◽  
...  
Keyword(s):  
Gap Junction ◽  
Cyclic Nucleotides ◽  
Gap Junction Channels ◽  
Specific Permeability

scholarly journals Gap junction permeability: selectivity for anionic and cationic probes

2011 ◽  
Vol 300 (3) ◽  
pp. C600-C609 ◽  
Author(s):  
G. Kanaporis ◽  
P. R. Brink ◽  
V. Valiunas
Keyword(s):  
Gap Junction ◽  
Lucifer Yellow ◽  
Second Messengers ◽  
Small Interfering Rnas ◽  
Weak Charge ◽  
Axial Diameter ◽  
Gap Junction Channels ◽  
Charge Selectivity ◽  
Specific Permeability ◽  
A Charge

Gap junction channels formed by different connexins exhibit specific permeability to a variety of larger solutes including second messengers, polypeptides, and small interfering RNAs. Here, we report the permeability of homotypic connexin26 (Cx26), Cx40, Cx43, and Cx45 gap junction channels stably expressed in HeLa cells to solutes with different size and net charge. Channel permeability was determined using simultaneous measurements of junctional conductance and the cell-cell flux of a fluorescent probe. All four connexins allowed passage of both cationic and anionic probes, but the transfer rates were connexin dependent. The negatively charged probes [Lucifer yellow (LY; median axial diameter 9.9 Å, charge −2), carboxyfluorescein (CF; 8.2 Å; −2), and Alexa Fluor350 (AF350, 5.4 Å; −1)] exhibited the following permeability order: Cx43 > Cx45 > Cx26 > Cx40. In contrast, for the positively charged species permeability, the orders were as follows: Cx26 ≈ Cx43 ≈ Cx40 ≈ Cx45 for N, N, N-trimethyl-2-[methyl-(7-nitro-2,1,3-benzoxadiol-4-yl) amino] ethanaminium (NBD-m-TMA; 5.5 Å, +1) and Cx26 ≥ Cx43 ≈ Cx40 > Cx45 for ethidium bromide (10.3 Å, +1). Comparison of probe permeability relative to K+ revealed that Cx43 and Cx45 exhibited similar permeability for NBD-m-TMA and AF350, indicating weak charge selectivity. However, lesser transfer of CF and LY through Cx45 relative to Cx43 channels suggests stronger size-dependent discrimination of solute. The permeability of NBD-m-TMA for Cx40 and Cx26 channels was approximately three times higher than to anionic AF350 despite the fact that both have similar minor diameters, suggesting charge selectivity. In conclusion, these results confirm that channels formed from individual connexins can discriminate for solutes based on size and charge, suggesting that channel selectivity may be a key factor in cell signaling.

scholarly journals Gap Junction Channels Exhibit Connexin-specific Permeability to Cyclic Nucleotides

2008 ◽  
Vol 131 (4) ◽  
pp. 293-305 ◽  
Author(s):  
Giedrius Kanaporis ◽  
Gulistan Mese ◽  
Laima Valiuniene ◽  
Thomas W. White ◽  
Peter R. Brink ◽  
...  
Keyword(s):  
Gap Junction ◽  
Cyclic Nucleotide ◽  
Recipient Cell ◽  
Second Messengers ◽  
Functional Changes ◽  
Gap Junction Channels ◽  
Wide Range ◽  
Junctional Conductance ◽  
Specific Permeability

Gap junction channels exhibit connexin dependent biophysical properties, including selective intercellular passage of larger solutes, such as second messengers and siRNA. Here, we report the determination of cyclic nucleotide (cAMP) permeability through gap junction channels composed of Cx43, Cx40, or Cx26 using simultaneous measurements of junctional conductance and intercellular transfer of cAMP. For cAMP detection the recipient cells were transfected with a reporter gene, the cyclic nucleotide-modulated channel from sea urchin sperm (SpIH). cAMP was introduced via patch pipette into the cell of the pair that did not express SpIH. SpIH-derived currents (Ih) were recorded from the other cell of a pair that expressed SpIH. cAMP diffusion through gap junction channels to the neighboring SpIH-transfected cell resulted in a five to sixfold increase in Ih current over time. Cyclic AMP transfer was observed for homotypic Cx43 channels over a wide range of conductances. However, homotypic Cx40 and homotypic Cx26 exhibited reduced cAMP permeability in comparison to Cx43. The cAMP/K+ permeability ratios were 0.18, 0.027, and 0.018 for Cx43, Cx26, and Cx40, respectively. Cx43 channels were ∼10 to 7 times more permeable to cAMP than Cx40 or Cx26 (Cx43 > Cx26 ≥ Cx40), suggesting that these channels have distinctly different selectivity for negatively charged larger solutes involved in metabolic/biochemical coupling. These data suggest that Cx43 permeability to cAMP results in a rapid delivery of cAMP from cell to cell in sufficient quantity before degradation by phosphodiesterase to trigger relevant intracellular responses. The data also suggest that the reduced permeability of Cx26 and Cx40 might compromise their ability to deliver cAMP rapidly enough to cause functional changes in a recipient cell.

scholarly journals Two Drosophila Innexins Are Expressed in Overlapping Domains and Cooperate to Form Gap-Junction Channels

2000 ◽  
Vol 11 (7) ◽  
pp. 2459-2470 ◽  
Author(s):  
Lucy A. Stebbings ◽  
Martin G. Todman ◽  
Pauline Phelan ◽  
Jonathan P. Bacon ◽  
Jane A. Davies
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Ectopic Expression ◽  
In Vivo Studies ◽  
Electrophysiological Properties ◽  
Gap Junction Channels ◽  
Overlapping Domains ◽  
In Vitro Data

Members of the innexin protein family are structural components of invertebrate gap junctions and are analogous to vertebrate connexins. Here we investigate two Drosophila innexin genes,Dm-inx2 and Dm-inx3 and show that they are expressed in overlapping domains throughout embryogenesis, most notably in epidermal cells bordering each segment. We also explore the gap-junction–forming capabilities of the encoded proteins. In pairedXenopus oocytes, the injection of Dm-inx2mRNA results in the formation of voltage-sensitive channels in only ∼ 40% of cell pairs. In contrast, Dm-Inx3 never forms channels. Crucially, when both mRNAs are coexpressed, functional channels are formed reliably, and the electrophysiological properties of these channels distinguish them from those formed by Dm-Inx2 alone. We relate these in vitro data to in vivo studies. Ectopic expression ofDm-inx2 in vivo has limited effects on the viability ofDrosophila, and animals ectopically expressingDm-inx3 are unaffected. However, ectopic expression of both transcripts together severely reduces viability, presumably because of the formation of inappropriate gap junctions. We conclude that Dm-Inx2 and Dm-Inx3, which are expressed in overlapping domains during embryogenesis, can form oligomeric gap-junction channels.

scholarly journals Regulation of gap junction channels by infectious agents and inflammation in the CNS

2014 ◽  
Vol 8 ◽  
Author(s):  
Paul Castellano ◽  
Eliseo A. Eugenin
Keyword(s):  
Gap Junction ◽  
Infectious Agents ◽  
Gap Junction Channels

scholarly journals Cannabinoids prevent the opposite regulation of astroglial connexin43 hemichannels and gap junction channels induced by pro-inflammatory treatments

2009 ◽  
Vol 111 (6) ◽  
pp. 1383-1397 ◽  
Author(s):  
Nicolas Froger ◽  
Juan A. Orellana ◽  
Martine Cohen-Salmon ◽  
Pascal Ezan ◽  
Edwige Amigou ◽  
...  
Keyword(s):  
Gap Junction ◽  
Gap Junction Channels
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