Connexin43 hemichannels mediate secondary cellular damage spread from the trauma zone to distal zones in astrocyte monolayers.
The mechanism of secondary damage spread after brain trauma remains unsolved. In this work, we redirected the attention to astrocytic communication pathways. Using an in vitro trauma model that consists of a scratch injury applied to an astrocyte monolayer, we found a significant and transient induction of connexin43 (Cx43) hemichannel activity in regions distal from the injury, which was maximal ∼1 h after scratch. Two connexin hemichannel blockers, La(3+) and the peptide Gap26, abolished the increased activity, which was also absent in Cx43 KO astrocytes. In addition, the scratch-induced increase of hemichannel activity was prevented by inhibition of P2 purinergic receptors. Changes in hemichannel activity took place with a particular spatial distribution, with cells located at ∼17 mm away from the scratch presenting the highest activity (dye uptake). In contrast, the functional state of gap junction channels (dye coupling) was not significantly affected. Cx43 hemichannel activity was also enhanced by the acute extracellular application of 60 mM K(+) . The increase in hemichannel activity was associated with an increment in apoptotic cells at 24 h after scratch that was totally prevented by Gap26 peptide. These findings suggest that Cx43 hemichannels could be a new approach to prevent or reduce the secondary cell damage of brain trauma.
Laboratorio de Neurociencias, Departamento de Neurología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; Departamento de Medicina Intensiva, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
Maximiliano
M
Rovegno
Paola A
PA
Soto
Pablo J
PJ
Sáez
Christian C
CC
Naus
Juan C
JC
Sáez
Rommy
R
von Bernhardi
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D001930:Brain Injuries; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002491:Central Nervous System Agents / Q000494:pharmacology; D018031:Connexin 43 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D018345:Mice, Knockout; D010455:Peptides / Q000008:administration & dosage; D011188:Potassium / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000378:metabolism
D002491:Central Nervous System Agents; D018031:Connexin 43; C543076:GJA1 protein, mouse; C514423:Gap 26 peptide; C580592:Gja1 protein, rat; D010455:Peptides; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D011188:Potassium
P2 receptors; apoptosis; astroglia; connexins; traumatic brain injury