Connexin43 and pannexin1 channels in osteoblasts: who is the "hemichannel"?
Osteoblasts sense and respond to mechanical stimuli in a process involving influx and release of large ions and signaling molecules. Unapposed gap junction hemichannels formed of connexin43 (Cx43) have been proposed as a major route for such exchange, in particular for release of ATP and prostaglandin E₂ (PGE₂) in osteocytes. However, we have found that Cx43-null osteoblasts have unaltered, mechanically induced PGE₂ release and ATP-induced YoPro dye uptake. In contrast, PGE₂ release in response to fluid shear stress is abolished in P2X₇ receptor (P2X₇R)-null osteoblasts, and ATP-induced dye uptake is attenuated following treatment of wild-type cells with a P2X₇R or Pannexin1 (Panx1) channel blocker. These data indicate that Panx1 channels, in concert with P2X₇R, likely form a molecular complex that performs the hemichannel function in osteoblast mechanosignaling.
Department of Orthopedic Surgery, Albert Einstein College of Medicine, Bronx, NY 10461, USA. mia.thi@einstein.yu.edu
Mia M
MM
Thi
Shalena
S
Islam
Sylvia O
SO
Suadicani
David C
DC
Spray
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism*; D017630:Connexins / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism*; D010011:Osteocytes / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism
D018031:Connexin 43; D017630:Connexins; D009419:Nerve Tissue Proteins; C503631:Panx1 protein, mouse; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D015232:Dinoprostone