title: Regulation of connexin36 gap junction channels by n-alkanols and arachidonic acid.
abstract: We examined junctional conductance (gj) and its dependence on transjunctional voltage in gap junction (GJ) channels formed of wild-type connexin36 (Cx36) or its fusion form with green fluorescent protein (Cx36-EGFP) transfected in HeLa cells or endogenously expressed in primary culture of pancreatic β-cells. Only a very small fraction (∼0.8%) of Cx36-EGFP channels assembled into junctional plaques of GJs were open under control conditions. We found that short carbon chain n-alkanols (SCCAs) increased gj, while long carbon chain n-alkanols resulted in full uncoupling; cutoff is between heptanol and octanol. The fraction of functional channels and gj increased several fold under an exposure to SCCAs, or during reduction of endogenous levels of arachidonic acid (AA) by exposure to fatty acid-free BSA or cytosolic phospholipase A2 inhibitors. Moreover, uncoupling caused by exogenously applied AA can be rescued by BSA, which binds AA and other polyunsaturated fatty acids (PUFAs), but not by BSA modified with 1,2-cyclohexanedione, which does not bind AA and other PUFAs. We propose that under control conditions, Cx36 GJ channels in HeLa transfectants and β-cells are inhibited by endogenous AA, which stabilizes a closed conformational state of the channel that leads to extremely low fraction of functional channels. In addition, SCCAs increase gj by interfering with endogenous AA-dependent inhibition, increasing open probability and the fraction of functional channels.
authors: Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors: Alina
authors: A
authors: Marandykina
authors: Nicolás
authors: N
authors: Palacios-Prado
authors: Lina
authors: L
authors: Rimkutė
authors: Vytenis A
authors: VA
authors: Skeberdis
authors: Feliksas F
authors: FF
authors: Bukauskas
mesh_terms: D000438:Alcohols / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D002460:Cell Line; D017630:Connexins / Q000502:physiology*; D017629:Gap Junctions / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000502:physiology; D051379:Mice; D012710:Serum Albumin, Bovine / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology; D000097004:Gap Junction delta-2 Protein
chemical_list: D000438:Alcohols; D016718:Arachidonic Acid; D017630:Connexins; D012710:Serum Albumin, Bovine; D019284:Thapsigargin; D000097004:Gap Junction delta-2 Protein