Assembly and sealing of tight junctions: possible participation of G-proteins, phospholipase C, protein kinase C and calmodulin.
The making and sealing of a tight junction (TJ) requires cell-cell contacts and Ca2+, and can be gauged through the development of transepithelial electrical resistance (TER) and the accumulation of ZO-1 peptide at the cell borders. We observe that pertussis toxin increases TER, while AIF3 and carbamil choline (carbachol) inhibit it, and 5-guanylylimidodiphosphate (GTPTs) blocks the development of a cell border pattern of ZO-1, suggesting that G-proteins are involved. Phospholipase C (PLC) and protein kinase C (PKC) probably participate in these processes since (i) activation of PLC by thyrotropin-1 releasing hormone increases TER, and its inhibition by neomycin blocks the development of this resistance; (ii) 1,2-dioctanoylglycerol, an activator of PKC, stimulates TER development, while polymyxin B and 1-(5-isoquinoline sulfonyl)-2-methyl-piperazine dihydrochloride (H7), which inhibit this enzyme, abolish TER. Addition of 3-isobutyl-1-methyl-xanthine, dB-cAMP or forskolin do not enhance the value of TER, but have just the opposite effect. Trifluoperazine and calmidazoline inhibit TER development, suggesting that calmodulin (CaM) also plays a role in junction formation. These results indicate that junction formation may be controlled by a network of reactions where G-proteins, phospholipase C, adenylate cyclase, protein kinase C and CaM are involved.
Balda
M S
MS
Center for Research and Advanced Studies, Department of Physiology and Biophysics, D.F., Mexico.
González-Mariscal
L
L
Contreras
R G
RG
Macias-Silva
M
M
Torres-Marquez
M E
ME
García-Sáinz
J A
JA
Cereijido
M
M
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D037361:Adenylate Cyclase Toxin; D000818:Animals; D002118:Calcium / Q000502:physiology; D002147:Calmodulin / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D004553:Electric Conductivity / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism / Q000502:physiology; D019204:GTP-Binding Proteins / Q000502:physiology*; D007365:Intercellular Junctions / Q000378:metabolism / Q000502:physiology*; D007546:Isoquinolines / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009355:Neomycin / Q000494:pharmacology; D037342:Pertussis Toxin; D010879:Piperazines / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D014268:Trifluoperazine / Q000494:pharmacology; D010738:Type C Phospholipases / Q000502:physiology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D002147:Calmodulin; D007546:Isoquinolines; D010879:Piperazines; D010566:Virulence Factors, Bordetella; D014268:Trifluoperazine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D002217:Carbachol; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D009355:Neomycin; D011112:Polymyxin B; D002118:Calcium