Interplay between cystic fibrosis transmembrane regulator and gap junction channels made of connexins 45, 40, 32 and 50 expressed in oocytes.
The cystic fibrosis transmembrane regulator (CFTR) is a Cl(-) channel known to influence other channels, including connexin (Cx) channels. To study the functional interaction between CFTR and gap junction channels, we coexpressed in Xenopus oocytes CFTR and either Cx45, Cx40, Cx32 or Cx50 and monitored junctional conductance (G (j)) and its sensitivity to transjunctional voltage (V (j)) by the dual voltage-clamp method. Application of forskolin induced a Cl(-) current; increased G (j) approximately 750%, 560%, 64% and 8% in Cx45, Cx40, Cx32 and Cx50, respectively; and decreased sensitivity to V (j ) gating, monitored by a change in the ratio between G (j) steady state and G (j) peak (G (j)SS/G (j)PK) at the pulse. In oocyte pairs expressing just Cx45 in one oocyte (#1) and both Cx45 and CFTR in the other (#2), with negative pulses applied to oocyte #1 forskolin application still increased G (j) and decreased the sensitivity to V (j) gating, indicating that CFTR activation is effective even when it affects only one of the two hemichannels and that the G (j) and V (j) changes are not artifacts of decreased membrane resistance in the pulsed oocyte. COOH-terminus truncation reduced the forskolin effect on Cx40 (Cx40TR) but not on Cx32 (Cx32TR) channels. The data suggest a cross-talk between CFTR and a variety of gap junction channels. Cytoskeletal scaffolding proteins and/or other intermediate cytoplasmic proteins are likely to play a role in CFTR-Cx interaction.
Kotsias
Basilio A
BA
Department of Pharmacology and Physiology, University of Rochester School of Medicine, 601 Elmwood Avenue, Rochester, NY 14642-8711, USA.
Salim
Mohammad
M
Peracchia
Lillian L
LL
Peracchia
Camillo
C
D000818:Animals; D002712:Chlorides / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D017629:Gap Junctions / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009865:Oocytes / Q000166:cytology; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins; D014982:Xenopus laevis; D000097002:Gap Junction beta-1 Protein; D000097003:Gap Junction alpha-5 Protein; D000099264:Connexin 50
D002712:Chlorides; D005576:Colforsin; D017630:Connexins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D003598:Cytoskeletal Proteins; D005136:Eye Proteins; D011994:Recombinant Proteins; D000097002:Gap Junction beta-1 Protein; D000097003:Gap Junction alpha-5 Protein; D000099264:Connexin 50; C082920:connexin 45