The tyrosine kinase p56lck mediates activation of swelling-induced chloride channels in lymphocytes.
Osmotic cell swelling activates Cl- channels to achieve anion efflux. In this study, we find that both the tyrosine kinase inhibitor herbimycin A and genetic knockout of p56lck, a src-like tyrosine kinase, block regulatory volume decrease (RVD) in a human T cell line. Activation of a swelling-activated chloride current (ICl-swell) by osmotic swelling in whole-cell patch-clamp experiments is blocked by herbimycin A and lavendustin. Osmotic activation of ICl-swell is defective in p56lck-deficient cells. Retransfection of p56lck restores osmotic current activation. Furthermore, tyrosine kinase activity is sufficient for activation of ICl-swell. Addition of purified p56lck to excised patches activates an outwardly rectifying chloride channel with 31 pS unitary conductance. Purified p56lck washed into the cytoplasm activates ICl-swell in native and p56lck-deficient cells even when hypotonic intracellular solutions lead to cell shrinkage. When whole-cell currents are activated either by swelling or by p56lck, slow single-channel gating events can be observed revealing a unitary conductance of 25-28 pS. In accordance with our patch-clamp data, osmotic swelling increases activity of immunoprecipitated p56lck. We conclude that osmotic swelling activates ICl-swell in lymphocytes via the tyrosine kinase p56lck.
Lepple-Wienhues
A
A
Department of Physiology, University of Tübingen, D-72076 Tübingen, Germany. alepplew@uni-tuebingen.de
Szabò
I
I
Laun
T
T
Kaba
N K
NK
Gulbins
E
E
Lang
F
F
D016227:Benzoquinones; D002460:Cell Line; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007038:Hypotonic Solutions; D019169:Jurkat Cells; D047029:Lactams, Macrocyclic; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000096:biosynthesis / Q000172:deficiency / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D010636:Phenols / Q000494:pharmacology; D011809:Quinones / Q000494:pharmacology; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D017828:Rifabutin / Q000031:analogs & derivatives; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology*; D014162:Transfection
D016227:Benzoquinones; D018118:Chloride Channels; D004791:Enzyme Inhibitors; D007038:Hypotonic Solutions; D047029:Lactams, Macrocyclic; D010636:Phenols; D011809:Quinones; D011994:Recombinant Proteins; D017828:Rifabutin; C020754:herbimycin; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)