Related Experiment Videos
Tyrosine phosphorylation-dependent suppression of a voltage-gated K+ channel in T lymphocytes upon Fas stimulation
1Physiology Institute I, Eberhard-Karls University, D-72076 Tübingen, Germany.
Abstract:
Selective cell death plays a critical role in the development of the immune system and in the elimination of target cells expressing foreign antigens. Most of programmed cell death occurs by apoptosis. Apoptotic cell death of lymphocytes can be triggered by ligation of APO-1/Fas (CD95) antigen (Suda, T., and Nagata, S. (1994) J. Exp. Med. 179, 873-879; Nagata, S., and Golstein, P. (1995) Science 267, 1449-1456). We find that activation of Fas leads to the inhibition of the voltage-dependent n-type K+ channels (Kv1.3) studied by patch clamp technique in Jurkat T lymphocytes. Tyrosine kinases have been shown to be crucial in Fas-induced cell death (Eischen, C. M., Dick, C. J., and Leibson, P. J. (1994) J. Immunol. 153, 1947-1954). The inhibition of the current is correlated with the tyrosine phosphorylation of immunoprecipitated and blotted K+ channel protein. We show, that the Src-like protein-tyrosine kinase inhibitor herbimycin A and the deficiency of the p56(lck) tyrosine kinase in mutant Jurkat cells abolished the channel inhibition and phosphorylation by anti-Fas antibody, while reconstitution of the p56(lck) kinase partly restored these effects of Fas receptor triggering. These results suggest a regulation of n-type K+ channels by tyrosine kinases upon Fas receptor triggering, which might be important for apoptosis.
Insights
Fas receptor activation inhibits crucial Kv1.3 potassium channels in T lymphocytes. This inhibition, mediated by tyrosine kinases like p56(lck), plays a role in programmed cell death (apoptosis).
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Selective cell death, primarily apoptosis, is vital for immune system development and eliminating foreign antigens.
- Apoptotic cell death in lymphocytes can be initiated by Fas (CD95) antigen ligation.
Purpose of the Study:
- To investigate the effect of Fas receptor activation on voltage-dependent n-type K+ channels (Kv1.3) in Jurkat T lymphocytes.
- To explore the role of tyrosine kinases in Fas-induced Kv1.3 channel inhibition and apoptosis.
Main Methods:
- Patch clamp technique to study Kv1.3 channel activity.
- Immunoprecipitation and Western blotting to detect tyrosine phosphorylation of Kv1.3 channels.
- Use of herbimycin A (tyrosine kinase inhibitor) and p56(lck) deficient Jurkat cells.
Main Results:
- Fas activation led to the inhibition of Kv1.3 channels in Jurkat T lymphocytes.
- Channel inhibition correlated with increased tyrosine phosphorylation of the Kv1.3 channel protein.
- Inhibition and phosphorylation were abolished by a tyrosine kinase inhibitor and p56(lck) deficiency, and partially restored by p56(lck) reconstitution.
Conclusions:
- Fas receptor triggering regulates n-type K+ channels (Kv1.3) via tyrosine kinases, including p56(lck).
- This tyrosine kinase-mediated regulation of Kv1.3 channels may be a critical mechanism in Fas-induced apoptosis.