Clofazimine inhibits human Kv1.3 potassium channel by perturbing calcium oscillation in T lymphocytes.

Abstract

The Kv1.3 potassium channel plays an essential role in effector memory T cells and has been implicated in several important autoimmune diseases including multiple sclerosis, psoriasis and type 1 diabetes. A number of potent small molecule inhibitors of Kv1.3 channel have been reported, some of which were found to be effective in various animal models of autoimmune diseases. We report herein the identification of clofazimine, a known anti-mycobacterial drug, as a novel inhibitor of human Kv1.3. Clofazimine was initially identified as an inhibitor of intracellular T cell receptor-mediated signaling leading to the transcriptional activation of human interleukin-2 gene in T cells from a screen of the Johns Hopkins Drug Library. A systematic mechanistic deconvolution revealed that clofazimine selectively blocked the Kv1.3 channel activity, perturbing the oscillation frequency of the calcium-release activated calcium channel, which in turn led to the inhibition of the calcineurin-NFAT signaling pathway. These effects of clofazimine provide the first line of experimental evidence in support of a causal relationship between Kv1.3 and calcium oscillation in human T cells. Furthermore, clofazimine was found to be effective in blocking human T cell-mediated skin graft rejection in an animal model in vivo. Together, these results suggest that clofazimine is a promising immunomodulatory drug candidate for treating a variety of autoimmune disorders.

• Authors: Yunzhao R Ren, Fan Pan, Suhel Parvez, Andrea Fleig, Curtis R Chong, Jing Xu, Yongjun Dang, Jin Zhang, Hongsi Jiang, Reinhold Penner, Jun O Liu
• Journal: PloS one (PLoS One) Vol. 3 Issue 12 Pg. e4009 ( 2008) ISSN: 1932-6203 [Electronic] United States
• PMID: 19104661 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Immunologic Factors
• Interleukin-2
• Kv1.3 Potassium Channel
• NFATC Transcription Factors
• Clofazimine

Topics

• Animals
• Anti-Bacterial Agents (metabolism, pharmacology)
• Calcium Signaling (drug effects, immunology)
• Cells, Cultured
• Clofazimine (metabolism, pharmacology)
• Drug Evaluation, Preclinical
• Humans
• Immunologic Factors (metabolism, pharmacology)
• Interleukin-2 (metabolism)
• Jurkat Cells
• Kv1.3 Potassium Channel (antagonists & inhibitors, genetics, metabolism)
• Mice
• Models, Biological
• NFATC Transcription Factors (metabolism)
• Protein Binding
• Protein Multimerization (drug effects)
• Skin Transplantation (immunology)
• T-Lymphocytes (drug effects, metabolism)
• Transfection