Document Type
Article
Publication Date
2-2019
Abstract
Calcium ion elevations are required for human T-lymphocyte proliferation in response to antigen recognition by a T-cell receptor. Calcium influx through the plasma membrane is necessary for efficient T-cell proliferation and effector function. The calcium channels responsible for Ca2+ influx in lymphocytes have been identified and Orai interacting with ER Ca2+ sensor STIM were shown to be crucial for persistent calcium mobilization. Loss-of-function mutations in Orai1 or STIM1 result in severe combined immunodeficiency (SCID) with muscle hypotonia. Suppression of calcium influx through Orai/STIM channels gives rise to various lymphoproliferative defects. Thus, deletion of Orai or STIM in mice results in lymphoproliferative disorders and hair loss. Gain-of-function mutations in Orai or STIM resulting in constitutively activated channels cause tubular aggregate myopathy (TAM). Despite the importance of Orai/STIM pathway in multiple signaling pathways and diseases, small molecule high affinity specific inhibitors of these channels are lacking. In this work we examined a class of indole-3-carboxamides for their potential to inhibit store-operated Ca2+ entry. They were tested in vitro for their ability to inhibit Orai1 mediated Ca2+ entry and currents. At 10 μM and higher the less lipophilic BIC-154 was the most potent blocker in the group. We used a constitutively active Orai1 variant implicated in TAM, which does not require STIM1 for function. BIC-154 rapidly and reversibly inhibited Orai1 currents. BTP2 (YM-58483) and 2-APB also inhibited Orai1 mutant channels in the same cells. TRPM7, a Ca2+/Mg2+ permeable channel highly expressed in lymphocytes was insensitive to these compounds tested at 100 μM. Future investigations will test their effectiveness in T-cell blastogenesis and proliferation assays. We anticipate that Orai1-specific compounds will be useful for proof of concept studies of the contribution of this channel to human disease.
Repository Citation
Zhelay, T.,
Szteyn, K.,
Liardo, E.,
Cheong, J. E.,
Koerner, S.,
Ekkati, A.,
Sun, L.,
& Kozak, J. A.
(2019). Initial Characterization of the Indole-3-Carboxamide Bic-154 as a Fast Onset and Reversible ORAI Channel Blocker. Biophysical Journal, 116 (3), 249A, Supplement 1.
https://corescholar.libraries.wright.edu/ncbp/1144
DOI
10.1016/j.bpj.2018.11.1359
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