Polychlorinated biphenyl 19 blocks the most common form of store-operated Ca2+ entry through Orai.

PCB19, a 2,2',6-trichlorinated biphenyl, is one of many non-dioxin-like polychlorinated biphenyls (NDL-PCBs), which are ubiquitous pollutants. NDL-PCBs affect cytosolic Ca2+ signaling by promoting Ca2+ release from ryanodine receptor-sensitive Ca2+ pools and inhibiting store-operated Ca2+ entry (SOCE) from the extracellular space. However, NDL-PCB-mediated SOCE inhibition has only been demonstrated in PC12 cells, in which SOCE is thought to be mainly mediated by TRPC family channels. Here, we investigated the effect of PCB19 on SOCE using human embryonic kidney 293 (HEK293) cells, human leukemia T cell line Jurkat-T cells and human promyelocytoma HL-60 cells which are the cell lines that are previously demonstrated to mediate the most common form of SOCE solely by the intrinsic Orai channels. PCB19 reduced thapsigargin-induced Ca2+ influx after Ca2+ pool depletion in HEK293 cells. SOCEs in HEK293, Jurkat T, HL-60 and PC12 cells showed distinct sensitivities to SOCE inhibitors such as Gd3+ and ML-9; however, PCB19 also showed a common effect of inhibiting SOCEs in all cell lines. PCB19-mediated SOCE inhibition was confirmed by demonstrating the ability of PCB19 to inhibit the SOCE current but not the TRPM7 current. These results imply that PCB19 inhibits not only TRPC-mediated SOCE as in PC12 cells but also Orai-mediated SOCE as in many other cells including HEK293, Jurkat T and HL-60 cells.