Cell-intrinsic activation of Orai1 regulates human T cell motility

Ca 2+ signaling through the store-operated Ca 2+ channel, Orai1, is crucial for T cell function, but a role in regulating T cell motility in lymph nodes has not been previously reported. Tracking human T cells in immunodeficient mouse lymph nodes and in microfabricated PDMS channels, we show that inhibition of Orai1 channel activity with a dominant-negative Orai1-E106A construct increases average T cell velocities by reducing the frequency of pauses in motile T cells. Orai1-dependent motility arrest occurs spontaneously during confined motility in vitro , even in the absence of extrinsic cell contacts or antigen recognition. Utilizing a novel ratiometric genetically encoded cytosolic Ca 2+ indicator, Salsa6f, we show these spontaneous pauses during T cell motility in vitro coincide with episodes of spontaneous cytosolic Ca 2+ signaling. Our results demonstrate that Orai1, activated in a cell-intrinsic manner, regulates T cell motility patterns that accompany immune surveillance.