Figure 1. SOCE in HSG cells is determined by Orai1, TRPC1, and STIM1.

(A) [Ca²⁺]_i measurements in fura-2 loaded HSG cells or (B) whole cell patch clamp recordings (see Material and Methods for details) in HSG cells treated as indicated to knock down either Orai1, STIM1, or TRPC1. Tg and Ca²⁺ were added as indicated. Right panel in (A) shows the average data for internal Ca²⁺ release (fluorescence increase prior to Ca²⁺ addition) and Ca²⁺ influx (fluorescence increase after Ca²⁺ addition; in each case resting fluorescence was subtracted from peak 340/380 ratio). ** indicate values that are significantly different (p<0.01) from the respective control value (black bars indicate values obtained in control cells). Data represent results from six different experiments and include at least 50–150 cells for each condition (see Figure S1 for additional data on TRPC1 knockdown under these conditions and the sensitivity of Tg-stimulated Ca²⁺ entry to Gd³⁺ and 2APB). (B) Left panel shows development of currents in cells following inclusion of Tg in normal external solution (arrow, traces depict currents measured at −80 mV; composition of the solutions used here and in the following experiments are provided in Materials and Methods). Right panel shows I–V relationship of the maximum currents recorded under the various conditions (note that currents are not detected without Tg stimulation of cells).