Ca2+ dependence of proPO-casp release and the inhibitory effect of a caspase-1 inhibitor and caspase-1 knockdown in vitro.

Granular cells (GC) were incubated in buffer containing different concentrations of Ca2+. The presence of proPO-casps outside the cells was examined in medium at 30 and 60 min. The release of proPO-casps was Ca2+ and time dependent (A) and was inhibited when the cells were preincubated for 30 min with the caspase-1 inhibitor Z-YVAD-FMK prior to Ca2+ addition (B). The caspase-1-like transcript was completely decreased after 65 h of caspase-1 dsRNA (dsCaspase-1) treatment when compared to the dsGFP control (C). The level of proPO-casp fragments were decreased in both cell lysate and medium in dsCaspase-1 treated group when compared to dsGFP (D).