Constitutive secretion of CXCL4L1 and PKC-dependent regulated secretion of CXCL4 in HEK transfectants. (A) BFA treatment induced a strong dose-dependent decrease in CXCL4L1 secretion by CXCL4L1 transfectants and low effects in CXCL4 secretion by CXCL4 transfectants. Cells were cultured for 6 hours in serum-free medium at a concentration of 1 × 106 cells/mL medium in presence or absence of 100 to 500 ng/mL BFA. Mean ± SEM of 4 experiments performed in 2 selected clones is shown. *P < .001 versus untreated cells. (B) CHX treatment induced a strong dose-dependent decrease in CXCL4L1 secretion by CXCL4L1 transfectants. No effect was observed on CXCL4 secretion by CXCL4 transfectants. Cells were cultured for 10 hours in serum-free medium at a concentration of 1 × 106 cells/mL medium in presence or absence of 1 to 10 μg/mL CHX. Mean ± SEM of 4 experiments performed in 2 selected clones is shown. *P < .001 versus untreated cells. (C) PMA treatment induced a dose-dependent increase in CXCL4 secretion by CXCL4 transfectants. No effect was observed in CXCL4L1 transfectants. Cells were cultured for 6 hours in serum-free medium at a concentration of 1 × 106 cells/mL medium in the presence or absence of 25 to 50 ng/mL PMA. Mean ± SEM of 4 experiments performed in 2 selected clones is shown. *P < .001 versus untreated cells. (D) Effect of PKC inhibitors on PMA-induced CXCL4 secretion by CXCL4 transfectants. Cells were cultured for 6 hours in serum-free medium at a concentration of 1 × 106 cells/mL medium in presence or absence of 50 ng/mL PMA, and in the presence or absence of different PKC inhibitors. Data represent mean ± SEM of 3 independent experiments performed in duplicate in 2 selected clones. *P < .001 versus PMA-treated cells.
