Interaction of Apoptotic Cells with Macrophages Upregulates COX-2/PGE2 and HGF Expression via a Positive Feedback Loop
Figure 4
COX-2/PGE2 signaling is required for HGF production in response to apoptotic cells. (a) RAW 264.7 cells were treated with 1 or 10 nM of PGE2 for 24 h to detect secreted HGF. (b, c) After 1 h pretreatment of 10 μM NS-398, apoptotic Jurkat cells (ApoJ) with or without PGE2 were added to RAW cells for 2 h to detect HGF mRNA or for 24 h to detect secreted HGF. (d) Transfected RAW cells with siRNA against COX-2 were stimulated with ApoJ with or without 1 or 10 nM PGE2 for 24 h. (e) Raw cells were pretreated with 10 μM of EP2 receptor antagonist, AH-6809 (AH), or 10 μM of EP4 receptor antagonist, GW 627368X (GW), for 1 h and then stimulated with ApoJ for 24 h. (a, c–e) HGF levels in conditioned media were measured by ELISA. (b) HGF mRNA levels were analyzed by semiquantitative RT-PCR. Values represent mean ± SEM of three or more separate experiments; . (f) RAW cells were stimulated with ApoJ for a 24 h period and PGE2 and HGF levels in the supernatants were measured at each time points by EIA and ELISA, respectively, and expressed as percent of control. Data are representative from separate three experiments.
