Av. Ershov et al., Modulation of early response gene expression by prostaglandins in culturedrat retinal pigment epithelium cells, CURR EYE R, 21(6), 2000, pp. 968-974
Purpose. To explore the role of prostaglandins (PGs) as modulators of retin
al pigment epithelium (RPE) rod outer segment (ROS)-phagocytosis and ROS-ph
agocytosis- induced gene expression.
Methods. RPE cells in primary cell culture were pre-incubated with PGE(2),
PGD(2), PGF(2)alpha, PGJ(2), 15-deoxy-Delta (12,14)-PGJ(2) or U-46619 (stab
le analog of thromboxane A(2)), and fed with a suspension of ROS. Expressio
n of zif-268 and tis-1 mRNA was determined by Northern blotting. DNA-bindin
g activity of TIS-1 protein was assessed by electrophoretic mobility shift
assay. Concentration of PGE(2) and PGD(2) in the tissue culture medium was
measured by enzyme immuno-assay. Phagocytis-tosis was quantified by countin
g of double-immunostained bound and ingested ROS.
Results. PGE(2), the most potent of PGs, strongly elevated both basal and R
OS-phagocytosis- induced levels of tis-1 mRNA, while significantly inhibiti
ng both basal and phagocytosis-induced expression of zif-268 mRNA. PGD(2),
PGJ(2) and 15-deoxy-Delta (12,14)-PGJ(2) elevated ROS-phagocytosis-induced,
but not basal, expression of tis-1 mRNA expression. PGF(2 alpha) super-ind
uced both phagocytosis-induced and basal tis-1 mRNA expression. U-46619 and
carbaprostacyclin had no effect on expression of tis-1 mRNA. PGE(2) was th
e only PG to affect zif-268 expression. Exogenous PGE(2), PGD(2) and PGF(2)
, when added to the medium at 1-muM concentrations, significantly inhibited
ingestion of ROS, with PGE(2) being the most potent PG affecting ROS-phago
cytosis.
Conclusions. PGs act as selective regulators of phagocytosis-induced transc
ription factor gene expression in RPE cells, as well as of ROS-phagocytosis
itself. This modulation may help to ensure specificity in the differential
activation of target genes by ROS-phagocytosis receptor-mediated signal tr
ansduction in RPE cells.