Interleukin-1β induces gene expression and secretion of the secretory phospholipase A2 (sPLA2) and prostaglandin E2 (PGE2) release from rat mesangial cells. We have previousy shown that prolonged treatment of rat mesangial cells with interleukin-1β (IL-1β) also enhances the cytosolic phospholipase A; (cPLA2) activity. This effect of IL-1β on the cPLA2 activity is inhibited by actinomycin D and cycloheximide, indicating that both transcription and translation are involved. Here, we describe that IL-1β increases mRNA levels and protein synthesis of cPLA2 itself. In parallel with the effect of dexamethasone on the sPLA2, this glucocorticoid inhibits the IL-1β-enhanced cPLA2 activity as a result of the suppression of IL-1β-induced cPLA2 gene expression. This report suggests that the pro-inflammatory action of interleukin-1β may, in part, be mediated by its effects on cPLA2 activity.
