LLC-PK1 Cells derived from pig kidneys have a defect in cyclooxygenase.

Abstract

Two epithelial cell lines derived from mammalian kidneys, the MDCK, cell from dog kidney and the LLC-PK1 cell from pig kidney, were studied in terms of prostaglandin synthesis.The MDCKl cell line regularly produced prostaglandin E and 6-keto-PGF1, under basal conditions and following augmentation of prostaglandin synthesis by the addition of arachidonic acid or with stimulation of phospholipase by the calcium ionophore A23187.Addition of butyrate to the growth medium, a maneuver previously shown to induce new cyclooxygenase, augmented basal and A23187-stimulated-prostaglandin E production by MDCK, cells.In contrast, the LLC-PK1 cell line produced virtually no prostaglandins in any of these conditions.To evaluate the possible defect in prostaglandin synthesis present in the LLC-PK1 cell line, studies were performed in which radioactive arachidonic acid uptake into membrane lipids and subsequent release by activation of phospholipase were evaluated.Results with LLC-PK1 cells were similar to those found with the MDCKl cells.Thus, neither of these steps was defective in the LLC-PKl cell line.Since the radioactive arachidonic acid released by the LLC-PKI cell line remained almost completely as arachidonic acid, the next step in prostaglandin synthesis, i.e. cyclooxygenase, is likely to be the defective step in limiting this cell's ability to produce prostaglandins.In contrast to previous studies in mastocytoma cells and the present findings with MDCKl cells, addition of butyrate to the growth medium did not induce cyclooxygenase activity in LLC-PKI cells.Prostaglandin synthesis has been found in virtually all nucleated cells studied to date.Different cell types, however, can produce prostaglandins in different amounts and of different types.Because of this laboratory's interest in transepithelid transport, we have been studying two lines of kidney epithelial cells, the LLC-PKI cell line derived from the pig kidney (1) and the MDCKl cell line' derived from the dog kidney (2).Both of these cell lines actively transport electro-