Exp Mol Med.  2000 Sep;32(3):170-177.

Dexamethasone enhances phospholipase D activity in M-1 cells

• Kim WJ
• Lee MJ
• Park MA
• Jung JS
• Uhlinger D
• Kwak JY

Abstract

Phospholipase D (PLD) is an enzyme involved in signal transduction and widely distributed in mammalian cells. The signal transduction pathways and role for phospholipid metabolism during hormonal response in cortical collecting duct remain partly undefined. It has been reported that dexamethasone increases transepithelial transport in M-1 cells that are derived from the mouse cortical collecting duct. We investigated the expression and activity of PLD in M-1 cells. Basal PLD activity of M-1 cells cultured in the presence of dexamethasone (5 microM) was higher than in the absence of dexamethasone. Dexamethasone and ATP activated PLD in M-1 cells but phorbol ester did not stimulate PLD activity. Vasopressin, bradykinin, dibutyryl cyclic AMP, and ionomycin were ineffective in activating PLD of the cells. The PLD2 isotype was detected by immunoprecipitation but PLD1 was not detected in M-1 cells. Addition of GTPgammaS and ADP-ribosylation factor or phosphatidylinositiol 4,5-bisphosphate to digitonin-permeabilized cells did not augment PLD activity. In intact cells PLD activity was increased by sodium oleate but there was no significant change between dexamethasone treated- and untreated cells by oleate. These results suggest that at least two types of PLD are present in M-1 cells and PLD plays a role in the corticosteroid-mediated response of cortical collecting duct cells.

Keyword

Phospholipase D; dexamethasone; M-1 cell; oleate

MeSH Terms

Animal
Biological Transport/drug effects
Dexamethasone/pharmacology*
Dose-Response Relationship, Drug
Drug Interactions
Glycerophospholipids/analysis
Isoenzymes/drug effects
Kidney Cortex/cytology
Kidney Tubules, Collecting/drug effects*
Kidney Tubules, Collecting/cytology
Mice
Mice, Transgenic
Oleic Acid/pharmacology
Phospholipase D/drug effects*