Phospholipase D2: functional interaction with caveolin in low‐density membrane microdomains

Open Access
Publisher Website
Google Scholar
Abstract
Low‐density detergent‐insoluble membrane domains contain caveolin‐1 and are enriched in a phospholipase D activity that is not PLD1. Here we show that caveolin‐rich fractions, prepared from HaCaT human keratinocytes by either detergent‐based or detergent‐free methods, contain PLD2. Caveolar membrane PLD activity is stimulated 2‐fold by low concentrations (10–30 μM) of the caveolin‐1 and caveolin‐2 scaffolding domain peptides, whereas it is inhibited at higher concentrations of the peptides. Immunoisolated HA‐tagged PLD1 and PLD2 are not stimulated by the peptides, although both enzymes retain sensitivity to their inhibitory effect. Down‐regulation of caveolin‐1 expression by treatment of the cells with acetyl‐leucyl‐leucyl‐norleucinal decreased caveolar PLD activity by 50%. Similarly, expression of an active form of the sterol regulatory element‐binding protein (SREBP1–490) down‐regulated caveolin‐1 expression by 50% and decreased caveolar PLD activity by 60%. These data identify the PLD activity in caveolin‐rich membranes as PLD2 and provide in vivo evidence suggesting that caveolin‐1 regulates PLD2 activity.