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Phospholipase D2: functional interaction with caveolin in low-density membrane microdomains.
1Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.
FEBS Letters
|February 17, 2000
Summary
This study identifies phospholipase D2 (PLD2) as the primary enzyme in caveolin-rich membranes. Caveolin-1 regulates PLD2 activity, impacting cellular processes.
Area of Science:
- Cell Biology
- Biochemistry
- Membrane Biology
Background:
- Low-density detergent-insoluble membrane domains, known as caveolae, are enriched in caveolin-1.
- These domains possess phospholipase D (PLD) activity, but the specific enzyme involved was previously unidentified and not PLD1.
Purpose of the Study:
- To identify the specific phospholipase D enzyme present in caveolin-rich membrane domains.
- To investigate the role of caveolin-1 in regulating PLD activity within these domains.
Main Methods:
- Preparation of caveolin-rich fractions from HaCaT human keratinocytes using detergent-based and detergent-free methods.
- Assay of PLD activity in caveolar fractions and immunoisolated PLD1 and PLD2.
- Down-regulation of caveolin-1 expression using acetyl-leucyl-leucyl-norleucinal and sterol regulatory element-binding protein (SREBP).
Main Results:
- Caveolin-rich fractions contain phospholipase D2 (PLD2), not PLD1.
- PLD activity in caveolar membranes is modulated by caveolin scaffolding domain peptides.
- Down-regulation of caveolin-1 significantly reduces caveolar PLD activity.
- Expression of SREBP also down-regulates caveolin-1 and decreases caveolar PLD activity.
Conclusions:
- The phospholipase D activity in caveolin-rich membranes is identified as PLD2.
- Caveolin-1 plays a regulatory role in vivo for PLD2 activity within caveolae.
- These findings highlight a novel interaction between caveolin-1 and PLD2 in cellular signaling.