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Mitogenic phospholipase D activity is restricted to caveolin-enriched membrane microdomains
1Department of Biological Sciences, Hunter College of the City University of New York, 695 Park Avenue, New York, New York, 10021 USA.
Biochemical and Biophysical Research Communications
|June 30, 2000
Summary
Phospholipase D (PLD) activity, crucial for cell growth signaling, is elevated within specific membrane domains called caveolin-enriched membrane microdomains (CEMMs) in cancer cells. This localization explains how PLD contributes to mitogenic signaling pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Phospholipase D (PLD) activity increases with oncogenic stimuli and growth factors, suggesting a role in mitogenic signaling.
- Many mitogenic signaling proteins reside in caveolin-enriched membrane microdomains (CEMMs).
Purpose of the Study:
- To investigate the localization and role of Phospholipase D (PLD) activity in mitogenic signaling within caveolin-enriched membrane microdomains (CEMMs).
Main Methods:
- Utilized NIH 3T3 cells transformed with oncogenic Src, Ras, and Raf.
- Assessed PLD activity in response to epidermal growth factor (EGF).
- Examined PLD1 and PLD2 localization within CEMMs.
Main Results:
- Elevated PLD activity in transformed cells and EGF-stimulated cells was primarily localized to CEMMs.
- Neither PLD1 nor PLD2 showed enrichment in CEMMs of transformed cells, indicating increased specific activity.
- Observed substrate specificity for phosphatidylcholine lacking arachidonate acyl groups in transformed cells, linked to CEMM localization.
Conclusions:
- Mitogenic signaling via PLD is initiated within CEMMs, where key signaling molecules converge.
- The localization of PLD activity to CEMMs is critical for its role in oncogenic and growth factor-stimulated mitogenesis.