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Macrophage endoplasmic reticulum (ER) proteins and reducing elements stabilize paraoxonase 2 (PON2)
Mira Rosenblat1, Nina Volkova, Michael Aviram
1The Lipid Research Laboratory, Technion Faculty of Medicine, The Rappaport Family Institute for Research in the Medical Sciences, Rambam Medical Center, Haifa 31096, Israel.
Atherosclerosis
|November 2, 2010
Summary
The macrophage endoplasmic reticulum (ER) stabilizes paraoxonase 2 (PON2) activity through its proteins and redox environment. This finding is crucial for understanding PON2 function in cellular health.
Area of Science:
- Cell Biology
- Enzymology
- Macrophage Biology
Background:
- Paraoxonase 2 (PON2) is an enzyme with protective functions.
- Understanding factors that stabilize PON2 activity is important for cellular health.
Purpose of the Study:
- To investigate the ability of macrophage sub-cellular fractions to stabilize paraoxonase 2 (PON2).
Main Methods:
- Isolated macrophage sub-cellular fractions (nuclei, mitochondria, lysosomes, ER, cytosol).
- Incubated fractions with recombinant PON2 (rePON2).
- Assessed rePON2 lactonase activity and stability under various conditions, including redox environment manipulation.
Main Results:
- The endoplasmic reticulum (ER) fraction demonstrated the highest PON2 stabilizing ability.
- ER proteins and the redox environment (specifically NADPH) were identified as key factors for PON2 stabilization.
- ER from oxidized or cholesterol-loaded macrophages showed reduced PON2 stabilizing capacity.
Conclusions:
- Macrophage ER normally stabilizes PON2 activity.
- ER proteins and the cellular redox status are critical for maintaining PON2 stability.
- Dysfunctional ER conditions impair PON2 stabilization.
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