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Protein phosphatase 2A in stretch-induced endothelial cell proliferation
K Murata1, I Mills, B E Sumpio
1Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Journal of Cellular Biochemistry
|December 1, 1996
Summary
Cyclic strain inhibits protein phosphatase 2A (PP2A), a cell growth suppressor, in bovine aortic endothelial cells. This, along with protein kinase C activation, may enhance cell proliferation.
Area of Science:
- Biochemistry
- Cell Biology
- Physiology
Background:
- Protein kinase C activation is implicated in cell growth regulation under cyclic strain.
- The role of protein phosphatases, specifically protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A), in this process remains unclear.
Purpose of the Study:
- To investigate the activity of PP1 and PP2A in bovine aortic endothelial cells subjected to cyclic strain.
- To determine if PP2A activity is altered by cyclic strain and if it influences endothelial cell proliferation.
Main Methods:
- Bovine aortic endothelial cells were exposed to cyclic strain.
- Cytosolic and membrane fractions were analyzed for PP1 and PP2A activity.
- Cell proliferation was assessed following treatment with okadaic acid, a PP2A inhibitor.
Main Results:
- Cyclic strain significantly decreased cytosolic PP2A activity by 36.1% after 60 minutes.
- Membrane-associated PP2A activity remained unchanged.
- Low-concentration okadaic acid treatment enhanced proliferation in both static and cyclically strained cells.
Conclusions:
- Protein phosphatase 2A functions as a suppressor of endothelial cell growth.
- Cyclic strain may promote endothelial cell proliferation by inhibiting PP2A activity.
- These findings suggest a dual mechanism involving PP2A inhibition and protein kinase C activation in strain-induced cell growth.