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Published on: January 22, 2019
Protein phosphatase 2B inhibitor potentiates endothelial PKC activity and barrier dysfunction
H Lum1, J L Podolski, M E Gurnack
1Department of Pharmacology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA. hlum@rush.edu
Summary
Protein phosphatase 2B (PP2B) promotes endothelial barrier recovery by regulating protein kinase C (PKC). Inhibiting PP2B with FK506 impairs recovery, highlighting PP2B
Area of Science:
- Endothelial Biology
- Cell Signaling
- Protein Phosphatases
Background:
- Endothelial barrier dysfunction is linked to inflammatory mediators.
- Serine/threonine protein phosphatases (Ser/Thr PPs) are involved in barrier recovery.
- Protein kinase C (PKC) is a key signaling molecule in endothelial barrier regulation.
Purpose of the Study:
- To investigate the role of Ser/Thr PPs in endothelial barrier recovery.
- To determine if Ser/Thr PPs regulate PKC in promoting barrier recovery.
Main Methods:
- Western analysis to detect Ser/Thr PPs (PP1, PP2A, PP2B) in bovine pulmonary microvascular endothelial cells (BPMECs).
- Treatment with PP inhibitors (FK506, calyculin A, okadaic acid) and thrombin.
- Measurement of PKC phosphotransferase activity, PKC-alpha and PKC-beta phosphorylation, and transendothelial electrical resistance (TER).
- PKC downregulation using phorbol 12-myristate 13-acetate.
Main Results:
- BPMECs express PP1, PP2A, and PP2B.
- FK506 (PP2B inhibitor) potentiated thrombin-induced PKC activity and PKC-alpha phosphorylation, and inhibited barrier recovery.
- PP2B inhibition, but not PP1 or PP2A inhibition, impaired endothelial barrier recovery.
- PKC downregulation rescued the FK506-mediated inhibition of recovery.
Conclusions:
- Protein phosphatase 2B (PP2B) plays a significant role in endothelial barrier recovery.
- PP2B regulates protein kinase C (PKC) to restore endothelial barrier function.
- Targeting PP2B may offer therapeutic strategies for endothelial barrier dysfunction.
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