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Lysophosphatidylcholine (LPC) is a bioactive proinflammatory lipid that can be generated by pathological activities. We investigated the hypothesis that LPC signals increase in endothelial permeability. Stimulation of human dermal microvascular endothelial cells and bovine pulmonary microvascular endothelial cells with LPC (10-50 microM) induced decreases (within minutes) in transendothelial electrical resistance and increase of endothelial permeability. LPC activated (within 5 min) membrane-associated PKC phosphotransferase activity in the absence of translocation. Affinity-binding analysis indicated that LPC induced increases (also by 5 min) of GTP-bound RhoA, but not Rac1 or Cdc42. By 60 min, both signaling pathways decreased toward baseline. Inhibition of RhoA with C3 transferase inhibited approximately 50% of LPC-induced resistance decrease. Pretreatment with PKC inhibitor Gö-6983 (concentrations selective for classic PKC), PMA-induced depletion of PKCalpha, and transfection of antisense PKCalpha oligonucleotide each prevented 40-50% of the LPC-induced resistance decrease. Furthermore, these three PKC inhibition strategies inhibited 60-80% of the LPC-induced GTP-bound RhoA. These results show that LPC directly impairs the endothelial barrier function that was dependent, at least in part, on cross talk of PKCalpha and RhoA signals. The evidence indicates that elevated LPC levels can contribute to the activation of a proinflammatory endothelial phenotype.

Lysophosphatidylcholine (LPC) is a bioactive proinflammatory lipid that can be generated by pathological activities. We investigated the hypothesis that LPC signals increase in endothelial permeability. Stimulation of human dermal microvascular endothelial cells and bovine pulmonary microvascular endothelial cells with LPC (10-50 µM) induced decreases (within minutes) in transendothelial electrical resistance and increase of endothelial permeability. LPC activated (within 5 mm) membrane- associated PKC phosphotransferase activity in the absence of translocation. Affinity-binding analysis indicated that LPC induced in- creases (also by 5 mm) of GTP-bound RhoA, but not Rac1 or Cdc42. By 60 mm, both signaling pathways decreased toward baseline. Inhibition of RhoA with C3 transferase inhibited ∼50% of LPC-induced resistance decrease. Pretreatment with PKC inhibitor Go- 6983 (concentrations selective for classic PKC), PMA-induced depletion of PKCα, and transfection of antisense PKCα oligonucleotide each prevented 40-50% of the LPC-induced resistance decrease. Furthermore, these three PKC inhibition strategies inhibited 60-80% of the LPC-induced GTP-bound RhoA. These results show that LPC directly impairs the endothelial barrier function that was dependent, at least in part, on cross talk of PKCα and RhoA signals. The evidence indicates that elevated LPC levels can contribute to the activation of a proinflammatory endothelial phenotype. [ABSTRACT FROM AUTHOR]

Discusses the hypothesis that serine/threonine protein phosphatases may regulate protein kinase C, a critical signaling molecule in barrier dysfunction in the promotion of barrier recovery. Expression of protein phosphatases 1, 2A and 2B; Effects of inhibitors on thrombin-induced protein kinase C activity and phosphorylation.

Describes the protein kinase Cbeta (PKCbeta) modulation of the thrombin receptor (PAR-1) in endothelial cells. Heterologous desensitization of PAR-1; Control of the desensitization with the treatment of staurosporine, a PKC inhibitor; Relevance of the PKCbeta-activated pathway to signaling heterologous desensitization.

Examines the effect that the activation of protein kinase C (PKC) has on the endothelial cells and function of proteolytically stimulation of thrombin receptor 1 (PAR-1) in human. Assessment of the PAR-1 expression; Details on the treatment of cells with staurosporine; Methodology and materials used; Findings of the study.