TY - JOUR
T1 - Endothelial cell barrier protection by simvastatin
T2 - GTPase regulation and NADPH oxidase inhibition
AU - Chen, Weiguo
AU - Pendyala, Srikanth
AU - Natarajan, Viswanathan
AU - Garcia, Joe G.N.
AU - Jacobson, Jeffrey R.
PY - 2008/10
Y1 - 2008/10
N2 - The statins, hydroxy-3-methylglutaryl-CoA reductase inhibitors that lower serum cholesterol, exhibit myriad clinical benefits, including enhanced vascular integrity. One potential mechanism underlying increased endothelial cell (EC) barrier function is inhibition of geranylgeranylation, a covalent modification enabling translocation of the small GTPases Rho and Rac to the cell membrane. While RhoA inhibition attenuates actin stress fiber formation and promotes EC barrier function, Rac1 inhibition at the cell membrane potentially prevents activation of NADPH oxidase and subsequent generation of superoxides known to induce barrier disruption. We examined the relative regulatory effects of simvastatin on RhoA, Rac1, and NADPH oxidase activities in the context of human pulmonary artery EC barrier protection. Confluent EC treated with simvastatin demonstrated significantly decreased thrombin-induced FITC-dextran permeability, a reflection of vascular integrity, which was linked temporally to simvastatin-mediated actin cytoskeletal rearrangement. Compared with Rho inhibition alone (Y-27632), simvastatin afforded additional protection against thrombin-mediated barrier dysfunction and attenuated LPS-induced EC permeability and superoxide generation. Statin-mediated inhibition of both Rac translocation to the cell membrane and superoxide production were attenuated by geranylgeranyl pyrophosphate (GGPP), indicating that these effects are due to geranylgeranylation inhibition. Finally, thrombin-induced EC permeability was modestly attenuated by reduced Rac1 expression (small interfering RNA), whereas these effects were made more pronounced by simvastatin pretreatment. Together, these data suggest EC barrier protection by simvastatin is due to dual inhibitory effects on RhoA and Rac1 as well as the attenuation of superoxide generation by EC NADPH oxidase and contribute to the molecular mechanistic understanding of the modulation of EC barrier properties by simvastatin.
AB - The statins, hydroxy-3-methylglutaryl-CoA reductase inhibitors that lower serum cholesterol, exhibit myriad clinical benefits, including enhanced vascular integrity. One potential mechanism underlying increased endothelial cell (EC) barrier function is inhibition of geranylgeranylation, a covalent modification enabling translocation of the small GTPases Rho and Rac to the cell membrane. While RhoA inhibition attenuates actin stress fiber formation and promotes EC barrier function, Rac1 inhibition at the cell membrane potentially prevents activation of NADPH oxidase and subsequent generation of superoxides known to induce barrier disruption. We examined the relative regulatory effects of simvastatin on RhoA, Rac1, and NADPH oxidase activities in the context of human pulmonary artery EC barrier protection. Confluent EC treated with simvastatin demonstrated significantly decreased thrombin-induced FITC-dextran permeability, a reflection of vascular integrity, which was linked temporally to simvastatin-mediated actin cytoskeletal rearrangement. Compared with Rho inhibition alone (Y-27632), simvastatin afforded additional protection against thrombin-mediated barrier dysfunction and attenuated LPS-induced EC permeability and superoxide generation. Statin-mediated inhibition of both Rac translocation to the cell membrane and superoxide production were attenuated by geranylgeranyl pyrophosphate (GGPP), indicating that these effects are due to geranylgeranylation inhibition. Finally, thrombin-induced EC permeability was modestly attenuated by reduced Rac1 expression (small interfering RNA), whereas these effects were made more pronounced by simvastatin pretreatment. Together, these data suggest EC barrier protection by simvastatin is due to dual inhibitory effects on RhoA and Rac1 as well as the attenuation of superoxide generation by EC NADPH oxidase and contribute to the molecular mechanistic understanding of the modulation of EC barrier properties by simvastatin.
KW - Cytoskeleton
KW - Permeability
KW - Rac
KW - Rho
KW - Statins
UR - http://www.scopus.com/inward/record.url?scp=56149098127&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=56149098127&partnerID=8YFLogxK
U2 - 10.1152/ajplung.00428.2007
DO - 10.1152/ajplung.00428.2007
M3 - Article
C2 - 18658277
AN - SCOPUS:56149098127
SN - 1040-0605
VL - 295
SP - L575-L583
JO - American Journal of Physiology - Lung Cellular and Molecular Physiology
JF - American Journal of Physiology - Lung Cellular and Molecular Physiology
IS - 4
ER -