Rho modulates hepatic sinusoidal endothelial fenestrae via regulation of the actin cytoskeleton in rat endothelial cells

• Published in: Laboratory investigation Vol. 84; no. 7; pp. 857 - 864
• Main Authors: Yokomori, Hiroaki, Yoshimura, Kazunori, Funakoshi, Shinsuke, Nagai, Toshihiro, Fujimaki, Kayo, Nomura, Masahiko, Ishii, Hiromasa, Oda, Masaya
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.07.2004; Nature Publishing; Nature Publishing Group
• Subjects: actin; Actins - physiology; Animals; Biological and medical sciences; Biotechnology; Blotting, Western; Calcium - metabolism; Cytoskeleton - physiology; Endothelial Cells - physiology; Fundamental and applied biological sciences. Psychology; Liver - metabolism; Liver - ultrastructure; Male; Microscopy, Confocal; Microscopy, Electron; Myosin-Light-Chain Kinase - metabolism; Phosphorylation; Rats; Rats, Wistar; Rho; rho GTP-Binding Proteins - physiology; sinusoidal endothelial cell; sinusoidal endothelial fenestrae; sinusoidal endothelial cell; Rho; actin; sinusoidal endothelial fenestrae; Biotechnology; Endothelial cell; Rat; Liver; Rodentia; Vertebrata; Regulation(control); Mammalia; Actin; Animal; Clinical biology; Cytoskeleton; Sinusoidal; Regulation
• ISSN: 0023-6837; 1530-0307
• DOI: 10.1038/labinvest.3700114

The presence of actin-like microfilaments in the vicinity of sinusoidal endothelial fenestrae (SEF) indicates that the cytoskeleton of sinusoidal endothelial cells (SEC) plays an important role in the modulation of SEF. Rho has emerged as an important regulator of the actin cytoskeleton, and consequently cell morphology. The present study aimed to examine how a Rho stimulator; lysophosphatidic acid (LPA), and a Rho inhibitor; bacterial toxin C3 transferase (C3-transferase), affect the morphology of SEF. Monolayers of SEC culture were established by infusing a rat liver with collagenase for 30 min and then culturing in RMPI medium for 24 h. The cells were separated into three groups; control, LPA-treated (15 μM), and C3-transferase-treated (15 μg/ml) groups. SEF morphology was observed by scanning electron microscopy. Formation of F-actin stress fibers was observed by confocal microscopy. Rho A and phosphorylated myosin light-chain kinase were analyzed by Western blotting. Active Rho was measured by Ren's modification. Treatment of SECs with LPA contracted the SEF, concomitant with increases in F-actin stress fiber and actin microfilament, and high expression of phosphorylated myosin light-chain kinase. Following treatment with C3-transferase, SEF dilated and fused, concomitant with a loss of F-actin and microfilament, and low expression of phosphorylated myosin light chain. Rho A expression does not change by both treatments. In conclusion, these results indicate that Rho modulates fenestral changes in SEC via regulation of the actin cytoskeleton.