Actin realignment and cofilin regulation are essential for barrier integrity during shear stress.
Vascular endothelial cells and their actin microfilaments align in the direction of fluid shear stress (FSS) in vitro and in vivo. To determine whether cofilin, an actin severing protein, is required in this process, the levels of phospho-cofilin (serine-3) were evaluated in cells exposed to FSS. Phospho-cofilin levels decreased in the cytoplasm and increased in the nucleus during FSS exposure. This was accompanied by increased nuclear staining for activated LIMK, a cofilin kinase. Blocking stress kinases JNK and p38, known to play roles in actin realignment during FSS, decreased cofilin phosphorylation under static conditions, and JNK inhibition also resulted in decreased phospho-cofilin during FSS exposure. Inhibition of dynamic changes in cofilin phosphorylation through cofilin mutants decreased correct actin realignment. The mutants also decreased barrier integrity as did inhibition of the stress kinases. These results identify the importance of cofilin in the process of actin alignment and the requirement for actin realignment in endothelial barrier integrity during FSS.
Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
Joshua B
JB
Slee
Linda J
LJ
Lowe-Krentz
D000199:Actins / Q000378:metabolism*; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D001696:Biomechanical Phenomena; D015820:Cadherins / Q000378:metabolism; D002199:Capillary Permeability; D002417:Cattle; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D051338:Cofilin 1 / Q000378:metabolism*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007365:Intercellular Junctions; D054461:Lim Kinases / Q000378:metabolism; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D012694:Serine / Q000378:metabolism; D013314:Stress, Mechanical; D051176:beta Catenin / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000099152:Cadherin 5
D000199:Actins; D000873:Anthracenes; D015703:Antigens, CD; D015820:Cadherins; D051338:Cofilin 1; D004791:Enzyme Inhibitors; D007093:Imidazoles; D054461:Lim Kinases; D048670:MAP Kinase Kinase 4; D011725:Pyridines; D012694:Serine; D051176:beta Catenin; D048051:p38 Mitogen-Activated Protein Kinases; D000099152:Cadherin 5; C432165:pyrazolanthrone; C093642:SB 203580