Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave., Rochester, NY 14642, USA.
Blood. 2011 Feb 24;117(8):2527-37. doi: 10.1182/blood-2010-08-302281. Epub 2010 Dec 3.
Actin filament remodeling regulates several endothelial cell (EC) processes such as contraction, migration, adhesion, and shape determination. Mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2)-mediated phosphorylation of heat-shock protein 27 kDa (HSP27) promotes actin filament remodeling, but little is known about the regulation of this event in ECs. We found that tumor necrosis factor-α (TNF-α) SUMOylated MK2 at lysine (K)-339 affected EC actin filament organization and migration. Loss of the MK2 SUMOylation site (MK2-K339R) increased MK2 kinase activity and prolonged HSP27 phosphorylation, enhancing its effects on actin filament-dependent events. Both TNF-α-mediated EC elongation and steady laminar shear stress-mediated EC alignment were increased by MK2-K339R. Moreover, kinase-dead dominant-negative MK2 (DN-MK2) inhibited these effects. Cell migration is a dynamic process regulated by actin filament remodeling. Both wild-type MK2 (WT-MK2) and DN-MK2 significantly enhanced TNF-mediated inhibition of EC migration, and MK2-K339R further augmented this effect. Interestingly, the p160-Rho-associated coiled-coil kinase (ROCK) inhibitor Y-27632 reversed this effect by MK2-K339R, which strongly suggests that both excessive and insufficient levels of actin filament remodeling can block EC migration. Our study shows that MK2 SUMOylation is a new mechanism for regulating actin filament dynamics in ECs.
肌动蛋白丝重构调节内皮细胞（EC）的几种过程，如收缩、迁移、黏附和形态决定。丝裂原活化蛋白激酶（MAPK）-激活的蛋白激酶 2（MK2）介导的热休克蛋白 27 kDa（HSP27）磷酸化促进肌动蛋白丝重构，但关于 EC 中这一事件的调节知之甚少。我们发现肿瘤坏死因子-α（TNF-α）SUMO 化 MK2 的赖氨酸（K）-339 影响 EC 肌动蛋白丝组织和迁移。MK2 的 SUMO 化位点（MK2-K339R）缺失增加了 MK2 激酶活性并延长了 HSP27 的磷酸化，增强了其对肌动蛋白丝依赖事件的影响。TNF-α 介导的 EC 伸长和稳定层流剪切力介导的 EC 排列都被 MK2-K339R 增加。此外，激酶失活的显性负性 MK2（DN-MK2）抑制了这些效应。细胞迁移是受肌动蛋白丝重构调节的动态过程。野生型 MK2（WT-MK2）和 DN-MK2 均显著增强了 TNF 介导的对 EC 迁移的抑制作用，MK2-K339R 进一步增强了这种作用。有趣的是，p160-Rho 相关卷曲螺旋激酶（ROCK）抑制剂 Y-27632 通过 MK2-K339R 逆转了这种作用，这强烈表明肌动蛋白丝重构的过度和不足水平都可以阻止 EC 迁移。我们的研究表明，MK2 SUMO 化是调节 EC 中肌动蛋白丝动力学的新机制。
