Jamison Joshua, Wang James H-C, Wells Alan
Department of Pathology, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
Department of Orthopedic Surgery, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
PLoS One. 2014 Apr 3;9(4):e93968. doi: 10.1371/journal.pone.0093968. eCollection 2014.
Wound healing requires the vasculature to re-establish itself from the severed ends; endothelial cells within capillaries must detach from neighboring cells before they can migrate into the nascent wound bed to initiate angiogenesis. The dissociation of these endothelial capillaries is driven partially by platelets' release of growth factors and cytokines, particularly the chemokine CXCL4/platelet factor-4 (PF4) that increases cell-cell de-adherence. As this retraction is partly mediated by increased transcellular contractility, the protein kinase c-δ/myosin light chain-2 (PKCδ/MLC-2) signaling axis becomes a candidate mechanism to drive endothelial dissociation. We hypothesize that PKCδ activation induces contractility through MLC-2 to promote dissociation of endothelial cords after exposure to platelet-released CXCL4 and VEGF. To investigate this mechanism of contractility, endothelial cells were allowed to form cords following CXCL4 addition to perpetuate cord dissociation. In this study, CXCL4-induced dissociation was reduced by a VEGFR inhibitor (sunitinib malate) and/or PKCδ inhibition. During combined CXCL4+VEGF treatment, increased contractility mediated by MLC-2 that is dependent on PKCδ regulation. As cellular force is transmitted to focal adhesions, zyxin, a focal adhesion protein that is mechano-responsive, was upregulated after PKCδ inhibition. This study suggests that growth factor regulation of PKCδ may be involved in CXCL4-mediated dissociation of endothelial cords.
伤口愈合需要血管系统从断端重新建立；毛细血管内的内皮细胞必须与相邻细胞分离，才能迁移到新生的伤口床以启动血管生成。这些内皮毛细血管的分离部分是由血小板释放的生长因子和细胞因子驱动的，特别是趋化因子CXCL4/血小板因子-4（PF4），它会增加细胞间的去黏附。由于这种收缩部分是由跨细胞收缩力增加介导的，蛋白激酶c-δ/肌球蛋白轻链-2（PKCδ/MLC-2）信号轴成为驱动内皮细胞分离的候选机制。我们假设PKCδ激活通过MLC-2诱导收缩，以促进内皮索在暴露于血小板释放的CXCL4和VEGF后分离。为了研究这种收缩机制，在添加CXCL4后让内皮细胞形成索，以延续索的分离。在本研究中，VEGFR抑制剂（苹果酸舒尼替尼）和/或PKCδ抑制可减少CXCL4诱导的分离。在联合CXCL4+VEGF处理期间，由MLC-2介导的收缩增加，这依赖于PKCδ调节。由于细胞力传递到黏着斑，黏着斑蛋白zyxin是机械反应性的，在PKCδ抑制后上调。这项研究表明，PKCδ的生长因子调节可能参与CXCL4介导的内皮索分离。
