Debruin Erin J, Hughes Michael R, Sina Christina, Lu Alex, Cait Jessica, Jian Zhiqi, Lopez Martin, Lo Bernard, Abraham Thomas, McNagny Kelly M
The Biomedical Research Centre, University of British Columbia, Vancouver, BC, Canada.
UBC James Hogg Research Centre, Institute for Heart + Lung Health, Vancouver, BC, Canada; Penn State College of Medicine, Penn State University, Hershey, Pennsylvania, United States of America.
PLoS One. 2014 Oct 10;9(10):e108881. doi: 10.1371/journal.pone.0108881. eCollection 2014.
Despite the widespread use of CD34-family sialomucins (CD34, podocalyxin and endoglycan) as vascular endothelial cell markers, there is remarkably little known of their vascular function. Podocalyxin (gene name Podxl), in particular, has been difficult to study in adult vasculature as germ-line deletion of podocalyxin in mice leads to kidney malformations and perinatal death. We generated mice that conditionally delete podocalyxin in vascular endothelial cells (Podxl(ΔEC) mice) to study the homeostatic role of podocalyxin in adult mouse vessels. Although Podxl(ΔEC) adult mice are viable, their lungs display increased lung volume and changes to the matrix composition. Intriguingly, this was associated with increased basal and inflammation-induced pulmonary vascular permeability. To further investigate the etiology of these defects, we isolated mouse pulmonary endothelial cells. Podxl(ΔEC) endothelial cells display mildly enhanced static adhesion to fibronectin but spread normally when plated on fibronectin-coated transwells. In contrast, Podxl(ΔEC) endothelial cells exhibit a severely impaired ability to spread on laminin and, to a lesser extent, collagen I coated transwells. The data suggest that, in endothelial cells, podocalyxin plays a previously unrecognized role in maintaining vascular integrity, likely through orchestrating interactions with extracellular matrix components and basement membranes, and that this influences downstream epithelial architecture.
尽管CD34家族唾液酸黏蛋白（CD34、足突蛋白和内聚糖）作为血管内皮细胞标志物被广泛使用，但对其血管功能的了解却非常少。特别是足突蛋白（基因名Podxl），由于小鼠中足突蛋白的种系缺失会导致肾脏畸形和围产期死亡，因此很难在成年血管系统中进行研究。我们构建了在血管内皮细胞中条件性缺失足突蛋白的小鼠（Podxl(ΔEC)小鼠），以研究足突蛋白在成年小鼠血管中的稳态作用。虽然Podxl(ΔEC)成年小鼠能够存活，但其肺部显示肺容积增加且基质组成发生变化。有趣的是，这与基础和炎症诱导的肺血管通透性增加有关。为了进一步研究这些缺陷的病因，我们分离了小鼠肺内皮细胞。Podxl(ΔEC)内皮细胞对纤连蛋白的静态黏附略有增强，但接种在纤连蛋白包被的Transwell上时能正常铺展。相比之下，Podxl(ΔEC)内皮细胞在层粘连蛋白以及程度较轻的I型胶原包被的Transwell上的铺展能力严重受损。数据表明，在内皮细胞中，足突蛋白可能通过协调与细胞外基质成分和基底膜的相互作用，在维持血管完整性方面发挥了以前未被认识到的作用，并且这会影响下游的上皮结构。
