Kondo Shuji, Scheef Elizabeth A, Sheibani Nader, Sorenson Christine M
Dept. of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-4108, USA.
Am J Physiol Cell Physiol. 2007 Jun;292(6):C2070-83. doi: 10.1152/ajpcell.00489.2006.
Platelet endothelial cell adhesion molecule-1 (PECAM-1) has been implicated in angiogenesis through its involvement in endothelial cell-cell and cell-matrix interactions and signal transduction. Recent studies indicate that the cytoplasmic domain of PECAM-1 plays an important role in its cell adhesive and signaling properties. However, the role PECAM-1 isoforms play during angiogenic events such as cell adhesion and migration requires further delineation. To gain insight into the role PECAM-1 plays during vascular development and angiogenesis, we examined the expression pattern of PECAM-1 isoforms during kidney vascularization. We show that multiple isoforms of PECAM-1 are expressed during renal vascular development with different frequencies. The PECAM-1 that lacks exons 14 and 15 (Delta14&15) was the predominant isoform detected in the renal vasculature. To further study PECAM-1 isoform-specific functions we isolated kidney endothelial cells (EC) from wild-type and PECAM-1-deficient (PECAM-1-/-) mice with B(4)-lectin-coated magnetic beads. PECAM-1-/- kidney EC showed reduced migration, inability to undergo capillary morphogenesis in Matrigel, dense peripheral focal adhesions, and peripheral cortical actin distribution compared with wild-type cells. PECAM-1-/- kidney EC secreted increased amounts of fibronectin and decreased amounts of tenascin-C and thrombospondin-1. Reexpression of Delta14&15, but not full-length, PECAM-1 in PECAM-1-/- kidney EC restored cell migration and capillary morphogenesis defects. Thus PECAM-1 may regulate the adhesive and migratory properties of kidney EC in an isoform-specific fashion through modulation of integrin activity and extracellular matrix protein expression. Our results indicate that regulated expression of specific PECAM-1 isoforms may enable EC to accommodate the different stages of angiogenesis.
血小板内皮细胞黏附分子-1（PECAM-1）通过参与内皮细胞间以及细胞与基质的相互作用和信号转导，与血管生成有关。最近的研究表明，PECAM-1的胞质结构域在其细胞黏附及信号传导特性中起重要作用。然而，PECAM-1同工型在诸如细胞黏附和迁移等血管生成事件中所起的作用仍需进一步阐明。为深入了解PECAM-1在血管发育和血管生成过程中的作用，我们检测了PECAM-1同工型在肾脏血管形成过程中的表达模式。我们发现，在肾脏血管发育过程中，多种PECAM-1同工型以不同频率表达。在肾脏血管系统中检测到的主要同工型是缺失外显子14和15的PECAM-1（Delta14&15）。为进一步研究PECAM-1同工型特异性功能，我们用包被有B(4)-凝集素的磁珠从野生型和PECAM-1缺陷型（PECAM-1-/-）小鼠中分离出肾脏内皮细胞（EC）。与野生型细胞相比，PECAM-1-/-肾脏EC迁移减少，在基质胶中无法形成毛细血管形态，外周致密黏着斑以及外周皮质肌动蛋白分布异常。PECAM-1-/-肾脏EC分泌的纤连蛋白量增加，腱生蛋白-C和血小板反应蛋白-1量减少。在PECAM-1-/-肾脏EC中重新表达Delta14&15而非全长PECAM-1可恢复细胞迁移和毛细血管形态形成缺陷。因此，PECAM-1可能通过调节整合素活性和细胞外基质蛋白表达，以同工型特异性方式调节肾脏EC的黏附和迁移特性。我们的结果表明，特定PECAM-1同工型的调控表达可能使EC适应血管生成的不同阶段。
