AIM Protein kinase (PK) A anchoring protein (AKAP) 12 is a scaffolding protein that anchors PKA to compartmentalize cyclic AMP signalling. This study assessed the consequences of the downregulation or deletion of AKAP12 on endothelial cell migration and angiogenesis. METHODS The consequences of siRNA-mediated downregulation AKAP12 were studied in primary cultures of human endothelial cells as well as in endothelial cells and retinas from wild-type versus AKAP12-/- mice. Molecular interactions were investigated using a combination of immunoprecipitation and mass spectrometry. RESULTS AKAP12 was expressed at low levels in confluent endothelial cells but its expression was increased in actively migrating cells, where it localized to lamellipodia. In the postnatal retina, AKAP12 was expressed by actively migrating tip cells at the angiogenic front, and its deletion resulted in defective extension of the vascular plexus. In migrating endothelial cells, AKAP12 was co-localized with the PKA type II-α regulatory subunit as well as multiple key regulators of actin dynamics and actin filament-based movement; including components of the Arp2/3 complex and the vasodilator-stimulated phosphoprotein (VASP). Fitting with the evidence of a physical VASP/AKAP12/PKA complex, it was possible to demonstrate that the VEGF-stimulated and PKA-dependent phosphorylation of VASP was dependent on AKAP12. Indeed, AKAP12 colocalized with phospho-Ser157 VASP at the leading edge of migrating endothelial cells. CONCLUSION The results suggest that compartmentalized AKAP12/PKA signalling mediates VASP phosphorylation at the leading edge of migrating endothelial cells to translate angiogenic stimuli into altered actin dynamics and cell movement.

中文翻译：

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AKAP12缺乏会损害VEGF诱导的内皮细胞迁移和发芽。

AIM蛋白激酶（PK）锚定蛋白（AKAP）12是一种锚定蛋白，可锚定PKA来分隔环AMP信号传导。这项研究评估了AKAP12的下调或缺失对内皮细胞迁移和血管生成的影响。方法在人内皮细胞的原代培养物中以及野生型和AKAP12-/-小鼠的内皮细胞和视网膜中研究了siRNA介导的AKAP12下调的后果。分子相互作用的研究使用免疫沉淀和质谱的结合。结果AKAP12在融合内皮细胞中低水平表达，但在活跃迁移的细胞中表达增加，AKAP12定位于片状脂膜。在出生后的视网膜中，AKAP12是通过在血管生成前沿主动迁移尖端细胞而表达的，并且其缺失导致血管丛延伸缺陷。在迁移内皮细胞时，AKAP12与PKAII-α型调节亚基以及肌动蛋白动力学和基于肌动蛋白丝的运动的多个关键调节剂共定位。包括Arp2 / 3复合物和血管扩张剂刺激的磷蛋白（VASP）的成分。符合物理VASP / AKAP12 / PKA复合物的证据，有可能证明VASP的VEGF刺激和PKA依赖性磷酸化依赖于AKAP12。实际上，AKAP12与磷酸Ser157 VASP共定位在迁移的内皮细胞的前沿。