Department of Internal Medicine, Yale Cardiovascular Research Center, and.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA.
J Clin Invest. 2019 Aug 13;129(11):4863-4874. doi: 10.1172/JCI127692.
Fibronectin in the vascular wall promotes inflammatory activation of the endothelium during vascular remodeling and atherosclerosis. These effects are mediated in part by fibronectin binding to integrin α5, which recruits and activates phosphodiesterase 4D5 (PDE4D5) by inducing its dephosphorylation on an inhibitory site Ser651. Active PDE then hydrolyzes anti-inflammatory cAMP to facilitate inflammatory signaling. To test this model in vivo, we mutated the integrin binding site in PDE4D5 in mice. This mutation reduced endothelial inflammatory activation in athero-prone regions of arteries, and, in a hyperlipidemia model, reduced atherosclerotic plaque size while increasing markers of plaque stability. We then investigated the mechanism of PDE4D5 activation. Proteomics identified the PP2A regulatory subunit B55α as the factor recruiting PP2A to PDE4D5. The B55α-PP2A complex localized to adhesions and directly dephosphorylated PDE4D5. This interaction also unexpectedly stabilized the PP2A-B55α complex. The integrin-regulated, pro-atherosclerotic transcription factor Yap is also dephosphorylated and activated through this pathway. PDE4D5 therefore mediates matrix-specific regulation of EC phenotype via an unconventional adapter role, assembling and anchoring a multifunctional PP2A complex with other targets. These results are likely to have widespread consequences for control of cell function by integrins.
血管壁中的纤连蛋白在血管重塑和动脉粥样硬化过程中促进内皮细胞的炎症激活。这些作用部分是通过纤连蛋白与整合素α5结合介导的，纤连蛋白结合整合素α5通过诱导其在抑制性位点 Ser651 去磷酸化来招募和激活磷酸二酯酶 4D5 (PDE4D5)。然后，活性 PDE 将抗炎性 cAMP 水解为促进炎症信号。为了在体内测试该模型，我们在小鼠中突变了 PDE4D5 的整合素结合位点。该突变减少了动脉粥样易损区域内皮细胞的炎症激活，并且在高脂血症模型中，减少了动脉粥样硬化斑块的大小，同时增加了斑块稳定性的标志物。然后，我们研究了 PDE4D5 激活的机制。蛋白质组学鉴定出 PP2A 调节亚基 B55α 是招募 PP2A 到 PDE4D5 的因子。B55α-PP2A 复合物定位于黏附处，并直接使 PDE4D5 去磷酸化。这种相互作用还出人意料地稳定了 PP2A-B55α 复合物。整合素调节的促动脉粥样硬化转录因子 yap 也通过该途径被去磷酸化和激活。因此，PDE4D5 通过一种非传统的衔接子作用介导细胞外基质特异性调节 EC 表型，组装并锚定具有其他靶标的多功能 PP2A 复合物。这些结果可能对整合素控制细胞功能具有广泛的影响。
