Akt1 signaling regulates integrin activation, matrix recognition, and fibronectin assembly
Akt1 signaling regulates integrin activation, matrix recognition, and fibronectin assembly
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DOI：
10.1074/jbc.m700241200
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发表时间：
2007-08-03
影响因子：
4.8
通讯作者：
Byzova, Tatiana V.
中科院分区：
文献类型：
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作者：
Somanath, Payaningal R.;Kandel, Eugene S.;Byzova, Tatiana V.
Akt 是一种丝氨酸-苏氨酸激酶，调节血管细胞中的多种细胞过程。我们之前已经记录过 Akt 激活整合素，而 Akt1 缺陷会导致体内皮肤和血管的基质异常。基于这些观察，我们假设 Akt1 对于成纤维细胞的整合素激活和基质组装是必需的。在这项研究中，我们使用各种细胞系统表明，Akt1 对于内皮细胞和成纤维细胞中整合素的由内而外激活至关重要，而整合素反过来又介导基质组装。纤连蛋白是皮肤和血管基底膜的主要细胞外基质成分，具有许多整合素和细胞外基质蛋白的结合位点。与对照成纤维细胞相比，表达显性失活 Akt1 (K179M-Akt1) 的 Akt1(-)/(-) 成纤维细胞和 NIH 成纤维细胞显示纤连蛋白组装受损。相反，组成型活性 Akt1 (myrAkt1) 的表达导致纤连蛋白组装增强。虽然表达 myrAkt1 的人包皮成纤维细胞增加的纤连蛋白组装通过抗整合素 β(1) 阻断抗体治疗而被消除，但用 β(1) 刺激抗体治疗可挽救由于缺乏 Akt 活性而导致的纤连蛋白组装受损。最后，myrAkt1 的表达纠正了 Akt1(-/-) 成纤维细胞的表型，从而表明 Akt1 通过激活整合素 alpha(5)beta(1) 来调节纤连蛋白组装。
Akt, a serine-threonine kinase, regulates multiple cellular processes in vascular cells. We have previously documented that Akt activates integrins and Akt1 deficiency results in matrix abnormalities in skin and blood vessels in vivo. Based on these observations, we hypothesized that Akt1 is necessary for integrin activation and matrix assembly by fibroblasts. In this study, using various cell systems, we show that Akt1 is essential for the inside-out activation of integrins in endothelial cells and fibroblasts, which in turn, mediates matrix assembly. Fibronectin is a major extracellular matrix component of the skin and the vascular basement membrane, which possesses binding sites for many integrins and extracellular matrix proteins. Akt1(-)/(-) fibroblasts and NIH fibroblasts expressing dominant negative Akt1 (K179M-Akt1) showed impaired fibronectin assembly compared with control fibroblasts. In contrast, expression of constitutively active Akt1 (myrAkt1) resulted in enhanced fibronectin assembly. Although increased fibronectin assembly by myrAkt1-expressing human foreskin fibroblasts was abolished by treatment with anti-integrin beta(1) blocking antibodies, treatment with beta(1)-stimulating antibodies rescued the impaired fibronectin assembly that was due to lack of Akt activity. Finally, expression of myrAkt1 corrected the phenotype of Akt1(-/-) fibroblasts thus showing that Akt1 regulates fibronectin assembly through activation of integrin alpha(5)beta(1).