Activation pathways of α4β1 integrin leading to distinct T-cell cytoskeleton reorganization, Rac1 regulation and Pyk2 phosphorylation
Activation pathways of α4β1 integrin leading to distinct T-cell cytoskeleton reorganization, Rac1 regulation and Pyk2 phosphorylation
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DOI：
10.1002/jcp.20624
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发表时间：
2006-06-01
影响因子：
5.6
通讯作者：
Garcia-Pardo, A
中科院分区：
文献类型：
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作者：
Maqueda, A;Moyano, JV;Garcia-Pardo, A
α 4 β 1整联蛋白在淋巴细胞中高度表达，并且在造血、外渗和炎症反应中是必需的。α 4 β 1可以被细胞内信号激活，所述细胞内信号是在T细胞被佛波醇酯、CD 3交联或某些趋化因子/受体相互作用（由内而外激活）激活时引起的。二价阳离子或某些抗β 1 mAb（即，TS 2/16）也可以直接结合和激活整联蛋白（由外向内激活）。在这两种情况下，活化导致对配体的粘附和/或亲和力增加。尚不清楚这些不同的刺激是否产生相同或不同的粘附后事件。为了解决这个问题，我们研究了Jurkat细胞和人T淋巴母细胞中α 4 β 1激活后的细胞骨架组织和细胞内信号传导。用Mn 2+、α-CD 3 mAb或趋化因子SDF-1 α治疗。随后附着于纤连蛋白片段H89或内皮分子VCAM-1（α 4 β 1配体），导致细胞极化和迁移。相比之下，PMA或TS 2/ 16活化诱导细胞铺展和强粘附。视频显微镜和Transwell分析证实了这些结果，这与不同的阻力下分离流动。激活小GTdR RhoA或转染组成型活性突变体V14 RhoA或V12 Rac 1，废除了α 4p 1诱导的细胞极化，但不影响细胞扩散。此外，Rac 1活性明显调制剂，诱导极化或传播表型。酪氨酸激酶Pyk 2在诱导细胞极性时高度磷酸化，但在细胞铺展过程中不高度磷酸化。这些结果揭示了α 4 β 1整联蛋白的新特性，即触发具有不同信号传导需求的两种类型的T细胞细胞骨架应答的能力。
a4 beta 1 integrin is highly expressed in lyrnphocytes and is essential in hematopoiesis, extravasation, and the inflammatory response. alpha 4 beta 1 can be activated by intracellular signals elicited upon T-cell activation by phorbol esters, CD3 crosslinking, or certain chemokine/receptor interactions (inside-out activation). Divalent cations or certain anti-beta 1 mAbs (i.e., TS2/16) can also bind and activate integrins directly (outside-in activation). in both cases, activation results in increased adhesion and/or affinity for ligands. It is not known if these various Stimuli produce the same or different post-adhesion events. To address this, we have Studied the cytoskeleton organization and intracellular signaling following activation of alpha 4 beta 1 in Jurkat cells and in human T-lymphoblasts. Treatment with Mn2+, alpha-CD3 mAb or the chemokine SDF-1 alpha. followed by attachment to the fibronectin fragment H89 or the endothelial molecule VCAM-1 (alpha 4 beta 1 ligands), resulted in cell polarization and migration. In contrast, activation with PMA or TS2/ 16 induced cell spreading and strong adherence. Video microscopy and Transwell analyses confirmed these results, which correlated with different resistance to detachment under flow. Activation of the small GTPase RhoA or transfection with the constitutively active mutants V14RhoA or V12Rac1, abolished the alpha 4p1-induced cell polarization but did not affect cell spreading. Moreover, Rac1 activity was distinctly modulated by agents that induce a polarized or spread phenotype. The tyrosine kinase Pyk2 was highly phosphorylated upon induction of cell polarity but not during cell spreading. These results reveal novel properties of alpha 4 beta 1 integrin, namely the ability to trigger two types of T-cell cytoskeletal response with different signaling requirements.