T淋巴細胞過度累積在發炎處會造成發炎病程的惡化，它是導致慢性發炎疾病的原因之一。因此了解T淋巴細胞遷移而累積在發炎處的機制，是澄清許多發炎相關疾病的重要課題。T淋巴細胞遷移受到化學趨化物(chemoattractants)以及整合素受體 (integrin receptors)傳遞的訊號所調控。ZAP70，不只是結合在T細胞受體胞內區調控T細胞活化重要的酪氨酸激酶(tyrosine kinase)，它同時也受到SDF-1-CXCR4信號的活化而調控T細胞的趨向性移動。先前的研究顯示，Jurkat T細胞若有ZAP70缺陷(P116 T細胞)則失去對SDF-1的趨向性移動，此功能失常的原因是由於失去移動的方向性而非其運動性。目前，ZAP70調控T淋巴細胞移動的方向性之機制尚未完全明瞭。為了在T細胞動態移動中研究ZAP70的功能角色，我們構建hZAP70與螢光蛋白EGFP結合的融合蛋白，並將此hZAP70-EGFP融合蛋白轉染至T細胞中。在Jurkat與P116 T細胞中表現的hZAP70-EGFP融合蛋白可被SDF-1刺激而活化，並且仍保有其激酶的功能。表現hZAP70-EGFP可讓P116 T細胞對MCF-7細胞的條件培養液與SDF-1的穿透性移動以及方向性回復正常。但是ZAP70蛋白並不會影響T細胞移動的距離和速度。ZAP70蛋白促進T細胞與細胞外基質間形成穩定的黏著，而且SDF-1刺激ZAP70活化1整合素(1 integrin)後讓T細胞的黏附能力更提高。在懸浮的T細胞中hZAP70-EGFP綠色螢光蛋白均勻的分布於細胞膜附近。在cell^R即時影像研究中可見，聚集在移動中的T細胞前端之hZAP70-EGFP蛋白可能與控制方向性偽足的形成有關。在移動的細胞中hZAP70-EGFP蛋白先聚集到細胞前端後吸引骨架蛋白Talin聚集到相近的位置，爾後牽引著肌動蛋白細絲(actin filament)前來，三者共同控制方向性偽足的形成。綜合以上的結果顯示，ZAP70蛋白增加T淋巴細胞與細胞外基質的黏附性，並且與骨架蛋白Talin、肌動蛋白細絲(actin filament)一同調控方向性偽足的形成，控制著T淋巴細胞的趨向性移動之方向性。

Aberrant accumulation of T lymphocytes in the site of inflammation will promote the inflammation into chronic inflammation disorders. Comprehending the mechanism of T lymphocyte migration is critical for clarifying the etiology of many inflammation related disorders. T lymphocyte migration is a highly integrated process that regulates by chemoattractants and different sets of integrin receptors mediated signaling. It has been shown that ZAP70, an important tyrosine kinase binding to intracellular domain of T cell receptor, is also activated by SDF-1-CXCR4 signaling for T lymphocyte chemotaxis. Our previous studies showed that ZAP70-deficient Jurkat T cells (P116 T cells) exhibit impaired migration toward chemokine SDF-1 due to loss of the directionality but not the motility. However, the mechanism regulating the direction of T lymphocyte migration by ZAP70 is not clear so far. To investigate how ZAP70 regulated the direction of T lymphocyte migration, we have constructed ZAP70-EGFP fusion protein for easily studying the dynamic location of ZAP70 during living T cell migration and we transfected the hZAP70-EGFP plasmid into T cells. hZAP70-EGFP fusion protein of Jurkat and P116 T cells could be activated by chemokine SDF-1 stimulation and had its kinase function. hZAP70-EGFP transfected P116 T cells restored the transmigration rate and the directionality toward conditioned medium of MCF-7 cells and chemokine SDF-1, but ZAP70 protein did not significant affect the migration distance and velocity of T cells. ZAP70 proteins increased the firm adhesion of T cells on the extracellular matrix (ECM) and chemokine SDF-1 simulation of ZAP70 kinase activity to activate 1 integrin further enhanced the adhesion ability. Fluorescence microscopic imaging showed that hZAP70-EGFP located close to the membrane of suspension T cells. Using cell^R time-lapse imaging system, we observed that hZAP70-EGFP accumulated close to the leading edge in migrating T cells may guide the directional lamellipodia formation. Besides, hZAP70-EGFP accumulated close to the leading edge recruited cytoskeletal protein Talin, followed by actin filament that regulated the directional lamellipodia formation. In conclusion, ZAP70 protein regulated the chemotactic directionality of T lymphocyte migration by firm adhesion onto the ECM and associated with Talin and actin filament to modulate the directional lamellipodia formation.

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