中文摘要：

本研究通过向SGC-7901细胞中加入可溶性纤维连接蛋白（fibronectin，FN）探讨可溶性纤维连接蛋白对PKA活性的影响。实验采用蛋白印迹技术检测可溶性FN在不同浓度及作用时间情况下对PKAC。亚基表达水平以及PKA作用底物血管扩张刺激磷蛋白fvasodilator-stimulatedphos．phoprotein，VASP）磷酸化水平的影响；采用免疫荧光技术检测可溶性FN对PKA作用底物P—VASP分布的影响。结果显示，在SGC一7901细胞中，可溶性FN在0．5～8μg／ml浓度区间内，对PKA活性存在剂量依赖性抑制效应；选取lμg／ml可溶性FN作用12h以后，可溶性FN对PKA活性存在时间依赖性抑制效应；同时，我们建立了能够稳定表达人甲状腺A激酶锚定蛋白（humanthyroidAKAP,Ht311肽段的SGC细胞，Ht3l破坏PKA锚定后，FN对PKA活性的抑制作用消失：免疫荧光显示可溶性FN可以使VASP磷酸化位置聚集于细胞边缘。因此，我们认为在SGC．7901细胞中可溶性FN对PKA活性存在抑制作用，这种抑制效应与可溶性FN的浓度及作用时间呈正比且取决于PKA能否正常锚定：可溶性FN可以影响PKA活化位置。

英文摘要：

To investigate the effect of soluble fibronectin on protein kinase A activation in gastric cancer cell line SGC-7901, we treated Gastric cancer cell line SGC-7901 with soluble fibronectin of different concentrations or different time, expression of PKA catalytic subunit and the phosphorylation level of vasodilator-stimulated phosphoprotein （VASP）, one of PKA substrates were determined by Western blot, the distribute of p-VASP was determined by immumofluorescence method. The results revealed that, FN can inhibit the PKA activation in SGC- 7901 among concentrations of 0.5-8μg/ml. As the dose and time increased, the inhibitory of FN on PKA activation of SGC-7901 was significantly increased after 12 h. FN mediate p-VASP accumlate on the edge of cell. However, these effect disapper in stably transfected SGC cells expressing the AKAP inhibitory peptide Ht31. These data suggest that PKA activation in SGC-7901 could be inhibited by FN, the inhibition determined by FN concentration, functionary time and PKA anchor. FN mediate localized activation of PKA.