蛋白酪氨酸激酶活性变化在大鼠胃粘膜损伤修复中的作用及机理

Protein tyrosine kinase activation in the repair of rat gastric mucosa after damage

目的 探讨大鼠胃粘膜损伤后蛋白酪氨酸激酶 (PTK)活性的变化及通过影响细胞核蛋白质磷酸化和转录因子激活蛋白 1(Activatingprotein 1,AP 1)的活性对胃粘膜修复的作用及意义。方法 以 2 0mmol/L去氧胆酸钠 (DOC)给SD大鼠灌胃 ,损伤胃粘膜 ,损伤后 3小时取胃 ,抽提分离细胞膜和细胞核组分 ,以膜结合法检测细胞膜PTK活性和细胞核蛋白质的磷酸化 ,以凝胶电泳漂移实验(gelshiftassay)检测AP 1活性 ,应用PTK抑制剂Tyrphostin 5 1和丝裂原激活蛋白激酶激酶 (MAPKK)抑制剂PD0 980 5 9观察其信号传导的调控。结果 2 0mmol/LDOC导致大鼠中度胃粘膜损伤 ,损伤后 3小时 ,细胞膜PTK活性增高 1倍 ,而细胞核蛋白质的磷酸化程度增加 4倍 ,AP 1活性明显增强。应用tyrphostin 5 1后细胞核蛋白质的磷酸化程度抑制 85 3 % ,应用PD0 980 5 9则抑制 61 6% ,两者均使AP 1活性明显减弱。结论 PTK活性增高是胃粘膜损伤后早期快速修复的重要因素 ,其机理是通过影响细胞核蛋白质的磷酸化和AP 1活性 ,在向细胞核传导的过程中 ,PTK的效应被放大 ,其信号传导主要经MAPK通路。

Objective To investigate the possible role of protein tyrosine kinase (PTK) and its effect on nuclear protein phosphorylation and activating protein 1 (AP 1) activity in the rat gastric epithelial restitution Methods Rat gastric mucosae were damaged with 20 mmol/L Deoxysodium cholate (DOC) Mucosal scrapings from the oxyntic gland area were obtained 3 hours after damage The cellular membrane and nuclear fractions were dissociated from the extraction of the mucosal scrapings to assay the activity of PTK and AP 1, and the phosphorylation of nuclear protein Different blockers, including Tyrphostin 51 for PTK and PD098059 for mitogen activated protein kinase kinase (MAPKK), were used to study the signaling control for a better understanding of the mechanisms of gastric reepithelium Results 20 mmol/L DOC caused moderate damage in rat gastric mucosae PTK activity 3 hours after damage was 1 time that of the primary level, while nuclear protein phosphorylation level was incresed about 4 folds Tyrphostin 51 and PD098059 inhibited such effects by 85 3% and 61 6%, respectively AP 1 activity was also greatly elevated after gastric mucosal damage and the effect was attenuated by both Tyrpsotin 51 and PD098059 Conclusion PTK activation improves the rat gastric mucosal repair ability in the early phase after damage through the promotion of nuclear protein phospharylation and the increase in AP 1 activity The effect of PTK is greatly magnified when the signals fly into the cellular nuclea, mainly through MAPK pathway