Gibson P R, Birchall I, Rosella O, Albert V, Finch C F, Barkla D H, Young G P
Department of Medicine, The Royal Melbourne Hospital, Victoria, Australia.
Gut. 1998 Nov;43(5):656-63. doi: 10.1136/gut.43.5.656.
The functions of urokinase in intestinal epithelia are unknown.
To determine the relation of urokinase expressed by intestinal epithelial cells to their position in the crypt-villus/surface axis and of mucosal urokinase activity to epithelial proliferative kinetics in the distal colon.
Urokinase expression was examined immunohistochemically in human intestinal mucosa. Urokinase activity was measured colorimetrically in epithelial cells isolated sequentially from the crypt-villus axis of the rat small intestine. In separate experiments, urokinase activity and epithelial kinetics (measured stathmokinetically) were measured in homogenates of distal colonic mucosa of 14 groups of eight rats fed diets known to alter epithelial turnover.
From the crypt base, an ascending gradient of expression and activity of urokinase was associated with the epithelial cells. Median mucosal urokinase activities in each of the dietary groups of rats correlated positively with autologous median number of metaphase arrests per crypt (r=0.68; p<0.005) and per 100 crypt cells (r=0.75; p<0.001), but not with crypt column height.
Localisation of an enzyme capable of leading to digestion of cell substratum in the region where cells are loosely attached to their basement membrane, and the association of its activity with indexes of cell turnover, suggest a role for urokinase in facilitating epithelial cell loss in the intestine.
尿激酶在肠上皮中的功能尚不清楚。
确定肠上皮细胞表达的尿激酶与其在隐窝 - 绒毛/表面轴上位置的关系，以及结肠远端黏膜尿激酶活性与上皮增殖动力学的关系。
采用免疫组织化学方法检测人肠黏膜中尿激酶的表达。采用比色法测定从大鼠小肠隐窝 - 绒毛轴依次分离的上皮细胞中的尿激酶活性。在另外的实验中，对14组每组8只喂食已知可改变上皮更新的饮食的大鼠的结肠远端黏膜匀浆，测定尿激酶活性和上皮动力学（采用静止分析法测量）。
从隐窝底部开始，尿激酶的表达和活性呈上升梯度，与上皮细胞相关。每组饮食大鼠的黏膜尿激酶活性中位数与每个隐窝（r = 0.68；p < 0.005）和每100个隐窝细胞（r = 0.75；p < 0.001）的中期停滞自体中位数呈正相关，但与隐窝柱高度无关。
在细胞与其基底膜松散附着的区域定位一种能够导致细胞基质消化的酶，并且其活性与细胞更新指标相关，提示尿激酶在促进肠道上皮细胞脱落中起作用。
