Han O, Sumpio B E, Basson M D
Departments of Surgery, Yale University School of Medicine and the Connecticut VA Health Care System, New Haven, Connecticut, 06520-8062, USA.
Biochem Biophys Res Commun. 1998 Sep 29;250(3):668-73. doi: 10.1006/bbrc.1998.9372.
Repetitive strain stimulates proliferation and modulates differentiation in human Caco-2 intestinal epithelial cells via tyrosine kinase activity. We therefore sought to characterize strain modulation of tyrosine phosphorylation in Caco-2 cells. Immunoblotting for phosphotyrosine demonstrated that repetitive strain (10 cpm, 10% strain) rapidly increased tyrosine phosphorylation of 125-, 70-, 60-, and 50-kDa bands in the soluble fraction by 94+/-31, 145+/-21, 365+/-46, and 1240+/-240%, respectively (p<0.05, n=4). However, strain decreased tyrosine phosphorylated band intensity of the 125-, 70-, 60-, and 50-kDa proteins in the particulate fraction by 81+/-17, 70+/-23, 79+/-7, and 59+/-23%, respectively (p<0.05, n=4). The decreased band intensity in the particulate fraction was not due to decreased tyrosine kinase activity because strain equally increased tyrosine kinase activity in both soluble and particulate fractions. Cyclic strain at a physiologically relevant amplitude and frequency appears to modulate the subcellular distribution of tyrosine phosphorylated proteins in human Caco-2 intestinal cells.
重复性应变通过酪氨酸激酶活性刺激人Caco-2肠上皮细胞增殖并调节其分化。因此，我们试图表征Caco-2细胞中酪氨酸磷酸化的应变调节。磷酸酪氨酸免疫印迹表明，重复性应变（10次循环/分钟，10%应变）使可溶部分中125 kDa、70 kDa、60 kDa和50 kDa条带的酪氨酸磷酸化分别迅速增加94±31%、145±21%、365±46%和1240±240%（p<0.05，n=4）。然而，应变使颗粒部分中125 kDa、70 kDa、60 kDa和50 kDa蛋白质的酪氨酸磷酸化条带强度分别降低81±17%、70±23%、79±7%和59±23%（p<0.05，n=4）。颗粒部分条带强度的降低并非由于酪氨酸激酶活性降低，因为应变在可溶部分和颗粒部分中均同等程度地增加了酪氨酸激酶活性。生理相关幅度和频率的周期性应变似乎调节人Caco-2肠细胞中酪氨酸磷酸化蛋白的亚细胞分布。
