Theobald J, Smith P D, Jacob S M, Moss S E
Department of Physiology, University College London, UK.
Biochim Biophys Acta. 1994 Sep 29;1223(3):383-90. doi: 10.1016/0167-4889(94)90099-x.
Human A431 cells exhibit many characteristics typical of transformed cells, such as lack of contact inhibition and reduced growth factor requirement. We have used these cells as a model for the study of annexin VI function, since they do not normally express this protein. In this study we isolated two stably transfected clones, both of which were found to express annexin VI at physiological levels, and examined various growth parameters associated with the transformed phenotype. In low serum, normal A431 cells had doubling times similar to those observed in high serum. However, although the annexin VI transfectants grew only slightly more slowly than controls in high serum, their doubling time was significantly increased in low serum. Moreover, in low serum the annexin VI transfectants stopped proliferating after reaching confluence, indicating contact inhibition. Fluorescence activated cell sorting analysis revealed that the annexin VI+ cells were growth arrested in the G1 phase of the cell cycle when cultured in low serum, whereas annexin VI- clones exhibited the same proportion of mitotic cells in both low and high serum. Thus, expression of annexin VI in a heterologous cell line has a moderating influence on cell proliferation suggesting a possible role for annexin VI in cell growth regulation.
人A431细胞表现出许多典型的转化细胞特征，如缺乏接触抑制和对生长因子需求降低。我们将这些细胞用作研究膜联蛋白VI功能的模型，因为它们通常不表达这种蛋白质。在本研究中，我们分离出两个稳定转染的克隆，发现它们均在生理水平表达膜联蛋白VI，并检测了与转化表型相关的各种生长参数。在低血清中，正常A431细胞的倍增时间与在高血清中观察到的相似。然而，尽管膜联蛋白VI转染细胞在高血清中的生长速度仅比对照稍慢，但在低血清中其倍增时间显著增加。此外，在低血清中，膜联蛋白VI转染细胞在达到汇合后停止增殖，表明存在接触抑制。荧光激活细胞分选分析显示，在低血清中培养时，膜联蛋白VI阳性细胞在细胞周期的G1期生长停滞，而膜联蛋白VI阴性克隆在低血清和高血清中表现出相同比例的有丝分裂细胞。因此，膜联蛋白VI在异源细胞系中的表达对细胞增殖具有调节作用，提示膜联蛋白VI在细胞生长调节中可能发挥作用。
