Albers M W, Williams R T, Brown E J, Tanaka A, Hall F L, Schreiber S L
Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138.
J Biol Chem. 1993 Oct 25;268(30):22825-9.
Upon entering a cell the natural product rapamycin, like the structurally related immunosuppressant FK506, associates with members of the FKBP family of proteins. One or more of the resulting FKBP-rapamycin complexes blocks signaling pathways emanating from some growth factor receptors. Recently, the addition of rapamycin was shown to inhibit the phosphorylation and activation of a 70-kDa ribosomal S6 protein kinase, which normally occurs minutes after the activation of certain cytokine and growth factor receptors. We now report that rapamycin can be added 4 to 6 h after the addition of serum growth factors to quiescent human osteosarcoma cells and still arrest these cells in G1. This window of action correlates with the inducible appearance of a cyclin-dependent kinase (cdk) activity, and the induction of this activity is inhibited by the addition of rapamycin. Furthermore, p36cyclin D1 associates with this cdk protein complex in lysates of untreated cells, but does not associate with this cdk protein complex in lysates of rapamycin-treated cells. Together, these studies demonstrate that FKBP-rapamycin can modulate a cyclin-dependent kinase activity and a cyclin D1-cdk association during early G1 in MG-63 human osteosarcoma cells.
天然产物雷帕霉素进入细胞后，与结构相关的免疫抑制剂FK506一样，会与FKBP蛋白家族的成员结合。由此形成的一种或多种FKBP - 雷帕霉素复合物会阻断某些生长因子受体发出的信号通路。最近研究表明，添加雷帕霉素可抑制一种70 kDa核糖体S6蛋白激酶的磷酸化和激活，这种磷酸化和激活通常在某些细胞因子和生长因子受体激活数分钟后发生。我们现在报告，对于静止的人骨肉瘤细胞，在添加血清生长因子后4至6小时添加雷帕霉素，仍可使这些细胞停滞在G1期。这一作用窗口期与细胞周期蛋白依赖性激酶（cdk）活性的诱导出现相关，而添加雷帕霉素可抑制这种活性的诱导。此外，在未处理细胞的裂解物中，p36细胞周期蛋白D1与这种cdk蛋白复合物相关联，但在雷帕霉素处理细胞的裂解物中，p36细胞周期蛋白D1不与这种cdk蛋白复合物相关联。总之，这些研究表明，FKBP - 雷帕霉素可在MG - 63人骨肉瘤细胞G1早期调节细胞周期蛋白依赖性激酶活性和细胞周期蛋白D1 - cdk关联。
