A cell cycle and mutational analysis of anchorage-independent growth: cell adhesion and TGF-beta 1 control G1/S transit specifically.
A cell cycle and mutational analysis of anchorage-independent growth: cell adhesion and TGF-beta 1 control G1/S transit specifically.
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DOI：
10.1083/jcb.122.2.461
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发表时间：
1993-07
期刊：
影响因子：
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通讯作者：
Assoian RK
中科院分区：
文献类型：
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作者：
Han EK;Guadagno TM;Dalton SL;Assoian RK
我们已经研究了非转化成纤维细胞的锚定非依赖性生长的细胞周期控制。在以前的研究中，使用G 0-同步NRK和NIH-3 T3细胞，我们表明，锚定非依赖性生长的G1/S，类似于启动控制点在酿酒酵母细胞周期的附着依赖性过渡调节。在这里报道的研究中，我们在这种附着依赖性转变后立即同步NRK和NIH-3 T3成纤维细胞，以确定成纤维细胞周期的其他部分是否也受到粘附的类似调节。我们的研究结果表明，S-，G2-和M-期进展进行的情况下，附件。因此，我们的结论是，这些细胞的增殖的粘附要求可以解释在单START样过渡。在相关研究中，我们发现TGF-β 1在NRK和AKR-2B成纤维细胞（其中TGF-β 1诱导锚定非依赖性生长的细胞系）中覆盖附着依赖性转变，但在NIH-3 T3或Balb/c 3 T3成纤维细胞（其中TGF-β 1未能诱导锚定非依赖性生长的细胞系）中不覆盖。这些结果表明，（a）粘附和TGF-β 1在刺激细胞周期从G1进展到S中具有相似的作用，和（B）TGF-β 1对各种成纤维细胞系的锚定非依赖性生长的不同作用直接反映在生长因子在G1/S的不同作用中。最后，我们随机诱变NRK成纤维细胞产生突变株，这些突变株失去了G1/S转运所需的附着/TGF-β 1，同时保留了增殖所需的正常有丝分裂原。这些克隆在添加有丝分裂原的软琼脂中容易增殖，在单层中表现为非转化：它们铺展良好，无触变性，接触抑制。这种新的成纤维细胞表型的存在表明：（a）细胞周期进程的生长因子和粘附/TGF-β 1需求在遗传上是可分离的，（B）成纤维细胞周期中的两个主要控制点是细胞周期的调控因子，（B）细胞周期的调控因子，（C）细胞周期的调控因子，（D）细胞周期的调控因子，（E）细胞周期的调控因子，（G 0/G1和G1/S）由不同的细胞外信号调节，和（c）调节非锚定依赖性生长的基因不需要参与调节接触抑制，焦点形成或生长因子依赖。
We have examined cell cycle control of anchorage-independent growth in nontransformed fibroblasts. In previous studies using G0-synchronized NRK and NIH-3T3 cells, we showed that anchorage-independent growth is regulated by an attachment-dependent transition at G1/S that resembles the START control point in the cell cycle of Saccharomyces cerevisiae. In the studies reported here, we have synchronized NRK and NIH-3T3 fibroblasts immediately after this attachment-dependent transition to determine if other portions of the fibroblast cell cycle are similarly regulated by adhesion. Our results show that S-, G2-, and M-phase progression proceed in the absence of attachment. Thus, we conclude that the adhesion requirement for proliferation of these cells can be explained in terms of the single START-like transition. In related studies, we show that TGF-beta 1 overrides the attachment-dependent transition in NRK and AKR-2B fibroblasts (lines in which TGF-beta 1 induces anchorage-independent growth), but not in NIH-3T3 or Balb/c 3T3 fibroblasts (lines in which TGF-beta 1 fails to induce anchorage- independent growth). These results show that (a) adhesion and TGF-beta 1 can have similar effects in stimulating cell cycle progression from G1 to S and (b) the differential effects of TGF-beta 1 on anchorage- independent growth of various fibroblast lines are directly reflected in the differential effects of the growth factor at G1/S. Finally, we have randomly mutagenized NRK fibroblasts to generate mutant lines that have lost their attachment/TGF-beta 1 requirement for G1/S transit while retaining their normal mitogen requirements for proliferation. These clones, which readily proliferate in mitogen-supplemented soft agar, appear non-transformed in monolayer: they are well spread, nonrefractile, and contact inhibited. The existence of this new fibroblast phenotype demonstrates (a) that the growth factor and adhesion/TGF-beta 1 requirements for cell cycle progression are genetically separable, (b) that the two major control points in the fibroblast cell cycle (G0/G1 and G1/S) are regulated by distinct extracellular signals, and (c) that the genes regulating anchorage- independent growth need not be involved in regulating contact inhibition, focus formation, or growth factor dependence.