Mitsudomi T, Kimura G
J Cell Physiol. 1985 Jun;123(3):353-60. doi: 10.1002/jcp.1041230310.
Four temperature-sensitive (ts) mutants of rat 3Y1 fibroblasts, representing independent complementation groups, cease to proliferate predominantly with a 2n DNA content, at the restrictive temperature (39.8 degrees C) (temperature arrest) or at the permissive temperature (33.8 degrees C) at a confluent cell density (density arrest) (Ohno et al., 1984). We studied the temperature- or the density-arrested cells of these mutants infected with simian virus 40 (SV40) or its mutants affecting large T or small t antigen with respect to kinetics at 39.8 degrees C of entry into S phase and cellular proliferation. Three mutants, 3Y1tsD123, 3Y1tsF121 and 3Y1tsG125, expressed T antigen and entered S phase at 39.8 degrees C from both the arrested states after infection with either wild-type, tsA mutants, or a .54/.59 deletion mutant of SV40, whereas in the density-arrested 3Y1tsH203, expression of T antigen and entry into S phase were inefficient and ts. Following the WT-SV40 induced entry into S phase, the temperature-arrested 3Y1tsD123 detached from the substratum with no detectable increase in cell number, whereas the density-arrested ones completed a round of the cell cycle and then detached. 3Y1tsF121 and 3Y1tsG125 in the both arrested states proliferated through more than one generation. 3Y1tsF121 and 3Y1tsG125 in the density-arrested state infected with tsA mutants once proliferated and then ceased to increase in number as the percentage of T-antigen positive population decreased. These results suggest that wild-type and tsA-mutated large T antigens are able to overcome the cellular ts blocks of entry into S phase in the 3 ts mutants of 3Y1 cells in both the arrested states, and that small t antigen is not required to overcome the blocks. It is also suggested that cellular behaviors subsequent to S phase (viability, mitosis, and proliferation in the following generations) depend on cellular arrest states, on traits of cellular ts defects, and on the duration of large T antigen expression.
大鼠3Y1成纤维细胞的四个温度敏感（ts）突变体，代表独立的互补组，在限制温度（39.8℃）（温度阻滞）或在汇合细胞密度下的允许温度（33.8℃）（密度阻滞）时，主要以2n DNA含量停止增殖（Ohno等人，1984年）。我们研究了感染猿猴病毒40（SV40）或其影响大T或小t抗原的突变体的这些突变体的温度或密度阻滞细胞在39.8℃进入S期和细胞增殖的动力学。三个突变体3Y1tsD123、3Y1tsF121和3Y1tsG125，在用野生型、tsA突变体或SV40的.54/.59缺失突变体感染后，在39.8℃时从两种阻滞状态都表达T抗原并进入S期，而在密度阻滞的3Y1tsH203中，T抗原的表达和进入S期效率低下且呈温度敏感。在野生型SV40诱导进入S期后，温度阻滞的3Y1tsD123从基质上脱离，细胞数量没有可检测到的增加，而密度阻滞的细胞完成一轮细胞周期然后脱离。处于两种阻滞状态的3Y1tsF121和3Y1tsG125增殖超过一代。用tsA突变体感染的处于密度阻滞状态的3Y1tsF121和3Y1tsG125一旦增殖，然后随着T抗原阳性群体百分比的降低数量不再增加。这些结果表明，野生型和tsA突变的大T抗原能够克服3Y1细胞的3个ts突变体在两种阻滞状态下进入S期的细胞ts阻滞，并且小t抗原不是克服阻滞所必需的。还表明S期后的细胞行为（活力、有丝分裂和后代中的增殖）取决于细胞阻滞状态、细胞ts缺陷的特征以及大T抗原表达持续时间。
