Changes in nuclear distribution of large tumor antigen correlate with the proliferative activity of simian virus 40-transformed cells.
A correlation between intranuclear distribution of large tumor antigen (T-ag) and proliferative activity in Simian virus 40 (SV40)-transformed cells has been established. Nuclear T-ag was cytochemically detected by the immunoperoxidase reaction. Cell populations with a high growth rate displayed a heterogeneous pattern with patches of positive reaction surrounded by large and irregular negative areas. By contrast, cell populations with a low growth rate presented a rather homogeneous distribution of nuclear T-ag with a finely granular positive reaction all over the nucleus, excluding nucleolus-like areas. The latter pattern was also observed in cells that had been inhibited from traversing S phase. In this case, the heterogeneous distribution of T-ag within the nucleus was recovered once the cells were allowed to proceed again through S phase, or through G2 phase. Highly condensed chromatin in mitotic chromosomes appeared to exclude T-ag fully as early as in prophase. Then, nuclear distribution of T-ag changes throughout the cell cycle, thus suggesting it might be a cell cycle-dependent event. Interestingly, thymidine-labeled cells from cultures with a high growth rate presented a heterogeneous distribution of autoradiographic grains. Regardless of their mechanism(s) of origin, T-ag-enriched areas might correspond to nuclear sites where a specific function, such as DNA synthesis, is being carried out.
Ordenes
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GE
Dipartamento di Biologia Celular y Genetica, Facultad de Medicina, Universidad de Chile, Santiago.
Beck
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Carmona
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MT
Santos
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D000818:Animals; D000957:Antigens, Viral, Tumor / Q000378:metabolism* / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D002461:Cell Line, Transformed / Q000378:metabolism / Q000473:pathology; D002467:Cell Nucleus / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D002472:Cell Transformation, Viral / Q000276:immunology* / Q000502:physiology; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D007150:Immunohistochemistry; D007399:Interphase; D007668:Kidney / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D010641:Phenotype; D013539:Simian virus 40 / Q000502:physiology*
D000957:Antigens, Viral, Tumor; D004247:DNA