Cell growth and differentiation in vitro in mouse macrophages transformed by a tsA mutant of simian virus 40. III. Large T antigen level and cell proliferation and survival in an SV40 tsA640‐transformed macrophage line

Abstract

The levels of simian virus 40 (SV40) large T antigen in a tsA-transformed mouse macrophage line at the permissive (33 degrees C) and the nonpermissive (39 degrees C) temperature were examined by immunofluorescence, sodium dodecylsulfate-polyacrylamide gel electrophoresis, complement fixation, and enzyme-linked immunosorbent assay. When the cells were confluent and rested at 33 degrees C, and then were shifted to 39 degrees C, the amount of large T antigen per cell decreased, and most cells survived and remained phagocytic. When the cells were proliferating at 33 degrees C, and then were shifted to 39 degrees C, the cells died with only a small reduction in the amount of large T antigen. Therefore, the physiological state of the cells may determine the survival of cells by affecting the level of large T antigen after exposure to 39 degrees. The confluent cells may be rested with a concomitant decrease of large T antigen. The proliferating cells may not survive in the presence of a relatively high level of functionally defective large T antigen at 39 degrees C.

Induction of fibronectin expression, actin cable formation, and entry into S phase following reexpression of T antigen in mouse macrophages transformed by the tsA640 mutant of SV40

“…When these resting cells are replated at a low cell density and incubated at 33.0°C, the majority of the cells begin to express large T antigen by 24 hr, and the cells are increased in number by 4 days after shift down. In contrast, parallel cultures incubated at 39.0"C remain in the resting state without cellular changes detectable at 33.0"C (Tanigawa et al, 1983(Tanigawa et al, , 1984(Tanigawa et al, ,1985. In the present experiments, much the same results were obtained (Fig.…”

“…Temporal order of responses of tsA640-transformed macrophages to shifting the temperature to 33.0"C When confluent cultures of tsA640-transformed macrophage lines are further incubated at 39.0"C for 5 days, cells enter a resting state with a diploid DNA content, express no significant amounts of SV40 large T and small t antigens, and fully express the macrophage characteristics, such as immune phagocytosis (Tanigawa et al, 1983(Tanigawa et al, , 1984(Tanigawa et al, , 1985. When these resting cells are replated at a low cell density and incubated at 33.0°C, the majority of the cells begin to express large T antigen by 24 hr, and the cells are increased in number by 4 days after shift down.…”

“…In the present study, we used the mouse macrophage lines transformed (rendered immortal) with an SV40 gene A mutant whose mutation renders large T antigen temperature-sensitive (tsA640; Kimura and Dulbecco, 1973;Tanigawa et al, 1985). To see whether SV40 large T antigen influences the expression of fibronectin and actin distribution in macrophages, tsA640-transformed macrophages were exposed to temperatures permissive and nonpermissive for large T antigen.…”

Alteration in cyclic adenosine 3′:5′‐monophosphate binding proteins during the phenotypic change of mouse macrophages transformed by a temperature‐sensitive mutant (tsA640) of SV40

“…The macrophage lines established by transformation of mouse bone marrow cells by the tsA mutant of SV40 enter a resting state with a 2N DNA content, show a 0 1986 ALAN R. LISS. INC reduced amount of SV40 T antigen, and restore macrophage markers such as Fc-and complement-mediated phagocytosis when confluent cultures are shifted to a nonpermissive temperature (Tanigawa et al, 1983(Tanigawa et al, ,1984(Tanigawa et al, , 1985. When these resting cells are shifted from the nonpermissive temperature to a permissive temperature, tsA640 transformants become positive for SV40 T antigen in the majority of the cells by 24 hr, and then the number of cells begins to increase and nonphagocytic cells, like fibroblasts, appear in 4-5 days (Tanigawa et al, 1983).…”

Accumulation of cells with 4N DNA content at nonpermissive temperature in rat embryo diploid cells transformed by tsA mutant of simian virus 40

“…Hou r s (Tegtmeyer et al, 1975;Edwards et al, 1979;Tanigawa et al, 1985). All the A640-t ransformants showed far less efficiencies of colony formation on the plastic substratum and in soft agar at the nonpermissive temperature (39.6"C) than at the permissive temperature (335°C) ( Table 1).…”