Arrest states in a set of mutants of rat 3Y1 cells temperature‐sensitive for entering S phase

Zaitsu, Hirokazu; Kimura, Genki

doi:10.1002/jcp.1041190114

Cited by 20 publications

(30 citation statements)

References 24 publications

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“…Experiment 2 in table 1 (shown in figure 1) is representative of the time course experiment. Ten-day cells re quired a longer lag time for entry into S phase after serum stimulation (45 h) than did 2-day cells (28 h), thus confirming our reported results [1,2], The lag time for expression of T antigen after SV40 infection in 10-day cells (17.5 h) was similar to that in 2-day cells (17.0 h). When observed with a fluorescence mic roscope, we did not observe a difference in intensity between 2-day and 10-day cells (data not shown).…”

supporting

confidence: 81%

“…We compared cells ar rested at 33.8° at saturation density for 2 days (2-day cells) with those at saturation density for 7 days (7-day cells) or 10 days (10-day cells). After incubation in the density-ar rested state for 7 days, the lag time for entry into S phase after serum stimulation could not be prolonged; in other words, there was a time limit, as described previously [1,2]. Here, the lag time is defined as the time required for 50% of cells to express T antigen, as determined by immunofluorescence, or to enter S phase, as determined by autoradiog raphy.…”

mentioning

confidence: 99%

“…After incubation for 7 days in the density-arrested state, the time reached a li mit. A decrease in the prepardedness of cells to enter the S phase may cause this prolonga tion; in other words, a retreat toward a deeper GO phase [1,2], To our knowledge, how the difference between GO and deeper GO phases (difference of internal factor which is caused before SV40 infection) af fects T antigen expression and induction of Number in parentheses are ratios of lag time (7-day/2-day or IO-day/2-day). a Incubation period of cells in the density-arrested state.…”

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confidence: 99%

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Deeper ‘GO’ Phase in Rat Fibroblasts Affects the Lag Time Required for T Antigen Induced DNA Synthesis, but not the Lag Time Required for SV40 T Antigen Expression

Zaitsu¹,

Kimura²

1989

Intervirology

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In density-arrested rat 3YltsG125 cells, the time required for entry into S phase after serum stimulation is prolonged with increase in duration of the arrest. When these cells were infected with simian virus 40, the time required for expression of T antigen did not change, but the time required for entry into S phase was prolonged with increase in duration of the arrest. The extent of prolongation of the interval between T antigen expression and entry into S phase correlated well with the extent of the prolongation detected with serum stimulation. These observations suggest that: (1) expression of T antigen was not affected by the level of cellular preparedness for entry into S phase, i.e., it did not depend on cellular functions directly involved in the preparedness, and (2) T antigen induced cellular DNA synthesis, at least in part, by a mechanism similar to that of serum-induced DNA synthesis.

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confidence: 99%

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confidence: 99%

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Deeper ‘GO’ Phase in Rat Fibroblasts Affects the Lag Time Required for T Antigen Induced DNA Synthesis, but not the Lag Time Required for SV40 T Antigen Expression

Zaitsu¹,

Kimura²

1989

Intervirology

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“…The rat 3Y1 fibroblastic cell line has been utilized as a model system to study transforming activities of oncogenes (32)(33)(34)(35)(36)(37). Transformed 3Y1 cells bearing adenovirus E1A fragment or simian virus 40 show slow rate of tumorigenesis despite of the increases in both saturation cell density and anchorage-independent growth (33,35).…”

Section: Ha Is a Linear Polysaccharide Composed Of The Repeating Disamentioning

confidence: 99%

“…Transformed 3Y1 cells bearing adenovirus E1A fragment or simian virus 40 show slow rate of tumorigenesis despite of the increases in both saturation cell density and anchorage-independent growth (33,35). On the other hand, cell transformation driven by v-Ha-ras or v-src causes significantly high tumorigenesis or acquires metastatic potential (35)(36)(37). Here the transformed 3Y1 cell lines that have different degrees of transforming ability were examined the changes in HAS activity and transcriptional levels during the malignant transformation.…”

Section: Ha Is a Linear Polysaccharide Composed Of The Repeating Disamentioning

confidence: 99%

Selective Expression and Functional Characteristics of Three Mammalian Hyaluronan Synthases in Oncogenic Malignant Transformation

Itano

Sawai

Atsumi

et al. 2004

Journal of Biological Chemistry

133

102

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Malignant transformation of fibroblasts and epithelial cells is often accompanied by increased hyaluronan production and accumulation. Despite recent progress in the study of hyaluronan biosynthesis, the mechanisms underlying the transformation-induced overproduction of hyaluronan have not been elucidated. Here we report that activity and transcriptional levels of hyaluronan synthase (HAS) significantly increased after oncogenic malignant transformation of a rat 3Y1 fibroblast cell line. Of three HAS isoforms (HAS1, HAS2, and HAS3), only HAS2 gene expression was increased in the v-Ha-ras transformed 3Y1 cells, which show less malignancy. In contrast, both HAS1 and HAS2 expressions were elevated in the highly malignant cells transformed with v-src and/or v-fos. To assess the contribution of HAS expression to the oncogenic malignant transformation, we established stable cell transfectants expressing sense and antisense HAS genes. Antisense suppression of the HAS2 expression significantly decreased hyaluronan production in the cells transformed by the oncogenic v-Ha-ras and eventually led to a reduction in tumorigenicity in the rat peritoneum. The introduction of the HAS1 and HAS2 genes promoted the growth of subcutaneous tumors in a manner dependent on the levels of hyaluronan synthesis. Significant growth promotion was observed within a wide range of HAS1 expression. In contrast, the growth stimulation was only seen within a narrow range of HAS2 expression, and high levels of HAS2 expression even inhibited tumor growth. These results suggest that proper regulation of the expression of each HAS isoform is required for optimal malignant transformation and tumor growth.

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Advance toward S phase and retreat toward deeper “GO” states in resting 3Y1 cells with environmental changes

Zaitsu

Kimura

1984

Journal Cellular Physiology

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To elucidate conditions which affect the lag time for resting cells to enter S phase after serum stimulation, we used a wild-type 3Y1 rat fibroblast line and four temperature-sensitive mutants of 3Y1 (3Y1tsD123, 3Y1tsF121, 3Y1tsG125, and 3Y1tsH203). Among these five lines, in only tsG125 cells was there an obviously prolonged lag time with increase in time in resting state at 33.8 degrees C. The resting wild-type 3Y1 cells, preexposed to 39.8 degrees C, also showed a prolongation of lag time. The prolongation in tsG125 had a certain limit. Preexposure to 39.8 degrees C before serum stimulation accelerated such prolongation in tsG125 to its limit, but did not change the limit, per se. Resting tsG125 cells stimulated by serum at 39.8 degrees C, did not enter S phase, yet they did advance toward S phase. When they were kept at 39.8 degrees C, they retreated toward a deeper resting state ("G0") with time. These retreats correlated with the decrease in stimulating activity in the culture media. About 20% of the resting tsG125 cells stimulated by serum at 39.8 degrees C were committed to enter S phase, when the extent of commitment was examined at 33.8 degrees C. Most of the tsG125 cells committed at 33.8 degrees C did not enter S phase, when the extent of commitment was examined at 39.8 degrees C. More cells were committed after stimulation at 33.8 degrees C than at 39.8 degrees C, when the test was done at 33.8 degrees C. We suggest that resting cells may be reversibly changed within range of resting states, in either direction, that is, advance toward S phase or retreat toward deeper "G0." These changes may be determined by alterations in the balance between synthesis and decay of the preparedness for the initiation of DNA synthesis caused by cellular response to environmental changes (e.g., medium activity, temperature, etc.). The ts defect in tsG125 may affect the cell cycle progression, both before and after commitment by serum.

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Arrest states in a set of mutants of rat 3Y1 cells temperature‐sensitive for entering S phase

Cited by 20 publications

References 24 publications

Deeper ‘GO’ Phase in Rat Fibroblasts Affects the Lag Time Required for T Antigen Induced DNA Synthesis, but not the Lag Time Required for SV40 T Antigen Expression

Deeper ‘GO’ Phase in Rat Fibroblasts Affects the Lag Time Required for T Antigen Induced DNA Synthesis, but not the Lag Time Required for SV40 T Antigen Expression

Selective Expression and Functional Characteristics of Three Mammalian Hyaluronan Synthases in Oncogenic Malignant Transformation

Advance toward S phase and retreat toward deeper “GO” states in resting 3Y1 cells with environmental changes

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