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Effect of serum step‐down on protein metabolism and proliferation kinetics of NHIK 3025 cells
Author(s) -
Rønning Øystein W.,
Lindmo Tore,
Pettersen Erik O.,
Seglen Per O.
Publication year - 1981
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041070107
Subject(s) - doubling time , cell cycle , mitosis , andrology , population , chemistry , cell growth , growth rate , steady state (chemistry) , metabolism , biology , cell , zoology , endocrinology , medicine , biochemistry , microbiology and biotechnology , geometry , mathematics , environmental health
Human NHIK 3025 cells growing exponentially in 30% or 3% serum had population doubling times of 19.1 and 27.6 hours, respectively. These values were equal to the calculated protein doubling times (17.6 and 26.5 hours, respectively), showing that the cells were in balanced growth at both serum concentrations. Stepdown from 30% to 3% serum reduced the rate of protein synthesis within 1–2 hours, from 5.7% hour to 4.3% hour, while the rate of protein degradation was unchanged (1.7%/hour). In cells synchronized by mitotic selection from an exponentially growing population, the median cell cycle durations in 30% and 3% serum were 17.2 and 23.6 hours, respectively, which were also in good agreement with the protein doubling times. The median G 1 durations were 7.1 and 9.6 hours, respectively. Thus the duration of G 1 relative to the total cell cycle duration was the same in the two cases. Complete removal of serum for a period of 3 hours resulted in a 3‐hour prolongation of the cell cycle regardless of the time after mitotic selection at which the serum was removed. For synchronized cells, the rate of entry into both the S phase and into the subsequent cell cycle were reduced in 3% serum as compared to 30% serum, the former rate being significantly greater than the latter at both serum concentrations. Our results thus indicate that these cells are continuously dependent upon serum throughout the entire cell cycle.