Open AccessRegulation of NIH‐3T3 cell G 1 phase transit by serum during exponential growth
Author(s) -
DiSalvo C. V.,
Zhang D.,
Jacobberger J. W.
Publication year - 1995
Publication title -
cell proliferation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.647
H-Index - 74
eISSN - 1365-2184
pISSN - 0960-7722
DOI - 10.1111/j.1365-2184.1995.tb00089.x
Subject(s) - exponential growth , cell growth , 3t3 cells , contact inhibition , cell cycle , phase (matter) , cell , microbiology and biotechnology , function (biology) , cell culture , biology , chemistry , biochemistry , transfection , genetics , mathematical analysis , mathematics , organic chemistry
The proliferation rate of mammalian cells is regulated normally in the G 1 phase of the cell cycle. During this phase, it is convenient to assign positive and negative roles to the molecular programs that regulate the duration of G 1 and the phase transition from G 1 to S phase. Density‐dependent inhibition of cellular proliferation results in an increase in the duration of G 1 . This form of regulation is due to both secreted factors and cell—cell contact. Serum is mitogenic to a variety of mammalian cell types. Because quiescent cells enter S phase as a result of serum addition to culture media, serum is usually regarded as a source of positive regulatory growth factors. We have measured the length of the G 1 , S and G 2 + M phases of NIH 3T3 cells during exponential growth as a function of cell density and serum concentration. The G 1 length increases during exponential growth as a function of density while S and G 2 + M are relatively constant. Further, this increase in G 1 phase time, or density mediated negative regulation, is inhibited by increasing serum concentration. This phenotype is saturable between 10% to 20% serum. Serum concentrations above 2.5% are able to increase the rate of cell cycling (decrease the G 1 phase time) by inhibiting density dependent negative regulation of NIH 3T3.