Altered cell cycle progression and aberrant mitosis in adenovirus‐infected rodent cells

Abstract

Actively growing mouse or rat embryo cells suffered structural chromosome damage, mitotic anomalies, and polyploidy after infection by human adenovirus type 5. Chromosome damage required expression of one or more early viral genes and showed regular periodicity in its frequency. The growth cycle time of some of the infected cells was reduced by about 5 hours due to a decrease in G1, and the interval between successive waves of chromosome damage corresponded to this reduced cycle time. After infection there was a decrease in cells with G1 DNA content and an increase in cells with G2 diploid, aneuploid, and polyploid DNA contents. We suggest these effects are due to the expression in semipermissive cells fo early viral gene(s), whose function in productive infection in vivo is to alter cell cycle controls in order to maximize the number of cells able to replicate viral DNA and the time such cells spend in DNA replication.

Control functions of adenovirus transformation region E1A gene products in rat and human cells.

“…RESULTS Altered cell cycle progression does not require E3 or E4 functions. As found previously (1,3,5,18,19), WT AdS caused a decrease in the number of rat cells in the Gl phase and increases in the numbers of cells in S and G2, and caused up to 40% of cells to enter further rounds of DNA replication without undergoing a normal mitosis (Fig. 2a).…”

“…1. ElA mutants were grown in 293 cells and titrated by methods described previously (4,5,18,19), and with the exception of pm975 had a ratio of titer on 293 cells to that on HeLa cells of 103 to 104.…”

“…1. ElA mutants were grown in 293 cells and titrated by methods described previously (4,5,18,19), and with the exception of pm975 had a ratio of titer on 293 cells to that on HeLa cells of 103 to 104.Mutant d1808, deleted from between 91.4 and 92.0 to between 97.2 and 98.4 map units (m.u.) (7), and thus defective in subregions 1 or 2 through 7 of early region E4, was kindly supplied by G. Ketner, The Johns Hopkins University, Baltimore, Md.…”

“…The function of ElA in transformation appears to be "immortalization" of the cell and reduction of requirements for serum growth factors. The ability of adenovirus to induce a growth cycle in rodent cells arrested in the Gi phase by deprivation of serum or reduction of Ca2+ concentration, and to alter cycle progression in growing cells (1,5,8,18), may be related to the ElA transformation functions. Experiments with mutant viruses showed that alteration of control of the rat cell growth cycle requires expression of ElA, but not of E1B, E2A, E2B, or late genes (1,5,8,19).…”

“…Rat cells were labeled with [35S]methionine (10 ,uCi/ml; Amersham Corp.) from about 24 to 40 h after infection, the time of maximal synthesis of the viral E2A DNA-binding protein (DBP) in these cells (18); HeLa cells were labeled from 8 to 24 h after infection. Cell extracts were prepared and precipitated with 'P' antiserum (which reacts with E2A DBP and some late proteins) as described previously (3) taining the probe) was denatured and used directly for hybridization.…”