Previous Article | Next Article ![]()
Journal of Virology, September 2000, p. 7842-7850, Vol. 74, No. 17
The Marjorie B. Kovler Viral Oncology
Laboratories1 and Department of
Radiation and Cellular Oncology,2 The
University of Chicago, Chicago, Illinois 60637
Received 24 March 2000/Accepted 3 June 2000
The transition from G1 to S phase in the cell cycle
requires sequential activation of cyclin-dependent kinase 4 (cdk4) and cdk2, which phosphorylate the retinoblastoma protein, causing the
release of E2F. Free E2F upregulates the transcription of genes
involved in S phase and cell cycle progression. Recent studies from
this and other laboratories have shown that herpes simplex virus 1 stabilizes cyclin D3 early in infection and that early events in viral
replication are sensitive to inhibitors of some cdks. On the other hand
cdk2 is not activated. Here we report studies on the status of members
of E2F family in cycling HEp-2 and HeLa cells and quiescent
serum-starved, contact-inhibited human lung fibroblasts. The results
show that (i) at 8 h postinfection or thereafter, E2F-1 and E2F-5
were posttranslationally modified and/or translocated from nucleus to
the cytoplasm, (ii) E2F-4 was hyperphophorylated, and (iii) overall,
E2F binding to cognate DNA sites was decreased at late times after
infection. These results concurrent with those cited above indicate
that late in infection activation of S-phase genes is blocked both by
posttranslational modification and translocation of members of E2F
family to inactive compartments and by the absence of active cdk2. The
observation that E2F were also posttranslationally modified in
quiescent human lung fibroblasts that were not in S phase at the time
of infection suggests that specific viral gene products are responsible
for modification of the members of E2F family and raises the
possibility that in infected cells, activation of the S phase gene is
an early event in viral infection and is then shut off at late times.
This is consistent with the timing of stabilization of cyclin D3 and the events blocked by inhibitors of cdks.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
E2F Proteins Are Posttranslationally Modified
Concomitantly with a Reduction in Nuclear Binding Activity in Cells
Infected with Herpes Simplex Virus 1
*
Corresponding author. Mailing address: The Marjorie B. Kovler Viral Oncology Laboratories, The University of Chicago, 910 E. 58th St., Chicago, IL 60637. Phone: (773) 702-1898. Fax: (773) 702-1631. E-mail: bernard{at}cummings.uchicago.edu.
This article has been cited by other articles:
| J. Bacteriol. | Mol. Cell. Biol. | Microbiol. Mol. Biol. Rev. |
|---|
| Clin. Vaccine Immunol. | ALL ASM JOURNALS |
|---|