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The effects of human cytomegalovirus infection on cytoskeleton-associated polysomes
1Department of Biochemistry, Wake Forest University, Bowman Gray School of Medicine, Winston-Salem, NC 27103.
Abstract:
Human cytomegalovirus (HCMV) infection induces disruption of the host cell's cytoskeleton (CSK). This disruption is accompanied by three transient phases of actin depolymerization that occur at 20 min, 5 to 10 h and 48 to 72 h post infection (pi). During the 20 min peak of actin depolymerization, the level of cellular polysomes associated with the CSK was reduced, due to release of ribosomes from CSK-associated polysomes. Cellular mRNAs previously existing in these polysomes, however, remained associated with the CSK. Also during this period, nuclear to cytoplasmic transport of host cellular mRNA as well as the association of newly synthesized mRNA with the CSK was temporarily delayed. By 60 min pi, ribosomes, preexisting host cellular mRNA, and newly synthesized mRNAs (host and viral) had reestablished a distribution in the infected cell comparable to that of uninfected cells. Sedimentation profiles of soluble and CSK fractions at various times throughout the viral infection indicated that, although the amount of polysomes associated with the CSK at 20 min pi was reduced, essentially all HCMV and all host cell polysomes present were associated with the CSK. The majority of HCMV DNA hybridizable poly(A)+ RNAs were associated with the CSK throughout the viral infection. These early events appear to correlate with a transient interruption of host cellular mRNA translation early in infection and may represent a process whereby HCMV gene expression becomes competitive with that of the host cell.
Insights
Human cytomegalovirus (HCMV) infection disrupts host cell cytoskeleton, impacting mRNA translation. Early events show transient delays in host mRNA transport and translation, potentially aiding viral gene expression.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Human cytomegalovirus (HCMV) infection is known to alter host cell functions.
- The host cell cytoskeleton (CSK) plays a critical role in cellular processes, including mRNA transport and translation.
Purpose of the Study:
- To investigate the early effects of HCMV infection on host cell cytoskeleton-associated mRNA and protein synthesis.
- To understand how HCMV manipulates host cell machinery for its own gene expression.
Main Methods:
- Analysis of actin depolymerization at various time points post-infection.
- Sedimentation profiling of soluble and CSK fractions to assess polysome and mRNA association.
- Quantification of host and viral mRNA and polysome distribution within the cell.
Main Results:
- HCMV infection induced transient actin depolymerization and reduced CSK-associated polysomes early post-infection.
- Host cellular mRNA remained CSK-associated despite ribosome release, and nuclear-cytoplasmic transport was delayed.
- Viral and host mRNAs and polysomes re-established distribution by 60 minutes post-infection, with viral RNAs predominantly CSK-associated.
Conclusions:
- HCMV infection transiently interrupts host mRNA translation early in infection.
- This interruption may facilitate HCMV's ability to compete with host gene expression.
- CSK association is crucial for both host and viral mRNA regulation during HCMV infection.