Human cytomegalovirus UL76 induces chromosome aberrations.
BACKGROUND
Human cytomegalovirus (HCMV) is known to induce chromosome aberrations in infected cells, which can lead to congenital abnormalities in infected fetuses. HCMV UL76 belongs to a conserved protein family from herpesviruses. Some reported roles among UL76 family members include involvement in virulence determination, lytic replication, reactivation of latent virus, modulation of gene expression, induction of apoptosis, and perturbation of cell cycle progression, as well as potential nuclease activity. Previously, we have shown that stable expression of UL76 inhibits HCMV replication in glioblastoma cells.


METHODS
To examine chromosomal integrity and the DNA damage signal gamma-H2AX in cells constitutively expressing UL76, immunofluorescent cell staining and Western blotting were performed. The comet assay was employed to assess DNA breaks in cells transiently expressing UL76.


RESULTS
We report that stably transfected cells expressing UL76 developed chromosome aberrations including micronuclei and misaligned chromosomes, lagging and bridging. In mitotic cells expressing UL76, aberrant spindles were increased compared to control cells. However, cells with supernumerary centrosomes were marginally increased in UL76-expressing cells relative to control cells. We further demonstrated that UL76-expressing cells activated the DNA damage signal gamma-H2AX and caused foci formation in nuclei. In addition, the number of cells with DNA breaks increased in proportion to UL76 protein levels.


CONCLUSIONS
Our findings suggest that the virus-associated protein UL76 induces DNA damage and the accumulation of chromosome aberrations.
Siew
Voon-Kwan
VK
Department of Microbiology, Institute of Medicine, College of Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan. u9451005@kmu.edu.tw
Duh
Chang-Yih
CY
Wang
Shang-Kwei
SK
D000818:Animals; D019556:COS Cells; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D002869:Chromosome Aberrations; D020552:Comet Assay; D003587:Cytomegalovirus / Q000235:genetics*; D003586:Cytomegalovirus Infections / Q000235:genetics*; D004249:DNA Damage; D005786:Gene Expression Regulation; D005909:Glioblastoma / Q000821:virology; D006657:Histones / Q000737:chemistry; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods
C468783:H2AX protein, human; D006657:Histones