Department of Microbiology, Institute of Medicine, College of Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan.
J Biomed Sci. 2009 Nov 25;16(1):107. doi: 10.1186/1423-0127-16-107.
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.
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.
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.
Our findings suggest that the virus-associated protein UL76 induces DNA damage and the accumulation of chromosome aberrations.
人巨细胞病毒（HCMV）已知可诱导感染细胞中的染色体畸变，从而导致感染胎儿的先天性异常。HCMV UL76 属于疱疹病毒的保守蛋白家族。一些报道的 UL76 家族成员的作用包括参与毒力决定、裂解复制、潜伏病毒的重新激活、基因表达的调节、细胞凋亡的诱导以及细胞周期进程的干扰，以及潜在的核酸酶活性。先前，我们已经表明，UL76 的稳定表达抑制胶质母细胞瘤细胞中的 HCMV 复制。
为了检查稳定表达 UL76 的细胞中的染色体完整性和 DNA 损伤信号 γ-H2AX，进行了免疫荧光细胞染色和 Western blot 分析。采用彗星试验评估瞬时表达 UL76 的细胞中的 DNA 断裂。
我们报告说，稳定转染表达 UL76 的细胞发生了染色体畸变，包括微核和染色体错位、滞后和桥接。在表达 UL76 的有丝分裂细胞中，与对照细胞相比，异常纺锤体增加。然而，与对照细胞相比，表达 UL76 的细胞中超数中心体略有增加。我们进一步表明，表达 UL76 的细胞激活了 DNA 损伤信号 γ-H2AX，并在核中引起焦点形成。此外，随着 UL76 蛋白水平的增加，具有 DNA 断裂的细胞数量增加。
我们的发现表明，病毒相关蛋白 UL76 诱导 DNA 损伤和染色体畸变的积累。
