Influence Of Human Cytomegalovirus Infection On Cell Cycle And Expressions Of MCM2 And MCM8 In Human Embryonic Lung Fibroblastic Cells

Objective To study the influence of HCMV infection on cell cycleand expressions of MCM2 and MCM8 in human embryonic lungfibroblastic cells(HEL), explore the pathogenesis of HCMV infection.Method Synchronized HEL cells were infected by HCMV,simultaneously set up the mock-infected group as control group. Flowcytometry analysis detected the cell cycle of HEL cells. During the time,observation of the pathomorphological change of infected HEL cells wasperformed until 7 days post infection by inverted phase contrastmicroscope. Infected HEL cells were harvested at 12 hours post infection(h p.i.),24h p.i.,48h p.i.,72h p.i. and 96h p.i.. The expression levels ofMCM2 and MCM8 mRNA in HEL cell were detected withsemi-quantitative RT-PCR method.Results1. The change of morphology was not observed in the mock-infectedcells. In HCMV-infected group, the distortion of cells evidently occurredafter 48h, the greater part of cells grew into sphericity, the changes weremore obvious after 72h, the cells became round, bulgy, and their cubageand nucleolus became large; Their cytoplast was indistinct, and thediaphaneity were depressed. Cytopathic effect(CPE) was observed in allinfected cells in 7days p.i..2. At 12h p.i.,71.4ï¼…of the infected cells were in G₁ phase,63.5ï¼…of themock-infected cells were in G₁ phase. At 24h p.i., 70.2ï¼…of the infectedcells were still in G₁ phase, however only 45.5ï¼…of the mock-infectedcells were in G₁ phase. The statistical analysis of the number of cells inG₁ phase has significant difference(P＜0.01) between the HCMV-infected group and mock-infected group both at 12h p.i. and 24h p.i..3. The statistical analysis showed the expression levels of MCM2 andMCM8 mRNA in HCMV-infected group were statistically lower(P＜0.05)than the ones in the mock-infected group at 12h p.i., 24h p.i., butat 48h p.i. , 72hp.i. and 96h p.i.,the expression levels of MCM2 andMCM8 mRNA in HCMV-infected group were statistically higher(P＜0.05)than the ones in the mock-infected group. The graphs of the expressionlevels of MCM2 and MCM8 mRNA suggested that the expression levelsreached a peak at 24h p.i. in the mock-infected group, but inHCMV-infected group reached a peak at 48h p.i.,which markedly laggedbehirid the ones in the mock-infected group.Conclusion1. HCMV infection can influence the cell cycle progression of HELcells and leave them lag during G₁ phase.2. HCMV infection can induce the abnormal expressions of MCM2and MCM8 mRNA, and delays their expressions, which could beresponsible for the blockage in cell cycle in G₁ phase by HCMVinfection.