CDK2 regulates HBV replication by controlling SAMHD1 phosphorylation in hepatoma cells

Abstract:

Objective：To investigate the molecular mechanism of phosphorylation of sterile alpha motif and histidine/aspartic acid do－main-containing protein 1（SAMHD1） in hepatoma carcinoma cell. Methods：By knocking down CDK1 or CDK2 expression in hep－atoma carcinoma cell，how CDK1 or CDK2 regulated cell cycle，HBV replication and phosphorylation of SAMHD1 was investigated. Furthermore，the interaction of SAMHD1 and CDK2 was analyzed by coimmunoprecipitation assays（Co-IP） and immunofluorescence. Results：Flow cytometry assay confirmed most Huh7.0 cells were arrested at S/G2 phase（P=0.001） or G1 phase（P=0.001），respectively when knockdown CDK1 or CDK2. Meanwhile，HBV replication and SAMHD1 phosphorylation levels were significantly influenced by knocking down CDK2 expression（P=0.003），not by CDK1 expression（P=0.325）. In hepatoma cells，SAMHD1 can bind to CDK2，and this interaction located in nucleus. Conclusion：Our results provide evidences that HBV employs CDK2，not CDK1 to regulate SAMHD1 phosphorylation during cell cycle，thus contribute to viral replication.