Hepatitis C virus up-regulates B-cell receptor signaling: a novel mechanism for HCV-associated B-cell lymphoproliferative disorders

B-cell receptor (BCR) signaling is essential for the development of B-cells and plays a critical role in B-cell neoplasia. Increasing evidence indicates an association between chronic hepatitis C virus (HCV) infection and B-cell lymphoma, however, the mechanisms by which HCV causes B-cell lymphoproliferative disorder are still unclear. Herein, we demonstrate the expression of HCV viral proteins in B-cells of HCV-infected patients and show that HCV up-regulates BCR signaling in human primary B-cells. HCV nonstructural protein NS3/4A interacts with CHK2 and down-regulates its activity, modulating HuR posttranscriptional regulation of a network of target mRNAs associated with B-cell lymphoproliferative disorders. Interestingly, the BCR signaling pathway was found to have the largest number of transcripts with increased association with HuR and was up-regulated by NS3/4A. Our study reveals a previously unidentified role of NS3/4A in regulation of host BCR signaling during HCV infection, contributing to a better understanding of the molecular mechanisms underlying HCV-associated B-cell lymphoproliferative disorders. A series of FLAG epitope-tagged NS3/4A truncation and deletion mutants were cloned into a lentiviral-vector CD532, and stable cell lines of SUDHL6-overexpressing FLAG epitope-tagged NS3/4A truncation and deletion mutants generated by lentiviral transduction, selection and maintenance with 0.5 mg/ml puromycin. Ribonucleoprotein immunoprecipitation (RNP IP) using an anti-HuR antibody of control (CTR_S6_532_2_x) and NS3/4A-overexpressing (NS3_S6_8_2_x) SUDHL6-cells generated HuR-IP RNA samples for microarray analysis of differences in HuR binding activity caused by NS3/4A-overexpression. Three independent experiments are reported for each condition.