Activation Of PI3K/AKT And ERK MAPK Signal Pathways Is Required For The Induction Of Lytic Cycle Replication Of Kaposi’s Sarcoma-Associated Herpesvirus By Herpes Simplex Virus Type1

Background: Kaposi’s sarcoma-associated herpesvirus (KSHV) is causally linked tothree acquired immunodeficiency syndrome (AIDS)-related malignancies: Kaposi’ssarcoma (KS), primary effusion lymphoma (PEL) and a subset of multicentricCastleman’s disease. Regulation of viral lytic replication is critical to the initiationand progression of KS. Our last reports showed that herpes simplex virus type1(HSV-1) as an important cofactor, can activate lytic cycle of KSHV. IL-10、IL-4andtheir signalings play an important role in modulation of HSV-1-induced KSHVreplication. However, the detailed mechanisms were not well known.Objective: To explore the molecular mechanisms and the possible signalingpathways involved in reactivation of KSHV from Latency induced by HSV-1.Methods: Firstly, Western blot was used to detect the key kinase involved inJAK1/STAT3, JAK1/STAT6, PI3K/AKT and ERK MAPK pathways in BCBL-1cellsinfectd with HSV-1. And then the dominant negative plasmid of STAT3and STAT6were used to investigate whether JAK1/STAT3and JAK1/STAT6pathway couldinfluence KSHV replication induced by HSV-1. Next, the PI3K chemical inhibitorLY294002and the dominant negative plasmid PI3K-DN were used to examine therole of PI3K/AKT pathway in KSHV reactivation induced by HSV-1. The mRNAtranscription and protein expression were respectively checked by RT-PCR, Westernblot and IFA; the copy number of KSHV virions in the supernatant was detected by Real-time DNA-PCR. At last the dominant negative construct of MEK1/2and ERKspecific inhibitor Peptide II were used to evaluate the role of ERK MAPK pathway inHSV-1mediated lytic replication of KSHV. The expression of KSHV Rta, ORF26and vIL-6were detected by Western blot and Real-time DNA-PCR and the ORF59was tested by IFA.Results: By using a series of dominant negative mutants/protein expressingconstructs and pharmacologic inhibitors, we found that both JAK1/STAT3andJAK1/STAT6signaling failed to regulate HSV-1induced KSHV replication. However,PTEN/PI3K/AKT/GSK-3β pathway was found to be involved in HSV-1-inducedKSHV reactivation. Additionally, ERK MAPK pathway also partially contributed toHSV-1induced KSHV replication.Conclusions: HSV-1infection stimulated PI3K/AKT and ERK MAPK signalingpathways that in turn contributed to KSHV reactivation, which provided furtherinsights into the molecular mechanism controlling KSHV lytic replication,particularly in the context of HSV-1and KSHV co-infection.