Noncoding RNAs in gamma-Herpesvirus Biology and AIDS Malignancies

Project Summary
The transforming human gammaherpesviruses EBV and KSHV establish stable latent infections in B cells,
providing a lifelong reservoir of virus that can contribute to the development of malignant disease. Thus, defining
the mechanisms that govern long-term latency and tumorigenesis is critical for designing rational strategies to
prevent disease. In vivo studies of gammaherpesviruses in humans have been severely limited by the difficulties
of working in the natural host. Murine gammaherpesvirus 68 (MHV68) is related to EBV and KSHV and causes
lymphomas and lymphoproliferative disease in mice, providing a readily manipulatable small animal model for
mechanistic studies of the virus/host relationship in vivo. Like EBV and KSHV, MHV68 expresses multiple forms
of ncRNAs whose functions during infection and pathogenesis are largely unknown. In contrast to most
gammaherpesvirus protein-coding genes, gammaherpesvirus ncRNAs are abundantly expressed in vivo during
chronic infection and in hyperplastic lesions during lymphoproliferative disease, suggesting that these ncRNAs
may play key conserved roles in latency and tumorigenesis. In support of this, we have demonstrated that
MHV68 TMER4 and EBV EBER1 share a conserved function in hematogenous dissemination, and that in vivo
suppression of a conserved miRNA target promotes B cell latency. Further, our new preliminary findings implicate
both small ncRNAs and miRNAs in the genesis and progression of virus-induced B cell lymphoma. Thus, we
hypothesize that gammaherpesviruses utilize a broad array of ncRNAs to shape critical B cell signaling pathways
and thereby promote virus dissemination, latency and tumorigenesis. In Aim 1 (in collaboration with Project 2
and with support from Core C and D), we will define the mechanisms by which gammaherpesvirus small RNAs
promote the egress and dissemination of infected B cells, facilitate B cell latency at peripheral sites, and drive
key stages of lymphomagenesis. In Aim 2 (in collaboration with Projects 2 and 3, and with support from Cores
B, C and D) we will define the contribution of gammaherpesvirus miRNA repression of host mRNAs and lncRNAs
to B cell latency and lymphomagenesis. The highly collaborative nature of this program, along with the systematic
in vivo analyses of ncRNA mutants and recombinant viruses carrying EBV or KSHV genes, provides an
extremely powerful means to determine the specific molecular mechanisms by which ncRNAs contribute to
gammaherpesvirus latency and tumorigenesis.