Marek's disease virus type 1 encoded analog of miR-155 promotes proliferation of chicken embryo fibroblast and DF-1 cells by targeting hnRNPAB

Marek's disease virus type 1 (MDV-1) is a representative oncogenic Alpha herpesvirus that causes an immunosuppressive and neoplastic lymphoproliferative avian disease, namely Marek's disease (MD). The rapid onset T-cell lymphoma in chickens induced by MDV-1 has been historically regarded as an ideal natural model for herpesvirus-related cancer research. As a viral analog of cellular miR-155, the MDV-1-encoded miR-M4-5p has been shown to be crucial for the virally-induced MD tumorigenesis. Our previous studies demonstrated that miR-M4-5p induces an over-expression of oncogene c-Myc by targeting LTBP1 and suppressing the TGF-D signaling pathway during MDV-1 infection. We have now further identified the chicken heterogeneous nuclear ribonucleoprotein AB (hnRNPAB) as a new cellular biological target for miR-M4-5p. Suppression of hnRNPAB expression mediated by miR-M4-5p promotes the proliferation, but not the apoptosis, of both primary chicken embryo fibroblasts (CEFs) and transformed chicken fibroblast DF-1 cell line. HnRNPAB is a member of the hnRNP family of proteins that play important roles in normal biological processes as well as cancer development. Our data suggests that the recognition and down-regulation of hnRNPAB by miR-M4-5p may be one of the important strategies for MDV-1 to trigger the development of MD lymphomas.