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Title: Studies on Sam68 a cell factor involved in the life cycle of foot-and-mouth disease virus

Author
item Lawrence, Paul
item Rieder, Aida - Elizabeth

Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2009
Publication Date: 7/10/2009
Citation: Lawrence, P.J., Rieder, A.E. 2009. Studies on Sam68 a cell factor involved in the life cycle of foot-and-mouth disease virus. American Society for Virology Meeting. Paper No. W36-8: p. 177.

Interpretive Summary:

Technical Abstract: As with other RNA viruses, Foot-and-Mouth Disease Virus (FMDV) recruits various host cell factors to assist in translation and replication of the virus genome. While FMDV translation has been thoroughly investigated, much remains unknown regarding replication of the positive-sense RNA genome. In this study we investigated the role of Sam68 (the 68 kDa Src-associated in mitosis protein) in FMDV genome replication. Specifically, gene-specific siRNA constructs were utilized to knockdown Sam68 expression in cell culture, which rendered these cells partially resistant to infection with FMDV A24-Cruzeiro. In contrast, no significant reduction of virus titers was observed when the cells were treated with non-specific siRNA constructs. Using immunofluorescent microscopy, we found that as the virus infection proceeds, the predominantly nuclear distribution of Sam68 is altered, where cytoplasmic peri-nuclear localization is detected at 3-4 hours post-infection. The redistribution of Sam68 to the cytoplasm could be achieved in the absence of virus by treating the cells with methylation inhibitors, suggesting that similar to the case of RNA Helicase A (RHA), FMDV infection might also promote the accumulation of non-methylated Sam68. Interestingly, the cytoplasmic Sam68 co-localized with non-methylated RHA (DM-RHA) as FMDV infection proceeded. Cytoplasmic Sam68 co-localized with several FMDV non-structural proteins including 3B, 3Cpro, and 3Dpol. Current efforts to produce these protein factors in a purified form will facilitate studies of protein-protein and RNA-protein interaction and will assist in the development of a detailed model of the host cell proteins that facilitate RNA replication during FMDV infection.