Virus-host cell interactions, cell-death, chromatin, DNA
The adenovirus E4orf4 protein is a multifunctional viral regulator, which contributes to temporal regulation of the progression of viral infection and to inhibition of anti-viral defense mechanisms induced by the host cell. When expressed outside the context of virus infection, E4orf4 induces p53-independent cell-death in transformed cells. Oncogenic transformation of primary cells in tissue culture sensitizes them to cell killing by E4orf4, indicating that E4orf4 research may have exciting implications for cancer therapy. It has been further reported that E4orf4 induces a non-classical, caspase-independent apoptotic pathway, which maintains a crosstalk with the classical caspase-dependent pathways. The mechanisms underlying this unique mode of cell death are highly conserved in evolution, underscoring their importance to cell regulation. This finding suggests that several model organisms can be used for studies on E4orf4, and published work from our laboratory describes novel findings obtained in mammalian tissue culture cells, the yeast Saccharomyces cerevisiae and Drosophila melanogaster. We are currently studying the contribution of cellular E4orf4 partners, such as PP2A, the ACF chromatin-remodeling factor, and a Golgi apyrase to E4orf4 functions in cell death and virus infection. We also use fly cancer models to investigate the differential response of normal and cancer cells to E4orf4-induced cell death.
Mittelman, K., Ziv, K., Maoz, T., and Kleinberger, T. The cytosolic tail of the Golgi apyrase Ynd1 mediates E4orf4-induced toxicity in Saccharomyces cerevisiae. 2010. PLOS ONE, 2010 Nov 22;5(11):e15539.
Brestovitsky, A., Sharf, R., Mittelman, K., and Kleinberger, T. The adenovirus E4orf4 protein targets PP2A to the ACF chromatin-remodeling factor and induces cell death through regulation of SNF2h-containing complexes. 2011. Nucleic Acids Res. 39, 6414-6427.
Brestovitsky, A., Sharf, R., and Kleinberger, T. Preparation of cell-lines for conditional knockdown of gene expression and measurement of the knockdown effects on E4orf4-induced cell death. J. Vis. Exp. J Vis Exp. 2012 Oct 21;(68). doi:pii: 4442. 10.3791/4442. (2012).
Horowitz,B., Sharf,R., Avital-Shacham, M., Pechkovsky, A., and Kleinberger, T. Structure- and modeling-based identification of the adenovirus E4orf4 binding site in the protein phosphatase 2A B55 subunit. 2013 Mar 25. [Epub ahead of print]. J Biol Chem.
Pechkovsky, A., Lahav, M., Bitman, E., Salzberg, A., and Kleinberger, T. E4orf4 induces PP2A- and Src-dependent cell-death in Drosophila melanogaster and at the same time inhibits classical apoptosis pathways. 2013. Proc. Natl. Acad. Sci. USA. 2013 Apr 23. [Epub ahead of print].