Histone deacetylase classes I and II regulate Kaposi's sarcoma-associated herpesvirus reactivation.
In primary effusion lymphoma (PEL) cells infected with latent Kaposi's sarcoma-associated herpesvirus (KSHV), the promoter of the viral lytic switch gene, Rta, is organized into bivalent chromatin, similar to cellular developmental switch genes. Histone deacetylase (HDAC) inhibitors (HDACis) reactivate latent KSHV and dramatically remodel the viral genome topology and chromatin architecture. However, reactivation is not uniform across a population of infected cells. We sought to identify an HDACi cocktail that would uniformly reactivate KSHV and reveal the regulatory HDACs. Using HDACis with various specificities, we found that class I HDACis were sufficient to reactivate the virus but differed in potency. Valproic acid (VPA) was the most effective HDACi, inducing lytic cycle gene expression in 75% of cells, while trichostatin A (TSA) induced less widespread lytic gene expression and inhibited VPA-stimulated reactivation. VPA was only slightly superior to TSA in inducing histone acetylation of Rta's promoter, but only VPA induced significant production of infectious virus, suggesting that HDAC regulation after Rta expression has a dramatic effect on reactivation progression. Ectopic HDACs 1, 3, and 6 inhibited TPA-stimulated KSHV reactivation. Surprisingly, ectopic HDACs 1 and 6 stimulated reactivation independently, suggesting that the stoichiometries of HDAC complexes are critical for the switch. Tubacin, a specific inhibitor of the ubiquitin-binding, proautophagic HDAC6, also inhibited VPA-stimulated reactivation. Immunofluorescence indicated that HDAC6 is expressed diffusely throughout latently infected cells, but its expression level and nuclear localization is increased during reactivation. Overall, our data suggest that inhibition of HDAC classes I and IIa and maintenance of HDAC6 (IIb) activity are required for optimal KSHV reactivation.
Department of Microbiology and Molecular Genetics, New Jersey Medical School and Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, Rutgers University, Newark, New Jersey, USA.
Hye Jin
HJ
Shin
Jennifer
J
DeCotiis
Mario
M
Giron
Diana
D
Palmeri
David M
DM
Lukac
D002460:Cell Line; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D006566:Herpesviridae Infections / Q000201:enzymology* / Q000235:genetics / Q000821:virology*; D019288:Herpesvirus 8, Human / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D014775:Virus Activation / Q000187:drug effects; D017735:Virus Latency / Q000187:drug effects
D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; C012589:trichostatin A; D006655:Histone Deacetylases