Increased Replication of Human Cytomegalovirus in Retinal Pigment Epithelial Cells by Valproic Acid Depends on Histone Deacetylase Inhibition

• Published in: Investigative ophthalmology & visual science Vol. 46; no. 9; pp. 3451 - 3457
• Main Authors: Michaelis, Martin, Suhan, Tatyana, Reinisch, Alexander, Reisenauer, Agnes, Fleckenstein, Corinna, Eikel, Daniel, Gumbel, Hermann, Doerr, Hans Wilhelm, Nau, Heinz, Cinatl, Jindrich, Jr
• Format: Journal Article
• Language: English
• Published: Rockville, MD ARVO 01.09.2005; Association for Research in Vision and Ophtalmology
• Subjects: Acetylation; Antigens, Viral - genetics; Antigens, Viral - metabolism; Biological and medical sciences; Blotting, Western; Cells, Cultured; Cytomegalovirus - physiology; Enzyme Inhibitors - pharmacology; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Histone Deacetylase Inhibitors; Histones - metabolism; Humans; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; Phosphorylation; Pigment Epithelium of Eye - enzymology; Pigment Epithelium of Eye - virology; Reverse Transcriptase Polymerase Chain Reaction; Valproic Acid - pharmacology; Vertebrates: nervous system and sense organs; Virus Replication - drug effects; 4-Aminobutyrate transaminase; Enzyme; Herpesviridae; Transferases; Enzyme inhibitor; Retina; Anticonvulsant; Valproic acid; Betaherpesvirinae; Human cytomegalovirus; Virus; Mood stabilizer; Transaminases; Epithelial cell; Replication; Inhibition; Ophthalmology; Histone; Retinal; Pigment cell
• ISSN: 0146-0404; 1552-5783; 1552-5783
• DOI: 10.1167/iovs.05-0369

Human cytomegalovirus (HCMV) replication depends on different cellular pathways, including histone acetylation and extracellular-signal regulated kinases 1 and 2 (Erk 1/2). In the present study, the influence of therapeutic valproic acid (VPA) concentrations was investigated on HCMV replication in retinal pigment epithelial (RPE) cells. HCMV antigen expression and replication were detected by immunostaining, real-time RT-PCR, and determination of virus titers. Histone acetylation and Erk 1/2 phosphorylation were detected by Western blot. Pretreatment with VPA < or =1 mM enhanced HCMV antigen expression and replication by up to ninefold. In addition to histone deacetylase (HDAC) inhibition, VPA stimulated Erk 1/2 phosphorylation in RPE cells. Investigation of six VPA derivatives revealed that S-2-pentyl-4-pentynoic acid was the only derivative that induced histone hyperacetylation, indicating HDAC inhibition, in the observed concentrations < or =1 mM and that increased HCMV antigen expression. Other derivatives did not enhance HCMV replication in the tested concentrations, although some were found to induce Erk 1/2 phosphorylation. The mitogen-activated protein kinase kinase (MEK) inhibitor PD98059 inhibited VPA-induced Erk 1/2 phosphorylation but did not affect VPA-induced increased HCMV replication. In addition, the structurally nonrelated HDACI trichostatin A enhanced HCMV replication but did not affect Erk 1/2 phosphorylation in RPE cells. The data demonstrate that VPA stimulates HCMV replication by HDAC inhibition independent of Erk 1/2 phosphorylation in therapeutic concentrations in RPE cells. Therefore, patients at risk of HCMV retinitis who are treated with VPA or other HDAC inhibitors should be carefully monitored.