HIV-1 Infection Induces Acetylation of NPM1 That Facilitates Tat Localization and Enhances Viral Transactivation Shrikanth S. Gadad 1 †, Roshan Elizabeth Rajan 2 †, Parijat Senapati 1 , Snehajyoti Chatterjee 1 , Jayasha Shandilya 1 , Prasanta Kumar Dash 2 , Udaykumar Ranga 2 and Tapas K. Kundu 1 ⁎ 1 Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India 2 HIV AIDS Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India Received 31 January 2011; received in revised form 1 April 2011; accepted 4 April 2011 Edited by M. F. Summers Keywords: acetylation; HIV; NPM1; Tat; transactivation Human immunodeficiency virus type 1 (HIV-1) following integration hijacks host cell machineries where chromatinization of the viral genome regulates its latency, transcription, and replication. The cooperation among ATP-dependent chromatin remodeling factors, posttranslational modifying enzymes, and histone chaperones is well established during transcriptional activation in eukaryotes. However, the role of histone chaperones in transcription of the HIV promoter is poorly understood. Previous studies from our group have established the role of the human histone chaperone nucleophosmin (NPM1) in the acetylation-dependent chromatin transcrip- tion. NPM1 is known to interact with HIV-Tat. Here, we report that infection by HIV-1 induces the acetylation of histone chaperone NPM1. Acetylation of NPM1 was found to be critical for nuclear localization of Tat as well as Tat- mediated transcription alluding to the critical role for the host factor towards viral pathogenesis. Furthermore, knockdown experiments mediated by small interfering RNA identified the critical role played by the chaperone NPM1 in transcriptional activation of the integrated provirus. These results shed further insights into the possible role of histone chaperone NPM1 acetylation in viral gene transcription, which could be a potential therapeutic target. © 2011 Elsevier Ltd. All rights reserved. Introduction Upon infecting susceptible cells, the viral genome of the human immunodeficiency virus (HIV) and other retroviruses integrates into the host chromo- somes. The chromosomal integration packages the proviral DNA into specifically positioned nucleo- somes, and as a consequence, viral gene expression is transcriptionally silenced until stimulated. 1 Such latent viruses reside in specific cellular reservoirs and allow the infected cells to escape from antiretroviral therapies. Viral latency thus forms a *Corresponding author. E-mail address: tapas@jncasr.ac.in. † S.S.G. and R.E.R. contributed equally to this work. Abbreviations used: HIV-1, human immunodeficiency virus type 1; NPM1, nucleophosmin; LTR, long terminal repeat; HAT, histone acetyltransferase; siRNA, small interfering RNA; ChIP, chromatin immunoprecipitation; PBS, phosphate-buffered saline; EDTA, ethylenediaminetetraacetic acid. doi:10.1016/j.jmb.2011.04.009 J. Mol. Biol. (2011) 410, 997–1007 Contents lists available at www.sciencedirect.com Journal of Molecular Biology journal homepage: http://ees.elsevier.com.jmb 0022-2836/$ - see front matter © 2011 Elsevier Ltd. All rights reserved.