title: FACT Proteins, SUPT16H and SSRP1, Are Transcriptional Suppressors of HIV-1 and HTLV-1 That Facilitate Viral Latency.
abstract: Our functional genomic RNAi screens have identified the protein components of the FACT (facilitates chromatin transcription) complex, SUPT16H and SSRP1, as top host factors that negatively regulate HIV-1 replication. FACT interacts specifically with histones H2A/H2B to affect assembly and disassembly of nucleosomes, as well as transcription elongation. We further investigated the suppressive role of FACT proteins in HIV-1 transcription. First, depletion of SUPT16H or SSRP1 protein enhances Tat-mediated HIV-1 LTR (long terminal repeat) promoter activity. Second, HIV-1 Tat interacts with SUPT16H but not SSRP1 protein. However, both SUPT16H and SSRP1 are recruited to LTR promoter. Third, the presence of SUPT16H interferes with the association of Cyclin T1 (CCNT1), a subunit of P-TEFb, with the Tat-LTR axis. Removing inhibitory mechanisms to permit HIV-1 transcription is an initial and key regulatory step to reverse post-integrated latent HIV-1 proviruses for purging of reservoir cells. We therefore evaluated the role of FACT proteins in HIV-1 latency and reactivation. Depletion of SUPT16H or SSRP1 protein affects both HIV-1 transcriptional initiation and elongation and spontaneously reverses latent HIV-1 in U1/HIV and J-LAT cells. Similar effects were observed with a primary CD4+ T cell model of HIV-1 latency. FACT proteins also interfere with HTLV-1 Tax-LTR-mediated transcription and viral latency, indicating that they may act as general transcriptional suppressors for retroviruses. We conclude that FACT proteins SUPT16H and SSRP1 play a key role in suppressing HIV-1 transcription and promoting viral latency, which may serve as promising gene targets for developing novel HIV-1 latency-reversing agents.
authors.affiliation: Departments of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642.
authors.forename: Huachao
authors.initials: H
authors.lastname: Huang
authors.affiliation: Departments of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642.
authors.forename: Netty
authors.initials: N
authors.lastname: Santoso
authors.affiliation: Departments of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642.
authors.forename: Derek
authors.initials: D
authors.lastname: Power
authors.affiliation: the School of Arts and Sciences, University of Rochester, Rochester, New York 14627.
authors.forename: Sydney
authors.initials: S
authors.lastname: Simpson
authors.affiliation: the School of Arts and Sciences, University of Rochester, Rochester, New York 14627.
authors.forename: Michael
authors.initials: M
authors.lastname: Dieringer
authors.affiliation: Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, New York 14642.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Miao
authors.affiliation: Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, New York 14263.
authors.forename: Katerina
authors.initials: K
authors.lastname: Gurova
authors.affiliation: Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814.
authors.forename: Chou-Zen
authors.initials: CZ
authors.lastname: Giam
authors.affiliation: the Division of Genetics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Boston, Massachusetts 02115; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Elledge
authors.affiliation: Departments of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642; Departments of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642. Electronic address: Jian_Zhu@urmc.rochester.edu.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhu
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000502:physiology / Q000821:virology; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D056906:Cyclin T / Q000502:physiology; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D057809:HEK293 Cells; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006609:High Mobility Group Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000502:physiology; D015368:Human T-lymphotropic virus 1 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D042925:Positive Transcriptional Elongation Factor B / Q000502:physiology; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D035602:Transcriptional Elongation Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D017735:Virus Latency / Q000235:genetics / Q000502:physiology*
chemical_list: C503684:CCNT1 protein, human; D018797:Cell Cycle Proteins; D056906:Cyclin T; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; C073537:SSRP1 protein, human; C489489:SUPT16H protein, human; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; D042925:Positive Transcriptional Elongation Factor B
keywords: CD4 T cell; FACT complex; RNA interference (RNAi); SSRP1; SUPT16H; host-pathogen interaction; human immunodeficiency virus (HIV); latency; transcription repressor; viral transcription