TRIM22 inhibits HIV-1 transcription independently of its E3 ubiquitin ligase activity, Tat, and NF-kappaB-responsive long terminal repeat elements

• Published in: Journal of virology Vol. 85; no. 10; pp. 5183 - 5196
• Main Authors: Kajaste-Rudnitski, Anna, Marelli, Sara S, Pultrone, Cinzia, Pertel, Thomas, Uchil, Pradeep D, Mechti, Nadir, Mothes, Walther, Poli, Guido, Luban, Jeremy, Vicenzi, Elisa
• Format: Journal Article
• Language: English
• Published: United States 01.05.2011
• Subjects: Cell Line; HIV-1 - growth & development; HIV-1 - immunology; Humans; Minor Histocompatibility Antigens; Monocytes - immunology; Monocytes - virology; Repressor Proteins - metabolism; T-Lymphocytes - immunology; T-Lymphocytes - virology; Transcription, Genetic; Tripartite Motif Proteins; Virus Replication
• ISSN: 1098-5514
• DOI: 10.1128/jvi.02302-10

Previous studies identified clones of the U937 promonocytic cell line that were either permissive or nonpermissive for human immunodeficiency virus type 1 (HIV-1) replication. These clones were investigated further in the search for host restriction factors that could explain their differential capacity to support HIV-1 replication. Among known HIV-1 restriction factors screened, tripartite motif-containing protein 22 (TRIM22) was the only factor constitutively expressed in nonpermissive and absent in permissive U937 cells. Stable TRIM22 knockdown (KD) rescued HIV-1 long-terminal-repeat (LTR)-driven transcription in KD-nonpermissive cells to the levels observed in permissive cells. Conversely, transduction-mediated expression of TRIM22 in permissive cells reduced LTR-driven luciferase expression by ∼7-fold, supporting a negative role of TRIM22 in HIV-1 transcription. This finding was further confirmed in the human T cell line A3.01 expressing TRIM22. Moreover, overexpression of TRIM22 in 293T cells significantly impaired basal and phorbol myristate acetate-ionomycin-induced HIV-1 LTR-driven gene expression, whereas inhibition of tumor necrosis factor alpha-induced viral transcription was a consequence of lower basal expression. In agreement, TRIM22 equally inhibited an LTR construct lacking the tandem NF-κB binding sites. In addition, TRIM22 did not affect Tat-mediated LTR transactivation. Finally, these effects were independent of TRIM22 E3 ubiquitin-ligase activity. In the context of replication-competent virus, significantly higher levels of HIV-1 production were observed in KD-nonpermissive versus control nonpermissive U937 cells after infection. In contrast, lower peak levels of HIV-1 replication characterized U937 and A3.01 cells expressing TRIM22 versus their control transduced counterpart. Thus, nuclear TRIM22 significantly impairs HIV-1 replication, likely by interfering with Tat- and NF-κB-independent LTR-driven transcription.