HIV-1 virus titers were quantified by determining the TCID50 on 293T cells [71]

HIV-1 virus titers were quantified by determining the TCID50 on 293T cells [71]. == LTR-driven transcription in HEK293T, TZM-bl and J-Lat cells == HEK293T cells were transfected with pLKO. 1 constructs expressing a shRNA against DYRK1A, a control shRNA (TRCN199464 or SHC001; Sigma-Aldrich, USA [72]) and/or the long terminal repeat (HXB2 LTR) luciferase reporter constructs pBlue3 LTR-luc [73], and pBlue3 LTRNFAT/NF-kB-luc and/or HIV-1 Tat expression construct sv-Tat using the calcium phosphate method. the viral LTR and thus increasing viral transcription. == Conclusions == Our data indicate that host factor DYRK1A plays a role in the regulation of viral transcription and latency. Therefore , DYRK1A might be an attractive candidate for therapeutic strategies targeting the viral reservoir. == Background == The ability of the human immunodeficiency virus type 1 (HIV-1) to replicate in a host cell is influenced by numerous host factors that act on different steps of the viral life cycle ranging from virus entry to budding of the newly formed virions. Recent genome wide RNAi studies have identified almost 1000 host proteins that support HIV-1 replication [19]. On the other hand, a number of host factors, such as MX2 [1012], TRIM5 [13, 14], SAMHD1 [15, 16], APOBEC3 [1719] and Tetherin [20] have been described to display antiviral effects and restrict viral replication. Recently, we have performed a genome wide association study to assess the effect of genetic polymorphisms on HIV-1 replication in macrophages and we identified polymorphisms in a number of host genes that were strongly associated with HIV-1 replication [21]. One of these polymorphisms was located in thedual specificity tyrosine-phosphorylation-regulated kinase 1A(DYRK1A). In addition , this polymorphism was also associated with HIV-1 disease progression in two independent cohorts, suggesting an important role for this protein in HIV-1 replication [21]. DYRK1A is a kinase that is involved in regulation of the cell cycle and neurogenesis during brain development [2227]. DYRK1A regulates the activity of several transcription factors [2835], some of which have been implicated in the regulation of HIV-1 transcription [3639]. DYRK1A phosphorylates the Nuclear Factor of Activated T-cells (NFAT) and the class III histone deacetylase Sirtuin 1 (SIRT1) [34, 35]. Phosphorylation of NFAT by DYRK1A results in its translocation from the nucleus to the cytoplasm, which decreases AHU-377 (Sacubitril calcium) nuclear NFAT levels [32, 33]. SIRT1 phosphorylation by DYRK1A results in the activation of SIRT1, which deacetylates the RelA/p65 subunit of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-B) complex, and thus inhibits NF-kB activity [34]. Both NFAT and NF-kB AHU-377 (Sacubitril calcium) are transcription factors that bind to the HIV-1 long terminal repeat (LTR) promoter thereby regulating proviral transcription [3641]. Here we investigated the role of DYRK1A in HIV-1 replication. We show that DYRK1A controls HIV-1 replication at a transcriptional level in multiple cell lines and primary PBMC. DYRK1A inhibits LTR-driven transcription by limiting the nuclear localization of transcription factor NFAT. Inhibition of DYRK1A in TZM-bl cells and J-Lat AHU-377 (Sacubitril calcium) cells, which carry a latent HIV-1 provirus, resulted in reactivation of the latent HIV-1 to a similar extent as treatment with TNF and two commonly used broad-spectrum HDAC inhibitors. These data suggest that DYRK1A can control HIV-1 replication and might be involved in viral latency. == Results == == DYRK1A knockdown or inhibition increases HIV-1 replication == The effect of DYKR1A knockdown on HIV-1 replication was analyzed in HEK293T cells. HEK293T cells express high levels GP9 of endogenous DYRK1A and after transfection with a shRNA that targets DYRK1A mRNA, a dose-dependent decrease in DYRK1A protein expression was observed (Fig 1A). When the DYRK1A knockdown cells were infected with a VSV-G pseudotyped HIV-1 luciferase reporter virus, a dose dependent increase in luciferase activity was observed (Fig 1BandS1A Fig). This indicates that AHU-377 (Sacubitril calcium) DYRK1A represses viral replication in HEK293T cells. A similar observation on virus replication was made using INDY, a selective inhibitor of DYRK1A [42, 43]. When INDY was added to the HEK293T cells at 24 hours after infection with a VSV-G pseudotyped HIV-1 luciferase reporter virus, a dose dependent increase in luciferase activity was observed (Fig 1CandS1B Fig). Next, we analyzed whether DYKR1A is also an important regulator of HIV-1 replication in primary cells. Activated PBMCs were infected with a VSV-G pseudotyped HIV-1 luciferase reporter virus and 24-hours after infection different concentrations of the DYRK1A inhibitor INDY were added to.