Project description:Herpes simplex virus replicates and forms progeny in the nucleus where it must overcome host chromatin to establish a successful infection. During lytic infection, newly formed viral capsids navigate through heterochromatin channels at the nuclear periphery to egress out of the nucleus. In uninfected cells, specific histone marks such as trimethylation on histone H3 lysine 27 (H3K27me3) and the histone variant macroH2A1 delineate heterochromatin regions, or repressed chromatin, that are predominantly located in the nuclear periphery. We examined these markers during HSV-1 lytic infection in primary cells and discovered a striking increase in the levels of macroH2A1 and H3K27me3. Here, we demonstrate that the loss of macroH2A1 results in significantly lower viral titers but does not impair viral transcription, protein production, or replication. By inhibiting the deposition of H3K27me3 by EZH2, we further show that reduction of H3K27me3 also leads to a significant decrease in viral titers. Through chromatin profiling via Cleavage Under Targets and tagmentation (CUT&Tag) of macroH2A1 and H3K27me3, we define the specific chromatin regions that change dynamically during HSV-1 lytic infection and show that regions with increased macroH2A1 and H3K27me3 correlate with decreased host transcription as measured by RNA-seq. Furthermore, we find by electron microscopy that loss of macroH2A1 results in reduced heterochromatin at the nuclear periphery and significantly more viral capsids trapped in the nuclear compartment. Using both high and low shedding clinical isolates of HSV-1, we similarly find that HSV-1 titers are significantly reduced in the absence of macroH2A1. Our work demonstrates that HSV-1 takes advantage of the dynamic nature of host heterochromatin formation during infection for efficient viral egress from the nuclear compartment.
Project description:Herpes simplex virus replicates and forms progeny in the nucleus where it must overcome host chromatin to establish a successful infection. During lytic infection, newly formed viral capsids navigate through heterochromatin channels at the nuclear periphery to egress out of the nucleus. In uninfected cells, specific histone marks such as trimethylation on histone H3 lysine 27 (H3K27me3) and the histone variant macroH2A1 delineate heterochromatin regions, or repressed chromatin, that are predominantly located in the nuclear periphery. We examined these markers during HSV-1 lytic infection in primary cells and discovered a striking increase in the levels of macroH2A1 and H3K27me3. Here, we demonstrate that the loss of macroH2A1 results in significantly lower viral titers but does not impair viral transcription, protein production, or replication. By inhibiting the deposition of H3K27me3 by EZH2, we further show that reduction of H3K27me3 also leads to a significant decrease in viral titers. Through chromatin profiling via Cleavage Under Targets and tagmentation (CUT&Tag) of macroH2A1 and H3K27me3, we define the specific chromatin regions that change dynamically during HSV-1 lytic infection and show that regions with increased macroH2A1 and H3K27me3 correlate with decreased host transcription as measured by RNA-seq. Furthermore, we find by electron microscopy that loss of macroH2A1 results in reduced heterochromatin at the nuclear periphery and significantly more viral capsids trapped in the nuclear compartment. Using both high and low shedding clinical isolates of HSV-1, we similarly find that HSV-1 titers are significantly reduced in the absence of macroH2A1. Our work demonstrates that HSV-1 takes advantage of the dynamic nature of host heterochromatin formation during infection for efficient viral egress from the nuclear compartment.
Project description:Herpes simplex virus (HSV-1) progeny form in the nucleus and exit to successfully infect other cells. Newly formed capsids navigate complex chromatin architecture to reach the inner nuclear membrane (INM) and egress. Here, we demonstrate by transmission electron microscopy (TEM) that HSV-1 capsids traverse heterochromatin associated with trimethylation on histone H3 lysine 27 (H3K27me3) and the histone variant macroH2A1. Through chromatin profiling during infection, we revealed global redistribution of these marks whereby massive host genomic regions bound by macroH2A1 and H3K27me3 correlate with decreased host transcription in active compartments. We found that the loss of these markers resulted in significantly lower viral titers but did not impact viral genome or protein accumulation. Strikingly, we discovered that loss of macroH2A1 or H3K27me3 resulted in nuclear trapping of capsids. Finally, by live-capsid tracking, we quantified this decreased capsid movement. Thus, our work demonstrates that HSV-1 takes advantage of the dynamic nature of host heterochromatin formation during infection for efficient nuclear egress.
Project description:This SuperSeries is composed of the following subset Series: GSE40684: Foxp3 exploits a preexistent enhancer landscape for regulatory T cell lineage specification [ChIP-Seq] GSE40685: Foxp3 exploits a preexistent enhancer landscape for regulatory T cell lineage specification [Expression] Refer to individual Series
Project description:The herpes simplex virus (HSV)-1 protein pUL21 is essential for efficient virus replication and dissemination. While pUL21 has been shown to promote multiple steps of virus assembly and spread, the molecular basis of its function remained unclear. Here we identify that pUL21 is a virus-encoded adaptor of protein phosphatase 1 (PP1). pUL21 directs the dephosphorylation of cellular and virus proteins, including components of the viral nuclear egress complex, and we define a conserved non-canonical linear motif in pUL21 that is essential for PP1 recruitment. In vitro evolution experiments reveal that pUL21 directly antagonises the activity of the virus-encoded kinase pUS3, with growth and spread of pUL21 PP1-binding mutant viruses being restored when pUS3 activity is disrupted. This study shows that virus-directed phosphatase activity is essential for efficient herpesvirus assembly and spread, highlighting the fine balance between kinase and phosphatase activity required for optimal virus replication.
Project description:Loss of Pggt1b leads to marked defects in thymocyte egress and T cell lymphopenia in peripheral lymphoid organs in vivo CD4SP thymocytes (n = 4 per genotype) were isolated from the thymus of WT and Pggt1b KO mice