Biology subjects

Texier, P.

Publications and source records attributed to Texier, P..

4 recordsLinked to original sources

bioRxiv2024

The HUSH epigenetic repressor complex silences PML nuclear bodies-associated HSV-1 quiescent genomes

Herpes simplex virus 1 (HSV-1) latently infected neurons show multiple patterns in the distribution of the viral genomes within the nucleus, at least in mouse models. One of the major patterns is characterized by the presence of quiescent HSV-1 genomes trapped in promyelocytic leukemia nuclear bodies (PML NBs) to form viral DNA-containing PML-NBs (vDCP NBs). Using a cellular model reproducing the formation of vDCP NBs we previously showed that viral genomes are chromatinized with the H3.3 histone variant modified on its lysine 9 by tri-methylation (H3.3K9me3) a chromatin mark associated with transcriptional repression. Here we identify an essential role for the HUSH complex and its SETDB1 and MORC2 effectors in the acquisition of the H3K9me3 mark on the PML NBs-associated HSV-1 and in the maintenance of HSV-1 transcriptional repression. ChiP-seq analyses highlight the association of the H3K9me3 mark with the entire viral genome. Inactivating the HUSH-SETDB1-MORC2 repressor complex prior to viral infection results in a significant reduction of H3K9me3 on the viral genome, while the overall impact on the cellular genome is minimal, except for expected changes in families of LINE1 retroelements. Depletion of HUSH, SETDB1, or MORC2, relieves the repressive state of HSV-1 in infected primary human fibroblasts as well as human induced pluripotent stem cell-derived sensory neurons (hiPSDN). We discovered that the viral protein ICP0 induces MORC2 degradation via the proteasome machinery. This process is concurrent with ICP0 and MORC2 depletion capability to reactivate silenced HSV-1 in hiPSDN. Overall, our findings underscore the robust antiviral function of the HUSH-SETDB1-MORC2 repressor complex against a herpesvirus by modulating chromatin marks linked to repression, thus presenting promising avenues for novel anti-herpesvirus therapeutic strategies. Significance statementHerpes simplex virus 1 (HSV-1) is a major human pathogen, which remains latent in the trigeminal ganglia (TG) neurons of the infected individuals. Its reactivation is characterized by a variety of clinical symptoms the most severe ones being keratitis and herpesvirus encephalitis. The colonization of the CNS by the virus during the individual life is a well-known fact but the pathophysiological effects on neurons homeostasis are still underestimated. It is thus paramount to understand the molecular mechanisms that control HSV-1 latency and maintain the virus in a pseudo silent state.

microbiology↗

bioRxiv2021

Interplay between PML NBs and HIRA for H3.3 deposition on transcriptionally active interferon-stimulated genes

Promyelocytic Leukemia Nuclear Bodies (PML NBs) are nuclear membrane-less organelles physically associated with chromatin underscoring their crucial role in genome function. The H3.3 histone chaperone complex HIRA accumulates in PML NBs upon senescence, viral infection or IFN-I treatment in primary cells. Yet, the molecular mechanisms of this partitioning and its function in regulating histone dynamics have remained elusive. By using specific approaches, we identify intermolecular SUMO-SIM interactions as an essential mechanism for HIRA recruitment in PML NBs. Upon IFN-I stimulation, PML is required for interferon-stimulated genes (ISGs) transcription and PML NBs become juxtaposed to ISGs loci at late time points of IFN-I treatment. HIRA and PML are necessary for the prolonged H3.3 deposition at the transcriptional end sites of ISGs, well beyond the peak of transcription. Though, HIRA accumulation in PML NBs is dispensable for H3.3 deposition on ISGs. Hence, we describe an independent role of PML NBs as nuclear depot centers to regulate HIRA distribution in the nucleus, as a consequence of the availability of the pool of H3.3-H4 dimers or chromatin compaction. We thus uncover a dual function for PML/PML NBs in regulating ISGs transcription and H3.3 deposition at ISGs, and in modulating the nuclear distribution of HIRA upon inflammatory response.

genetics↗

bioRxiv2018

CENP-B dynamics at centromeres is regulated by a SUMOylation/ubiquitination and proteasomal-dependent degradation mechanism involving the SUMO-targeted ubiquitin E3 ligase RNF4

Centromeric protein B (CENP-B) is a major constituent of the centromere. It is a DNA binding protein that recognizes a specific 17-nt sequence present in the centromeric alphoid satellite repeats. CENP-B importance for centromere stability has only been revealed recently. In addition to its DNA binding properties, CENP-B interacts with the histone H3 variant CENP-A and CENP-C. These interactions confer a mechanical strength to the kinetochore that enables accurate sister chromatids segregation to avoid aneuploidy. Therefore, understanding the mechanisms that regulate CENP-B stability at the centromere is a major unresolved issue for the comprehension of centromere function. In this study, we demonstrate that lysine K402 of CENP-B is a substrate for SUMO post-translational modifications. We show that K402 regulates CENP-B stability at centromeres through a SUMOylation/ubiquitination and proteasomal-dependent degradation mechanism involving the SUMO-Targeted Ubiquitin E3 Ligase RNF4/SNURF. Our study describes SUMOylation of CENP-B as a major post-translational modification involved in centromere dynamics.

cell biology↗

bioRxiv2017

Promyelocytic Leukemia (PML) Nuclear Bodies (NBs) Induce Latent/Quiescent HSV-1 Genomes Chromatinization Through a PML-NB/Histone H3.3/H3.3 Chaperone Axis

Herpes simplex virus 1 (HSV-1) latency establishment is tightly controlled by promyelocytic leukemia (PML) nuclear bodies (NBs) (or ND10), although their exact implication is still elusive. A hallmark of HSV-1 latency is the interaction between latent viral genomes and PML-NBs, leading to the formation of viral DNA-containing PML-NBs (vDCP-NBs). Using a replication-defective HSV-1-infected human primary fibroblast model reproducing the formation of vDCP-NBs, combined with an immuno-FISH approach developed to detect latent/quiescent HSV-1, we show that vDCP-NBs contain both histone H3.3 and its chaperone complexes, i.e., DAXX/ATRX and HIRA complex (HIRA, UBN1, CABIN1, and ASF1a). HIRA also co-localizes with vDCP-NBs present in trigeminal ganglia (TG) neurons from HSV-1-infected wild type mice. ChIP-qPCR performed on fibroblasts stably expressing tagged H3.3 (e-H3.3) or H3.1 (e-H3.1) show that latent/quiescent viral genomes are chromatinized almost exclusively with e-H3.3, consistent with an interaction of the H3.3 chaperones with multiple viral loci. Depletion by shRNA of single proteins from the H3.3 chaperone complexes only mildly affects H3.3 deposition on the latent viral genome, suggesting a compensation mechanism. In contrast, depletion (by shRNA) or absence of PML (in mouse embryonic fibroblast (MEF) pml-/- cells) significantly impacts the chromatinization of the latent/quiescent viral genomes with H3.3 without any overall replacement with H3.1. Consequently, the study demonstrates a specific epigenetic regulation of latent/quiescent HSV-1 through an H3.3-dependent HSV-1 chromatinization involving the two H3.3 chaperones DAXX/ATRX and HIRA complexes. Additionally, the study reveals that PML-NBs are major actors in latent/quiescent HSV-1 H3.3 chromatinization through a PML-NB/histone H3.3/H3.3 chaperone axis.\n\nAuthor summaryAn understanding of the molecular mechanisms contributing to the persistence of a virus in its host is essential to be able to control viral reactivation and its associated diseases. Herpes simplex virus 1 (HSV-1) is a human pathogen that remains latent in the PNS and CNS of the infected host. However, the latency is unstable, and frequent reactivations of the virus are responsible for PNS and CNS pathologies. It is thus crucial to understand the physiological, immunological and molecular levels of interplay between latent HSV-1 and the host. Promyelocytic leukemia (PML) nuclear bodies (NBs) play a major role in controlling viral infections by preventing the onset of lytic infection. In previous studies, we showed a major role of PML-NBs in favoring the establishment of a latent state for HSV-1. A hallmark of HSV-1 latency establishment is the formation of PML-NBs containing the viral genome, which we called \"viral DNA-containing PML-NBs\" (vDCP-NBs). The genome entrapped in the vDCP-NBs is transcriptionally silenced. This naturally occurring latent/quiescent state could, however, be transcriptionally reactivated. Therefore, understanding the role of PML-NBs in controlling the establishment of HSV-1 latency and its reactivation is essential to design new therapeutic approaches based on the prevention of viral reactivation.

microbiology↗