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Cellular senescence, a stress-induced stable proliferation arrest associated with an inflammatory Senescence-Associated Secretory Phenotype (SASP), is a cause of aging. In senescent cells, Cytoplasmic Chromatin Fragments (CCFs) activate SASP via the anti-viral cGAS/STING pathway. PML protein organizes PML nuclear bodies (NBs), also involved in senescence and anti-viral immunity. The HIRA histone H3.3 chaperone localizes to PML NBs in senescent cells. Here, we show that HIRA and PML are essential for SASP expression, tightly linked to HIRA's localization to PML NBs. Inactivation of HIRA does not directly block expression of NF-κB target genes. Instead, an H3.3-independent HIRA function activates SASP through a CCF-cGAS-STING-TBK1-NF-κB pathway. HIRA physically interacts with p62/SQSTM1, an autophagy regulator and negative SASP regulator. HIRA and p62 co-localize in PML NBs, linked to their antagonistic regulation of SASP, with PML NBs controlling their spatial configuration. These results outline a role for HIRA and PML in regulation of SASP.
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http://dx.doi.org/10.1101/2023.06.24.546372 | DOI Listing |
PLoS Pathog
August 2025
The Wistar Institute, Philadelphia, Pennsylvania, United States of America.
Transcription-replication conflicts frequently occur at repetitive DNA elements involved in genome maintenance functions. The KSHV terminal repeats (TR) function as the viral episome maintenance element when bound by the viral encoded nuclear antigen LANA. Here, we show that transcription-replication conflicts occur at or near LANA binding sites in the TR.
View Article and Find Full Text PDFCell Death Dis
August 2025
Division of Cancer and Senescence Biology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa, Japan.
Accumulating evidence suggests that mitogenic signaling during cell cycle arrest can lead to severe cytotoxic outcomes, such as senescence, though the underlying mechanisms remain poorly understood. Here, we explored the link between cell cycle dynamics and the formation of PML-nuclear bodies (PML-NBs), intranuclear structures known to mediate cellular stress responses. Our findings demonstrate that PML-NBs increase their number during interphase arrest.
View Article and Find Full Text PDFInt J Mol Sci
July 2025
Basic Research Center of Chinese and Western Medicine on the Prevention and Treatment of Vascular Diseases, Changsha 410208, China.
SUMOylation plays a crucial role in regulating gene expression by promoting interactions between transcription factors and corepressors. Daxx, a multifunctional scaffold protein, specifically recognizes and binds SUMOylated transcription factors through its SUMO-interacting motifs (SIMs), acting as a transcriptional corepressor. In this review, we systematically elucidate the structural basis of the interaction between Daxx and SUMO, revealing the synergistic mechanism by which Daxx SIM phosphorylation and SUMO acetylation dynamically regulate Daxx function.
View Article and Find Full Text PDFMol Cell
July 2025
Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA; Livestrong Cancer Institutes, Dell Medical School, The University of Texas at Austin, Austin, TX 78712, USA. Electronic address:
An inability to replicate the genome can cause replication stress and genome instability. Here, we develop biotinylation of lac operator (LacO) array replication stress protein network identification (BLOCK-ID) in human cancer cells, a proteomic method to identify and visualize proteins at stressed replication forks. This approach identified mediators of the replication stress response, including the chromatin acetylation reader protein tripartite motif containing 24 (TRIM24).
View Article and Find Full Text PDFbioRxiv
March 2025
Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
PML nuclear bodies (PML-NBs) are dynamic subnuclear structures important for chromatin dynamics and anti-viral defense. In this study we investigate the role of Sp100 isoforms in promoting localization of the H3.3 histone chaperone HIRA to PML-NBs in human keratinocytes.
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