H3K27me3 Research Articles

Dual targeting PPARα and NPC1L1 metabolic vulnerabilities blocks tumorigenesis.

Dysregulated lipid metabolism is linked to tumor progression. In this study, we identified Niemann-Pick C1-like 1 (NPC1L1) as a downstream effector of PKM2. In breast cancer cells, PKM2 knockout (KO) enhanced NPC1L1 expression while downregulating peroxisome proliferator-activated receptor α (PPARα) signaling pathway. PPARα and nuclear factor-E2 p45-related factor 1/2(Nrf1/2) are transcription factors regulating NPC1L1. In vitro PKM2 KO enhanced recruitment of Nrf1/2 to the NPC1L1 promoter region. Fenofibrate, a PPARα activator, promoted NPC1L1 expression; ezetimibe, an NPC1L1 inhibitor and effective Nrf2 activator, also elevated NPC1L1 expression. Combined administration of fenofibrate and ezetimibe significantly induced cytoplasmic vacuolation, and cell apoptosis. Mechanistically, this combined administration activated inositol required enzyme 1α(IRE1α) and produced the spliced form of X-box binding protein (XBP1s), which in turn enhanced lysine demethylase 6B (KDM6B) transcription. XBP1s interacts with KDM6B to activate genes involved in the unfolded protein response by demethylating di- and tri-methylated lysine 27 of histone H3 (H3K27), consequently increasing H3K27 acetylation levels in breast cancer cell lines. Fenofibrate and ezetimibe synergistically inhibited tumor growth in vivo. Our findings reveal that dual targeting of PPARα and NPC1L1 may represent a novel therapeutic regimen for breast cancer therapy.

Tannic acid reactivates HIV-1 latency by mediating CBX4 degradation.

HIV-1 can integrate viral DNA into host cell chromosomes and establish a long-term stable latent viral reservoir, a major obstacle in curing HIV-1 infection. The reactivation of latent proviruses with latency-reversing agents (LRAs) is a prerequisite for the eradication of viral reservoirs. Previous reports have shown that tannic acid (TA) exerts several biological functions, including antioxidant and antitumor activities. Here, we identified a novel function of TA as a reactivator of HIV-1 latency. TA showed similar features to the HIV-1 transactivator of transcription (Tat) and was able to reactivate a larger number of proviruses from various integration sites. TA also showed a strong synergistic effect with other LRAs acting on different signaling pathways. Further studies revealed that the polycomb repressive complex 1 component, chromobox protein homolog 4 (CBX4), is specifically degraded by TA through ubiquitination. CBX4 is associated with the tri-methylation at lysine 27 of histone H3 (H3K27me3) which was enriched on HIV-1 long terminal repeat regions. The TA-induced CBX4 degradation decreased the H3K27me3 enrichment and subsequently enhanced the transcriptional activity of the integrated proviruses. These results suggest that TA is an efficient LRA aiming to a new target for HIV-1 latency, which could be developed to eradicate latent proviruses.IMPORTANCEHIV-1 remains a global health challenge, with its ability to integrate into the host genome and evade the effects of drugs. To overcome this obstacle, the "shock and kill" strategy was proposed, targeting the reactivation of latent HIV-1 for subsequent eradication through antiretroviral medication and immune system reinforcement. Here, we found a new reactivator for HIV-1 latency, tannic acid (TA), which can reactivate HIV-1 latency widely and deeply. Moreover, we demonstrated that TA could promote the interaction between the polycomb repressive complex 1 component CBX4 and the E3 ubiquitin ligase cullin 4A (CUL4A), resulting in CBX4 degradation through the ubiquitin-proteasome system. These events reduce H3K27me3 enrichment in the HIV-1 long terminal repeat region, thereby promoting HIV-1 transcription and ultimately reactivating HIV-1 latent infection. Our work may facilitate the identification of new latency-reversing agents and provide more theoretical evidence for the molecular mechanism of HIV-1 latency.

Porphyromonas gingivalis-Lipopolysaccharide Induced Gingival Fibroblasts Trained Immunity Sustains Inflammation in Periodontitis.

To investigate whether trained immunity occurs in gingival fibroblasts (GFs) and its relationship to the persistence of inflammation in periodontitis. Periodontally healthy and inflammatory gingival fibroblasts (HGFs and IGFs) were cultured through continuous adherence subculture of tissue blocks. Trained immunity in HGFs was evaluated via a classic invitro model, with relevant markers assessed via enzyme-linked immunosorbent assay, lactate content assay, glycolytic rate assay, and chromatin immunoprecipitation. A histone methyltransferase blocker and a PI3K inhibitor were added to investigate the mechanisms underlying trained immunity. The relationship between trained immunity and periodontitis was further examined via immunofluorescence staining and chromatin immunoprecipitation on IGFs. Compared with untrained cells, GFs trained with Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) exhibited a significant increase in IL-6 and TNF-α secretion, enhanced glycolytic metabolism, and enriched mono-methylation of lysine 4 on histone H3 (H3K4me1) at the enhancer regions of TNF-α and IL-6. The addition of a histone methyltransferase blocker and a PI3K inhibitor greatly reduced trained immunity. Additionally, the response of IGFs to P. gingivalis-LPS stimulation and their epigenetic modifications were similar to those observed in trained HGFs. This study novelly discovered that both P. gingivalis-LPS-stimulated HGFs and IGFs in periodontitis acquired trained immunity. Following P. gingivalis-LPS stimulation, HGFs underwent metabolic and epigenetic changes via the PI3K/AKT pathway, with these epigenetic changes also observed in IGFs. This finding suggests that trained immunity in GFs may be a key mechanism underlying the recurrence and persistence of periodontitis.

The C-terminal PHDVC5HCH tandem domain of NSD2 is a combinatorial reader of unmodified H3K4 and tri-methylated H3K27 that regulates transcription of cell adhesion genes in multiple myeloma.

Histone methyltransferase NSD2 (MMSET) overexpression in multiple myeloma (MM) patients plays an important role in the development of this disease subtype. Through the expansion of transcriptional activating H3K36me2 and the suppression of repressive H3K27me3 marks, NSD2 activates an aberrant set of genes that contribute to myeloma growth, adhesive and invasive activities. NSD2 transcriptional activity also depends on its non-catalytic domains, which facilitate its recruitment to chromatin through histone binding. In this study, using NMR, ITC and molecular dynamics simulations, we show that the tandem PHD domain of NSD2 (PHDVC5HCHNSD2) is a combinatorial reader of unmodified histone H3K4 and tri-methylated H3K27 (H3K27me3). This is the first PHD tandem cassette known to decode the methylation status of H3K27. Importantly, in a NSD2-dependent MM cellular model, we show that expression of NSD2 mutants, engineered to disrupt the interaction between H3K27me3 and PHDVC5HCH, display in comparison to wild-type NSD2: incomplete loss of H3K27 methylation throughout the genome, decreased activation of adhesive properties and cell adhesion genes, and a decrease of the corresponding H3K27ac signal at promoters. Collectively, these data suggest that the PHDVC5HCH domain of NSD2 plays an important role in modulating gene expression and chromatin modification, providing new opportunities for pharmacological intervention.

ALFIN-like proteins link histone H3K4me3 to H2A ubiquitination and coordinate diverse chromatin modifications in Arabidopsis.

Trimethylation of histone H3K4 (H3K4me3) is widely distributed at numerous actively transcribed protein-coding genes throughout the genome. However, the interplay between H3K4me3 and other chromatin modifications in plants remains poorly understood. In this study, we find that the Arabidopsis thaliana ALFIN-LIKE (AL) proteins contain a C-terminal PHD finger capable of binding to H3K4me3, along with a PHD-associated AL (PAL) domain that interacts with components of the Polycomb repressive complex 1 (PRC1), thereby facilitating H2A ubiquitination (H2Aub) at H3K4me3-enriched genes throughout the genome. Furthermore, we demonstrate that the loss of SDG2, a key histone H3K4 methyltransferase, leads to a reduction in H3K4me3 level, which subsequently causes a decrease in H2Aub on a genome-wide scale, revealing a strong association between H3K4me3 and H2Aub. Additionally, we show that the PAL domain interacts with various other chromatin-related proteins or complexes, including those involved in regulating H2A.Z deposition, H3K27me3 demethylation, histone deacetylation, and chromatin accessibility. Our genome-wide analysis suggests that the AL proteins play a crucial role in coordinating H3K4me3 with multiple other chromatin modifications across the genome.

The prognostic value of H3 K27me3 in meningiomas: A review on current evidence and methodological challenges.

Meningiomas are the most common primary intracranial neoplasms. Although they mostly exhibit a benign course, some cases recur after surgery and show high morbidity and mortality rates. In addition to currently established prognostic factors, such as the extent of surgical resection and tumor grade assessed according to World Health Organization (WHO) criteria, the prognostic significance of the immunohistochemical loss of Histone 3 trimethylation in Lysine 27 (H3 K27me3) has emerged in meningiomas. This review examined original studies that analyzed the immunohistochemical expression of H3 K27me3 in meningiomas and its correlation with various features, including overall survival (OS), recurrence-free survival (RFS), and WHO grade. A literature search was conducted in PubMed for English-language publications up to July 8, 2024. Sixteen studies were included in this review. In summary, current evidence indicates that H3 K27me3 loss is more frequent in tumors exhibiting higher biological aggressiveness, as reflected by a significant association with a higher WHO grade, proliferative index, and prognostically unfavorable methylation classes. In addition, published studies consistently indicate a negative prognostic significance for progression-recurrence-free survival (PFS/RFS) in WHO grade 2 meningiomas and OS in WHO grade 3 tumors. However, the lack of a standardized definition for H3 K27me3 loss significantly hampers the incorporation of the H3 K27me3 immunohistochemical assay into routine practice to establish the prognosis of meningiomas.

Clinico-Pathological Features of Diffuse Midline Glioma, H3 K27-Altered in Adults: A Comprehensive Review of the Literature with an Additional Single-Institution Case Series.

Background: Diffuse midline glioma (DMG), H3 K27-altered, is a WHO grade 4 malignant glioma located at midline structures, including the thalamus, brainstem and spinal cord. While H3 K27-altered DMG is more common in pediatric age in which it shows a uniformly aggressive clinical behavior, its occurrence is relatively unusual among adults, and its clinico-pathological and prognostic features are not fully characterized in this age group. Methods: In this present paper, a review of the literature, including all cases of adult H3 K27-altered DMG published from January 2010 to December 2023 was performed, and the following clinical parameters were evaluated: sex, age (median and range), anatomic site, median follow-up, leptomeningeal dissemination, local recurrence and treatment. In addition, the clinico-pathological features of three additional adult cases from our retrospective series were also reported and discussed. Results: All tumors from our series exhibited a high-grade morphology with brisk mitotic activity; microvascular proliferation and necrosis were seen only in one case. The immunohistochemical loss of H3 K27me3 along with diffuse and strong immunoreactivity for H3 K27M was found in all cases, leading to the diagnosis of H3 K27-altered DMG. Conclusions: The literature review showed that adult H3 K27-altered DMG more frequently occurred in males aged between 18 and 40 years. The thalamus was the most affected site, followed by the brainstem and spinal cord, in both sex groups. Adult tumors exhibited less aggressive clinical behavior, with leptomeningeal dissemination and local recurrence reported in only 23.78% and 37.75% of cases, respectively.

Maternally expressed FERTILIZATION-INDEPENDENT ENDOSPERM1 regulates seed dormancy and aleurone development in rice.

Seed dormancy, an essential trait for plant adaptation, is determined by the embryo itself and the surrounding tissues. Here, we found that rice (Oryza sativa) FERTILIZATION-INDEPENDENT ENDOSPERM1 (OsFIE1) regulates endosperm-imposed dormancy and the dorsal aleurone thickness in a manner dependent on the parent of origin. Maternally expressed OsFIE1 suppresses gibberellin (GA) biosynthesis in the endosperm by depositing trimethylation of lysine 27 on histone H3 (H3K27me3) marks on GA biosynthesis-related genes, thus inhibiting germination and aleurone differentiation. Knockout of rice GA 20-oxidase1 (OsGA20ox1) alleviated the phenotypic defects in osfie1. The aleurone-positive determinant Crinkly 4 (OsCR4) is another target of the OsFIE1-containing Polycomb repressive complex 2 (PRC2). We found that OsFIE1 plays an important role in genomic imprinting in the endosperm of germinating seeds, particularly for paternally expressed genes associated with H3K27me3. The increased aleurone thickness of osfie1 substantially improved grain nutritional quality, indicating that the osfie1 gene may be utilized for breeding nutrient-enriched rice. The findings provide insights into the essential roles of PRC2-mediated H3K27me3 methylation in the acquisition of seed dormancy and endosperm cell differentiation in rice.

EXTH-37. ALLOSTERIC MITOCHONDRIAL CLPP AGONIST ONC206 ALTERS STRESS RESPONSE, METABOLIC AND EPIGENETIC PROFILES TO ELICIT ANTI-CANCER EFFICACY IN HIGH-GRADE GLIOMAS

Abstract Dordaviprone (ONC201) is a dopamine receptor D2/3 (DRD2/3) antagonist and allosteric ClpP agonist that has demonstrated durable responses in recurrent H3 K27M-mutant glioma patients. ONC206, a derivative of ONC201 with nanomolar potency that also targets DRD2/3 and ClpP, is in Phase I trials for central nervous system tumors. We characterized target relevance, human ClpP binding, in vitro efficacy, downstream signaling and response determinants associated with ONC206 in high-grade gliomas (HGG). Co-crystallization with ClpP that assembles as a tetradecameric complex revealed an allosteric ligand interaction with distinctions in the ONC206-ClpP overall conformation relative to the ONC201-bound or apo complex, including an increase in the resolved pore size and decreased complex height. ONC206 was more potent than ONC201 in cell-free human ClpP casein/peptide degradation assays). Accordingly, HGG cell lines and patient-derived cells exhibited increased sensitivity to ONC206 relative to ONC201 and generally required a shorter duration of exposure. Unlike DRD2, CRISPR-mediated ClpP knockout in HGG cell lines blunted ONC206 sensitivity. Metabolomics revealed elevated α-ketoglutaric acid, α-hydroxyglutaric acid, and glutaric acid. Proteomics indicated inhibition of multiple mitochondrial pathways including OXPHOS and TCA cycle. TCA cycle enzyme α-ketoglutarate dehydrogenase (KGDH) was inhibited in a ClpP-dependent manner. Western blotting showed downregulated ClpX, and upregulated ATF4/CHOP, H3 K27me3 and H3 K36me3. Next-generation sequencing of acquired resistance cell lines, which exhibited cross-resistance to ONC201 and ONC206, revealed diverse ClpP missense mutations distributed across various monomer interfaces. Both intrinsic and well as ONC206-stimulated ClpP proteolysis were mitigated by these mutations, which was congruent with an absence of the tetradecameric assembly. These ClpP mutations recapitulated resistance and, conversely, wildtype ClpP overexpression restored sensitivity. Thus, allosteric ClpP agonism is a key determinant of ONC206 activity in HGG by altering stress response, metabolic, and epigenetic profiles.

PATH-37. A NEW SUBTYPE OF DIFFUSE MIDLINE GLIOMA, H3 K27 AND BRAF/FGFR1 CO-ALTERED, EXHIBITS SPECIFIC BIOLOGICAL CHARACTERISTICS AND NEW THERAPEUTIC VULNERABILITIES

Abstract Diffuse midline gliomas (DMG) H3 K27-altered are incurable grade 4 gliomas and represent a major challenge in neuro-oncology. This tumor type is classified in four subtypes by the 2021 edition of the WHO Classification of the Central Nervous System tumors. However, we recently identified a new subtype of DMG by assembling a retrospective cohort of 60 adult and pediatric DMG cases harboring BRAF or FGFR1 mutations in addition to the H3K27M mutation or EZHIP overexpression. Comprehensive clinical, histological, radiological, and genomic, analyses allowed to identify distinct genotype-phenotype characteristics. Contrary to other DMG, these tumors occur more frequently in the thalamus (27% vs. 70% for BRAFV600E or 58% for FGFR1MUT), and in adults in the case of FGFRMUT tumors. Importantly, these patients display a longer overall survival with a median above three years. Unsupervised analysis of DNA methylation profiles regrouped these MAPK-altered DMG in a methylation cluster distinct from other DMG H3K27, but also lower-grade midline tumors driven by FGFR1 or BRAF mutations Additionally, this new DMG subtype harbors atypical radiological and histopathological profiles with calcification and/or a solid tumor component both for BRAFV600E and FGFR1MUT cases that can suggest this differential diagnosis. Further analyses of the transcriptome of these tumors compared to canonical DMG H3K27-altered showed an expression signature of senescence with activation of a TP53/CDKN1A axis, together with a strong upregulation of the PI3K/AKT/MTOR pathway. Our current modelling of the drug response using patient-derived models of these specific DMG will permit to rapidly prioritize treatment strategies. Additionally, our clinical experience in treating these patients suggests a higher response to everolimus and imipridone ONC201 in this specific subtype. In conclusion, DMG H3 K27 and BRAF/FGFR1 co-altered, represent a new subtype of DMG with distinct specific characteristics compared to canonical DMG H3K27 and data accumulated strongly support their separate stratification in clinical trials and specific therapeutic managements.

EMBRYONIC FLOWER 1 regulates male reproduction by repressing the jasmonate pathway downstream transcription factor MYB26.

The evolutionarily conserved Polycomb repressive complexes (PRCs) mediate genome-wide transcriptional silencing and regulate a plethora of development, as well as environmental responses in multicellular organisms. The PRC2-catalyzed trimethylation of lysine 27 on histone H3 (H3K27me3) is recognized by reader-effector modules of Polycomb repressive complex 1 (PRC1) to implement gene repression. Here, we report that the Arabidopsis (Arabidopsis thaliana) H3K27me3 effector EMBRYONIC FLOWER 1 (EMF1) interacts with and constrains the R2R3 DNA binding transcription factor MYB26 by a eudicot-conserved motif in the stamen. MYB26 activates the transcription of two NAC domain genes, NAC SECONDARY WALL THICKENING PROMOTING FACTOR1 (NST1) and NST2, whose encoded proteins mediate anther secondary cell thickening in jasmonate (JA)-regulated stamen maturation. In this process, the transcriptional activity of MYB26 is negatively modulated by the JAZ-PRC repressive complex to precisely regulate the expression of NST1 and NST2. Disruption of EMF1 repression stimulates MYB26, leading to the excessive transcription of the two NAC genes and male sterility. Our results reveal a novel mechanism in Polycomb-mediated gene silencing and illustrate that the plant Polycomb complex regulates stamen development by preventing the hypersensitivity of JA responses in male reproduction.

Interaction of PGC7 and HP1BP3 Maintains Meg3-DMR Methylation by Regulating Chromatin Configuration.

Genomic imprinting is essential for mammalian development. PGC7, an important maternal factor, binds to dimethylated histone H3K9 (H3K9me2), maintaining DNA methylation in zygotes and stem cells. However, the underlying molecular mechanisms of PGC7-maintained genomic imprinting in stem cells are not clear. Our previous study has identified that PGC7 interacts with HP1BP3, a novel member of the histone H1 family. In this study, we found that PGC7 interacts with the central globular domain of HP1BP3 through its C-terminal tail and that HP1BP3 is responsible for the recruitment of PGC7 at the Meg3 differentially methylated region (DMR) in the Dlk1-Dio3 imprinted domain. HP1BP3 or PGC7 depletion decreases enrichment in the Meg3-DMR, leading to DNA hypermethylation in this region. Moreover, the cooperative binding of PGC7 and HP1BP3 can antagonize the enrichment of DNMT3A in the Meg3-DMR, and the depletion of HP1BP3 or PGC7 separately induces chromosome decondensation in this region. In summary, this is the first study demonstrating that PGC7 and HP1BP3 synergistically maintain the methylation status of the Meg3-DMR by enabling a chromatin configuration that interferes with the binding of the de novo DNA methyltransferase DNMT3A.

Spinal Diffuse Midline Glioma H3 K27M-Altered: Report of a Rare Tumor with Extracranial Skeletal Metastases and Review of Literature.

Diffuse midline glioma, H3 K27-altered is a rare and aggressive pediatric brain tumor with a grim prognosis. Diffuse midline glioma is characterized by specific molecular alterations, including H3 K27 mutations, and involves deep midline structures such as the brainstem, cerebellum, spinal cord, and thalamus. These tumors present with a classic triad of symptoms and have limited surgical options due to their challenging locations. Extra-neural metastases are an unusual occurrence in diffuse midline glioma and have been rarely described. Here we report a 17-year-old girl with spinal diffuse midline glioma, H3 K27M-mutant, who presented with multiple metastatic osseous lesions confirmed on biopsy of the thoracic vertebral lesion. Due to the rapid disease progression, the patient was recommended palliative therapy. Extra-neural metastases in diffuse midline glioma are rare, with only 16 reported patients, and no standard therapy exists. An accurate and early diagnosis is necessary to develop a personalized plan of treatment. Further research is needed to gain insights into the molecular pathology of diffuse midline glioma, H3 K27-altered, and improve the quality of life and the outcome of patients with this deadly disease.

Npac Regulates Pre-mRNA Splicing in Mouse Embryonic Stem Cells.

As a reader of tri-methylated lysine 36 on histone H3 (H3K36me3), Npac has been shown to have a significant role in gene transcription elongation. However, its potential implication in RNA splicing remains unknown. Here, we characterized the phenotypes of Npac knockout in mES cells. We discovered that loss of Npac disrupts pluripotency and identity in mESCs. We also found that Npac is associated with many cellular activities, including cell proliferation, differentiation, and transcription regulation. Notably, we uncovered that Npac is associated with RNA splicing machinery. Furthermore, we found that Npac regulates alternative splicing through its interaction with the splicing factors, including Srsf1. Our research thus highlights the important role of Npac in maintaining ESC identity through the regulation of pre-mRNA splicing.

Eed-dependent histone modification orchestrates the iNKT cell developmental program alleviating liver injury.

Polycomb repressive complex 2 (PRC2) is an evolutionarily conserved epigenetic modifier responsible for tri-methylation of lysine 27 on histone H3 (H3K27me3). Previous studies have linked PRC2 to invariant natural killer T (iNKT) cell development, but its physiological and precise role remained unclear. To address this, we conditionally deleted Eed, a core subunit of PRC2, in mouse T cells. The results showed that Eed-deficient mice exhibited a severe reduction in iNKT cell numbers, particularly NKT1 and NKT17 cells, while conventional T cells and NKT2 cells remained intact. Deletion of Eed disrupted iNKT cell differentiation, leading to increased cell death, which was accompanied by a severe reduction in H3K27me3 levels and abnormal expression of Zbtb16, Cdkn2a, and Cdkn1a. Interestingly, Eed-deficient mice were highly susceptible to acetaminophen-induced liver injury and inflammation in an iNKT cell-dependent manner, highlighting the critical role of Eed-mediated H3K27me3 marks in liver-resident iNKT cells. These findings provide further insight into the epigenetic orchestration of iNKT cell-specific transcriptional programs.

Bivalent chromatin accommodates survivin and BRG1/SWI complex to activate DNA damage response in CD4+ cells

BackgroundBivalent regions of chromatin (BvCR) are characterized by trimethylated lysine 4 (H3K4me3) and lysine 27 on histone H3 (H3K27me3) deposition which aid gene expression control during cell differentiation. The role of BvCR in post-transcriptional DNA damage response remains unidentified. Oncoprotein survivin binds chromatin and mediates IFNγ effects in CD4+ cells. In this study, we explored the role of BvCR in DNA damage response of autoimmune CD4+ cells in rheumatoid arthritis (RA).MethodsWe performed deep sequencing of the chromatin bound to survivin, H3K4me3, H3K27me3, and H3K27ac, in human CD4+ cells and identified BvCR, which possessed all three histone H3 modifications. Protein partners of survivin on chromatin were predicted by integration of motif enrichment analysis, computational machine-learning, and structural modeling, and validated experimentally by mass spectrometry and peptide binding array. Survivin-dependent change in BvCR and transcription of genes controlled by the BvCR was studied in CD4+ cells treated with survivin inhibitor, which revealed survivin-dependent biological processes. Finally, the survivin-dependent processes were mapped to the transcriptome of CD4+ cells in blood and in synovial tissue of RA patients and the effect of modern immunomodulating drugs on these processes was explored.ResultsWe identified that BvCR dominated by H3K4me3 (H3K4me3-BvCR) accommodated survivin within cis-regulatory elements of the genes controlling DNA damage. Inhibition of survivin or JAK-STAT signaling enhanced H3K4me3-BvCR dominance, which improved DNA damage recognition and arrested cell cycle progression in cultured CD4+ cells. Specifically, BvCR accommodating survivin aided sequence-specific anchoring of the BRG1/SWI chromatin-remodeling complex coordinating DNA damage response. Mapping survivin interactome to BRG1/SWI complex demonstrated interaction of survivin with the subunits anchoring the complex to chromatin. Co-expression of BRG1, survivin and IFNγ in CD4+ cells rendered complete deregulation of DNA damage response in RA. Such cells possessed strong ability of homing to RA joints. Immunomodulating drugs inhibited the anchoring subunits of BRG1/SWI complex, which affected arthritogenic profile of CD4+ cells.ConclusionsBvCR execute DNA damage control to maintain genome fidelity in IFN-activated CD4+ cells. Survivin anchors the BRG1/SWI complex to BvCR to repress DNA damage response. These results offer a platform for therapeutic interventions targeting survivin and BRG1/SWI complex in autoimmunity.

The chromatin remodeler DEK promotes proliferation of mammary epithelium and is associated with H3K27me3 epigenetic modifications.

The DEK chromatin remodeling protein was previously shown to confer oncogenic phenotypes to human and mouse mammary epithelial cells using in vitro and knockout mouse models. However, its functional role in normal mammary gland epithelium remained unexplored. We developed two novel mouse models to study the role of Dek in normal mammary gland biology in vivo . Mammary gland-specific Dek over-expression in mice resulted in hyperproliferation of cells that visually resembled alveolar cells, and a transcriptional profile that indicated increased expression of cell cycle, mammary stem/progenitor, and lactation-associated genes. Conversely, Dek knockout mice exhibited an alveologenesis or lactation defect, resulting in dramatically reduced pup survival. Analysis of previously published single-cell RNA-sequencing of mouse mammary glands revealed that Dek is most highly expressed in mammary stem cells and alveolar progenitor cells, and to a lesser extent in basal epithelial cells, supporting the observed phenotypes. Mechanistically, we discovered that Dek is a modifier of Ezh2 methyltransferase activity, upregulating the levels of histone H3 trimethylation on lysine 27 (H3K27me3) to control gene transcription. Combined, this work indicates that Dek promotes proliferation of mammary epithelial cells via cell cycle deregulation. Furthermore, we report a novel function for Dek in alveologenesis and histone H3 K27 trimethylation.

Central nervous system dissemination in spinal cord astrocytomas: association with H3 K27M mutation.

Patients with spinal cord astrocytomas (SCAs) are at high risk for CNS dissemination, yet comprehensive data on characteristics of dissemination are lacking. This study depicts the exact incidence and patterns of dissemination by analyzing data from a large-scale dataset of SCA. The authors included 94 patients with SCA based on the 2021 WHO classification from 2011 to 2022, retrospectively collected their clinical and pathological characteristics, and analyzed factors influencing SCA dissemination. CNS dissemination, encompassing leptomeningeal spreading and/or subarachnoid seeding, was evaluated in 94 patients with and without H3 K27 alterations, with an overall dissemination rate reaching 85.0% at 5-year follow-up. Patients with altered H3 K27 had a significantly higher 5-year CNS dissemination rate than patients with H3 K27 wildtype status (95.2% vs 68.0%, p = 0.002). The median dissemination-free survival in H3 K27-altered patients was 14.37 (95% CI 2.84-25.89) months, significantly shorter than those with H3 K27 wildtype (statistics not calculated; p < 0.001). Based on univariate Cox regression analysis, H3 K27M alteration, higher histopathological grade, Ki-67 index (≥ 10%), and tumor length (≥ 4 segments) were identified as potential factors associated with CNS dissemination in SCAs. Multivariate Cox regression analysis revealed that H3 K27M alteration appeared to be a risk factor for this phenomenon (HR 2.089, 95% CI 0.940-4.642, p = 0.070). Following dissemination, H3 K27-altered patients had a median postdissemination survival of 8.83 (95% CI 7.13-10.54) months, which was significantly shorter than the 13.40 (95% CI 3.98-34.26) months in those with H3 K27 wildtype (p = 0.008). Factors indicative of higher SCA malignancy, such as H3 K27M alteration, higher histopathological grade, Ki-67 index (≥ 10%), and tumor length (≥ 4 segments), were similarly suggestive of higher rates of dissemination. The occurrence of dissemination is closely associated with the outcome events in patients with SCA.

Heterochromatin protein 1 alpha (HP1α) undergoes a monomer to dimer transition that opens and compacts live cell genome architecture.

Our understanding of heterochromatin nanostructure and its capacity to mediate gene silencing in a living cell has been prevented by the diffraction limit of optical microscopy. Thus, here to overcome this technical hurdle, and directly measure the nucleosome arrangement that underpins this dense chromatin state, we coupled fluorescence lifetime imaging microscopy (FLIM) of Förster resonance energy transfer (FRET) between histones core to the nucleosome, with molecular editing of heterochromatin protein 1 alpha (HP1α). Intriguingly, this super-resolved readout of nanoscale chromatin structure, alongside fluorescence fluctuation spectroscopy (FFS) and FLIM-FRET analysis of HP1α protein-protein interaction, revealed nucleosome arrangement to be differentially regulated by HP1α oligomeric state. Specifically, we found HP1α monomers to impart a previously undescribed global nucleosome spacing throughout genome architecture that is mediated by trimethylation on lysine 9 of histone H3 (H3K9me3) and locally reduced upon HP1α dimerisation. Collectively, these results demonstrate HP1α to impart a dual action on chromatin that increases the dynamic range of nucleosome proximity. We anticipate that this finding will have important implications for our understanding of how live cell heterochromatin structure regulates genome function.

Branched-chain amino acid transaminase 1 confers EGFR-TKI resistance through epigenetic glycolytic activation

Third-generation EGFR tyrosine kinase inhibitors (TKIs), exemplified by osimertinib, have demonstrated promising clinical efficacy in the treatment of non-small cell lung cancer (NSCLC). Our previous work has identified ASK120067 as a novel third-generation EGFR TKI with remarkable antitumor effects that has undergone New Drug Application (NDA) submission in China. Despite substantial progress, acquired resistance to EGFR-TKIs remains a significant challenge, impeding the long-term effectiveness of therapeutic approaches. In this study, we conducted a comprehensive investigation utilizing high-throughput proteomics analysis on established TKI-resistant tumor models, and found a notable upregulation of branched-chain amino acid transaminase 1 (BCAT1) expression in both osimertinib- and ASK120067-resistant tumors compared with the parental TKI-sensitive NSCLC tumors. Genetic depletion or pharmacological inhibition of BCAT1 impaired the growth of resistant cells and partially re-sensitized tumor cells to EGFR TKIs. Mechanistically, upregulated BCAT1 in resistant cells reprogrammed branched-chain amino acid (BCAA) metabolism and promoted alpha ketoglutarate (α-KG)-dependent demethylation of lysine 27 on histone H3 (H3K27) and subsequent transcriptional derepression of glycolysis-related genes, thereby enhancing glycolysis and promoting tumor progression. Moreover, we identified WQQ-345 as a novel BCAT1 inhibitor exhibiting antitumor activity both in vitro and in vivo against TKI-resistant lung cancer with high BCAT1 expression. In summary, our study highlighted the crucial role of BCAT1 in mediating resistance to third-generation EGFR-TKIs through epigenetic activation of glycolysis in NSCLC, thereby supporting BCAT1 as a promising therapeutic target for the treatment of TKI-resistant NSCLC.