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Double-strand breaks (DSBs) threaten genomic stability and need immediate attention from DNA damage response (DDR) machinery involved in homologous recombination (HR) or nonhomologous end joining (NHEJ). DDR in heterochromatin is challenging owing to the distinct chromatin organization. Heterochromatin protein 1 (HP1) isoforms are central to heterochromatin structure and have been implicated in DDR. Mammalian HP1 has three isoforms, HP1α, HP1β, and HP1γ, which possess significant homology and yet have distinct functions. HP1α is the only isoform known to undergo liquid-liquid phase separation mediated by phosphorylation on the N-terminal extension (NTE). We show that the minute-scale dynamics of HP1α and HP1β differ dramatically and differentially influence the recruitment of HR vs. NHEJ factors at sites of laser-induced clustered DSBs. Perturbing HP1α phosphorylation impairs HR factor recruitment and reduces HR efficiency. Our study provides a potential link between phase separation and DDR-centric roles of HP1α and hints at spatial partitioning of repair pathways in response to damage in heterochromatin. Show less

During arbuscular mycorrhiza (AM) symbiosis AM fungi form tree-shaped structures called arbuscules in root cortex cells of host plants. Arbuscules and their host cells are central for reciprocal nutrient exchange between the symbionts. Show less

Chromobox (CBX) proteins are essential components of the Polycomb group and play pivotal roles in tumor onset, progression, and metastasis. However, the prognostic significance and functions of CBXs in the advancement of breast cancer (BC) have not been sufficiently investigated. A comprehensive analysis of the expression and prognostic relevance of CBX1-8 in BC was conducted comprehensively using The Cancer Genome Atlas (TCGA) and multiple databases. High mRNA expression of CBX2, CBX3, and CBX5 in BC patients was significantly associated with reduced overall survival (OS). Results from univariate and multivariate Cox regression analysis revealed that the mRNA expression level of CBX2 in BC patients served as an independent prognostic factor. In Luminal A and Luminal B BC subtypes, high expression of CBX2 correlated with unfavorable prognosis. Subsequent Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated a strong association between CBX2 and the cell cycle as well as DNA replication processes. CCK-8 and EdU assays demonstrated that silencing CBX2 inhibited the proliferation of T47D and MCF7 cell lines. Moreover, the cell cycle assay indicated that CBX2 silencing led to cell cycle arrest, accompanied by a significant decrease in the levels of CDK4 and CyclinD1. Elevated CBX2 expression significantly correlated with the infiltration of T cells, B cells, macrophages, and dendritic cells in BC. Our findings could provide new perspectives for identifying potential prognostic markers within the CBX family in BC. Targeting CBX2 may present a promising approach to address endocrine resistance in BC therapy. Show less

Neuroblastoma (NB) is the most common solid tumor in children, characterized by high recurrence rates, drug resistance, and significant mortality. In this study, we analyzed the proteomic profiles of NB tissue samples alongside other pathological categories, including ganglioneuroma (GN) and ganglioneuroblastoma (GNB). Using weighted gene co-expression network analysis (WGCNA), the core prognostic gene models associated with histopathology of NB were identified. Furthermore, by mapping our core prognostic gene models onto drug-perturbed transcriptome profiles from the L1000FWD and CMap databases, repurposing drug candidates were screened and validated for NB. Our proteomic analysis reveals that pathways associated with the cell cycle and DNA replication are significantly upregulated in NB, while oxidative phosphorylation, pyruvate metabolism, and the TCA cycle are notably downregulated compared to GNB and GN. By applying WGCNA, we identified a core prognostic gene model strongly associated with the unfavorable subtype and high MKI of NB and primarily related to chromatin binding and mRNA metabolic process. Protein-protein interaction network analysis identified 15 hub genes in this core prognostic module: SMARCA4, SMARCA5, SMARCC2, SMARCC1, PBRM1, BRD3, ARID1A, BRD2, ARID1B, KDM1A, TP53BP1, ALYREF, CBX1, SF3B1, and ADNP, which mainly related to chromatin remodeling. Notably, SMARCA4 and ALYREF are also high-risk genes of mortality and validated as potential prognostic biomarkers for NB. Through repurposing drugs screening, mocetinostat and clofarabine were validated as effective treatments in two NB cell lines. Mocetinostat and clofarabine offer valuable insights for the development of novel targeted therapies in neuroblastoma. Show less

Cyclic peptides exhibit important biological activities and are widely found in natural products and peptide-based drugs. Therefore, the development of synthesis methods for cyclic peptides is essential. In recent years, tryptophan-mediated cyclic peptides have emerged as bioactive molecules, but current methods require unique unnatural amino acids and transition metals as catalysts. Our group recently reported a tryptophan site-selective crosslinking in the protein binding pocket by sulfonium peptide Show less

Long noncoding RNAs (lncRNAs) are involved in various biological events. Previously we reported that lncRNA CCDC26 controls myeloid leukemia cell proliferation and mortality by regulating the proto-oncogene KIT. However, the mechanism of lncRNA CCDC26 effects on carcinogenesis and cell differentiation remains unclarified. To investigate the mechanism of lncRNA CCDC26 activity, we analyzed its protein partners using the S1 aptamer/cross-linking-immunoprecipitation (S1-CLIP) experiment. We identified a cytoskeleton protein (vimentin), chromatin proteins (chromobox 1/5 transcription factors [CBX1 and CBX5]) and a nuclear splicing-related protein heterogeneous nuclear ribonucleoprotein C (HNRNPC) as its interaction partners. As lncRNA CCDC26 is ubiquitously present in the cell (in cytoplasm, nucleoplasm, and chromatin cellular fractions); these results evidence that lncRNA CCDC26 is a unique multifunctional lncRNA that functions by interacting with several proteins in multiple intracellular compartments. We further identified the sequence through which it interacts with proteins by using a series of truncated-lncRNA CCDC26 fragments and RNA immunoprecipitation (RIP) experiments. Furthermore, using RIP, we identified the vimentin domain required for the lncRNA CCDC26 binding. Notably, CCDC26 knockdown reduced CBX1/CBX5 binding at certain gene promoters, correlating with increased gene expression. These findings suggest that CCDC26 may regulate transcription by interacting with CBX1 and CBX5. Show less

Pharmaceutical and personal care products (PPCPs), as ubiquitous emerging contaminants, present undercharacterized neuropsychiatric hazards through environmental exposure. This investigation employs convergent multi-omics strategies - integrating toxicogenomic discovery, disease-associated genomic mapping, and transcriptomic profiling - to elucidate mechanistic linkages between PPCPs bioactivity and depressive pathogenesis. Through systematic analysis of Nanjing's aquatic chemical burden (prioritizing dimenhydrinate, ibuprofen, padimate-O, caffeine, and roxithromycin), we identified 3073 conserved molecular targets bridging PPCPs toxicity and depression etiology via Comparative Toxicogenomics Database and GeneCards interrogation. Functional ontology revealed dysregulated pathways encompassing lipidomic remodeling, IL-17-mediated neuroinflammation, and synaptic transmission deficits. Ensembled machine learning algorithms (Lasso regression, XGBoost, random forest) converged on seven high-fidelity candidate biomarkers (HSPA8, CBX1, CD59, CHAF1A, CUX1, ID2, RPL3) demonstrating stress-adaptive, chromatin regulatory, and immunomodulatory functions. Molecular docking predicted strong binding affinities between PPCPs and depression-related proteins, notably dimenhydrinate with CHAF1A (- 6.1 kcal/mol) and HSPA8 (- 6.1 kcal/mol), suggesting multi-target modulation. This work proposes a computational framework to map molecular interactions between specific PPCPs and depression-associated pathways. Candidate targets highlight testable hypotheses for future experimental validation. These findings suggest selected PPCPs with neuroactive properties may warrant further investigation as environmental modifiers of depression risk. Show less

Head and neck squamous cell carcinoma (HNSCC) poses a global health challenge. The management of HNSCC is complicated by the difficulty in detecting occult lymph node metastases, leading to dilemmas in elective neck dissection decisions, which will impair patients' quality of life without improving survival for nodal negative patients. We conducted a comparative analysis of the clinical features, genomic alterations, gene expression and methylation, tumor microenvironment and cellular states between the clinically N0 and pathologically N0 (cN0-pN0) patients and occult lymph node metastatic patients. Patients with occult lymph node metastases typically present with more poorly differentiated primary tumors and higher rates of angiolymphatic and perineural invasion. We identified a distinctive genomic mutation spectrum in the primary tumors of patients with occult metastases, notably in genes such as NSD1, ARHGAP15 and SMARCA4. A whole-genome DNA hypomethylation and altered gene expression profiles are identified in occult lymph node metastatic patients. Analysis of the tumor microenvironment revealed an enrichment of CARNS1 + NK cells and CBX1 + tumor cells in occult metastatic patients. In conclusion, patients with occult lymph node metastases exhibit distinct molecular and clinical features compared with cN0-pN0 patients. Show less

A large fraction of the genome interacts with the nuclear periphery through lamina-associated domains (LADs), repressive regions which play an important role in genome organization and gene regulation across development. Despite much work, LAD structure and regulation are not fully understood, and a mounting number of studies have identified numerous genetic and epigenetic differences within LADs, demonstrating they are not a uniform group. Here, we profile lamin B1, CBX1 (also known as HP1B), H3K9me3, H3K9me2, H3K27me3, H3K14ac, H3K27ac, and H3K9ac in MEF cell lines derived from the same mouse colony, and cluster LADs based on the abundance and distribution of these features across LADs. We find that LADs fall into three groups, each enriched in a unique set of histone modifications and genomic features. Each group is defined by a different heterochromatin modification (H3K9me3, H3K9me2, or H3K27me3), suggesting that all three of these marks play important roles in regulation of LAD chromatin and potentially of lamina association. We also discover unique features of LAD borders, including a LAD border-specific enrichment of H3K14ac. These results reveal important distinctions between LADs and highlight the rich diversity and complexity in LAD structure and regulatory mechanisms. Show less

The formation of self-perpetuating protein aggregates such as amyloids is associated with various diseases and provides a basis for transmissible (infectious or heritable) protein isoforms (prions). Many human proteins involved in the regulation of transcription contain potentially amyloidogenic regions. Here, it is shown that short N-terminal isoforms of the human protein PHC3, a component of the chromatin-modifying complex PRC1 (Polycomb repressive complex 1), can form prion-like aggregates in yeast assays, exhibit amyloid properties in the Show less

The role of histone methyltransferase SETDB1 in renal ischemia-reperfusion (I/R) injury has not been explored yet. This study aims to investigate the potential mechanism of SETDB1 in regulating renal I/R injury and its impact on mitochondrial damage and oxidative stress. The in vivo model of renal I/R in mice and the in vitro model of hypoxia/reoxygenation (H/R) in human renal tubular epithelial cells (HK-2) were constructed to detect the expression of SETDB1. Next, the specific inhibitor (R,R)-59 and knockdown viruses were used to inhibit SETDB1 and verify its effects on mitochondrial damage and oxidative stress. Chromatin immunoprecipitation (ChIP) and coimmunoprecipitation (CoIP) were implemented to explore the in-depth mechanism of SETDB1 regulating renal I/R injury. The study found that SETDB1 had a regulatory role in mitochondrial damage and oxidative stress during renal I/R injury. Notably, SESN2 was identified as a target of SETDB1, and its expression was under the influence of SETDB1. Besides, SESN2 mediated the regulation of SETDB1 on renal I/R injury. Through deeper mechanistic studies, we uncovered that SETDB1 collaborates with heterochromatin HP1β, facilitating the labeling of H3K9me3 on the SESN2 promoter and impeding SESN2 expression. The SETDB1/HP1β-SESN2 axis emerges as a potential therapeutic strategy for mitigating renal I/R injury. Show less

The aberrant expression of methyltransferase Set7/9 plays a role in various diseases. However, the contribution of Set7/9 in ischemic stroke remains unclear. Here, we show ischemic injury results in a rapid elevation of Set7/9, which is accompanied by the downregulation of Sirt5, a deacetylase reported to protect against injury. Proteomic analysis identifies the decrease of chromobox homolog 1 (Cbx1) in knockdown Set7/9 neurons. Mechanistically, Set7/9 promotes the binding of Cbx1 to H3K9me2/3 and forms a transcription repressor complex at the Sirt5 promoter, ultimately repressing Sirt5 transcription. Thus, the deacetylation of Sirt5 substrate, glutaminase, which catalyzes the hydrolysis of glutamine to glutamate and ammonia, is decreased, promoting glutaminase expression and triggering excitotoxicity. Blocking Set7/9 eliminates H3K9me2/3 from the Sirt5 promoter and normalizes Sirt5 expression and Set7/9 knockout efficiently ameliorates brain ischemic injury by reducing the accumulation of ammonia and glutamate in a Sirt5-dependent manner. Collectively, the Set7/9-Sirt5 axis may be a promising epigenetic therapeutic target. Show less

The Chromobox (CBX) family proteins are crucial elements of the epigenetic regulatory machinery and play a significant role in the development and advancement of cancer. Nevertheless, there is limited understanding regarding the role of CBXs in development or progression of prostate cancer (PCa). Our objective is to develop a unique prognostic model associated with CBXs to improve the accuracy of predicting outcomes of patients with PCa. Data from TCGA and GEO databases were analyzed to assess differential expression, prognostic value, gene pathway enrichment, and immune cell infiltration. COX regression analysis was utilized to identify the independent prognostic factors that impact disease-free survival (DFS). The expression of CBX2 and FOXP3 CBX2, CBX3, CBX4, and CBX8 were upregulated, while CBX6 and CBX7 were downregulated in PCa tissues. CBXs expression varied by stage and grade. Elevated expression of CBX1, CBX2, CBX3, CBX4 and CBX8 is correlated with poor outcome. CBX2 expression, T stage, and Gleason score were independent prognostic factors. The expression level of CBX2 in PCa tissues was significantly higher than that in adjacent normal tissues. More Treg infiltration was observed in the group with high CBX2 expression. CBX2 expression affected PCa cell growth, migration, and invasion. CBX2 is involved in the development and advancement of PCa, suggesting its potential as a reliable prognostic indicator for PCa patients. Show less

In a previous report, we demonstrated that Cbx1, PurB and Sp3 inhibited cardiac muscle differentiation by increasing nucleosome density around cardiac muscle gene promoters. Since cardiac and skeletal muscle express many of the same proteins, we asked if Cbx1, PurB and Sp3 similarly regulated skeletal muscle differentiation. In a C2C12 model of skeletal muscle differentiation, Cbx1 and PurB knockdown increased myotube formation. In contrast, Sp3 knockdown inhibited myotube formation, suggesting that Sp3 played opposing roles in cardiac muscle and skeletal muscle differentiation. Consistent with this finding, Sp3 knockdown also inhibited various muscle-specific genes. The Cbx1, PurB and Sp3 proteins are believed to influence gene-expression in part by altering nucleosome position. Importantly, we developed a statistical approach to determine if changes in nucleosome positioning were significant and applied it to understanding the architecture of muscle-specific genes. Through this novel statistical approach, we found that during myogenic differentiation, skeletal muscle-specific genes undergo a set of unique nucleosome changes which differ significantly from those shown in commonly expressed muscle genes. While Sp3 binding was associated with nucleosome loss, there appeared no correlation with the aforementioned nucleosome changes. In summary, we have identified a novel role for Sp3 in skeletal muscle differentiation and through the application of quantifiable MNase-seq have discovered unique fingerprints of nucleosome changes for various classes of muscle genes during myogenic differentiation. Show less

Chromobox Homolog 1 (CBX1) plays a crucial role in the pathogenesis of numerous diseases, including the evolution and advancement of diverse cancers. The role of CBX1 in pan-cancer and its mechanism in hepatocellular carcinoma (HCC), however, remains to be further investigated. Bioinformatics approaches were harnessed to scrutinize CBX1's expression profile, its association with tumor staging, and its potential impact on patient outcomes across various cancers. Single-cell RNA sequencing data facilitated the investigation of CBX1 expression patterns at the individual cell level. The CBX1 expression levels in HCC and adjacent non-tumor tissues were quantified through Real-Time Polymerase Chain Reaction (RT-PCR), Western Blotting (WB), and Immunohistochemical analyses. A tissue microarray was employed to explore the relationship between CBX1 levels, patient prognosis, and clinicopathological characteristics in HCC. Various in vitro assays-including CCK-8, colony formation, Transwell invasion, and scratch tests-were conducted to assess the proliferative and motility properties of HCC cells upon modulation of CBX1 expression. Moreover, the functional impact of CBX1 on HCC was further discerned through xenograft studies in nude mice. CBX1 was found to be upregulated in most cancer forms, with heightened expression correlating with adverse patient prognoses. Within the context of HCC, elevated levels of CBX1 were consistently indicative of poorer clinical outcomes. Suppression of CBX1 through knockdown methodologies markedly diminished HCC cell proliferation, invasive capabilities, migratory activity, Epithelial-mesenchymal transition (EMT) processes, and resistance to Tyrosine kinase inhibitors (TKIs). Contrastingly, CBX1 augmentation facilitated the opposite effects. Subsequent investigative efforts revealed CBX1 to be a promoter of EMT and a contributor to increased TKI resistance within HCC cells, mediated via the IGF-1R/AKT/SNAIL signaling axis. The oncogenic activities of CBX1 proved to be attenuable either by AKT pathway inhibition or by targeted silencing of IGF-1R. The broad overexpression of CBX1 in pan-cancer and specifically in HCC positions it as a putative oncogenic entity. It is implicated in forwarding HCC progression and exacerbating TKI resistance through its interaction with the IGF-1R/AKT/SNAIL signaling cascade. Show less

Psoriasis is renowned for its chronic nature and complex pathophysiology, with exosomes playing a crucial regulatory role within it. However, the proteomic composition of exosomes extracted from psoriasis cells remains largely unexplored. This study aimed to analyze the proteomic makeup of exosomes derived from psoriasis-model keratinocytes and compare it with that of normal controls, with the goal of identifying specific proteins that could aid in understanding the disease's pathology and potentially serve as biomarkers or therapeutic targets. The normal cultured keratinocyte line HaCaT served as the control group, while a concentration of 10 ng/mL of TNF-α was utilized to stimulate HaCaT cells and induce the formation of psoriasis model cells for the test group. Exosomes were extracted and prepared from the culture supernatant using the magnetic bead method, and their identity was confirmed through transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. Data-independent acquisition (DIA) mass spectrometry was employed to detect the protein composition of exosomes, followed by GO, KEGG, Reactome, and PPI analyses. The analysis revealed a total of 2796 proteins within the exosomes, with 131 showing significant differential expression between the test and control groups. Notably, this study identified the proteins ADO, CBX1, and MIF within the exosomes derived from psoriasis model cells for the first time, highlighting their potential roles in angiogenesis, epigenetic regulation, and inflammatory responses in psoriasis. Several differentially expressed proteins identified in the KEGG enrichment analysis were implicated in immune infiltration pathways, keratinocyte-regulating pathways, angiogenesis pathways, and inflammation pathways. The identification of unique proteins within exosomes derived from psoriasis-model cells offers novel insights into the molecular mechanisms underlying psoriasis. These findings pave the way for further research into the biological functions of these exosomal proteins and their potential utility in diagnosing and treating psoriasis. Show less

High-density genomic data analyzed by accurate statistical methods are of potential to enlighten past breeding practices such as selection by unraveling fixed regions. In this study, four native Turkish sheep breeds (80 samples) were genotyped via 296.097 single nucleotide polymorphisms (SNPs) detected by double-digest restriction site-associated DNA (ddRADseq) library preparation combined with the Illumina HiSeq X Ten instrument in order to identify genes under selection pressure. A total of 32, 136, 133, and 119 protein-coding genes were detected under selection pressure by runs of homozygosity (ROH), integrated haplotype score (iHS), the ratio of extended haplotype homozygosity (Rsb), and fixation index (F Show less

Lung cancer has a high morbidity and mortality among malignant tumors, and lung adenocarcinoma (LUAD) is the main type of lung cancer. In recent years, circular RNAs (circRNAs) have been confirmed to play an important role in the generation and development of human cancer. However, the specific role and mechanism of circ-NUP98 in LUAD are still unclear and need to be further investigated. Circ-NUP98, microRNA-188-3p (miR-188-3p), and chromobox homolog 1 (CBX1) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell-counting Kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, wound healing, and transwell assay were used to observe LUAD cell proliferation, apoptosis, migration, invasion, and cell-cycle progression. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were examined using special assay kits. CyclinD1, Bcl-2-related X protein (Bax), matrix metalloproteinase 9 (MMP9) protein, and CBX1 protein levels were determined using Western blot. The interaction between miR-188-3p and circ-NUP98 or CBX1 was identified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assay. In vivo efficacy of circ-NUP98 was evaluated in a xenograft tumor model. Besides, the expression of CBX1 and KI67 in the tumors was detected by immunohistochemical (IHC) assay. Circ-NUP98 and CBX1 expressions were upregulated in LUAD tissues and cells, and miR-188-3p was decreased. Downregulation of circ-NUP98 could inhibit the proliferation, migration, invasion, and oxidative stress, and promote apoptosis of LUAD cells. Mechanism experiments showed that circ-NUP98 acted as a sponge for miR-188-3p to increase CBX1 expression. Knockdown of circ-NUP98 could inhibit the growth of LUAD tumors in vivo. Circ-NUP98 might promote the malignant development of LUAD via the miR-188-3p/CBX1 axis, which might provide a potential new marker for early diagnosis of LUAD. Show less

Bone formation and homeostasis are controlled by environmental factors and endocrine regulatory cues that initiate intracellular signaling pathways capable of modulating gene expression in the nucleus. Bone-related gene expression is controlled by nucleosome-based chromatin architecture that limits the accessibility of lineage-specific gene regulatory DNA sequences and sequence-specific transcription factors. From a developmental perspective, bone-specific gene expression must be suppressed during the early stages of embryogenesis to prevent the premature mineralization of skeletal elements during fetal growth in utero. Hence, bone formation is initially inhibited by gene suppressive epigenetic regulators, while other epigenetic regulators actively support osteoblast differentiation. Prominent epigenetic regulators that stimulate or attenuate osteogenesis include lysine methyl transferases (e.g., EZH2, SMYD2, SUV420H2), lysine deacetylases (e.g., HDAC1, HDAC3, HDAC4, HDAC7, SIRT1, SIRT3), arginine methyl transferases (e.g., PRMT1, PRMT4/CARM1, PRMT5), dioxygenases (e.g., TET2), bromodomain proteins (e.g., BRD2, BRD4) and chromodomain proteins (e.g., CBX1, CBX2, CBX5). This narrative review provides a broad overview of the covalent modifications of DNA and histone proteins that involve hundreds of enzymes that add, read, or delete these epigenetic modifications that are relevant for self-renewal and differentiation of mesenchymal stem cells, skeletal stem cells and osteoblasts during osteogenesis. Show less

Diffuse large B-cell lymphoma (DLBCL) is one of the most aggressive malignant tumors. Chromobox (CBX) family plays the role of oncogenes in various malignancies. The transcriptional and protein levels of CBX family were confirmed by GEPIA, Oncomine, CCLE, and HPA database. Screening of co-expressed genes and gene function enrichment analysis were performed by GeneMANIA and DAVID 6.8. The prognostic value, immune cell infiltration and drug sensitivity analysis of CBX family in DLBCL were performed by Genomicscape, TIMER2.0, and GSCALite database. Confirmatory Tests of CBX family protein expression in DLBCL were performed by immunohistochemistry. The mRNA and protein expressions of CBX1/2/3/5/6 were higher in DLBCL tissues than control groups. Enrichment analysis showed that the functions of CBX family were mainly related to chromatin remodeling, methylation-dependent protein binding, and VEGF signaling pathway. The high mRNA expressions of CBX2/3/5/6 were identified to be associated with short overall survival (OS) in DLBCL patients. Multivariate COX regression indicated that CBX3 was independent prognostic marker. Immune infiltration analysis revealed that the mRNA expressions of CBX family (especially CBX1, CBX5, and CBX6) in DLBCL were significantly correlated with the infiltration of most immune cells (including B cells, CD8 + T cells, CD4 + T cells, neutrophils, monocytes, macrophages, and Treg cells). Meanwhile, there was a strong correlation between the expression levels of CBX1/5/6 and surface markers of immune cells, such as the widely studied PVR-like protein receptor/ligand and PDL-1 immune checkpoint. Notably, our study found that DLBCL cells with CBX1 over-expression were resistant to the common anti-tumor drugs, but CBX2/5 had two polarities. Finally, we confirmed the higher expressions of CBX1/2/3/5/6 in DLBCL tissues compared with control groups by immunohistochemistry. We provided a detailed analysis of the relationship between the CBX family and the prognosis of DLBCL. Distinguished from other studies, We found that high mRNA expressions of CBX2/3/5/6 were associated with poor prognosis in DLBCL patients, and Multivariate COX regression indicated that CBX3 was independent prognostic marker. Besides, our study also found an association between the CBX family and anti-tumour drug resistance, and provided a relationship between CBX family expression and immune cell infiltration. Show less

Chromobox proteins are canonical components of the Polycomb group family and play pivotal roles in several cancers. However, little is known about the function, prognostic value and drug sensitivity of CBX family members in breast cancer. In this study we investigated the expression, prognosis value and drug sensitivity of CBX family in breast cancer using the ONCOMINE, GEPIA, Human Protein Atlas and Kaplan-Meier Plotter databases, etc. and preliminary verified the expression of CBX family in breast cancer cell lines by RT-qPCR. We found that the expression levels of CBX1/2/3/4/8 members were elevated in breast cancer tissues compared to adjacent normal breast tissues, while the expression levels of CBX6/7 genes were reduced in breast cancer tissue. In vitro qRT-PCR validated the expression differences of CBX1/2/3/4/8 in breast cancer cell lines. Further analysis showed expression of CBX family members was remarkably correlated with cancer subgroups. As nodal metastasis status increased, the mRNA expression of CBX1/2/3/4/8 members tended to be higher, while CBX6/7 tended to be lower. The expression of CBX1/2/3 was higher in patients with TP53 mutation and CBX6/7 expression tended to be lower in patients with TP53 mutation groups. High transcription levels of CBX2/3 were significantly associated with shorter overall survival in breast cancer patients, while lower expression of CBX4/5/6/7 members was associated with unfavorable overall survival. Moreover, a high mutation rate of CBX gene members (43%) was observed in breast cancer patients, and genetic alterations in CBX genes was associated with poor prognosis. Taken together, our results indicated that CBX2/3/6/7/8 could be considered prognostic and therapeutic biomarkers of breast cancer and are worthy of further study. Show less

Arbuscular mycorrhizal (AM) symbiosis is a widespread, ancient mutualistic association between plants and fungi, and facilitates nutrient uptake into plants. Cell surface receptor-like kinases (RLKs) and receptor-like cytoplasmic kinases (RLCKs) play pivotal roles in transmembrane signaling, while few RLCKs are known to function in AM symbiosis. Here, we show that 27 out of 40 AM-induced kinases (AMKs) are transcriptionally upregulated by key AM transcription factors in Lotus japonicus. Nine AMKs are only conserved in AM-host lineages, among which the SPARK-RLK-encoding gene KINASE3 (KIN3) and the RLCK paralogues AMK8 and AMK24 are required for AM symbiosis. KIN3 expression is directly regulated by the AP2 transcription factor CTTC MOTIF-BINDING TRANSCRIPTION FACTOR1 (CBX1), which regulates the reciprocal exchange of nutrients in AM symbiosis, via the AW-box motif in the KIN3 promoter. Loss of function mutations in KIN3, AMK8, or AMK24 result in reduced mycorrhizal colonization in L. japonicus. AMK8 and AMK24 physically interact with KIN3. KIN3 and AMK24 are active kinases and AMK24 directly phosphorylates KIN3 in vitro. Moreover, CRISPR-Cas9-mediated mutagenesis of OsRLCK171, the sole homolog of AMK8 and AMK24 in rice (Oryza sativa), leads to diminished mycorrhization with stunted arbuscules. Overall, our results reveal a crucial role of the CBX1-driven RLK/RLCK complex in the evolutionarily conserved signaling pathway enabling arbuscule formation. Show less

In an effort to unravel the unknown "binary switch" mechanisms underlying the "histone code" hypothesis of gene silencing and activation, we study the dynamics of Heterochromatin Protein 1 (HP1). We find in the literature that when HP1 is bound to tri-methylated Lysine9 (K9me3) of histone-H3 through an aromatic cage consisting of two tyrosines and one tryptophan, it is evicted upon phosphorylation of Serine10 (S10phos) during mitosis. In this work, the kick-off intermolecular interaction of the eviction process is proposed and described in detail on the basis of quantum mechanical calculations: specifically, an electrostatic interaction competes with the cation-π interaction and draws away K9me3 from the aromatic cage. An arginine, abundant in the histonic environment, can form an intermolecular "complex salt bridge" with S10phos and dislodge HP1. The study attempts to reveal the role of phosphorylation of Ser10 on the H3 tail in atomic detail. Show less

This study aimed to establish variants in CBX1, encoding heterochromatin protein 1β (HP1β), as a cause of a novel syndromic neurodevelopmental disorder. Patients with CBX1 variants were identified, and clinician researchers were connected using GeneMatcher and physician referrals. Clinical histories were collected from each patient. To investigate the pathogenicity of identified variants, we performed in vitro cellular assays and neurobehavioral and cytological analyses of neuronal cells obtained from newly generated Cbx1 mutant mouse lines. In 3 unrelated individuals with developmental delay, hypotonia, and autistic features, we identified heterozygous de novo variants in CBX1. The identified variants were in the chromodomain, the functional domain of HP1β, which mediates interactions with chromatin. Cbx1 chromodomain mutant mice displayed increased latency-to-peak response, suggesting the possibility of synaptic delay or myelination deficits. Cytological and chromatin immunoprecipitation experiments confirmed the reduction of mutant HP1β binding to heterochromatin, whereas HP1β interactome analysis demonstrated that the majority of HP1β-interacting proteins remained unchanged between the wild-type and mutant HP1β. These collective findings confirm the role of CBX1 in developmental disabilities through the disruption of HP1β chromatin binding during neurocognitive development. Because HP1β forms homodimers and heterodimers, mutant HP1β likely sequesters wild-type HP1β and other HP1 proteins, exerting dominant-negative effects. Show less

Bladder urothelial carcinoma (BLCA) accounts for 95% of all cases of bladder cancer worldwide, with a high incidence and poor prognosis. Chromobox (CBX) proteins play a key role in numerous malignant tumors; however, the role of CBX in BLCA remains unknown. Herein, the present study found that, compared with in normal bladder tissues, the expression levels of CBX1, CBX2, CBX3, CBX4 and CBX8 were markedly increased in BLCA tissues, as determined by Tumor Immune Estimation Resource, UALCAN and ONCOMINE analyses, whereas CBX6 and CBX7 were decreased in BLCA tissues. Furthermore, evident hypomethylation in the promoters of CBX1, and CBX2, as well as significant hypermethylation in the promoters of CBX5, CBX6 and CBX7, was detected in BLCA tissues compared with in normal bladder tissues. The expression of CBX1, CBX2 and CBX7 was involved in the prognosis of patients with BLCA. Low CBX7 expression was strongly associated with poorer overall survival in patients with BLCA, whereas high CBX1 and CBX2 expression was associated with poorer progression-free survival. Besides, significant associations were determined between the expression of CBXs and immune cell infiltration, including dendritic cells, neutrophils, macrophages, CD4 Show less

Nucleoli are nuclear compartments regulating ribosome biogenesis and cell growth. In embryonic stem cells (ESCs), nucleoli containing transcriptionally active ribosomal genes are spatially separated from pericentromeric satellite repeat sequences packaged in largely repressed constitutive heterochromatin (PCH). To date, mechanisms underlying such nuclear partitioning and the physiological relevance thereof are unknown. Here we show that repressive chromatin at PCH ensures structural integrity and function of nucleoli during cell cycle progression. Loss of heterochromatin proteins HP1α and HP1β causes deformation of PCH, with reduced H3K9 trimethylation (H3K9me3) and HP1γ levels, absence of H4K20me3 and upregulated major satellites expression. Spatially, derepressed PCH aberrantly associates with nucleoli accumulating severe morphological defects during S/G2 cell cycle progression. Hp1α/β deficiency reduces cell proliferation, ribosomal RNA biosynthesis and mobility of Nucleophosmin, a major nucleolar component. Nucleolar integrity and function require HP1α/β proteins to be recruited to H3K9me3-marked PCH and their ability to dimerize. Correspondingly, ESCs deficient for both Suv39h1/2 H3K9 HMTs display similar nucleolar defects. In contrast, Suv4-20h1/2 mutant ESCs lacking H4K20me3 at PCH do not. Suv39h1/2 and Hp1α/β deficiency-induced nucleolar defects are reminiscent of those defining human ribosomopathy disorders. Our results reveal a novel role for SUV39H/HP1-marked repressive constitutive heterochromatin in regulating integrity, function and physiology of nucleoli. Show less