Epigenetic Regulation Of Transcription Research Articles

The significance of long non-coding RNAs in the pathogenesis, diagnosis and treatment of inflammatory bowel disease.

Inflammatory bowel diseases (IBD) are a group of chronic relapsing gastrointestinal inflammatory diseases with significant global incidence. Although the pathomechanism of IBD has been extensively investigated, several aspects of its pathogenesis remain unclear. Long non-coding RNAs (lncRNAs) are transcripts with more than 200 nucleotides in length that have potential protein-coding functions. LncRNAs play important roles in biological processes such as epigenetic modification, transcriptional regulation and post-transcriptional regulation. In this review, we summarize recent advances in research on IBD-related lncRNAs from the perspective of the overall intestinal microenvironment, as well as their potential roles as immune regulators, diagnostic biomarkers and therapeutic targets or agents for IBD.

Synthesis and HDAC1 inhibitory activity of a novel series of coumarin-based amide derivatives for treatment of cancer.

Background: Histone deacetylases (HDACs) play a vital role in the epigenetic regulation of transcription and expression. HDAC1 overexpression is seen in many cancers. Methodology: The authors synthesized and evaluated 27 novel coumarin-based amide derivatives for HDAC1 inhibitory activity. The compounds were screened at the US National Cancer Institute, and 5k and 5u were selected for five-dose assays. Compound 5k showed GI50 values of 0.294 and 0.264μM against MOLT-4 and LOX-IMVI, respectively; whereas 5u had GI50 values of 0.189and 0.263μM, respectively. Both derivatives showed better activity than entinostat and suberoylanilide hydroxamic acid. Compound 5k exhibited an IC50 value of 1.00μM on ACHN cells. Conclusion: Coumarin derivatives exhibited promising HDAC1 inhibitory potential and warrant future development as anticancer agents.

Epigenetic regulation of nuclear processes in fungal plant pathogens.

Through the association of protein complexes to DNA, the eukaryotic nuclear genome is broadly organized into open euchromatin that is accessible for enzymes acting on DNA and condensed heterochromatin that is inaccessible. Chemical and physical alterations to chromatin may impact its organization and functionality and are therefore important regulators of nuclear processes. Studies in various fungal plant pathogens have uncovered an association between chromatin organization and expression of in planta-induced genes that are important for pathogenicity. This review discusses chromatin-based regulation mechanisms as determined in the fungal plant pathogen Verticillium dahliae and relates the importance of epigenetic transcriptional regulation and other nuclear processes more broadly in fungal plant pathogens.

Perturbed epigenetic transcriptional regulation in AML with IDH mutations causes increased susceptibility to NK cells

Isocitrate dehydrogenase (IDH) mutations are found in 20% of acute myeloid leukemia (AML) patients. However, only 30–40% of the patients respond to IDH inhibitors (IDHi). We aimed to identify a molecular vulnerability to tailor novel therapies for AML patients with IDH mutations. We characterized the transcriptional and epigenetic landscape with the IDH2i AG-221, using an IDH2 mutated AML cell line model and AML patient cohorts, and discovered a perturbed transcriptional regulatory network involving myeloid transcription factors that were partly restored after AG-221 treatment. In addition, hypermethylation of the HLA cluster caused a down-regulation of HLA class I genes, triggering an enhanced natural killer (NK) cell activation and an increased susceptibility to NK cell-mediated responses. Finally, analyses of DNA methylation data from IDHi-treated patients showed that non-responders still harbored hypermethylation in HLA class I genes. In conclusion, this study provides new insights suggesting that IDH mutated AML is particularly sensitive to NK cell-based personalized immunotherapy.

BET inhibitors induce NF-κB and E2F downregulation in Hodgkin and Reed–Sternberg cells

The prognosis of patients with relapsed and/or refractory classic Hodgkin lymphoma (cHL) continues to be poor. Therefore, there is a continuing need to develop novel therapies and to rationalize the use of target combinations. In recent years there has been growing interest in epigenetic targets for hematological malignancies under the rationale of the presence of common alterations in epigenetic transcriptional regulation. Since Hodgkin and Reed–Sternberg (HRS) cells have frequent inactivating mutations of the CREBBP and EP300 acetyltransferases, bromodomain and extra-terminal (BET) inhibitors can be a rational therapy for cHL. Here we aimed to confirm the efficacy of BET inhibitors (iBETs) using representative cell models and functional experiments, and to further explore biological mechanisms under iBET treatment using whole-transcriptome analyses. Our results reveal cytostatic rather than cytotoxic activity through the induction of G1/S and G2/M cell-cycle arrest, in addition to variable MYC downregulation. Additionally, massive changes in the transcriptome induced by the treatment include downregulation of relevant pathways in cHL disease: NF-kB and E2F, among others. Our findings support the therapeutic use of iBETs in selected cHL patients and reveal previously unknown biological mechanisms and consequences of pan-BET inhibition.

Inheritance of epigenetic transcriptional memory through read-write replication of a histone modification.

Epigenetic transcriptional regulation frequently requires histone modifications. Some, but not all, of these modifications are able to template their own inheritance. Here, I discuss the molecular mechanisms by which histone modifications can be inherited and relate these ideas to new results about epigenetic transcriptional memory, a phenomenon that poises recently repressed genes for faster reactivation and has been observed in diverse organisms. Recently, we found that the histone H3 lysine 4 dimethylation that is associated with this phenomenon plays a critical role in sustaining memory and, when factors critical for the establishment of memory are inactivated, can be stably maintained through multiple mitoses. This chromatin-mediated inheritance mechanism may involve a physical interaction between an H3K4me2 reader, SET3C, and an H3K4me2 writer, Spp1- COMPASS. This is the first example of a chromatin-mediated inheritance of a mark that promotes transcription.

Substrate DNA length regulates the activity of TET 5-methylcytosine dioxygenases.

The ten-eleven translocation (TET) isoforms (TET1-3) play critical roles in epigenetic transcription regulation. In addition, mutations in the TET2 gene are frequently detected in patients with glioma and myeloid malignancies. TET isoforms can oxidize 5-methylcytosine to 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine, by iterative oxidation. The in vivo DNA demethylation activity of TET isoforms may depend on many factors including enzyme's structural features, its interaction with DNA-binding proteins, chromatin context, DNA sequence, DNA length, and configuration. The rationale for this study is to identify the preferred DNA length and configuration in the substrates of TET isoforms. We have used a highly sensitive LC-MS/MS-based method to compare the substrate preference of TET isoforms. To this end, four DNA substrate sets (S1, S2, S3, S4) of different sequences were chosen. In addition, in each set, four different lengths of DNA substrates comprising 7-, 13-, 19-, and 25-mer nucleotides were synthesized. Each DNA substrate was further used in three different configurations, that is, double stranded symmetrically-methylated, double stranded hemi-methylated, and single stranded single-methylated to evaluate their effect on TET-mediated 5mC oxidation. We demonstrate that mouse TET1 (mTET1) and human TET2 (hTET2) have highest preference for 13-mer dsDNA substrates. Increasing or decreasing the length of dsDNA substrate reduces product formation. In contrast to their dsDNA counterparts, the length of ssDNA substrates did not have a predictable effect on 5mC oxidation. Finally, we show that substrate specificity of TET isoforms correlates with their DNA binding efficiency. Our results demonstrate that mTET1 and hTET2 prefer 13-mer dsDNA as a substrate over ssDNA. These results may help elucidate novel properties of TET-mediated 5mC oxidation and help develop novel diagnostic tools to detect TET2 function in patients.

#2999 APABETALONE REDUCES CARDIAC EVENTS IN CKD PATIENTS BY DOWNREGULATING FIBROTIC AND INFLAMMATORY PROCESSES

Abstract Background and Aims Major adverse cardiac events (MACE) are a leading cause of mortality in patients with chronic kidney disease (CKD). Apabetalone is an orally available inhibitor of bromodomain & extraterminal (BET) proteins – epigenetic readers that modulate gene expression involved in fibrosis & inflammation. In the phase 3 BETonMACE trial in patients with CVD & diabetes mellitus (NCT02586155), apabetalone reduced MACE by 50% in the subpopulation with CKD (eGFR < 60 mL/min/1.73 m2; HR 0.50 95% CI 0.26,0.96 p = 0.04) indicating favorable response along the kidney-heart axis. This study examines effects of apabetalone in human renal mesangial cells (HRMCs) on fibrotic & inflammatory pathways. In the clinic, we assess plasma levels of fibrotic factors in CKD patients & matched controls after receiving apabetalone. Method TGF-β1 is a pro-fibrotic cytokine that activates HRMCs to over-produce extracellular matrix (ECM). HRMCs were stimulated with TGF-β1 or LPS ± 1-25 µM apabetalone, 0.15-0.5 µM JQ1 or 0.1 µM MZ1 - BET inhibitors (BETi) with chemical scaffolds different than apabetalone. Gene expression was measured by RNA-seq & real-time PCR. RNA-seq was evaluated by Gene Ontology (GO) & Ingenuity Pathway Analysis (IPA). Proteins were measured by immunofluorescence microscopy or ELISA. Collagen gel contraction was assessed in 3D culture. In human subjects, proteomic analysis of plasma was performed via SOMAscan 1.3k 12 hours after 100 mg of apabetalone in CKD patients (n = 8 eGFR < 30 stage 4 or 5) and matched controls (n = 8 eGFR > 60). Results GO analysis of RNA-seq from TGF-β1 stimulated HRMCs showed multiple gene sets associated with ECM production & remodeling in the top 20 affected by BETi. IPA predicted NfkB-RelA and NFkB (complex) were inhibited by apabetalone, consistent with suppressed inflammation. IPA also predicted apabetalone activated pathways of glucose utilization & tolerance of ROS production, including Oxidative Phosphorylation (z-score 5.7, p = 2.95 × 10−3 at 25 µM) & NRF2-Mediated Oxidative Stress Response (z score 2.3, p = 7.9 × 10−12 at 25 µM; z-score 1.6, p = 1.5 × 10−5 at 5 µM). Predicted changes may allow tolerance of elevated glucose. Mechanistically, apabetalone suppressed TGF-β1 induced α-smooth muscle actin (α-SMA) gene expression, a marker of activation, up to 89% (p = 2.8 × 10−6 at 25 µM), and abolished α-SMA filament formation. Consequently, apabetalone opposed TGF-β1 induced collagen gel contraction up to 24% (p = 0.031 at 25 µM). Further, apabetalone countered TGF-β1 induced expression & protein production of key drivers of fibrosis including (a) thrombospondin, an activator of latent TGF-β1 (b) fibronectin, a key ECM component (c) periostin, a promoter of ECM production (d) osteonectin, a regulator of TGF-β1 expression and (e) IL6, a pro-inflammatory cytokine (Table 1). In addition, apabetalone dose dependently opposed LPS stimulated expression of inflammatory genes: IL6 up to 94%, IL1B up to 95% and PTGS2 up to 94% (p<0.001 for each). In all studies, JQ1 or MZ1 had similar activity as apabetalone, confirming on-target BETi effects. In humans, plasma levels of profibrotic and inflammatory markers were reduced 12 hours after receiving apabetalone specifically in those with CKD. Only periostin was reduced in subjects without renal impairment (Table 1). Conclusion Through epigenetic regulation of transcription in HRMCs, apabetalone reduces production of fibrotic & inflammatory factors known to signal along the kidney-heart axis & exacerbate kidney dysfunction. Predicted changes in energy metabolism suggest apabetalone facilitates adaptation to high glucose in kidneys. In a clinical trial, plasma levels of fibrotic & inflammatory factors were reduced specifically in CKD patients receiving apabetalone. Our results provide mechanistic insights into reduced MACE in CKD patients receiving apabetalone in the phase 3 BETonMACE trial & will be further evaluated in an upcoming Phase 3 trial.

Assessment of MGP gene expression in cancer and contribution to prognosis

Matrix Gla protein (MGP) was first identified as a calcification physiological inhibitor and the causal agent of the Keutel syndrome. MGP has been suggested to play a role in development, cell differentiation, and tumorigenesis. This study aimed to compare MGP expression and methylation status in different tumors and adjacent tissues, using The Cancer Genome Atlas (TCGA) data repository. We investigated if changes in MGP mRNA expression were correlated to cancer progression and whether the correlation coefficients could be used for prognosis. Strong correlations were observed between altered MGP levels and disease progression in breast, kidney, liver, and thyroid cancers, suggesting that it could be used to complement current clinical biomarker assays, for early cancer diagnosis.We have also analyzed MGP methylation and identified CpG sites in its promoter and first intron with clear differences in methylation status between healthy and tumoral tissue providing evidence for epigenetic regulation of MGP transcription. Furthermore, we demonstrate that these alterations correlate with the overall survival of the patients suggesting that its assessment can serve as an independent prognostic indicator of patients’ survival.

Epigenetic regulation of plastin 3 expression by the macrosatellite DXZ4 and the transcriptional regulator CHD4

Dysregulated Plastin 3 (PLS3) levels associate with a wide range of skeletal and neuromuscular disorders and the most common types of solid and hematopoietic cancer. Most importantly, PLS3 overexpression protects against spinal muscular atrophy. Despite its crucial role in F-actin dynamics in healthy cells and its involvement in many diseases, the mechanisms that regulate PLS3 expression are unknown. Interestingly, PLS3 is an X-linked gene and all asymptomatic SMN1-deleted individuals in SMA-discordant families who exhibit PLS3 upregulation are female, suggesting that PLS3 may escape X chromosome inactivation. To elucidate mechanisms contributing to PLS3 regulation, we performed a multi-omics analysis in two SMA-discordant families using lymphoblastoid cell lines and iPSC-derived spinal motor neurons originated from fibroblasts. We show that PLS3 tissue-specifically escapes X-inactivation. PLS3 is located ∼500 kb proximal to the DXZ4 macrosatellite, which is essential for X chromosome inactivation. By applying molecular combing in a total of 25 lymphoblastoid cell lines (asymptomatic individuals, individuals with SMA, control subjects) with variable PLS3 expression, we found a significant correlation between the copy number of DXZ4 monomers and PLS3 levels. Additionally, we identified chromodomain helicase DNA binding protein 4 (CHD4) as an epigenetic transcriptional regulator of PLS3 and validated co-regulation of the two genes by siRNA-mediated knock-down and overexpression of CHD4. We show that CHD4 binds the PLS3 promoter by performing chromatin immunoprecipitation and that CHD4/NuRD activates the transcription of PLS3 by dual-luciferase promoter assays. Thus, we provide evidence for a multilevel epigenetic regulation of PLS3 that may help to understand the protective or disease-associated PLS3 dysregulation.

Delivery and imaging of functionalized DNA origami in cells.

Human cells package over two meters of genetic information into the microscopic space of the nucleus in the form of chromatin (a complex between DNA and histone proteins). This packaging or “folding” of the genome is critical for the regulation of gene expression, maintenance of genomic stability, and defining cell fate during development. Change to the spatial organization of chromatin is implicated in a host of neurological disorders as well as in aging and cancer. Remodeling of chromatin via post-translational modifications allows for epigenetic regulation of transcription in healthy and diseased cells. Thus, tools to engineer chromatin epigenetics in a controlled manner are crucial to study the cause-consequence relationship between epigenetics, chromatin organization and gene expression. Previous approaches to chromatin engineering have significant limitations, namely the inability to perform multiple functions (visualize, modify, or detect downstream products) simultaneously. Our work seeks to develop and apply DNA origami nanodevices (DOs) as multi-functional platforms to probe and engineer chromatin epigenetics. We propose to leverage the versatility of DO and its potential as a platform for multiple functional elements to visualize, modify, and sense the transcriptional output of genomic regions in mammalian cell nuclei. We have taken an interdisciplinary approach to develop and test four different DNA origami structures (26-helix bundle, 14-helix bundle, 13-helix bundle, and 8-helix bundle) functionalized with fluorophores as well as an anti-RNA Polymerase II (Pol2) antibody. We show that electroporation enables delivery of these structures into cells and further, 8-helix bundle structures functionalized with RNA Pol2 antibodies are successfully piggybacked into the nucleus. Super-resolution imaging further demonstrates the delivery of single DNA origami structures into the cell nucleus. These results open the door for DNA origami as a multifunctional platform for targeting, modifying, and visualizing the genome.

Using epigenomics to understand cellular responses to environmental influences in diseases.

It is a generally accepted model that environmental influences can exert their effects, at least in part, by changing the molecular regulators of transcription that are described as epigenetic. As there is biochemical evidence that some epigenetic regulators of transcription can maintain their states long term and through cell division, an epigenetic model encompasses the idea of maintenance of the effect of an exposure long after it is no longer present. The evidence supporting this model is mostly from the observation of alterations of molecular regulators of transcription following exposures. With the understanding that the interpretation of these associations is more complex than originally recognised, this model may be oversimplistic; therefore, adopting novel perspectives and experimental approaches when examining how environmental exposures are linked to phenotypes may prove worthwhile. In this review, we have chosen to use the example of nonalcoholic fatty liver disease (NAFLD), a common, complex human disease with strong environmental and genetic influences. We describe how epigenomic approaches combined with emerging functional genetic and single-cell genomic techniques are poised to generate new insights into the pathogenesis of environmentally influenced human disease phenotypes exemplified by NAFLD.

Characterization of Hepatoma-Derived Growth Factor-Related Protein 2 Interactions with Heterochromatin.

The expression of genetic information is tightly controlled by chromatin regulatory proteins, including those in the heterochromatin gene repression family. Many of these regulatory proteins work together on the chromatin substrate to precisely regulate gene expression during mammalian development, giving rise to many different tissues in higher organisms from a fixed genomic template. Here we identify and characterize the interactions of two related heterochromatin regulatory proteins, heterochromatin protein 1 alpha (HP1α) and M-phase phosphoprotein 8 (MPP8), with hepatoma-derived growth factor-related protein 2 (HRP2). We find in biochemical experiments that HRP2 copurifies and co-sediments with heterochromatin-associated proteins, including HP1α and MPP8. Using the Chromatin in vivo Assay in multiple cell types, we demonstrate that HP1α-mediated gene repression dynamics are altered by the presence of HRP2. Furthermore, the knockout of HRP2 in MDA-MB-231 cells results in significant changes to chromatin structure and stability, which alter gene expression patterns. Here, we detail a mechanism by which HRP2 contributes to epigenetic transcriptional regulation through engagement with heterochromatin-associated proteins to stabilize the chromatin landscape and influence gene expression.

Epigenetic Regulation of HIV-1 Sense and Antisense Transcription in Response to Latency-Reversing Agents.

Nucleosomes positioned on the HIV-1 5' long terminal repeat (LTR) regulate sense transcription as well as the establishment and maintenance of latency. A negative-sense promoter (NSP) in the 3' LTR expresses antisense transcripts with coding and non-coding activities. Previous studies identified cis-acting elements that modulate NSP activity. Here, we used the two chronically infected T cell lines, ACH-2 and J1.1, to investigate epigenetic regulation of NSP activity. We found that histones H3 and H4 are present on the 3' LTR in both cell lines. Following treatment with histone deacetylase inhibitors (HDACi), the levels of H3K27Ac increased and histone occupancy declined. HDACi treatment also led to increased levels of RNA polymerase II (RNPII) at NSP, and antisense transcription was induced with similar kinetics and to a similar extent as 5' LTR-driven sense transcription. We also detected H3K9me2 and H3K27me3 on NSP, along with the enzymes responsible for these epigenetic marks, namely G9a and EZH2, respectively. Treatment with their respective inhibitors had little or no effect on RNPII occupancy at the two LTRs, but it induced both sense and antisense transcription. Moreover, the increased expression of antisense transcripts in response to treatment with a panel of eleven latency-reversing agents closely paralleled and was often greater than the effect on sense transcripts. Thus, HIV-1 sense and antisense RNA expression are both regulated via acetylation and methylation of lysine 9 and 27 on histone H3. Since HIV-1 antisense transcripts act as non-coding RNAs promoting epigenetic silencing of the 5' LTR, our results suggest that the limited efficacy of latency-reversing agents in the context of 'shock and kill' cure strategies may be due to concurrent induction of antisense transcripts thwarting their effect on sense transcription.

Analysis of differentially expressed genes on human X chromosome harboring large deletion induced by X-rays.

We examined here normal human cells with large deletions encompassing the hypoxanthine-phosphoribosyltransferase 1 (HPRT1) gene on X chromosome. Expression levels of genes on X chromosome were analyzed by microarray and RT-qPCR method, and differentially expressed genes (DEGs) were extracted. We found that DEGs were not limited to the genes flanking deleted regions but spread over the entire X chromosome. Interestingly, the gene regulation patterns were similar to a large extent among independent clones that have similar-sized large deletions involving the HPRT1 gene. Thus, it is indicated that an impact of large deletion on possible epigenetic transcriptional regulation is not limited to the regions proximal to the deletion region.

A distal super-enhancer activates oncogenic ETS2 via recruiting MECOM in inflammatory bowel disease and colorectal cancer

Abnormal activities of distal cis-regulatory elements (CREs) contribute to the initiation and progression of cancer. Gain of super-enhancer (SE), a highly active distal CRE, is essential for the activation of key oncogenes in various cancers. However, the mechanism of action for most tumor-specific SEs still largely remains elusive. Here, we report that a candidate oncogene ETS2 was activated by a distal SE in inflammatory bowel disease (IBD) and colorectal cancer (CRC). The SE physically interacted with the ETS2 promoter and was required for the transcription activation of ETS2. Strikingly, the ETS2-SE activity was dramatically upregulated in both IBD and CRC tissues when compared to normal colon controls and was strongly correlated with the level of ETS2 expression. The tumor-specific activation of ETS2-SE was further validated by increased enhancer RNA transcription from this region in CRC. Intriguingly, a known IBD-risk SNP resides in the ETS2-SE and the genetic variant modulated the level of ETS2 expression through affecting the binding of an oncogenic transcription factor MECOM. Silencing of MECOM induced significant downregulation of ETS2 in CRC cells, and the level of MECOM and ETS2 correlated well with each other in CRC and IBD samples. Functionally, MECOM and ETS2 were both required for maintaining the colony-formation and sphere-formation capacities of CRC cells and MECOM was crucial for promoting migration. Taken together, we uncovered a novel disease-specific SE that distantly drives oncogenic ETS2 expression in IBD and CRC and delineated a mechanistic link between non-coding genetic variation and epigenetic regulation of gene transcription.

D-2-Hydroxyglutarate Inhibits Calcineurin Phosphatase Activity to Abolish NF-AT Activation and IL-2 Induction in Stimulated Lymphocytes.

Gliomas expressing mutant isocitrate dehydrogenases excessively synthesize d-2-hydroxyglutarate (D2HG), suppressing immune surveillance. A portion of this D2HG is released from these tumor cells, but the way environmental D2HG inhibits lymphocyte function is undefined. We incubated human PBLs or Jurkat T cells with D2HG at concentrations present within and surrounding gliomas or its obverse l-2-hydroxyglutarate (L2HG) stereoisomer. We quantified each 2HG stereoisomer within washed cells by N-(p-toluenesulfonyl)-l-phenylalanyl chloride derivatization with stable isotope-labeled D2HG and L2HG internal standards, HPLC separation, and mass spectrometry. D2HG was present in quiescent cells and was twice as abundant as L2HG. Extracellular 2HG rapidly increased intracellular levels of the provided stereoisomer by a stereoselective, concentration-dependent process. IL-2 expression, even when elicited by A23187 and PMA, was abolished by D2HG in a concentration-dependent manner, with significant reduction at just twice its basal level. In contrast, L2HG was only moderately inhibitory. IL-2 expression is regulated by increased intracellular Ca2+ that stimulates calcineurin to dephosphorylate cytoplasmic phospho-NF-AT, enabling its nuclear translocation. D2HG abolished stimulated expression of a stably integrated NF-AT-driven luciferase reporter that precisely paralleled its concentration-dependent inhibition of IL-2. D2HG did not affect intracellular Ca2+. Rather, surface plasmon resonance showed D2HG, but not L2HG, bound calcineurin, and D2HG, but not L2HG, inhibited Ca2+-dependent calcineurin phosphatase activity in stimulated Jurkat extracts. Thus, D2HG is a stereoselective calcineurin phosphatase inhibitor that prevents NF-AT dephosphorylation and so abolishes IL-2 transcription in stimulated lymphocytes. This occurs at D2HG concentrations found within and adjacent to gliomas independent of its metabolic or epigenetic transcriptional regulation.

Integrative Analysis of Genetic and Epigenetic Alterations in the CBX7 Gene Reveals Its Tumor-Suppressive Function by Regulating the Cell Cycle in Human Breast Cancer

CBX7 is a member of the chromobox gene family, which plays an important role in epigenetic transcriptional regulation. In this study, we found that compared to normal mammary tissues, mRNA levels of CBX7 are consistently significantly downregulated in breast cancers (BCs) across different datasets. Integrative multiomics analysis revealed the genetic and epigenetic mechanisms for the loss of CBX7 expression in BCs. Lower expression levels of CBX7 are significantly associated with shorter overall, disease-free, and distant metastasis-free survival of patients with BC. These prognostic impacts of CBX7 are independent of estrogen receptor status and PAM50 molecular subtypes. Coexpression analysis identified 207 genes consistently coexpressed with CBX7 (157 negatively and 50 positively). Gene Ontology, KEGG, and Reactome enrichment analysis revealed that cell cycle‑, DNA replication‑, and mitosis-related pathways are significantly overrepresented within the set of CBX7 negatively coexpressed genes, suggesting that CBX7 functions as a suppressor of the cell cycle. Moreover, transcription factor enrichment analysis detected the E2F family of transcription factors significantly associated with CBX7 negatively coexpressed genes, consistent with E2F function regulating the cell cycle. Furthermore, we found that loss of CBX7 expression significantly increases genomic instability and tumor mutation burden. Our findings indicate that CBX7 acts as a tumor suppressor in BC through its potential role in the negative regulation of cell proliferation and the maintenance of genome integrity.

DPY30 Promotes Proliferation and Cell Cycle Progression of Colorectal Cancer Cells via Mediating H3K4 Trimethylation.

DPY30, a core subunit of the SET1/MLL histone H3K4 methyltransferase complexes, plays an important role in diverse biological functions through the epigenetic regulation of gene transcription, especially in cancer development. However, its involvement in human colorectal carcinoma (CRC) has not been elucidated yet. Here we demonstrated that DPY30 was overexpressed in CRC tissues, and significantly associated with pathological grading, tumor size, TNM stage, and tumor location. Furthermore, DPY30 knockdown remarkably suppressed the CRC cell proliferation through downregulation of PCNA and Ki67 in vitro and in vivo, simultaneously induced cell cycle arrest at S phase by downregulating Cyclin A2. In the mechanistic study, RNA-Seq analysis revealed that enriched gene ontology of cell proliferation and cell growth was significantly affected. And ChIP result indicated that DPY30 knockdown inhibited H3 lysine 4 trimethylation (H3K4me3) and attenuated interactions between H3K4me3 with PCNA, Ki67 and cyclin A2 respectively, which led to the decrease of H3K4me3 establishment on their promoter regions. Taken together, our results demonstrate overexpression of DPY30 promotes CRC cell proliferation and cell cycle progression by facilitating the transcription of PCNA, Ki67 and cyclin A2 via mediating H3K4me3. It suggests that DPY30 may serve as a potential therapeutic molecular target for CRC.

OGG1 in the Kidney: Beyond Base Excision Repair.

8-Oxoguanine DNA glycosylase (OGG1) is a repair protein for 8-oxoguanine (8-oxoG) in eukaryotic atopic DNA. Through the initial base excision repair (BER) pathway, 8-oxoG is recognized and excised, and subsequently, other proteins are recruited to complete the repair. OGG1 is primarily located in the cytoplasm and can enter the nucleus and mitochondria to repair damaged DNA or to exert epigenetic regulation of gene transcription. OGG1 is involved in a wide range of physiological processes, such as DNA repair, oxidative stress, inflammation, fibrosis, and autophagy. In recent years, studies have found that OGG1 plays an important role in the progression of kidney diseases through repairing DNA, inducing inflammation, regulating autophagy and other transcriptional regulation, and governing protein interactions and functions during disease and injury. In particular, the epigenetic effects of OGG1 in kidney disease have gradually attracted widespread attention. This study reviews the structure and biological functions of OGG1 and the regulatory mechanism of OGG1 in kidney disease. In addition, the possibility of OGG1 as a potential therapeutic target in kidney disease is discussed.