DOT1L regulates chromatin reorganization and gene expression during sperm differentiation.

Spermatozoa have a unique genome organization. Their chromatin is almost completely devoid of histones and is formed instead of protamines, which confer a high level of compaction and preserve paternal genome integrity until fertilization. Histone-to-protamine transition takes place in spermatids and is indispensable for the production of functional sperm. Here, we show that the H3K79-methyltransferase DOT1L controls spermatid chromatin remodeling and subsequent reorganization and compaction of the spermatozoon genome. Using a mouse model in which Dot1l is knocked-out (KO) in postnatal male germ cells, we found that Dot1l-KO sperm chromatin is less compact and has an abnormal content, characterized by the presence of transition proteins, immature protamine 2 forms and a higher level of histones. Proteomic and transcriptomic analyses performed on spermatids reveal that Dot1l-KO modifies the chromatin prior to histone removal and leads to the deregulation of genes involved in flagellum formation and apoptosis during spermatid differentiation. As a consequence of these chromatin and gene expression defects, Dot1l-KO spermatozoa have less compact heads and are less motile, which results in impaired fertility.

A genetic screen identifies BEND3 as a regulator of bivalent gene expression and global DNA methylation.

Epigenetic mechanisms are essential to establish and safeguard cellular identities in mammals. They dynamically regulate the expression of genes, transposable elements and higher-order chromatin structures. Consequently, these chromatin marks are indispensable for mammalian development and alterations often lead to disease, such as cancer. Bivalent promoters are especially important during differentiation and development. Here we used a genetic screen to identify new regulators of a bivalent repressed gene. We identify BEND3 as a regulator of hundreds of bivalent promoters, some of which it represses, and some of which it activates. We show that BEND3 is recruited to a CpG-containg consensus site that is present in multiple copies in many bivalent promoters. Besides having direct effect on the promoters it binds, the loss of BEND3 leads to genome-wide gains of DNA methylation, which are especially marked at regions normally protected by the TET enzymes. DNA hydroxymethylation is reduced in Bend3 mutant cells, possibly as consequence of altered gene expression leading to diminished alpha-ketoglutarate production, thus lowering TET activity. Our results clarify the direct and indirect roles of an important chromatin regulator, BEND3, and, more broadly, they shed light on the regulation of bivalent promoters.

Unique B-1 cells specific for both N-pyrrolated proteins and DNA evolve with apolipoprotein E deficiency.

Lysine N-pyrrolation, a posttranslational modification, which converts lysine residues to Nε-pyrrole-L-lysine, imparts electronegative properties to proteins, causing them to mimic DNA. Apolipoprotein E (apoE) has been identified as a soluble receptor for pyrrolated proteins (pyrP), and accelerated lysine N-pyrrolation has been observed in apoE-deficient (apoE-/-) hyperlipidemic mice. However, the impact of pyrP accumulation consequent to apoE deficiency on the innate immune response remains unclear. Here, we investigated B-1a cells known to produce germline-encoded immunoglobulin M (IgM) from mice deficient in apoE and identified a particular cell population that specifically produces IgM antibodies against pyrP and DNA. We demonstrated an expansion of B-1a cells involved in IgM production in the peritoneal cavity of apoE-/- mice compared with wild-type mice, consistent with a progressive increase of IgM response in the mouse sera. We found that pyrP exhibited preferential binding to B-1a cells and facilitated the production of IgM. B cell receptor analysis of pyrP-specific B-1a cells showed restricted usage of gene segments selected from the germline gene set; most sequences contained high levels of non-templated-nucleotide additions (N-additions) that could contribute to junctional diversity of B cell receptors. Finally, we report that a subset of monoclonal IgM antibodies against pyrP/DNA established from the apoE-/- mice also contained abundant N-additions. These results suggest that the accumulation of pyrP due to apoE deficiency may influence clonal diversity in the pyrP-specific B cell repertoire. The discovery of these unique B-1a cells for pyrP/DNA provides a key link connecting covalent protein modification, lipoprotein metabolism, and innate immunity.

Natural polyphenols convert proteins into histone-binding ligands.

Antioxidants are sensitive to oxidation and are immediately converted into their oxidized forms that can react with proteins. We have recently found that proteins incubated with oxidized vitamin C (dehydroascorbate) gain a new function as a histone-binding ligand. This finding led us to predict that antioxidants, through conversion to their oxidized forms, may generally have similar functions. In the present study, we identified several natural polyphenols as a source of histone ligands and characterized the mechanism for the interaction of protein-bound polyphenols with histone. Through screening of 25 plant-derived polyphenols by assessing their ability to convert bovine serum albumin into histone ligands, we identified seven polyphenols, including (-)-epigallocatechin-3-O-gallate (EGCG). Additionally, we found that the histone tail domain, which is a highly charged and conformationally flexible region, is involved in the interaction with the polyphenol-modified proteins. Further mechanistic studies showed the involvement of a complex heterogeneous group of the polyphenol-derived compounds bound to proteins as histone-binding elements. We also determined that the interaction of polyphenol-modified proteins with histones formed aggregates and exerted a protective effect against histone-mediated cytotoxicity toward endothelial cells. These findings demonstrated that histones are one of the major targets of polyphenol-modified proteins and provide important insights into the chemoprotective functions of dietary polyphenols.

Oxidative deamination of lysine residues by polyphenols generates an equilibrium of aldehyde and 2-piperidinol products.

Polyphenols, especially catechol-type polyphenols, exhibit lysyl oxidase-like activity and mediate oxidative deamination of lysine residues in proteins. Previous studies have shown that polyphenol-mediated oxidative deamination of lysine residues can be associated with altered electrical properties of proteins and increased crossreactivity with natural immunoglobulin M antibodies. This interaction suggested that oxidized proteins could act as innate antigens and elicit an innate immune response. However, the structural basis for oxidatively deaminated lysine residues remains unclear. In the present study, to establish the chemistry of lysine oxidation, we characterized oxidation products obtained via incubation of the lysine analog N-biotinyl-5-aminopentylamine with eggshell membranes containing lysyl oxidase and identified a unique six-membered ring 2-piperidinol derivative equilibrated with a ring-open product (aldehyde) as the major product. By monitoring these aldehyde-2-piperidinol products, we evaluated the lysyl oxidase-like activity of polyphenols. We also observed that this reaction was mediated by some polyphenols, especially o-diphenolic-type polyphenols, in the presence of copper ions. Interestingly, the natural immunoglobulin M monoclonal antibody recognized these aldehyde-2-piperidinol products as an innate epitope. These findings establish the existence of a dynamic equilibrium of oxidized lysine and provide important insights into the chemopreventive function of dietary polyphenols for chronic diseases.

Adsorption of Keggin-Type Polyoxometalates on Rh Metal Particles under Reductive Conditions.

The adsorption of POMs on Rh/SiO2 in water solvent under strongly reductive conditions was investigated. Aqueous solutions of α-Keggin type silicotungstate and silicovanadotungstates were mixed with Rh/SiO2 at 393-473 K under 1 MPa of H2. Monovanadium-substituted silicotungstate, α-SiVW11O405- (SiVW11), was more readily adsorbed than nonsubstituted silicotungstate, α-SiW12O404- (SiW12). After adsorption at 433 K, SiVW11 was desorbed from Rh/SiO2 by oxidation with Br2 water without change of the Keggin structure, as evidenced by 51V NMR. Trivanadium-substituted silicotungstate, α-1,2,3-SiV3W9O407-, was not stable, and the desorbed species from Rh/SiO2 by oxidation with Br2 did not maintain the Keggin structure. The very high temperature for adsorption (473 K) also led to the decomposition of the Keggin structure of SiVW11. An increase in the concentration of SiVW11 in the liquid phase gave a saturation of the amount of desorbable SiVW11, up to five SiVW11 anions per one Rh particle with a 3 nm size. The elemental analysis and W L3-edge extended X-ray absorption fine structure of Rh/SiO2 after the adsorption of SiVW11 showed that a part of SiVW11 was decomposed and irreversibly adsorbed as metallic W species incorporated into the surface of Rh metal particles. The amount of decomposed SiVW11 was almost the same as that of SiVW11 adsorbed as the original Keggin structure. The desorbable SiVW11 was probably bonded on the W atom incorporated on the Rh metal particles as the two-electron-reduced form (α-SiVIIIW11O407-).

Structure-based screening combined with computational and biochemical analyses identified the inhibitor targeting the binding of DNA Ligase 1 to UHRF1.

The accumulation of epigenetic alterations is one of the major causes of tumorigenesis. Aberrant DNA methylation patterns cause genome instability and silencing of tumor suppressor genes in various types of tumors. Therefore, drugs that target DNA methylation-regulating factors have great potential for cancer therapy. Ubiquitin-like containing PHD and RING finger domain 1 (UHRF1) is an essential factor for DNA methylation maintenance. UHRF1 is overexpressed in various cancer cells and down-regulation of UHRF1 in these cells reactivates the expression of tumor suppressor genes, thus UHRF1 is a promising target for cancer therapy. We have previously shown that interaction between the tandem Tudor domain (TTD) of UHRF1 and DNA ligase 1 (LIG1) di/trimethylated on Lys126 plays a key role in the recruitment of UHRF1 to replication sites and replication-coupled DNA methylation maintenance. An arginine binding cavity (Arg-binding cavity) of the TTD is essential for LIG1 interaction, thus the development of inhibitors that target the Arg-binding cavity could potentially repress UHRF1 function in cancer cells. To develop such an inhibitor, we performed in silico screening using not only static but also dynamic metrics based on all-atom molecular dynamics simulations, resulting in efficient identification of 5-amino-2,4-dimethylpyridine (5A-DMP) as a novel TTD-binding compound. Crystal structure of the TTD in complex with 5A-DMP revealed that the compound stably bound to the Arg-binding cavity of the TTD. Furthermore, 5A-DMP inhibits the full-length UHRF1:LIG1 interaction in Xenopus egg extracts. Our study uncovers a UHRF1 inhibitor which can be the basis of future experiments for cancer therapy.

Vascular endothelial growth factor signaling in VE-cadherin expression and tube-like formation by rheumatoid arthritic synovial fibroblast-like cells.

An increase in the vasculature is one of most representative changes in the synovial tissue of joints in rheumatoid arthritis (RA) and is closely associated with disease progression. Although the vasculatures are believed to be a result of VE-cadherin-dependent angiogenesis and a possible therapeutic target of the disease, synovial fibroblastic cells express VE-cadherin and form tube-like structures, suggesting that vasculatures in RA synovium may not simply result from angiogenesis. This paper analyzes a mechanism of VE-cadherin expression by rheumatoid arthritic synovial fibroblast-like cells (RSFLs) and their involvement in the tube-like formation. A representative angiogenic factor, vascular endothelial growth factor (VEGF), and its binding to a predominant receptor (VEGFR2) activated VE-cadherin expression and the signaling pathways of ERK/MAPK and PI3K/AKT/mTOR. Treatment of RSFLs with signaling pathway inhibitors, VEGFR2 siRNA and a VEGF-antagonizing mimicking peptide inhibited VE-cadherin expression dose-dependently. VEGF-stimulated tube-like formation by RSFLs on Matrigel was hindered by the mimicking peptide and inhibitor treatment. This data demonstrates that RSFLs activated by VEGF binding of VEGFR2 express VE-cadherin and formed tube-like structure under the control of ERK/MAPK and PI3K/AKT/mTOR pathways suggesting that the inhibition suppresses vascular development in RA synovium.

Epigenetic modifications and reprogramming in paternal pronucleus: sperm, preimplantation embryo, and beyond.

Pronuclear/zygotic stage is the very first stage of life. In this period, paternal pronucleus undergoes massive chromatin remodeling called "paternal reprogramming" including protamine-histone replacement and subsequent acquisition of epigenetic modifications. Although these consecutive events are required for the initiation of maternal-zygotic transition, the precise role of paternal reprogramming and its effect on subsequent embryonic development has been largely unknown to date. Recently, various new techniques, especially next-generation sequencing (NGS) and RNAi microinjection contribute to unveil the epigenetic transition from both paternal and maternal to early preimplantation embryos, suggesting not only the simple transcriptional regulation by transcription factors but also dynamic structural alteration of chromatin to initiate the wave of zygotic gene transcription. This review summarizes such recent progress for understanding the epigenetic transition in sperm and preimplantation embryos, and further argue about its transgenerational effect.

Krüppel-like factor 4 expression in oral carcinoma cells and hypermethylation at the gene promoter.

BACKGROUND: Krüppel-like factor 4 (KLF4) is a transcription factor regulating proliferation-differentiation balance of epithelium, and down-regulated in less-differentiated and advanced oral carcinomas. Although the expression is inactivated by the promoter hypermethylation in malignant tumor cells, it remains unknown in oral carcinoma cells. METHODS: Genomic DNA isolated from nine different oral carcinoma cell lines and a normal keratinocyte line was treated with sodium bisulfite, and methylation at KLF4 gene promoter was determined by PCR direct-sequence analysis. KLF4 expression in cells cultured with or without demethylation reagent was monitored by quantitative real-time PCR and immunoblot. RESULTS: A 237-bp promoter region spanning - 718 and - 482 of KLF4 gene was hypermethylated in oral carcinoma cells that express KLF4 at a low level, but the methylation was infrequent in cells expressing KLF4 high amount. The downstream region from - 481 to +192 was not methylated in any cell lines. Demethylation treatment of cells up-regulated the expression at mRNA and protein levels. CONCLUSION: This study demonstrated that hypermethylation at a narrow range of the promoter region down-regulates KLF4 expression, and suggests that the loss of expression by the hypermethylation contributes to oral carcinoma progression.

Molecular and structural basis of anti-DNA antibody specificity for pyrrolated proteins.

Anti-DNA antibodies (Abs), serological hallmarks of systemic lupus erythematosus (SLE) and markers for diagnosis and disease activity, show a specificity for non-nucleic acid molecules, such as N-pyrrolated proteins (pyrP) containing Nε-pyrrole-L-lysine (pyrK) residues. However, the detailed mechanism for the binding of anti-DNA Abs to pyrP remains unknown. In the present study, to gain structural insights into the dual-specificity of anti-DNA Abs, we used phage display to obtain DNA-binding, single-chain variable fragments (scFvs) from SLE-prone mice and found that they also cross-reacted with pyrP. It was revealed that a variable heavy chain (VH) domain is sufficient for the recognition of DNA/pyrP. Identification of an antigenic sequence containing pyrK in pyrP suggested that the presence of both pyrK and multiple acidic amino acid residues plays important roles in the electrostatic interactions with the Abs. X-ray crystallography and computer-predicted simulations of the pyrK-containing peptide-scFv complexes identified key residues of Abs involved in the interaction with the antigens. These data provide a mechanistic insight into the molecular basis of the dual-specificity of the anti-DNA Abs and provide a basis for therapeutic intervention against SLE.

Pembrolizumab-induced asthma exacerbation with hypereosinophilia and elevated interleukin-5 in endometrial cancer: A case report.

Pembrolizumab is an anti-programmed cell death-1 (PD-1) antibody used to treat various cancer types. Treatments with such immune checkpoint inhibitors cause immune-related adverse events. However, airway inflammation caused by immune-related adverse events has rarely been reported. A 54-year-old woman with endometrial cancer experienced asthma exacerbation, and increased blood eosinophil counts 3 months after pembrolizumab administration. Although asthma exacerbation improved, the resumption of pembrolizumab caused the recurrence of dry cough and hypereosinophilia. The discontinuation of pembrolizumab improved her symptoms. Serum interleukin-5 levels increased during pembrolizumab treatment but decreased upon discontinuation. The blockade of PD-1 and its ligand may exacerbate asthma through eosinophilic inflammation.

Non-canonical functions of UHRF1 maintain DNA methylation homeostasis in cancer cells.

DNA methylation is an essential epigenetic chromatin modification, and its maintenance in mammals requires the protein UHRF1. It is yet unclear if UHRF1 functions solely by stimulating DNA methylation maintenance by DNMT1, or if it has important additional functions. Using degron alleles, we show that UHRF1 depletion causes a much greater loss of DNA methylation than DNMT1 depletion. This is not caused by passive demethylation as UHRF1-depleted cells proliferate more slowly than DNMT1-depleted cells. Instead, bioinformatics, proteomics and genetics experiments establish that UHRF1, besides activating DNMT1, interacts with DNMT3A and DNMT3B and promotes their activity. In addition, we show that UHRF1 antagonizes active DNA demethylation by TET2. Therefore, UHRF1 has non-canonical roles that contribute importantly to DNA methylation homeostasis; these findings have practical implications for epigenetics in health and disease.

Solubilization of Mouse Sperm Chromatin for Sequencing Analyses Using a Chaperon Protein.

Sperm chromatin compaction is physiologically essential for sperm to acquire the fertility. However, this unique structure composed of protamines makes us unable to solubilize the chromatin due to its resistance to sonication and enzymes usually used for chromatin fragmentation in somatic cells. Even when intense enzymatic treatment is applied, it appears to solubilize only certain portions of sperm chromatin presumably because of the heterogeneous properties. To overcome this issue, we previously developed a method to treat the sperm with recombinant nucleoplasmin, a protamine remover in fertilized embryos, followed by sonication. The nucleoplasmin treatment dramatically increased the efficiency of sperm chromatin solubilization, while a relatively large amount of recombinant nucleoplasmin was required. Here, we describe an improvement of nucleoplasmin method with a less amount of recombinant protein and a shorter reaction time.

A genome-wide screen reveals new regulators of the 2-cell-like cell state.

In mammals, only the zygote and blastomeres of the early embryo are totipotent. This totipotency is mirrored in vitro by mouse '2-cell-like cells' (2CLCs), which appear at low frequency in cultures of embryonic stem cells (ESCs). Because totipotency is not completely understood, we carried out a genome-wide CRISPR knockout screen in mouse ESCs, searching for mutants that reactivate the expression of Dazl, a gene expressed in 2CLCs. Here we report the identification of four mutants that reactivate Dazl and a broader 2-cell-like signature: the E3 ubiquitin ligase adaptor SPOP, the Zinc-Finger transcription factor ZBTB14, MCM3AP, a component of the RNA processing complex TREX-2, and the lysine demethylase KDM5C. All four factors function upstream of DPPA2 and DUX, but not via p53. In addition, SPOP binds DPPA2, and KDM5C interacts with ncPRC1.6 and inhibits 2CLC gene expression in a catalytic-independent manner. These results extend our knowledge of totipotency, a key phase of organismal life.

Diagnostic and prognostic impact of serum-soluble UL16-binding protein 2 in lung cancer patients.

UL16-binding protein 2 (ULBP2) is one of the ligands for NKG2D (NKG2DL). ULBP2 expression is induced in transformed cells and is recognized by immune effector cells via the activating NKG2D immunoreceptor. Soluble forms of NKG2DL have been reported in the serum of patients with several types of cancer. The present study investigated the diagnostic and prognostic significance of serum-soluble ULBP2 (sULBP2) in lung cancer patients. We used flow cytometry to evaluate the surface expression of NKG2DL by various lung cancer cells, while sULBP2 was measured using our original ELISA. In addition, the immunological effect of sULBP2 on peripheral blood mononuclear cells (PBMC) was examined by the (51) Cr release assay. We found that ULBP2 was highly expressed and that the sULBP2 level was elevated in supernatants of cultured non-small-cell lung cancer (NSCLC) cells as well as in the serum of NSCLC patients. ULBP2 levels were especially high in squamous cell carcinoma (SQ) patients. Clinical stage IIIB and IV NSCLC patients with a sULBP2 level ≥ 8.7 pg/mL showed significantly shorter survival than patients with sULBP2 <8.7 pg/mL. In multivariate analysis, a sULBP2 level ≥ 8.7 pg/mL (hazard ratio [HR], 2.13; P = 0.038) and clinical stage IV (HR, 2.65; P = 0.019) were independent determinants of a poor outcome. As a possible mechanism, we demonstrated that sULBP2 directly suppresses the cytolytic activity of PBMC. In conclusion, ULBP2 is the most significant NKG2DL for lung cancer, and sULBP2 is useful in the diagnosis of SQ and as a prognostic indicator for patients with advanced NSCLC.

Large-Scale Chromatin Rearrangements in Cancer.

Epigenetic abnormalities are extremely widespread in cancer. Some of them are mere consequences of transformation, but some actively contribute to cancer initiation and progression; they provide powerful new biological markers, as well as new targets for therapies. In this review, we examine the recent literature and focus on one particular aspect of epigenome deregulation: large-scale chromatin changes, causing global changes of DNA methylation or histone modifications. After a brief overview of the one-dimension (1D) and three-dimension (3D) epigenome in healthy cells and of its homeostasis mechanisms, we use selected examples to describe how many different events (mutations, changes in metabolism, and infections) can cause profound changes to the epigenome and fuel cancer. We then present the consequences for therapies and briefly discuss the role of single-cell approaches for the future progress of the field.

Deoxydehydration of Biomass-Derived Polyols Over Silver-Modified Ceria-Supported Rhenium Catalyst with Molecular Hydrogen.

Olefin production from polyols via deoxydehydration (DODH) was carried out over Ag-modified CeO2 -supported heterogeneous Re catalysts with H2 as a reducing agent. Both high DODH activity and low hydrogenation ability for C=C bonds were observed in the reaction of erythritol, giving a 1,3-butadiene yield of up to 90 % under "solvent-free" conditions. This catalyst is applicable to other substrates such as methyl glycosides (methyl α-fucopyranoside: 91 % yield of DODH product; methyl ß-ribofuranoside: 88 % yield), which were difficult to be converted to the DODH products over the DODH catalysts reported previously. ReOx -Ag/CeO2 was reused 3 times without a decrease of activity or selectivity after calcination as regeneration. Although the transmission electron microscopy energy-dispersive X-ray spectroscopy and X-ray absorption fine structure analyses showed that Re species were highly dispersed and Ag was present as metal particles with various sizes from well-dispersed species (<1 nm) to around 5 nm particles, the catalysts prepared from size-controlled Ag nanoparticles showed similar performance, indicating that the catalytic performance is insensitive to the Ag particle size.

Histone functions as a cell-surface receptor for AGEs.

Reducing sugars can covalently react with proteins to generate a heterogeneous and complex group of compounds called advanced glycation end products (AGEs). AGEs are generally considered as pathogenic molecules, mediating a pro-inflammatory response and contributing to the development of a number of human diseases. However, the intrinsic function of AGEs remains to be elucidated. We now provide multiple lines of evidence showing that AGEs can specifically bind histone localized on the cell surface as an AGE-binding protein, regulate the function of histone as a plasminogen receptor, and result in the regulation of monocytes/macrophage recruitment to the site of inflammation. Our finding of histone as a cell-surface receptor for AGEs suggests that, beside our common concept of AGEs as danger-associated molecular patterns mediating a pro-inflammatory response, they may also be involved in the homeostatic response via binding to histone.

Pembrolizumab-induced aseptic meningitis in a patient with non-small cell lung cancer: A case report and literature review of aseptic meningitis as an immune-related adverse event.

Aseptic meningitis is a rare immune-related adverse event (irAE), which occurs during treatment with immune checkpoint inhibitors (ICIs). This condition has non-specific symptoms and exhibits no clear signs on magnetic resonance imaging (MRI). There are only a few reports of aseptic meningitis caused by pembrolizumab treatment for non-small cell lung cancer (NSCLC). The present study includes a report of such a case and a review of the related literature. A 67-year-old Japanese man received first-line pembrolizumab treatment for NSCLC and subsequently developed severe nausea and vomiting. No significant findings were observed following a computed tomography (CT) scan, MRI of the brain and upper gastrointestinal tract, or upper gastrointestinal endoscopy. Cerebrospinal fluid analysis revealed lymphocyte infiltration and elevation of the IgG index, without indications of metastasis or infection, which suggested the presence of aseptic meningitis. The symptoms immediately improved following prednisolone treatment, and aseptic meningitis was diagnosed as an irAE related to pembrolizumab treatment. Given that aseptic meningitis can cause non-specific symptoms, including headache and nausea, the possibility of an irAE should be considered in patients with non-specific symptoms who are receiving ICIs, and a cerebrospinal fluid examination should be performed.