CWAS-Plus: Estimating category-wide association of rare noncoding variation from whole-genome sequencing data with cell-type-specific functional data.

Variants in cis-regulatory elements link the noncoding genome to human brain pathology; however, detailed analytic tools for understanding the association between cell-level brain pathology and noncoding variants are lacking. CWAS-Plus, adapted from a Python package for category-wide association testing (CWAS) employs both whole-genome sequencing and user-provided functional data to enhance noncoding variant analysis, with a faster and more efficient execution of the CWAS workflow. Here, we used single-nuclei assay for transposase-accessible chromatin with sequencing to facilitate CWAS-guided noncoding variant analysis at cell-type specific enhancers and promoters. Examining autism spectrum disorder whole-genome sequencing data (n = 7,280), CWAS-Plus identified noncoding de novo variant associations in transcription factor binding sites within conserved loci. Independently, in Alzheimer's disease whole-genome sequencing data (n = 1,087), CWAS-Plus detected rare noncoding variant associations in microglia-specific regulatory elements. These findings highlight CWAS-Plus's utility in genomic disorders and scalability for processing large-scale whole-genome sequencing data and in multiple-testing corrections. CWAS-Plus and its user manual are available at https://github.com/joonan-lab/cwas/ and https://cwas-plus.readthedocs.io/en/latest/, respectively.

Structural insights into ubiquitin chain cleavage by Legionella ovarian tumor deubiquitinases.

Although ubiquitin is found only in eukaryotes, several pathogenic bacteria and viruses possess proteins that hinder the host ubiquitin system. Legionella, a gram-negative intracellular bacterium, possesses an ovarian tumor (OTU) family of deubiquitinases (Lot DUBs). Herein, we describe the molecular characteristics of Lot DUBs. We elucidated the structure of the LotA OTU1 domain and revealed that entire Lot DUBs possess a characteristic extended helical lobe that is not found in other OTU-DUBs. The structural topology of an extended helical lobe is the same throughout the Lot family, and it provides an S1' ubiquitin-binding site. Moreover, the catalytic triads of Lot DUBs resemble those of the A20-type OTU-DUBs. Furthermore, we revealed a unique mechanism by which LotA OTU domains cooperate together to distinguish the length of the chain and preferentially cleave longer K48-linked polyubiquitin chains. The LotA OTU1 domain itself cleaves K6-linked ubiquitin chains, whereas it is also essential for assisting the cleavage of longer K48-linked polyubiquitin chains by the OTU2 domain. Thus, this study provides novel insights into the structure and mechanism of action of Lot DUBs.

Effect of N doping on the microstructure and dry etch properties of amorphous carbon deposited with a DC sputtering system.

The importance of developing a hardmask with excellent performance, and physical and chemical properties to utilize in long-term etching is spotlighted due to the acceleration of development in high-density semiconductors. To develop such a hardmask, amorphous carbon hardmasks doped with various concentrations of N were fabricated with a DC magnetron sputtering system using varying inert gas (Ar to N2) ratios. In contrast to the expectation that doped nitrogen would block the permeation of fluorine and improve the etch resistance, as the nitrogen concentration increased, the selectivity of the doped amorphous carbon films decreased. To understand this degradation with increasing nitrogen concentration, systematic X-ray photoelectron spectroscopy (XPS), radial distribution function (RDF), and X-ray reflectometry (XRR) analyses were conducted. In this study, we found that as the amount of nitrogen increased, the density of the film decreased, and the amount of pyridinic and pyrrolic nitrogen bonds with low formation energy increased. In contrast, based on time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis of etched nitrogen-doped amorphous carbon films, the penetration depth of fluorine ions from the etchant decreased as the amount of nitrogen increased. Therefore, in order to develop an excellent hardmask using amorphous carbon, it is important to increase the density of the film and the nitrogen concentration in the film while lowering the ratio of pyrrolic N to pyridinic N, i.e., increasing the ratio of graphitic N.

Ubiquitin-regulating effector proteins from Legionella.

Ubiquitin is relatively modest in size but involves almost entire cellular signaling pathways. The primary role of ubiquitin is maintaining cellular protein homeostasis. Ubiquitination regulates the fate of target proteins using the proteasome- or autophagymediated degradation of ubiquitinated substrates, which can be either intracellular or foreign proteins from invading pathogens. Legionella, a gram-negative intracellular pathogen, hinders the host-ubiquitin system by translocating hundreds of effector proteins into the host cell's cytoplasm. In this review, we describe the current understanding of ubiquitin machinery from Legionella. We summarize structural and biochemical differences between the host-ubiquitin system and ubiquitin-related effectors of Legionella. Some of these effectors act much like canonical host-ubiquitin machinery, whereas others have distinctive structures and accomplish non-canonical ubiquitination via novel biochemical mechanisms. [BMB Reports 2022; 55(7): 316-322].

New pathway for the formation of metallic cubic phase Ge-Sb-Te compounds induced by an electric current.

The novel discovery of a current-induced transition from insulator to metal in the crystalline phase of Ge2Sb2Te5 and GeSb4Te7 have been studied by means of a model using line-patterned samples. The resistivity of cubic phase Ge-Sb-Te compound was reduced by an electrical current (~1 MA/cm(2)), and the final resistivity was determined based on the stress current density, regardless of the initial resistivity and temperature, which indicates that the conductivity of Ge-Sb-Te compound can be modulated by an electrical current. The minimum resistivity of Ge-Sb-Te materials can be achieved at high kinetic rates by applying an electrical current, and the material properties change from insulating to metallic behavior without a phase transition. The current-induced metal transition is more effective in GeSb4Te7 than Ge2Sb2Te5, which depends on the intrinsic vacancy of materials. Electromigration, which is the migration of atoms induced by a momentum transfer from charge carriers, can easily promote the rearrangement of vacancies in the cubic phase of Ge-Sb-Te compound. This behavior differs significantly from thermal annealing, which accompanies a phase transition to the hexagonal phase. This result suggests a new pathway for modulating the electrical conductivity and material properties of chalcogenide materials by applying an electrical current.

Mitogen-activated protein kinase phosphatase 2 regulates histone H3 phosphorylation via interaction with vaccinia-related kinase 1.

Mitogen-activated protein kinase phosphatase 2 (MKP2) is a member of the dual-specificity MKPs that regulate MAP kinase signaling. However, MKP2 functions are still largely unknown. In this study, we showed that MKP2 could regulate histone H3 phosphorylation under oxidative stress conditions. We found that MKP2 inhibited histone H3 phosphorylation by suppressing vaccinia-related kinase 1 (VRK1) activity. Moreover, this regulation was dependent on the selective interaction with VRK1, regardless of its phosphatase activity. The interaction between MKP2 and VRK1 mainly occurred in the chromatin, where histones are abundant. We also observed that the protein level of MKP2 and its interaction with histone H3 increased from G1 to M phase during the cell cycle, which is similar to the VRK1 profile. Furthermore, MKP2 specifically regulated the VRK1-mediated histone H3 phosphorylation at M phase. Taken together, these data suggest a novel function of MKP2 as a negative regulator of VRK1-mediated histone H3 phosphorylation.

Mind bomb-1 is an essential modulator of long-term memory and synaptic plasticity via the Notch signaling pathway.

BACKGROUND: Notch signaling is well recognized as a key regulator of the neuronal fate during embryonic development, but its function in the adult brain is still largely unknown. Mind bomb-1 (Mib1) is an essential positive regulator in the Notch pathway, acting non-autonomously in the signal-sending cells. Therefore, genetic ablation of Mib1 in mature neuron would give valuable insight to understand the cell-to-cell interaction between neurons via Notch signaling for their proper function. RESULTS: Here we show that the inactivation of Mib1 in mature neurons in forebrain results in impaired hippocampal dependent spatial memory and contextual fear memory. Consistently, hippocampal slices from Mib1-deficient mice show impaired late-phase, but not early-phase, long-term potentiation and long-term depression without change in basal synaptic transmission at SC-CA1 synapses. CONCLUSIONS: These data suggest that Mib1-mediated Notch signaling is essential for long-lasting synaptic plasticity and memory formation in the rodent hippocampus.

HnRNP A1 phosphorylated by VRK1 stimulates telomerase and its binding to telomeric DNA sequence.

The telomere integrity is maintained via replication machinery, telomere associated proteins and telomerase. Many telomere associated proteins are regulated in a cell cycle-dependent manner. Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), a single-stranded oligonucleotide binding protein, is thought to play a pivotal role in telomere maintenance. Here, we identified hnRNP A1 as a novel substrate for vaccinia-related kinase 1 (VRK1), a cell cycle regulating kinase. Phosphorylation by VRK1 potentiates the binding of hnRNP A1 to telomeric ssDNA and telomerase RNA in vitro and enhances its function for telomerase reaction. VRK1 deficiency induces a shortening of telomeres with an abnormal telomere arrangement and activation of DNA-damage signaling in mouse male germ cells. Together, our data suggest that VRK1 is required for telomere maintenance via phosphorylation of hnRNP A1, which regulates proteins associated with the telomere and telomerase RNA.

Macro histone H2A1.2 (macroH2A1) protein suppresses mitotic kinase VRK1 during interphase.

VRK1-mediated phosphorylation of histone H3 should be restricted in mitosis for consistent cell cycling, and defects in this process trigger cellular catastrophe. However, an interphasic regulator against VRK1 has not been actually investigated so far. Here, we show that the histone variant macrodomain-containing histone H2A1.2 functions as a suppressor against VRK1 during interphase. The level of macroH2A1.2 was markedly reduced in the mitotic phase, and the macroH2A1.2-mediated inhibition of histone H3 phosphorylation occurred mainly during interphase. We also found direct interaction and binding features between VRK1 and macroH2A1.2 by NMR spectroscopy. Hence, our findings might provide valuable insight into the underlying molecular mechanism regarding an epigenetic regulation of histone H3 during the cell cycle.

Protein kinase Cδ regulates vaccinia-related kinase 1 in DNA damage-induced apoptosis.

Vaccinia-related kinase 1 (VRK1) is a novel serine/threonine kinase that plays an important role in cell proliferation. However, little is known about the upstream regulators of VRK1 activity. Here we provide evidence for a role of protein kinase Cδ (PKCδ) in the regulation of murine VRK1. We show that PKCδ interacts with VRK1, phosphorylates the Ser-355 residue in the putative regulatory region, and negatively regulates its kinase activity in vitro. Intriguingly, PKCδ-induced cell death was facilitated by phosphorylation of VRK1 when cells were exposed to a DNA-damaging agent. In addition, p53 played a critical role in the regulation of DNA damage-induced cell death accompanied by PKCδ-mediated modulation of VRK1. In p53-deficient cells, PKCδ-mediated phosphorylation of VRK1 had no effect on cell viability. However, cells overexpressing p53 exhibited significant reduction of cell viability when cotransfected with both VRK1 and PKCδ. Taken together, these results indicate that PKCδ regulates phosphorylation and down-regulation of VRK1, thereby contributing to cell cycle arrest and apoptotic cell death in a p53-dependent manner.

Cooperative roles of c-Abl and Cdk5 in regulation of p53 in response to oxidative stress.

The p53 tumor suppressor protein, a critical modulator of cellular stress responses, is activated through diverse mechanisms that result in its stabilization and transcriptional activation. p53 activity is controlled by transcriptional, translational, and post-translational regulation. The major mechanisms of p53 regulation occur primarily through interactions with HDM2, an E3 ubiquitin ligase that leads to p53 nuclear export and degradation. Here, we demonstrate that hydrogen peroxide-induced oxidative stress elicits down-regulation of HDM2. c-Abl mediates down-regulation of HDM2, leading to an increase of p53 level. Moreover, Cdk5 (cyclin-dependent kinase 5), a proline-directed Ser/Thr kinase, additionally increases p53 stability via post-translational modification of p53 in response to hydrogen peroxide. The p53 protein stabilized by c-Abl and Cdk5 is transcriptionally active; however, transcription of its target gene is differentially regulated with selective binding of p53 on promoter regions of its target genes by c-Abl. In addition, c-Abl modulates Cdk5 activity via phosphorylation of tyrosine 15 in cooperation with cleavage of p35 to p25. Our results show that c-Abl and Cdk5 cooperatively regulate maximal activation of p53, resulting in neuronal death in response to oxidative stress by hydrogen peroxide. These findings aid in clarifying the mechanism underlying the occurrence of neuronal apoptosis as a result of c-Abl and Cdk5-mediated p53 stabilization and transcriptional activation.

Sphingosine-1-phosphate modulates both lipolysis and leptin production in differentiated rat white adipocytes.

Sphingosine-1-phosphate (S1P) is a pluripotent lipid mediator that transmits signals through a family of G protein-coupled receptors to control diverse biological processes. Here, we investigated the effects of S1P on the levels of intracellular calcium and cAMP in differentiated rat white adipocytes and two important aspects of adipocyte-specific physiology, lipolysis and leptin production. In adipocytes, S1P signaling pathway was functionally linked to phospholipase C via pertussis-toxin-sensitive G protein. Interestingly, at higher S1P concentration (1-30 microM), it also induced cAMP generation in a concentration-dependent manner, which was pertussis toxin insensitive and was mimicked by dihydro-S1P and sphingosylphosphoryl-choline but not by its related metabolites, ceramide and sphingosine, or by its structural analogs, phyto-S1P and lysophosphatidic acid. Suramin, a known inhibitor of ligand-receptor interactions, reduced S1P-induced cAMP generation by 60% of control, whereas forskolin-induced cAMP increase was not affected by treatment with suramin. The S1P-induced cAMP generation was functionally linked to cAMP response element-binding protein phosphorylation. Finally, S1P significantly reduced insulin-induced mRNA of ob gene and leptin secretion, whereas S1P increased glycerol release from adipocytes. Both effects of S1P were reversed by a selective adenylyl cyclase inhibitor, SQ22536, without significantly affecting basal values. In conclusion, extracellular S1P elicits the elevation of cytosolic Ca2+ and cAMP with a distinct concentration dependency, and S1P-induced cAMP generation may be mediated by S1P-selective receptors rather than intracellular targets, and the activated adenylyl cyclase-cAMP signaling pathways subsequently increase lipolysis and decrease insulin-induced leptin production in rat white adipocytes.

Effect of rottlerin, a PKC-delta inhibitor, on TLR-4-dependent activation of murine microglia.

In microglia, Toll-like receptors have been shown to recognize pathogen-associated molecular patterns and initiate innate immune responses upon interaction with infectious agents. The effect of rottlerin, a PKC-delta specific inhibitor, on TLR-4-mediated signaling was investigated in murine microglia stimulated with lipopolysaccharide and taxol. Pretreatment of microglia cells with rottlerin decreased LPS- and taxol-induced nitric oxide production in a concentration-dependent manner (IC50 = 99.1+/-1.5 nM). Through MTT and FACS analysis, we found that the inhibition effect of rottlerin was not due to microglial cell death. Rottlerin pretreatment also attenuated LPS-induced phosphorylation of IkappaB-alpha, nuclear translocation of NF-kappaB, and expression of type II nitric oxide synthase. In addition, microglial phagocytosis in response to TLR-4 activation was diminished in which rottlerin was pretreated. Together, these data raise the possibility that certain PKC-delta specific inhibitors can modulate TLR-4-derived signaling and inflammatory target gene expression, and can alter susceptibility to microbial infection and chronic inflammatory diseases in central nervous system.