Visible-Light-Promoted α-C(sp3)-H Amination of Ethers with Azoles and Amides.

A visible-light-induced highly efficient C(sp3)-H amination of ethers with amides and azoles has been presented under mild conditions via a nitrogen- and carbon-centered radical coupling process. This protocol successfully utilizes 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tert-butyl nitrite (TBN) as cocatalysts to deliver the aminated products of ethers under aerobic conditions. Notably, the developed reaction features the corresponding products in good yields (up to 93%) with a wide substrate scope. The mechanistic study indicates that C-N bond formation proceeds via a direct radical cross-coupling process. Preliminary biological activity analysis indicates that the resulting products have good and selective inhibitory activity on osteosarcoma (OS) cell lines and are promising for use as hits for drug discovery.

Enantioselective Construction of C3-Multifunctionalization α-Hydroxy-ß-amino Pyridines via α-Pyridyl Diazoacetate, Water, and Imines for Drug Hunting.

An asymmetric catalytic approach for the construction of C3-multifunctionalization α-hydroxy-ß-amino pyridines has been reported. The products can be accessed by the modulation of two chiral catalysts independently in high yield and with good enantioselectivity. The method features mild reaction conditions and an excellent functional group tolerance. Biological activity analysis shows that the resulting products have a selective antiosteosarcoma activity on 143B cells.

Effect of Process Parameters on the Performance of Drop-On-Demand 3D Inkjet Printing: Geometrical-Based Modeling and Experimental Validation.

As additive manufacturing has evolved, 3D inkjet printing (IJP) has become a promising alternative manufacturing method able to manufacture functional multi-material parts in a single process. However, issues with part quality in terms of dimensional errors and lack of precision still restrict its industrial and commercial applications. This study aims at improving the dimensional accuracy of 3D IJP parts by developing an optimization-oriented simulation tool of droplet behavior during the drop-on-demand 3D IJP process. The simulation approach takes into consideration the effect of droplet volume, droplet center-to-center distance, coverage percentage of jetted droplets, the contact angle of the ink on the solid substrate and coalescence performance of overlapping droplets, in addition to the number of printed layers. Following the development of the simulation tool using MATLAB, its feasibility was experimentally validated and the results showed a good agreement with a maximum deviation of 2.25% for horizontal features. In addition, the simulated horizontal features are compared with the results of "Inkraster" software, which also illustrates droplet behavior, however, only in 2D. For vertical features, a dial gauge indicator is used to measure the sample height, and the validation results show that the simulation tool can predicate the height of the sample with an average error of 10.89% for a large droplet diameter and 8.09% for a small diameter. The simulation results were found to be in a good agreement with the dimensions of the printed parts. The developed tool was then used to elucidate the effect of resolution of processed TIFF image and droplet diameter on the dimensional accuracy of 3D IJP parts.

LIN28B inhibition sensitizes cells to p53-restoring PPI therapy through unleashed translational suppression.

p53 is the most highly mutated tumor suppressor across multiple types of human cancers. The level and function of p53 are fine-tuned through multifaced mechanisms in which the protein-protein interaction between p53 and MDM2 is considered as a major circuit. Recent studies suggest therapeutic strategy attempts to restore p53 function by small molecule inhibitors targeting p53-MDM2 interaction can be a promising direction in treating cancers with wild-type or functional p53. Currently, clinical tests of the p53-MDM2 protein-protein interaction inhibitors (PPIs) are underway. However, it remains elusive about the biomarkers that may predict the therapeutic responses to those inhibitors. Here we report that RNA-binding protein LIN28B directly regulates p53 through binding to the 5'΄ untranslated region of p53 mRNA and blocks its translation by competing with a translation enhancer protein, ribosomal protein L26 (RPL26). This regulatory mechanism of LIN28B does not involve let-7 maturation or the canonical protein turnover pathway of p53. Furthermore, we show that inhibition of LIN28B unleashes the translational suppression of p53 through RPL26, and leads to enhanced sensitivities of cancer cells to inhibitors of p53-MDM2 interaction. Together, we demonstrate a competitive regulatory mechanism of p53 by LIN28B, which has important implications in developing biomarkers to the therapies aiming to reinstate p53 function.

Integrated Chemoenzymatic Approach to Streamline the Assembly of Complex Glycopeptides in the Liquid Phase.

Glycosylation of proteins is a complicated post-translational modification. Despite the significant progress in glycoproteomics, accurate functions of glycoproteins are still ambiguous owing to the difficulty in obtaining homogeneous glycopeptides or glycoproteins. Here, we describe a streamlined chemoenzymatic method to prepare complex glycopeptides by integrating hydrophobic tag-supported chemical synthesis and enzymatic glycosylations. The hydrophobic tag is utilized to facilitate peptide chain elongation in the liquid phase and expeditious product separation. After removal of the tag, a series of glycans are installed on the peptides via efficient glycosyltransferase-catalyzed reactions. The general applicability and robustness of this approach are exemplified by efficient preparation of 16 well-defined SARS-CoV-2 O-glycopeptides, 4 complex MUC1 glycopeptides, and a 31-mer glycosylated glucagon-like peptide-1. Our developed approach will open up a new range of easy access to various complex glycopeptides of biological importance.

Novel 2-phenyl-3-(Pyridin-2-yl) thiazolidin-4-one derivatives as potent inhibitors for proliferation of osteosarcoma cells in vitro and in vivo.

Due to unknown pathogenesis and unidentified drug target, no drug for the treatment of osteosarcoma (OS) has been launched to the market. Herein, thiazolidinone 1a was discovered as a hit compound by phenotypic screening with an in-house patrimonial collection of structural diversity. The following SAR (Structure-Activity Relationship) study affords the final water-soluble lead compound (R)-8i as a potential inhibitor for the proliferation of OS cells by the modulation of solubility of the compounds with remarkable cellular potency (IC50 = 21.9 nM for MNNG/HOS cells) and in vivo efficacy (52.9% inhibition OS growth in mice), as well as pharmacokinetic properties. (R)-8i also significantly suppresses OS cell migration in vitro and showed to be well-tolerated. Our preliminary investigation shows that the effects of (R)-8i are not dependent on p53 and myoferlin (MYOF). These results suggest that (R)-8i might be a potential drug candidate for OS treatment.

Clutter Suppression Method for Off-Grid Effects Mitigation in Airborne Passive Radars with Contaminated Reference Signals.

For an airborne passive radar with contaminated reference signals, the clutter caused by multipath (MP) signals involved in the reference channel (MP clutter) corrupts the covariance estimation in space-time adaptive processing (STAP). In order to overcome the severe STAP performance degradation caused by impure reference signals and off-grid effects, a novel MP clutter suppression method based on local search is proposed for airborne passive radar. In the proposed method, the global dictionary is constructed based on the sparse measurement model of MP clutter, and the global atoms that are most relevant to the residual are selected. Then, the local dictionary is designed iteratively, and local searches are performed to match real MP clutter points. Finally, the off-grid effects are mitigated, and the MP clutter is suppressed from all matched atoms. A range of simulations is conducted in order to demonstrate the effectiveness of the proposed method.

Detection of Long Noncoding RNA Expression by Real-Time PCR.

Recent advances in sequencing technology and bioinformatic analysis promote the identification of long noncoding RNA (lncRNA), a novel form of untranslated RNA transcript. Long coding RNA has been extensively investigated for its fundamental biological functions in a broad spectrum of pathogenetic and therapeutic studies. The level of lncRNA expression varies among different tissue types and contexts. Therefore, a quantitative method to accurately measure lncRNA expression is highly desired. Real-time PCR analysis enables us to conveniently determine the identity and abundance of lncRNA in a time-efficient manner. Here, we introduce how to use real-time PCR to analyze and quantify a defined lncRNA.

Diversity-Oriented Chemoenzymatic Synthesis of Sulfated and Nonsulfated Core 2 O-GalNAc Glycans.

A diversity-oriented chemoenzymatic approach for the collective preparation of sulfated core 2 O-GalNAc glycans and their nonsulfated counterparts was described. A sulfated trisaccharide and a nonsulfated trisaccharide were chemically synthesized by combining flexible protected group manipulations and sequential one-pot glycosylations. The divergent enzymatic extension of these two trisaccharides, using a panel of robust glycosyltransferases that can recognize sulfated substrates and differentiating the branches with specifically designed glycosylation sequences to achieve regioselective sialylation, provided 36 structurally well-defined O-GalNAc glycans.

OLIG2 maintenance is not essential for diffuse intrinsic pontine glioma cell line growth but regulates tumor phenotypes.

BACKGROUND: Diffuse intrinsic pontine glioma (DIPG) is a pediatric lethal high-grade brainstem glioma with no effective therapies. OLIG2 (oligodendrocyte transcription factor 2) was reported to be critical for the growth of a DIPG cell line CCHMC-DIPG-1. Surprisingly, we found that the CCHMC-DIPG-1 cells express little OLIG2 and exhibit a mesenchymal phenotype, which raised a question regarding the role of OLIG2 in the growth of DIPG cells. METHODS: We evaluated the function of OLIG2 in different DIPG cell lines through molecular and genetic approaches and performed transcriptomic and genomic landscape profiling including whole-genome bisulfite sequencing, RNA-seq, ATAC-seq, and ChIP-seq. shRNA-mediated knockdown and CRISPR-Cas9-mediated knockout approaches were utilized to assess OLIG2 functions in DIPG cell growth. RESULTS: We found that DIPG cells are phenotypically heterogeneous and exhibit the characteristics of distinct malignant gliomas including proneural, classical, and mesenchymal subtypes. OLIG2 knockdown did not impact the growth of CCHMC-DIPG-1 cells, wherein OLIG2 is epigenetically silenced. Moreover, OLIG2 deletion did not substantially impair OLIG2-expressing proneural-like DIPG growth but led to an upregulation of HIPPO-YAP1 and epidermal growth factor receptor (EGFR) signaling and a tumor phenotype shift. Targeting HIPPO-YAP1 and EGFR signaling in OLIG2-deficient DIPG cells inhibited tumor cell growth. CONCLUSIONS: Our data indicate that OLIG2 is dispensable for DIPG growth but regulates the phenotypic switch of DIPG tumor cells. OLIG2 downregulation leads to deregulation of adaptive YAP1 and EGFR signaling. Targeting YAP1 and EGFR pathways inhibits the growth of OLIG2-deficient DIPG cells, pointing to a therapeutic potential by targeting adaptive signaling to treat DIPG tumors with nominal OLIG2 expression.

Emerging role of SWI/SNF complex deficiency as a target of immune checkpoint blockade in human cancers.

Mammalian SWI/SNF complex is a key chromatin remodeler that reshapes nucleosomes and regulates DNA accessibility. Mutations in SWI/SNF subunits are found in a broad spectrum of human cancers; however, the mechanisms of how these aberrations of SWI/SNF complex would impact tumorigenesis and cancer therapeutics remain to be elucidated. Studies have demonstrated that immune checkpoint blockade (ICB) therapy is promising in cancer treatment. Nevertheless, suitable biomarkers that reliably predict the clinical response to ICB are still lacking. Emerging evidence has suggested that SWI/SNF components play novel roles in the regulation of anti-tumor immunity, and SWI/SNF deficiency can be therapeutically targeted by ICB. These findings manifest the prominence of the SWI/SNF complex as a stratification biomarker that predicts treatment (therapeutic) response to ICB. In this review, we summarize the recent advances in ICB therapy by harnessing the cancer-specific vulnerability elicited by SWI/SNF deficiency. We provide novel insights into a comprehensive understanding of the underlying mechanisms by which SWI/SNF functions as a modulator of anti-tumor immunity.

Microstructure and Mechanical Properties of AlSi7Mg0.6 Aluminum Alloy Fabricated by Wire and Arc Additive Manufacturing Based on Cold Metal Transfer (WAAM-CMT).

Wire and arc additive manufacturing based on cold metal transfer (WAAM-CMT) has aroused wide public concern in recent years as one of the most advanced technologies for manufacturing components with complex geometries. However, the microstructure and mechanical properties of the parts fabricated by WAAM-CMT technology mostly are intolerable for engineering application and should be improved necessarily. In this study, heat treatment was proposed to optimize the microstructure and enhance mechanical properties in the case of AlSi7Mg0.6 alloy. After heat treatment, the division between coarse grain zone and fine grain zone of as-deposited samples seemed to disappear and the distribution of Si and Mg elements was more uniform. What is more, the yield strength and ultimate tensile strength were improved significantly, while the ductility could be sustained after heat treatment. The improvement of strength is attributed to precipitation strengthening, and the shape change of Si phase. No reduction in ductility is due to the higher work hardening rate caused by nanostructured precipitate. It is proved that heat treatment as an effective method can control the microstructure and enhance comprehensive mechanical properties, which will boost rapid development of WAAM industrial technology.

Evaluation of root resorption after comprehensive orthodontic treatment using cone beam computed tomography (CBCT): a meta-analysis.

BACKGROUND: Orthodontic treatment can result in root resorption (RR). Traditional two-dimensional (2D) data exhibit magnification, deformation and positioning problems. Cone beam computed tomography (CBCT) contains more accurate three-dimensional (3D) information. This study identified and qualified the extent and location of root resorption using cone beam computed tomography (CBCT) after comprehensive orthodontic treatment. METHODS: Studies comparing the RR before and after comprehensive orthodontic treatment using CBCT were identified using electronic searches of databases, including Cochrane, PubMed, EMBASE, China National Knowledge Infrastructure (CNKI) and Web of Science, and manual searches in relevant journals and the reference lists of the included studies until Oct 25, 2017. The extraction of data and the risk of bias evaluation were conducted by two investigators independently. The methodological quality of the included studies was assessed using the methodological index for non-randomized studies (MINORS). Studies that reported the length and volume of teeth were used for quantitative analyses. RESULTS: Twelve studies were included in the meta-analysis. The length of all teeth after intervention was significantly shorter than that before treatment (MD = 0.80, 95% CI 0.56, 1.03, P < 0.00001). The sequence of RR from heaviest to lightest was maxillary lateral incisors, maxillary central incisors, mandibular anterior teeth, and maxillary canines. Studies were divided into two subgroups based on the use of tooth extraction. Root shortening after treatment was observed in both groups, and extraction caused more root resorption than was observed in the non-extraction group. CONCLUSIONS: There were different degrees of root resorption after orthodontics, but it was clinically acceptable. Root resorption established in CBCT research was less serious and more accurate than that observed in the two-dimensional research. Current evidence suggests that root length and volume were reduced after orthodontic treatment. The order of the amount of RR was maxillary lateral incisors, maxillary central incisors and mandibular anterior teeth. Most of the articles were complicated by different confounding factors. Therefore, more high-quality clinical trials are needed to determine the risk factors of root resorption and optimal protocols for treatment and to draw more reliable conclusions.

Dual Requirement of CHD8 for Chromatin Landscape Establishment and Histone Methyltransferase Recruitment to Promote CNS Myelination and Repair.

Disruptive mutations in chromatin remodeler CHD8 cause autism spectrum disorders, exhibiting widespread white matter abnormalities; however, the underlying mechanisms remain elusive. We show that cell-type specific Chd8 deletion in oligodendrocyte progenitors, but not in neurons, results in myelination defects, revealing a cell-intrinsic dependence on CHD8 for oligodendrocyte lineage development, myelination and post-injury remyelination. CHD8 activates expression of BRG1-associated SWI/SNF complexes that in turn activate CHD7, thus initiating a successive chromatin remodeling cascade that orchestrates oligodendrocyte lineage progression. Genomic occupancy analyses reveal that CHD8 establishes an accessible chromatin landscape, and recruits MLL/KMT2 histone methyltransferase complexes distinctively around proximal promoters to promote oligodendrocyte differentiation. Inhibition of histone demethylase activity partially rescues myelination defects of CHD8-deficient mutants. Our data indicate that CHD8 exhibits a dual function through inducing a cascade of chromatin reprogramming and recruiting H3K4 histone methyltransferases to establish oligodendrocyte identity, suggesting potential strategies of therapeutic intervention for CHD8-associated white matter defects.

Programming of Schwann Cells by Lats1/2-TAZ/YAP Signaling Drives Malignant Peripheral Nerve Sheath Tumorigenesis.

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive Schwann cell (SC)-lineage-derived sarcomas. Molecular events driving SC-to-MPNST transformation are incompletely understood. Here, we show that human MPNSTs exhibit elevated HIPPO-TAZ/YAP expression, and that TAZ/YAP hyperactivity in SCs caused by Lats1/2 loss potently induces high-grade nerve-associated tumors with full penetrance. Lats1/2 deficiency reprograms SCs to a cancerous, progenitor-like phenotype and promotes hyperproliferation. Conversely, disruption of TAZ/YAP activity alleviates tumor burden in Lats1/2-deficient mice and inhibits human MPNST cell proliferation. Moreover, genome-wide profiling reveals that TAZ/YAP-TEAD1 directly activates oncogenic programs, including platelet-derived growth factor receptor (PDGFR) signaling. Co-targeting TAZ/YAP and PDGFR pathways inhibits tumor growth. Thus, our findings establish a previously unrecognized convergence between Lats1/2-TAZ/YAP signaling and MPNST pathogenesis, revealing potential therapeutic targets in these untreatable tumors.

A reciprocal regulatory loop between TAZ/YAP and G-protein Gαs regulates Schwann cell proliferation and myelination.

Schwann cell (SC) myelination in the peripheral nervous system is essential for motor function, and uncontrolled SC proliferation occurs in cancer. Here, we show that a dual role for Hippo effectors TAZ and YAP in SC proliferation and myelination through modulating G-protein expression and interacting with SOX10, respectively. Developmentally regulated mutagenesis indicates that TAZ/YAP are critical for SC proliferation and differentiation in a stage-dependent manner. Genome-wide occupancy mapping and transcriptome profiling reveal that nuclear TAZ/YAP promote SC proliferation by activating cell cycle regulators, while targeting critical differentiation regulators in cooperation with SOX10 for myelination. We further identify that TAZ targets and represses Gnas, encoding Gαs-protein, which opposes TAZ/YAP activities to decelerate proliferation. Gnas deletion expands SC precursor pools and blocks peripheral myelination. Thus, the Hippo/TAZ/YAP and Gαs-protein feedback circuit functions as a fulcrum balancing SC proliferation and differentiation, providing insights into molecular programming of SC lineage progression and homeostasis.

miR-219 Cooperates with miR-338 in Myelination and Promotes Myelin Repair in the CNS.

A lack of sufficient oligodendrocyte myelination contributes to remyelination failure in demyelinating disorders. miRNAs have been implicated in oligodendrogenesis; however, their functions in myelin regeneration remained elusive. Through developmentally regulated targeted mutagenesis, we demonstrate that miR-219 alleles are critical for CNS myelination and remyelination after injury. Further deletion of miR-338 exacerbates the miR-219 mutant hypomyelination phenotype. Conversely, miR-219 overexpression promotes precocious oligodendrocyte maturation and regeneration processes in transgenic mice. Integrated transcriptome profiling and biotin-affinity miRNA pull-down approaches reveal stage-specific miR-219 targets in oligodendrocytes and further uncover a novel network for miR-219 targeting of differentiation inhibitors including Lingo1 and Etv5. Inhibition of Lingo1 and Etv5 partially rescues differentiation defects of miR-219-deficient oligodendrocyte precursors. Furthermore, miR-219 mimics enhance myelin restoration following lysolecithin-induced demyelination as well as experimental autoimmune encephalomyelitis, principal animal models of multiple sclerosis. Together, our findings identify context-specific miRNA-regulated checkpoints that control myelinogenesis and a therapeutic role for miR-219 in CNS myelin repair.

lncRNA Functional Networks in Oligodendrocytes Reveal Stage-Specific Myelination Control by an lncOL1/Suz12 Complex in the CNS.

Long noncoding RNAs (lncRNAs) are emerging as important regulators of cellular functions, but their roles in oligodendrocyte myelination remain undefined. Through de novo transcriptome reconstruction, we establish dynamic expression profiles of lncRNAs at different stages of oligodendrocyte development and uncover a cohort of stage-specific oligodendrocyte-restricted lncRNAs, including a conserved chromatin-associated lncOL1. Co-expression network analyses further define the association of distinct oligodendrocyte-expressing lncRNA clusters with protein-coding genes and predict lncRNA functions in oligodendrocyte myelination. Overexpression of lncOL1 promotes precocious oligodendrocyte differentiation in the developing brain, whereas genetic inactivation of lncOL1 causes defects in CNS myelination and remyelination following injury. Functional analyses illustrate that lncOL1 interacts with Suz12, a component of polycomb repressive complex 2, to promote oligodendrocyte maturation, in part, through Suz12-mediated repression of a differentiation inhibitory network that maintains the precursor state. Together, our findings reveal a key lncRNA epigenetic circuitry through interaction with chromatin-modifying complexes in control of CNS myelination and myelin repair.

Olig2-Targeted G-Protein-Coupled Receptor Gpr17 Regulates Oligodendrocyte Survival in Response to Lysolecithin-Induced Demyelination.

Demyelinating diseases, such as multiple sclerosis, are known to result from acute or chronic injury to the myelin sheath and inadequate remyelination; however, the underlying molecular mechanisms remain unclear. Here, we performed genome occupancy analysis by chromatin immunoprecipitation sequencing in oligodendrocytes in response to lysolecithin-induced injury and found that Olig2 and its downstream target Gpr17 are critical factors in regulating oligodendrocyte survival. After injury to oligodendrocytes, Olig2 was significantly upregulated and transcriptionally targeted the Gpr17 locus. Gpr17 activation inhibited oligodendrocyte survival by reducing the intracellular cAMP level and inducing expression of the pro-apoptotic gene Xaf1 The protein kinase A signaling pathway and the transcription factor c-Fos mediated the regulatory effects of Gpr17 in oligodendrocytes. We showed that Gpr17 inhibition elevated Epac1 expression and promoted oligodendrocyte differentiation. The loss of Gpr17, either globally or specifically in oligodendrocytes, led to an earlier onset of remyelination after myelin injury in mice. Similarly, pharmacological inhibition of Gpr17 with pranlukast promoted remyelination. Our findings indicate that Gpr17, an Olig2 transcriptional target, is activated after injury to oligodendrocytes and that targeted inhibition of Gpr17 promotes oligodendrocyte remyelination. SIGNIFICANCE STATEMENT: Genome occupancy analysis of oligodendrocytes in response to lysolecithin-mediated demyelination injury revealed that Olig2 and its downstream target Gpr17 are part of regulatory circuitry critical for oligodendrocyte survival. Gpr17 inhibits oligodendrocyte survival through activation of Xaf1 and cell differentiation by reducing Epac1 expression. The loss of Gpr17 in mice led to precocious myelination and an earlier onset of remyelination after demyelination. Pharmacological inhibition of Gpr17 promoted remyelination, highlighting the potential for Gpr17-targeted therapeutic approaches in demyelination diseases.

Olig2-Dependent Reciprocal Shift in PDGF and EGF Receptor Signaling Regulates Tumor Phenotype and Mitotic Growth in Malignant Glioma.

Malignant gliomas exhibit extensive heterogeneity and poor prognosis. Here we identify mitotic Olig2-expressing cells as tumor-propagating cells in proneural gliomas, elimination of which blocks tumor initiation and progression. Intriguingly, deletion of Olig2 resulted in tumors that grow, albeit at a decelerated rate. Genome occupancy and expression profiling analyses reveal that Olig2 directly activates cell-proliferation machinery to promote tumorigenesis. Olig2 deletion causes a tumor phenotypic shift from an oligodendrocyte precursor-correlated proneural toward an astroglia-associated gene expression pattern, manifest in downregulation of platelet-derived growth factor receptor-α and reciprocal upregulation of epidermal growth factor receptor (EGFR). Olig2 deletion further sensitizes glioma cells to EGFR inhibitors and extends the lifespan of animals. Thus, Olig2-orchestrated receptor signaling drives mitotic growth and regulates glioma phenotypic plasticity. Targeting Olig2 may circumvent resistance to EGFR-targeted drugs.