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  • 1
    Publication Date: 2018-08-09
    Description: Poly(diallyldimethylammonium chloride) (polyDADMAC) has been shown to be an important precursor of the probable human carcinogen N -nitrosodimethylamine (NDMA) when in contact with chloramine. In this study, we conducted an orthogonal experiment design to evaluate the effects of pH values, ammonia, bromide, natural organic matter (NOM) and monochloramine dosages on the formation of NDMA from polyDADMAC during chloramination. Meanwhile, single-factor experiments of pH, bromide and NOM prove the results of orthogonal experiment. The results supported that pH was the most critical factor affecting NDMA formation from polyDADMAC during chloramination, and the highest NDMA formation from polyDADMAC occurred at pH near 7 due to released DMA from polyDADMAC degradation and the critical importance of low concentrations of dichloramine in water. In the presence of excess bromide, the NDMA formation was enhanced significantly at all different pH values owing to bromochloramine, which has higher electronegativity of the brominated nitrogen atom than monochloramine or dichloramine. The NDMA formation from polyDADMAC in the presence of NOM was 41.7% lower than NDMA formation in the absence of NOM. The overwhelming majority of NDMA formation from polyDADMAC under simulated conditions was lower than the current advisory levels (i.e. 9 ng l –1 in Ontario, 10 ng l –1 in California).
    Keywords: environmental chemistry, environmental science
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 2
    Publication Date: 2018-07-03
    Description: Transforming growth factor–β (TGF-β) regulates reciprocal regulatory T cell (T reg) and T helper 17 (Th17) differentiation, the underlying mechanism of which is still not understood. Here, we report that tripartite motif-containing 33 (Trim33), a modulator of TGF-β signaling that associates with Smad2, regulates the proinflammatory function of Th17 cells. Trim33 deficiency in T cells ameliorated an autoimmune disease in vivo . Trim33 was required for induction in vitro of Th17, but not T reg cells. Moreover, Smad4 and Trim33 play contrasting roles in the regulation of IL-10 expression; loss of Trim33 enhanced IL-10 production. Furthermore, Trim33 was recruited to the Il17a and Il10 gene loci, dependent on Smad2, and mediated their chromatin remodeling during Th17 differentiation. Trim33 thus promotes the proinflammatory function of Th17 cells by inducing IL-17 and suppressing IL-10 expression.
    Keywords: Autoimmunity
    Print ISSN: 0022-1007
    Electronic ISSN: 1540-9538
    Topics: Medicine
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  • 3
    Publication Date: 2018-08-17
    Description: Shuang Li, Yong Suk Cho, Bing Wang, Shuangxi Li, and Jin Jiang Hedgehog (Hh) transduces signals by promoting cell surface accumulation and activation of the G-protein-coupled receptor (GPCR)-family protein Smoothened (Smo) in Drosophila , but the molecular mechanism underlying the regulation of Smo trafficking remains poorly understood. Here, we identified the Cul4–DDB1 E3 ubiquitin ligase complex as being essential for Smo ubiquitylation and cell surface clearance. We found that the C-terminal intracellular domain of Smo recruits Cul4–DDB1 through the β subunit of trimeric G protein (Gβ), and that Cul4–DDB1–Gβ promotes the ubiquitylation of both Smo and its binding partner G-protein-coupled-receptor kinase 2 (Gprk2) and induces the internalization and degradation of Smo. Hh dissociates Cul4–DDB1 from Smo by recruiting the catalytic subunit of protein kinase A (PKA) to phosphorylate DDB1, which disrupts its interaction with Gβ. Inactivation of the Cul4–DDB1 complex resulted in elevated Smo cell surface expression, whereas an excessive amount of Cul4–DDB1 blocked Smo accumulation and attenuated Hh pathway activation. Taken together, our study identifies an E3 ubiquitin ligase complex targeting Smo for ubiquitylation and provides new insight into how Hh signaling regulates Smo trafficking and cell surface expression.
    Keywords: Ubiquitin
    Print ISSN: 0021-9533
    Electronic ISSN: 1477-9137
    Topics: Biology , Medicine
    Published by Company of Biologists
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  • 4
    Publication Date: 2018-12-02
    Description: Eicosanoids and related metabolites (oxylipins) possess potent signaling properties, elicit numerous important physiologic responses, and serve as biomarkers of disease. In addition to their presence in free form, a considerable portion of these bioactive lipids is esterified to complex lipids in cell membranes and plasma lipoproteins. We developed a rapid and sensitive method for the analysis of esterified oxylipins using alkaline hydrolysis to release them followed by ultra-performance LC coupled with mass spectrometric analysis. Detailed evaluation of the data revealed that several oxylipins are susceptible to alkaline-induced degradation. Nevertheless, of the 136 metabolites we examined, 56 were reproducibly recovered after alkaline hydrolysis. We classified those metabolites that were resistant to alkaline-induced degradation and applied this methodology to quantify metabolite levels in a macrophage cell model and in plasma of healthy subjects. After alkaline hydrolysis of lipids, 34 metabolites could be detected and quantified in resting and activated macrophages, and 38 metabolites were recovered from human plasma at levels that were substantially greater than in free form. By carefully selecting internal standards and taking the observed experimental limitations into account, we established a robust method that can be reliably employed for the measurement of esterified oxylipins in biological samples.
    Print ISSN: 0022-2275
    Electronic ISSN: 1539-7262
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 5
    Publication Date: 2010-11-30
    Description: An ageing world population has fuelled interest in regenerative remedies that may stem declining organ function and maintain fitness. Unanswered is whether elimination of intrinsic instigators driving age-associated degeneration can reverse, as opposed to simply arrest, various afflictions of the aged. Such instigators include progressively damaged genomes. Telomerase-deficient mice have served as a model system to study the adverse cellular and organismal consequences of wide-spread endogenous DNA damage signalling activation in vivo. Telomere loss and uncapping provokes progressive tissue atrophy, stem cell depletion, organ system failure and impaired tissue injury responses. Here, we sought to determine whether entrenched multi-system degeneration in adult mice with severe telomere dysfunction can be halted or possibly reversed by reactivation of endogenous telomerase activity. To this end, we engineered a knock-in allele encoding a 4-hydroxytamoxifen (4-OHT)-inducible telomerase reverse transcriptase-oestrogen receptor (TERT-ER) under transcriptional control of the endogenous TERT promoter. Homozygous TERT-ER mice have short dysfunctional telomeres and sustain increased DNA damage signalling and classical degenerative phenotypes upon successive generational matings and advancing age. Telomerase reactivation in such late generation TERT-ER mice extends telomeres, reduces DNA damage signalling and associated cellular checkpoint responses, allows resumption of proliferation in quiescent cultures, and eliminates degenerative phenotypes across multiple organs including testes, spleens and intestines. Notably, somatic telomerase reactivation reversed neurodegeneration with restoration of proliferating Sox2(+) neural progenitors, Dcx(+) newborn neurons, and Olig2(+) oligodendrocyte populations. Consistent with the integral role of subventricular zone neural progenitors in generation and maintenance of olfactory bulb interneurons, this wave of telomerase-dependent neurogenesis resulted in alleviation of hyposmia and recovery of innate olfactory avoidance responses. Accumulating evidence implicating telomere damage as a driver of age-associated organ decline and disease risk and the marked reversal of systemic degenerative phenotypes in adult mice observed here support the development of regenerative strategies designed to restore telomere integrity.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057569/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057569/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jaskelioff, Mariela -- Muller, Florian L -- Paik, Ji-Hye -- Thomas, Emily -- Jiang, Shan -- Adams, Andrew C -- Sahin, Ergun -- Kost-Alimova, Maria -- Protopopov, Alexei -- Cadinanos, Juan -- Horner, James W -- Maratos-Flier, Eleftheria -- Depinho, Ronald A -- R01 CA084628/CA/NCI NIH HHS/ -- R01 CA084628-19/CA/NCI NIH HHS/ -- R01CA84628/CA/NCI NIH HHS/ -- U01 CA141508/CA/NCI NIH HHS/ -- U01 CA141508-01/CA/NCI NIH HHS/ -- U01CA141508/CA/NCI NIH HHS/ -- England -- Nature. 2011 Jan 6;469(7328):102-6. doi: 10.1038/nature09603. Epub 2010 Nov 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Belfer Institute for Applied Cancer Science and Departments of Medical Oncology, Medicine and Genetics, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21113150" target="_blank"〉PubMed〈/a〉
    Keywords: Aging/drug effects/*metabolism/*pathology ; Animals ; Avoidance Learning/drug effects ; Brain/anatomy & histology/cytology/drug effects/pathology ; Cell Differentiation/drug effects ; Cell Proliferation/drug effects ; Cells, Cultured ; DNA Damage/drug effects ; Enzyme Activation/drug effects ; Enzyme Reactivators/pharmacology ; Mice ; Mice, Inbred C57BL ; Models, Animal ; Myelin Sheath/metabolism ; Neural Stem Cells/cytology/drug effects/enzymology/pathology ; Organ Size/drug effects ; Phenotype ; Receptors, Estrogen/genetics/metabolism ; Recombinant Fusion Proteins/genetics/metabolism ; Regenerative Medicine ; Smell/drug effects/physiology ; Tamoxifen/analogs & derivatives/pharmacology ; Telomerase/*deficiency/genetics/*metabolism ; Telomere/drug effects/metabolism/pathology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2011-02-04
    Description: Effective clinical management of prostate cancer (PCA) has been challenged by significant intratumoural heterogeneity on the genomic and pathological levels and limited understanding of the genetic elements governing disease progression. Here, we exploited the experimental merits of the mouse to test the hypothesis that pathways constraining progression might be activated in indolent Pten-null mouse prostate tumours and that inactivation of such progression barriers in mice would engender a metastasis-prone condition. Comparative transcriptomic and canonical pathway analyses, followed by biochemical confirmation, of normal prostate epithelium versus poorly progressive Pten-null prostate cancers revealed robust activation of the TGFbeta/BMP-SMAD4 signalling axis. The functional relevance of SMAD4 was further supported by emergence of invasive, metastatic and lethal prostate cancers with 100% penetrance upon genetic deletion of Smad4 in the Pten-null mouse prostate. Pathological and molecular analysis as well as transcriptomic knowledge-based pathway profiling of emerging tumours identified cell proliferation and invasion as two cardinal tumour biological features in the metastatic Smad4/Pten-null PCA model. Follow-on pathological and functional assessment confirmed cyclin D1 and SPP1 as key mediators of these biological processes, which together with PTEN and SMAD4, form a four-gene signature that is prognostic of prostate-specific antigen (PSA) biochemical recurrence and lethal metastasis in human PCA. This model-informed progression analysis, together with genetic, functional and translational studies, establishes SMAD4 as a key regulator of PCA progression in mice and humans.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753179/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3753179/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ding, Zhihu -- Wu, Chang-Jiun -- Chu, Gerald C -- Xiao, Yonghong -- Ho, Dennis -- Zhang, Jingfang -- Perry, Samuel R -- Labrot, Emma S -- Wu, Xiaoqiu -- Lis, Rosina -- Hoshida, Yujin -- Hiller, David -- Hu, Baoli -- Jiang, Shan -- Zheng, Hongwu -- Stegh, Alexander H -- Scott, Kenneth L -- Signoretti, Sabina -- Bardeesy, Nabeel -- Wang, Y Alan -- Hill, David E -- Golub, Todd R -- Stampfer, Meir J -- Wong, Wing H -- Loda, Massimo -- Mucci, Lorelei -- Chin, Lynda -- DePinho, Ronald A -- P50 CA090381/CA/NCI NIH HHS/ -- P50 CA090381-08/CA/NCI NIH HHS/ -- P50 CA90381/CA/NCI NIH HHS/ -- R01 5R01CA136578/CA/NCI NIH HHS/ -- R01 CA131945/CA/NCI NIH HHS/ -- R01CA131945/CA/NCI NIH HHS/ -- R01CA141298/CA/NCI NIH HHS/ -- U01-CA84313/CA/NCI NIH HHS/ -- England -- Nature. 2011 Feb 10;470(7333):269-73. doi: 10.1038/nature09677. Epub 2011 Feb 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Belfer Institute for Applied Cancer Science, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21289624" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bone Morphogenetic Proteins/metabolism ; Cell Proliferation ; Cyclin D1/genetics/metabolism ; *Disease Progression ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Genes, Tumor Suppressor/physiology ; Humans ; Lung Neoplasms/secondary ; Lymphatic Metastasis ; Male ; Mice ; Mice, Transgenic ; Models, Biological ; Neoplasm Invasiveness/genetics/pathology ; Neoplasm Metastasis/genetics/*pathology ; Osteopontin/genetics/metabolism ; PTEN Phosphohydrolase/deficiency/genetics ; Penetrance ; Prognosis ; Prostate/metabolism ; Prostate-Specific Antigen/metabolism ; Prostatic Neoplasms/diagnosis/genetics/*pathology ; Smad4 Protein/deficiency/genetics/*metabolism ; Transforming Growth Factor beta
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2014-03-05
    Description: Recognition of modified histones by 'reader' proteins plays a critical role in the regulation of chromatin. H3K36 trimethylation (H3K36me3) is deposited onto the nucleosomes in the transcribed regions after RNA polymerase II elongation. In yeast, this mark in turn recruits epigenetic regulators to reset the chromatin to a relatively repressive state, thus suppressing cryptic transcription. However, much less is known about the role of H3K36me3 in transcription regulation in mammals. This is further complicated by the transcription-coupled incorporation of the histone variant H3.3 in gene bodies. Here we show that the candidate tumour suppressor ZMYND11 specifically recognizes H3K36me3 on H3.3 (H3.3K36me3) and regulates RNA polymerase II elongation. Structural studies show that in addition to the trimethyl-lysine binding by an aromatic cage within the PWWP domain, the H3.3-dependent recognition is mediated by the encapsulation of the H3.3-specific 'Ser 31' residue in a composite pocket formed by the tandem bromo-PWWP domains of ZMYND11. Chromatin immunoprecipitation followed by sequencing shows a genome-wide co-localization of ZMYND11 with H3K36me3 and H3.3 in gene bodies, and its occupancy requires the pre-deposition of H3.3K36me3. Although ZMYND11 is associated with highly expressed genes, it functions as an unconventional transcription co-repressor by modulating RNA polymerase II at the elongation stage. ZMYND11 is critical for the repression of a transcriptional program that is essential for tumour cell growth; low expression levels of ZMYND11 in breast cancer patients correlate with worse prognosis. Consistently, overexpression of ZMYND11 suppresses cancer cell growth in vitro and tumour formation in mice. Together, this study identifies ZMYND11 as an H3.3-specific reader of H3K36me3 that links the histone-variant-mediated transcription elongation control to tumour suppression.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142212/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142212/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wen, Hong -- Li, Yuanyuan -- Xi, Yuanxin -- Jiang, Shiming -- Stratton, Sabrina -- Peng, Danni -- Tanaka, Kaori -- Ren, Yongfeng -- Xia, Zheng -- Wu, Jun -- Li, Bing -- Barton, Michelle C -- Li, Wei -- Li, Haitao -- Shi, Xiaobing -- CA016672/CA/NCI NIH HHS/ -- P30 CA016672/CA/NCI NIH HHS/ -- R01 GM090077/GM/NIGMS NIH HHS/ -- R01 HG007538/HG/NHGRI NIH HHS/ -- R01GM090077/GM/NIGMS NIH HHS/ -- R01HG007538/HG/NHGRI NIH HHS/ -- England -- Nature. 2014 Apr 10;508(7495):263-8. doi: 10.1038/nature13045. Epub 2014 Mar 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [2] Center for Cancer Epigenetics, Center for Genetics and Genomics, and Center for Stem Cell and Developmental Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [3]. ; 1] MOE Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China [2] Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China [3]. ; 1] Dan L. Duncan Cancer Center, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA [2]. ; Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA. ; 1] MOE Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China [2] Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China. ; Dan L. Duncan Cancer Center, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA. ; Department of Molecular Biology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. ; 1] Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [2] Center for Cancer Epigenetics, Center for Genetics and Genomics, and Center for Stem Cell and Developmental Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [3] Genes and Development Graduate Program, The University of Texas Graduate School of Biomedical Sciences, Houston, Teaxs 77030, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24590075" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Breast Neoplasms/*genetics/metabolism/*pathology ; Carrier Proteins/chemistry/*metabolism ; Chromatin/genetics/metabolism ; Co-Repressor Proteins/chemistry/metabolism ; Crystallography, X-Ray ; Disease-Free Survival ; Female ; Gene Expression Regulation, Neoplastic/genetics ; Histones/chemistry/*metabolism ; Humans ; Lysine/*metabolism ; Methylation ; Mice ; Mice, Nude ; Models, Molecular ; Molecular Sequence Data ; Oncogenes/genetics ; Prognosis ; Protein Binding ; Protein Conformation ; Protein Structure, Tertiary ; RNA Polymerase II/*metabolism ; Substrate Specificity ; *Transcription Elongation, Genetic
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2013-06-07
    Description: Visualizing individual molecules with chemical recognition is a longstanding target in catalysis, molecular nanotechnology and biotechnology. Molecular vibrations provide a valuable 'fingerprint' for such identification. Vibrational spectroscopy based on tip-enhanced Raman scattering allows us to access the spectral signals of molecular species very efficiently via the strong localized plasmonic fields produced at the tip apex. However, the best spatial resolution of the tip-enhanced Raman scattering imaging is still limited to 3-15 nanometres, which is not adequate for resolving a single molecule chemically. Here we demonstrate Raman spectral imaging with spatial resolution below one nanometre, resolving the inner structure and surface configuration of a single molecule. This is achieved by spectrally matching the resonance of the nanocavity plasmon to the molecular vibronic transitions, particularly the downward transition responsible for the emission of Raman photons. This matching is made possible by the extremely precise tuning capability provided by scanning tunnelling microscopy. Experimental evidence suggests that the highly confined and broadband nature of the nanocavity plasmon field in the tunnelling gap is essential for ultrahigh-resolution imaging through the generation of an efficient double-resonance enhancement for both Raman excitation and Raman emission. Our technique not only allows for chemical imaging at the single-molecule level, but also offers a new way to study the optical processes and photochemistry of a single molecule.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhang, R -- Zhang, Y -- Dong, Z C -- Jiang, S -- Zhang, C -- Chen, L G -- Zhang, L -- Liao, Y -- Aizpurua, J -- Luo, Y -- Yang, J L -- Hou, J G -- England -- Nature. 2013 Jun 6;498(7452):82-6. doi: 10.1038/nature12151.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23739426" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2018-05-24
    Description: Intercalation and in situ formation of three fluorescent complexes, Al(III)-, Cr(III)- and Cu(II)-10-hydroxybenzo[h]quinolone (M-HBQ, M = Al, Cr and Cu), in the interlayer spaces of magadiite (mag) were studied by solid–solid reactions between metal ions exchanged mags (M-mag, M = Al, Cr and Cu) and HBQ. Results show that the basal spacings of the intercalated composites increase after the intercalation of HBQ into M-mags. The amount of HBQ in the intercalated compounds is different due to the amount of metal ions and the diversification of coordination ability of metal ions, and the order of the coordination ability of these three metal ions is Cu 2+ 〉 Cr 3+ 〉 Al 3+ . The amount of the metal cations in the interlayer of mag is enough for the in situ complex formation of M-HBQ complexes. The slight shift of the absorption and luminescence bands of the complexes suggests the different microstructures, including molecular packing of the complexes in the interlayer spaces of mags, resulting that the host–guest interactions are formed. These findings show that the intercalation and in situ formation of M-HBQ complexes (M = Al, Cr and Cu) in the interlayer space of mag are successfully achieved in the current work.
    Keywords: inorganic chemistry, materials science
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 10
    Publication Date: 2018-03-30
    Description: Wen Shi, Manuel A. Riquelme, Sumin Gu, and Jean X. Jiang Elevated oxidized stress contributes to lens cataracts, and gap junctions play important roles in maintaining lens transparency. As well as forming gap junctions, connexin (Cx) proteins also form hemichannels. Here, we report a new mechanism whereby hemichannels mediate transport of reductant glutathione into lens fiber cells and protect cells against oxidative stress. We found that Cx50 (also known as GJA8) hemichannels opened in response to H 2 O 2 in lens fiber cells but that transport through the channels was inhibited by two dominant-negative mutants in Cx50, Cx50P88S, which inhibits transport through both gap junctions and hemichannels, and Cx50H156N, which only inhibits transport through hemichannels and not gap junctions. Treatment with H 2 O 2 increased the number of fiber cells undergoing apoptosis, and this increase was augmented with dominant-negative mutants that disrupted both hemichannels formed from Cx46 (also known as GJA3) and Cx50, while Cx50E48K, which only impairs gap junctions, did not have such an effect. Moreover, hemichannels mediate uptake of glutathione, and this uptake protected lens fiber cells against oxidative stress, while hemichannels with impaired transport had less protective benefit from glutathione. Taken together, these results show that oxidative stress activates connexin hemichannels in the lens fiber cells and that hemichannels likely protect lens cell against oxidative damage through transporting extracellular reductants.
    Print ISSN: 0021-9533
    Electronic ISSN: 1477-9137
    Topics: Biology , Medicine
    Published by Company of Biologists
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