81 research outputs found

    γ-Glutamyl carboxylase mutations differentially affect the biological function of vitamin K–dependent proteins

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    γ-Glutamyl carboxylase (GGCX) is an integral membrane protein that catalyzes posttranslational carboxylation of a number of vitamin K–dependent (VKD) proteins involved in a wide variety of physiologic processes, including blood coagulation, vascular calcification, and bone metabolism. Naturally occurring GGCX mutations are associated with multiple distinct clinical phenotypes. However, the genotype–phenotype correlation of GGCX remains elusive. Here, we systematically examined the effect of all naturally occurring GGCX mutations on the carboxylation of 3 structure–function distinct VKD proteins in a cellular environment. GGCX mutations were transiently introduced into GGCX-deficient human embryonic kidney 293 cells stably expressing chimeric coagulation factor, matrix Gla protein (MGP), or osteocalcin as VKD reporter proteins, and then the carboxylation efficiency of these reporter proteins was evaluated. Our results show that GGCX mutations differentially affect the carboxylation of these reporter proteins and the efficiency of using vitamin K as a cofactor. Carboxylation of these reporter proteins by a C-terminal truncation mutation (R704X) implies that GGCX’s C terminus plays a critical role in the binding of osteocalcin but not in the binding of coagulation factors and MGP. This has been confirmed by probing the protein–protein interaction between GGCX and its protein substrates in live cells using bimolecular fluorescence complementation and chemical cross-linking assays. Additionally, using a minigene splicing assay, we demonstrated that several GGCX missense mutations affect GGCX’s pre–messenger RNA splicing rather than altering the corresponding amino acid residues. Results from this study interpreted the correlation of GGCX’s genotype and its clinical phenotypes and clarified why vitamin K administration rectified bleeding disorders but not nonbleeding disorders

    Fabrication of monodisperse magnetic nanorods for improving hyperthermia efficacy

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    Background: Hyperthermia is one of the promising cancer treatment strategies enabled by local heating with the use of tumor-targeting magnetic nanoparticles (MNP) under a non-invasive magnetic field. However, one of the remaining challenges is how to achieve therapeutic levels of heat (without causing damages to regular tissues) in tumors that cannot be effectively treated with anti-tumor drug delivery. Results: In this work, we report a facile method to fabricate magnetic nanorods for hyperthermia by one-step wet chemistry synthesis using 3-Aminopropyltrimethoxysilane (APTMS) as the shape-controlling agent and ferric and ferrous ions as precursors. By adjusting the concentration of APTMS, hydrothermal reaction time, ratios of ferric to ferrous ions, magnetic nanorods with aspect ratios ranging from 4.4 to 7.6 have been produced. At the clinically recommended field strength of 300 Oe (or less) and the frequency of 184 kHz, the specific absorption rate (SAR) of these nanorods is approximately 50 % higher than that of commercial Bionized NanoFerrite particles. Conclusions: This increase in SAR, especially at low field strengths, is crucial for treating deep tumors, such as pancreatic and rectal cancers, by avoiding the generation of harmful eddy current heating in normal tissues.[Figure not available: see fulltext.

    Molecular characterization of seven novel Glu-A1<sup>m</sup>x alleles from Triticum monococcum ssp. monococcum

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    Seven Glu-A1m allelic variants of the Glu-A1mx genes in Triticum monococcum ssp. monococcum, designated as 1Ax2.1a, 1Ax2.1b, 1Ax2.1c, 1Ax2.1d, 1Ax2.1e, 1Ax2.1f, and 1Ax2.1g were characterized. Their authenticity was confirmed by successful expression of the coding regions in E. coli, and except for the 1Ax2.1a with the presence of internal stop codons at position of 313 aa, all correspond to the subunit in seeds. However, all the active six genes had a same DNA size although their encoding subunits showed different molecular weight. Our study indicated that amino acid residue substitutions rather than previously frequently reported insertions/deletions played an important role on the subunit evolution of these Glu-A1mx alleles. Since variation in the Glu-A1x locus in common wheat is rare, these novel genes at the Glu-A1mx can be used as candidate genes for further wheat quality improvement

    Characterization of an expressed Triticum monococcum Glu-A1y gene containing a premature termination codon in its C-terminal coding region

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    Premature termination codons (PTCs) are an important reason for the silence of highmolecular- weight glutenin subunits in Triticum species. Although the Glu-A1y gene is generally silent in common wheat, we here isolated an expressed Glu-A1y gene containing a PTC, named 1Ay8.3, from Triticum monococcum ssp. monococcum (AmAm, 2n = 2x = 14). Despite the presence of a PTC (TAG) at base pair positions 1879–1881 in the C-terminal coding region, this did not obviously affect 1Ay8.3 expression in seeds. This was demonstrated by the fact that when the PTC TAG of 1Ay8.3 was mutated to the CAG codon, the mutant in Escherichia coli bacterial cells expressed the same subunit as in the seeds. However, in E. coli, 1Ay8.3 containing the PTC expressed a truncated protein with faster electrophoretic mobility than that in seeds, suggesting that PTC translation termination suppression probably occurs in vivo (seeds) but not in vitro (E. coli). This may represent one of only a few reports on the PTC termination suppression phenomenon in genes

    Prunella vulgaris: A comprehensive review of chemical constituents, pharmacological effects and clinical applications.

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    Prunella vulgaris (PV) is a perennial herb belonging to the Labiate family and is widely distributed in northeastern Asian countries such as Korea, Japan, and China. It is reported to display diverse biological activities including anti-microbial, anti-cancer, and anti-inflammation as determined by in vitro or in vivo studies. So far, about 200 compounds have been isolated from PV plant and majority of these have been characterized mainly as triterpenoids, sterols and flavonoids, followed by coumarins, phenylpropanoids, polysaccharides and volatile oils. This review summarizes and analyzes the current knowledge on the chemical constituents, pharmacological activities, mechanisms of action and clinical applications of the PV plant including its potential as a future medicinal plant. Although some of the chemical constituents of the PV plant and their mechanism of action have been investigated the biological activities of many of these remain unknown and further clinical trials are required to further enhance its reputation as a medicinal plant

    A Novel Alkaloid from the Seeds of Daphniphyllum calycinum

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    Self-adaptive root-like capillary diffusion channels enabled by TaN/Zr3N4 nanomultilayered architecture: Achieving superior corrosion resistance

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    The combined merits of high hardness and superior chemical inertness enable transition metal nitrides (TMNs) to be extensively coated onto the metal surfaces for avoiding erosion and corrosion attacks. However, the relatively large-size through-type diffusion channels commonly appear in the corroded layers as TMNs coatings subjected to corrosive environments. These channels can serve as short-circuit-diffusion paths for corrosive ions and worsen the corrosion-resistance ability, eventually, yielding unpredictable failure due to the heterogeneous growth of corrosion products. Obviously, comparing with the large-size through-type diffusion channels, the biomimetic multi-forked root-like capillary channels can significantly extend the diffusion distance and retard the transportation of corrosive ions by continuously deflecting and refining the diffusion paths. Herein, the nano-laminated TaN/Zr3N4 architecture, consisting of alternating 10 nm-thickness c-TaN nanolayers and 2 nm-thickness N-rich o-Zr3N4 nanolayers, has been fabricated by magnetron sputtering technology; it exhibits the characteristic of c-TaN/c-Zr3N4 local coherent growth. Such TaN/Zr3N4 nanomultilayered structure contributes to the self-adaptive assembly of TaO2@ZrO2 core–shell nanostructure in the corroded layer, thereby yielding appearance of uniformly root-like capillary diffusion channels instead of the typical through-type diffusion channels in the constitute monolayers; finally, it achieves superior corrosion-resistance with homogeneously general corrosion rate and avoids the uncontrollable failures
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