Inflammation is a major risk factor for pancreatic ductal adenocarcinoma (PDAC). When occurring in the context of pancreatitis, KRAS mutations accelerate tumor development in mouse models. We report ...that long after its complete resolution, a transient inflammatory event primes pancreatic epithelial cells to subsequent transformation by oncogenic KRAS. Upon recovery from acute inflammation, pancreatic epithelial cells display an enduring adaptive response associated with sustained transcriptional and epigenetic reprogramming. Such adaptation enables the reactivation of acinar-to-ductal metaplasia (ADM) upon subsequent inflammatory events, thereby limiting tissue damage through a rapid decrease of zymogen production. We propose that because activating mutations of KRAS maintain an irreversible ADM, they may be beneficial and under strong positive selection in the context of recurrent pancreatitis.
In miniature ion trap mass spectrometry, achieving a balance between isolation resolution and efficiency is a formidable challenge. The presence of absorption curves causes target ions to ...inadvertently absorb energy from AC signal components near their resonant frequencies. To mitigate this issue, SAM–SFM waveforms introduce a parameter known as the decreasing factor. Unlike SWIFT waveforms, SAM–SFM’s spectral profile intentionally departs from a rectangular window, adopting an arch-shaped excitation window to minimize the impact on target ions and improve ion isolation efficiency. SAM–SFM waveforms have the advantage of low computational complexity, enabling real-time computation using an embedded FPGA technology. Regardless of any parameter changes, the FPGA can consistently guarantee waveform output within 1 μs. This not only enhances throughput but also eliminates the need for a PC in miniature mass spectrometry devices. The performance of SAM–SFM has been validated on an improved “Brick” miniature ion trap mass spectrometer. Comparative experiments with SWIFT waveforms confirm the lossless unit-mass isolation capabilities of SAM–SFM. This waveform has the capability to simultaneously isolate multiple target ions, even allowing for the lossless isolation of ions with lower abundance within isotopic clusters, albeit at the cost of requiring extended isolation durations.
In this study, three novel and natural polysaccharides (FMP-1, FMP-2, and FMP-3) were obtained from Flos Magnoliae (FM, Xinyi in Chinese) using an efficient and green technique (hot-compressed water) ...for extraction and purified by DEAE-52 and Sephadex G-150. Their physicochemical properties, morphological and structural characteristics were investigated using chemical methods and instrumental analysis including methylation, partial acid hydrolysis, STA, GC-MS, HPGPC, HPAEC, FT-IR and NMR (1D and 2D). Results showed that FMPs all contained arabinose, rhamnose, galactose, xylose, mannose and galacturonic acid. FMP-2, with the highest yield and average molecular weight of the three (278.69 kDa), had large amounts of RG-I, minor amounts of HG with the molar ratio of 83.5:10.4, and trace amounts of RG-II domains. Thermal analys is exhibited that FMP-2 has a favorable thermal stability and it also exhibited effective antioxidant activities in a dose-dependent manner, which could be used as a potential stabilizer, thickening agent and natural antioxidant. These investigations provide a scientific basis for further investigation of FM polysaccharides in the context of their potential application in functional foods and medicines.
Display omitted
•Hot-compressed water (HCW) is an efficient and green technique to extract Flos Magnoliae pectins.•Flos Magnoliae (FM) can be a potential source of natural low methoxylated pectins.•FMP-2 was constituted mainly of rhamnogalacturonan I (RG-I) and a few homogalacturonan (HG) domains.•FMP-2 exhibited strong antioxidant activities and good thermal stability.
Precise gene insertion or replacement in cells and animals that requires incorporation of a foreign DNA template into the genome target site by homology-directed repair (HDR) remains an inefficient ...process. One of the limiting factors for the inefficiency of HDR lies in the limited chance for colocalization of the donor template and target in the huge genome space. We here present a strategy to enhance HDR efficiency in animal cells by spatial and temporal colocalization of the donor and Cas9 by coupling the CRISPR system with a transcription factor (TF). We first identified that THAP domain-containing 11 (THAP11) can coordinate with CRISPR/Cas9 to increase HDR stably through screening multiple TFs from different species. We next designed donor structures with different fusion patterns with TF-specific DNA-binding motifs and found that appending two copies of THAP11-specific DNA binding motifs to both ends of the double-stranded donor DNA has an optimal effect to promote HDR. The THAP11-fused CRISPR system achieved more than twofold increase in HDR-mediated knock-in efficiency for enhanced green fluorescent protein (EGFP) tagging of endogenous genes in 293T cells. We also demonstrated up to 6-fold increases of knock-in through the combinational use of the TF-fused CRISPR and valnemulin, a recently discovered small-molecule HDR enhancer. This modified CRISPR system provides a simple but highly efficient platform to facilitate CRISPR-mediated KI manipulations.
Polysaccharide-based gold nanomaterials have attracted great interest in biomedical fields such as cancer therapy and immunomodulation due to their prolonged residence time in vivo and enhanced ...immune response. This review aims to provide an up-to-date and comprehensive summary of polysaccharide-based Au NMs synthesis, including mechanisms, polysaccharide structure-effects, and anticancer activity. Firstly, research progress on the synthesis mechanism of polysaccharide-based Au NMs was addressed, which included three types based on the variety of polysaccharides and reaction environment: breaking of glycosidic bonds via Au (III) or base-mediated production of highly reduced intermediates, reduction of free hydroxyl groups in polysaccharide molecules, and reduction of free amino groups in polysaccharide molecules. Then, the potential effects of polysaccharide structure characteristics (molecular weight, composition of monosaccharides, functional groups, glycosidic bonds, and chain conformation) and reaction conditions (the reaction temperature, reaction time, pH, concentration of gold precursor and polysaccharides) on the size and shape of Au NMs were explored. Finally, the current status of polysaccharide-based Au NMs cancer therapy was summarized before reaching our conclusions and perspectives.
Rewired metabolism is a hallmark of pancreatic ductal adenocarcinomas (PDA). Previously, we demonstrated that PDA cells enhance glycosylation precursor biogenesis through the hexosamine biosynthetic ...pathway (HBP) via activation of the rate limiting enzyme, glutamine-fructose 6-phosphate amidotransferase 1 (GFAT1). Here, we genetically ablated GFAT1 in human PDA cell lines, which completely blocked proliferation in vitro and led to cell death. In contrast, GFAT1 knockout did not preclude the growth of human tumor xenografts in mice, suggesting that cancer cells can maintain fidelity of glycosylation precursor pools by scavenging nutrients from the tumor microenvironment. We found that hyaluronic acid (HA), an abundant carbohydrate polymer in pancreatic tumors composed of repeating
-acetyl-glucosamine (GlcNAc) and glucuronic acid sugars, can bypass GFAT1 to refuel the HBP via the GlcNAc salvage pathway. Together, these data show HA can serve as a nutrient fueling PDA metabolism beyond its previously appreciated structural and signaling roles.
Temperature stress restricts plant growth and development. Antifreeze protein (AFP) can improve plants antifreeze ability. In our previous study, the AnAFP gene cloned from Ammopiptanthus nanus was ...confirmed to be an excellent candidate enhancing plant cold resistance. But, AnAFP protein shared similar structures with KnS type dehydrins including K, N and S domains except ice crystal binding domain A. Here, we generated AnAFPΔA, AnAFPΔK, AnAFPΔN and AnAFPΔS, and transformed them into ordinary and cold sensitive strains of E. coli, and Arabidopsis KS type dehydrin mutant to evaluate their function. Expression of AnAFPΔA decreases cold and heat tolerance in E. coli, meanwhile, AnAFP enhances heat tolerance in Arabidopsis, suggesting that domain A is a thermal stable functional domain. AnAFP, AnAFPΔA and AnAFPΔS localize in whole cell, but AnAFPΔK and AnAFPΔN only localizes in nucleus and cytoplasm, respectively, exhibiting that K and N domains control localization of AnAFP. Likewise, K domain blocks interaction between AnAFP and AnICE1. The result of RT-qPCR showed that expression of AnAFP, AnICE1 and AnCBF genes was significantly induced by high-temperature, indicating that the AnAFP is likely regulated by ICE1-CBF-COR signal pathway. Taken together, the study provides insights into understanding the mechanism of AnAFP in response to temperature stress and gene resource to improve heat or cold tolerance of plants in transgenic engineering.
Abstract DNA base editors enable direct editing of adenine (A), cytosine (C), or guanine (G), but there is no base editor for direct thymine (T) editing currently. Here we develop two deaminase-free ...glycosylase-based base editors for direct T editing (gTBE) and C editing (gCBE) by fusing Cas9 nickase (nCas9) with engineered human uracil DNA glycosylase (UNG) variants. By several rounds of structure-informed rational mutagenesis on UNG in cultured human cells, we obtain gTBE and gCBE with high activity of T-to-S (i.e., T-to-C or T-to-G) and C-to-G conversions, respectively. Furthermore, we conduct parallel comparison of gTBE/gCBE with those recently developed using other protein engineering strategies, and find gTBE/gCBE show the outperformance. Thus, we provide several base editors, gTBEs and gCBEs, with corresponding engineered UNG variants, broadening the targeting scope of base editors.
Macroautophagy (autophagy) is a regulated catabolic pathway to degrade cellular organelles and macromolecules. The role of autophagy in cancer is complex and may differ depending on tumor type or ...context. Here we show that pancreatic cancers have a distinct dependence on autophagy. Pancreatic cancer primary tumors and cell lines show elevated autophagy under basal conditions. Genetic or pharmacologic inhibition of autophagy leads to increased reactive oxygen species, elevated DNA damage, and a metabolic defect leading to decreased mitochondrial oxidative phosphorylation. Together, these ultimately result in significant growth suppression of pancreatic cancer cells in vitro. Most importantly, inhibition of autophagy by genetic means or chloroquine treatment leads to robust tumor regression and prolonged survival in pancreatic cancer xenografts and genetic mouse models. These results suggest that, unlike in other cancers where autophagy inhibition may synergize with chemotherapy or targeted agents by preventing the up-regulation of autophagy as a reactive survival mechanism, autophagy is actually required for tumorigenic growth of pancreatic cancers de novo, and drugs that inactivate this process may have a unique clinical utility in treating pancreatic cancers and other malignancies with a similar dependence on autophagy. As chloroquine and its derivatives are potent inhibitors of autophagy and have been used safely in human patients for decades for a variety of purposes, these results are immediately translatable to the treatment of pancreatic cancer patients, and provide a much needed, novel vantage point of attack.
We explore novel optomechanically induced transparency (OMIT) and prolonged slow light in a linear and quadratic optomechanical system (OMS) with the Coulomb coupling. The hybrid OMS includes a ...Fabry–Pérot cavity and two charged mechanical resonators (MR1 inside the cavity and MR2 outside the cavity), where the interaction between the charged MR1 and the cavity field are both linear and quadratic in the MR1’s displacement, and the charged MR1 and the charged MR2 mutually coupled via Coulomb interaction. Specifically, the transmission of the output field exhibits three transparency window dips. The Coulomb coupling strength is responsible for creating two transparency window dips near
δ
/
ω
m
=
1
, which results from the mechanical dressed mode. Simultaneously, the quadratic coupling between the charged MR1 and the optical cavity field significantly contributes to another transparency window dip near
δ
/
ω
m
=
2
, which is attributed to the two-phonon process. In addition, by adjusting the value of Coulomb coupling strength, linear (quadratic) coupling and frequency of the two mechanical resonators, one can attain prolonged slow light with a group delay extending to tens of milliseconds. Furthermore, the positive (negative) value of quadratic coupling strength can determine the switching behavior of the group delay (i.e., from superluminal to subluminal propagation) on the right (left) side of
δ
/
ω
m
=
2
. We believe that the results have potential applications in manipulating the performance of OMIT devices and optical switching.
PDF
