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1.
Mol Cell ; 81(21): 4493-4508.e9, 2021 11 04.
Article in English | MEDLINE | ID: mdl-34555354

ABSTRACT

Initiation is the rate-limiting step in translation, and its dysregulation is vital for carcinogenesis, including hematopoietic malignancy. Thus, discovery of novel translation initiation regulators may provide promising therapeutic targets. Here, combining Ribo-seq, mass spectrometry, and RNA-seq datasets, we discovered an oncomicropeptide, APPLE (a peptide located in ER), encoded by a non-coding RNA transcript in acute myeloid leukemia (AML). APPLE is overexpressed in various subtypes of AML and confers a poor prognosis. The micropeptide is enriched in ribosomes and regulates the initiation step to enhance translation and to maintain high rates of oncoprotein synthesis. Mechanically, APPLE promotes PABPC1-eIF4G interaction and facilitates mRNA circularization and eIF4F initiation complex assembly to support a specific pro-cancer translation program. Targeting APPLE exhibited broad anti-cancer effects in vitro and in vivo. This study not only reports a previously unknown function of micropeptides but also provides new opportunities for targeting the translation machinery in cancer cells.


Subject(s)
Eukaryotic Initiation Factor-4F/chemistry , Eukaryotic Initiation Factor-4G/metabolism , Hematologic Neoplasms/metabolism , Peptides/chemistry , Protein Biosynthesis , Animals , Disease Progression , Genome, Human , HEK293 Cells , Humans , Male , Mice , Mice, Inbred NOD , Mice, SCID , Open Reading Frames , Polyribosomes/chemistry , RNA, Messenger/metabolism , RNA, Untranslated/metabolism , RNA-Binding Proteins/genetics , Ribosomes/metabolism , Sensitivity and Specificity , Treatment Outcome
2.
EMBO J ; 43(10): 1965-1989, 2024 May.
Article in English | MEDLINE | ID: mdl-38605224

ABSTRACT

The transition of mouse embryonic stem cells (ESCs) between serum/LIF and 2i(MEK and GSK3 kinase inhibitor)/LIF culture conditions serves as a valuable model for exploring the mechanisms underlying ground and confused pluripotent states. Regulatory networks comprising core and ancillary pluripotency factors drive the gene expression programs defining stable naïve pluripotency. In our study, we systematically screened factors essential for ESC pluripotency, identifying TEAD2 as an ancillary factor maintaining ground-state pluripotency in 2i/LIF ESCs and facilitating the transition from serum/LIF to 2i/LIF ESCs. TEAD2 exhibits increased binding to chromatin in 2i/LIF ESCs, targeting active chromatin regions to regulate the expression of 2i-specific genes. In addition, TEAD2 facilitates the expression of 2i-specific genes by mediating enhancer-promoter interactions during the serum/LIF to 2i/LIF transition. Notably, deletion of Tead2 results in reduction of a specific set of enhancer-promoter interactions without significantly affecting binding of chromatin architecture proteins, CCCTC-binding factor (CTCF), and Yin Yang 1 (YY1). In summary, our findings highlight a novel prominent role of TEAD2 in orchestrating higher-order chromatin structures of 2i-specific genes to sustain ground-state pluripotency.


Subject(s)
Chromatin , DNA-Binding Proteins , Mouse Embryonic Stem Cells , TEA Domain Transcription Factors , Transcription Factors , Animals , Mice , TEA Domain Transcription Factors/metabolism , Chromatin/metabolism , Chromatin/genetics , Transcription Factors/metabolism , Transcription Factors/genetics , DNA-Binding Proteins/metabolism , DNA-Binding Proteins/genetics , Mouse Embryonic Stem Cells/metabolism , Mouse Embryonic Stem Cells/cytology , Pluripotent Stem Cells/metabolism , Pluripotent Stem Cells/cytology , Promoter Regions, Genetic , Enhancer Elements, Genetic
3.
EMBO Rep ; 24(3): e55762, 2023 03 06.
Article in English | MEDLINE | ID: mdl-36597993

ABSTRACT

N6 -Methyladenosine (m6 A) is an important RNA modification catalyzed by methyltransferase-like 3 (METTL3) and METTL14. m6 A homeostasis mediated by the methyltransferase (MTase) complex plays key roles in various biological processes. However, the mechanism underlying METTL14 protein stability and its role in m6 A homeostasis remain elusive. Here, we show that METTL14 stability is regulated by the competitive interaction of METTL3 with the E3 ligase STUB1. STUB1 directly interacts with METTL14 to mediate its ubiquitination at lysine residues K148, K156, and K162 for subsequent degradation, resulting in a significant decrease in total m6 A levels. The amino acid regions 450-454 and 464-480 of METTL3 are essential to promote METTL14 stabilization. Changes in STUB1 expression affect METTL14 protein levels, m6 A modification and tumorigenesis. Collectively, our findings uncover an ubiquitination mechanism controlling METTL14 protein levels to fine-tune m6 A homeostasis. Finally, we present evidence that modulating STUB1 expression to degrade METTL14 could represent a promising therapeutic strategy against cancer.


Subject(s)
Adenosine , Methyltransferases , Adenosine/metabolism , Methyltransferases/genetics , Homeostasis
4.
Cereb Cortex ; 34(5)2024 May 02.
Article in English | MEDLINE | ID: mdl-38725291

ABSTRACT

A widely used psychotherapeutic treatment for post-traumatic stress disorder (PTSD) involves performing bilateral eye movement (EM) during trauma memory retrieval. However, how this treatment-described as eye movement desensitization and reprocessing (EMDR)-alleviates trauma-related symptoms is unclear. While conventional theories suggest that bilateral EM interferes with concurrently retrieved trauma memories by taxing the limited working memory resources, here, we propose that bilateral EM actually facilitates information processing. In two EEG experiments, we replicated the bilateral EM procedure of EMDR, having participants engaging in continuous bilateral EM or receiving bilateral sensory stimulation (BS) as a control while retrieving short- or long-term memory. During EM or BS, we presented bystander images or memory cues to probe neural representations of perceptual and memory information. Multivariate pattern analysis of the EEG signals revealed that bilateral EM enhanced neural representations of simultaneously processed perceptual and memory information. This enhancement was accompanied by heightened visual responses and increased neural excitability in the occipital region. Furthermore, bilateral EM increased information transmission from the occipital to the frontoparietal region, indicating facilitated information transition from low-level perceptual representation to high-level memory representation. These findings argue for theories that emphasize information facilitation rather than disruption in the EMDR treatment.


Subject(s)
Electroencephalography , Eye Movement Desensitization Reprocessing , Humans , Female , Male , Young Adult , Adult , Eye Movement Desensitization Reprocessing/methods , Eye Movements/physiology , Stress Disorders, Post-Traumatic/physiopathology , Stress Disorders, Post-Traumatic/therapy , Stress Disorders, Post-Traumatic/psychology , Visual Perception/physiology , Memory/physiology , Brain/physiology , Photic Stimulation/methods , Memory, Short-Term/physiology
5.
J Am Chem Soc ; 2024 Jun 06.
Article in English | MEDLINE | ID: mdl-38843049

ABSTRACT

The development of a catalytic method for stereogenic carbon center formation holds immense significance in organic synthesis. Transition-metal-catalyzed cross-coupling reaction has been regarded as a straightforward and efficient tool for stereoselectively forging C-C bond. Nevertheless, the creation of acyclic all-carbon quaternary-containing vicinal stereocenters remains notoriously challenging within the domain of cross-coupling chemistry despite their prominence in various bioactive small molecules. Herein, we describe a palladium-catalyzed asymmetric multicomponent cross-coupling of trisubstituted alkene with aryl diazonium salts and arylboronic acids to realize the formation of tertiary-quaternary carbon centers with high regio-, distereo-, and enantioselectivity. Specifically, the precise manipulation of the stereoconfiguration of trisubstituted alkenes enables the divergent stereoselective cross-coupling reaction, thus allowing for the facile construction of all four enantiomers. Harnessing the ligand-swap strategy involving a chiral bisoxazoline and an achiral fumarate individually accelerates the enantioselective migratory insertion and reductive elimination step in the cross-coupling process, as supported by density functional theory (DFT) calculations, thus obviating the requirement for a neighboring directing group within the internal olefin skeleton.

6.
Article in English | MEDLINE | ID: mdl-38972436

ABSTRACT

BACKGROUND & AIMS: There is limited clinical data regarding the additional yields of random biopsies during colorectal cancer surveillance in patients with inflammatory bowel disease. To assess the additional yield of RB, a systematic review and meta-analysis was conducted. METHODS: PubMed, Embase, Web of Science, and the Cochrane Library were searched for studies investigating the preferred colonoscopy surveillance approach for IBD patients. The additional yield, detection rate, procedure time, and withdrawal time were pooled. RESULTS: Thirty-seven studies (48 arms) were included in the meta-analysis with 9051 patients. The additional yields of RB were 10.34% in per-patient analysis, and 16.20% in per-lesion analysis. The detection rate were 1.31% and 2.82% in per-patient and per-lesion analysis, respectively. Subgroup analysis showed a decline in additional yields from 14.43% to 0.42% in the per-patient analysis and from 19.20% to 5.32% in the per-lesion analysis for studies initiated before and after 2011. In per-patient analysis, the additional yields were 4.83%, 10.29%, and 56.05% for PSC proportions of 0-10%, 10-30%, and 100%, respectively. The corresponding detection rates were 0.56%, 1.40%, and 19.45%. In the per-lesion analysis, additional yields were 11.23%, 21.06%, and 45.22% for PSC proportions of 0-10%, 10-30%, and 100%, respectively. The corresponding detection rates were 2.09%, 3.58%, and 16.24%. CONCLUSIONS: The additional yields of RB were 10.34% and 16.20% for per-patient and per-lesion analyses, respectively. Considering the decreased additional yields in studies initiated after 2011, and the influence of PSC, endoscopy centers lacking full HD equipment should consider incorporating RB in the standard colonoscopy surveillance for IBD patients, especially in those with PSC.

7.
Plant Cell Environ ; 2024 May 13.
Article in English | MEDLINE | ID: mdl-38736429

ABSTRACT

Day length modulates hypocotyl elongation in seedlings to optimize their overall fitness. Variations in cell growth-associated genes are regulated by several transcription factors. However, the specific transcription factors through which the plant clock increases plant fitness are still being elucidated. In this study, we identified the no apical meristem, Arabidopsis thaliana-activating factor (ATAF-1/2), and cup-shaped cotyledon (NAC) family transcription factor ATAF1 as a novel repressor of hypocotyl elongation under a short-day (SD) photoperiod. Variations in day length profoundly affected the transcriptional and protein levels of ATAF1. ATAF1-deficient mutant exhibited increased hypocotyl length and cell growth-promoting gene expression under SD conditions. Moreover, ATAF1 directly targeted and repressed the expression of the cycling Dof factor 1/5 (CDF1/5), two key transcription factors involved in hypocotyl elongation under SD conditions. Additionally, ATAF1 interacted with and negatively modulated the effects of phytochrome-interacting factor (PIF), thus inhibiting PIF-promoted gene expression and hypocotyl elongation. Taken together, our results revealed ATAF1-PIF as a crucial pair modulating the expression of key transcription factors to facilitate plant growth during day/night cycles under fluctuating light conditions.

8.
Opt Lett ; 49(10): 2785-2788, 2024 May 15.
Article in English | MEDLINE | ID: mdl-38748161

ABSTRACT

Single-molecule localization microscopy (SMLM) enables three-dimensional (3D) super-resolution imaging of nanoscale structures within biological samples. However, prolonged acquisition introduces a drift between the sample and the imaging system, resulting in artifacts in the reconstructed super-resolution image. Here, we present a novel, to our knowledge, 3D drift correction method that utilizes both the reflected and scattered light from the sample. Our method employs the reflected light of a near-infrared (NIR) laser for focus stabilization while synchronously capturing speckle images to estimate the lateral drift. This approach combines high-precision active compensation in the axial direction with lateral post-processing compensation, achieving the abilities of 3D drift correction with a single laser light. Compared to the popular localization events-based cross correlation method, our approach is much more robust, especially for datasets with sparse localization points.

9.
Rapid Commun Mass Spectrom ; 38(3): e9669, 2024 Feb 15.
Article in English | MEDLINE | ID: mdl-38211350

ABSTRACT

RATIONALE: Sinomenine, a major bioactive compound isolated from Sinomenium acutum, has been used for the treatment of rheumatoid arthritis and other cardio-cerebrovacular diseases. However, the metabolism of this drug has not been fully investigated. The current work was carried out to investigate the in vitro metabolism of sinomenine in liver microsomes. METHODS: The metabolites were generated by incubating sinomenine (3 µM) with the liver microsomes in the presence of NADPH at 37°C. The structure of the metabolites was characterized using liquid chromatography coupled to high-resolution mass spectrometry (HRMS). Two major metabolites synthesized and their structures were further confirmed using nuclear magnetic resonance spectroscopy. RESULTS: Under the current conditions, 12 metabolites were found and structurally identified using high resolution MS and MS2 spectra. Among these metabolites, M1, M2, M3, M4, M5, M6, M7, M9, M11, and M12 were first reported. The metabolites M8 and M10 were synthesized and unambiguously identified as N-desmethyl-sinomenine and sinomenine N-oxide, respectively. The phenotyping study revealed that the formation of M8 was catalyzed by CYP2C8, 2C19, 2D6, and 3A4, whereas the formation of M3, M6, and M10 were exclusively catalyzed by CYP3A4. The metabolic pathways of sinomenine include N-demethylation, O-demethylation, dehydrogenation, oxygenation, and N-oxygenation. CONCLUSIONS: N-Demethylation and N-oxygenation were the primary metabolic pathways of sinomenine. This study provides new insight into the in vitro metabolism of sinomenine, which would help prospects of sinomenine disposition and safety assessments.


Subject(s)
Microsomes, Liver , Morphinans , Mass Spectrometry/methods , Chromatography, Liquid , Magnetic Resonance Spectroscopy , Microsomes, Liver/metabolism , Chromatography, High Pressure Liquid/methods
10.
Environ Res ; 258: 119411, 2024 Jun 13.
Article in English | MEDLINE | ID: mdl-38876423

ABSTRACT

Epidemiological evidence on the impact of airborne organic pollutants on lung function among the elderly is limited, and their underlying biological mechanisms remain largely unexplored. Herein, a longitudinal panel study was conducted in Jinan, Shandong Province, China, involving 76 healthy older adults monitored over a span of five months repetitively. We systematically evaluated personal exposure to a diverse range of airborne organic pollutants using a wearable passive sampler and their effects on lung function. Participants' pulmonary function indicators were assessed, complemented by comprehensive multi-omics analyses of blood and urine samples. Leveraging the power of interaction analysis, causal inference test (CIT), and integrative pathway analysis (IPA), we explored intricate relationships between specific organic pollutants, biomolecules, and lung function deterioration, elucidating the biological mechanisms underpinning the adverse impacts of these pollutants. We observed that bis (2-chloro-1-methylethyl) ether (BCIE) was significantly associated with negative changes in the forced vital capacity (FVC), with glycerolipids mitigating this adverse effect. Additionally, 31 canonical pathways [e.g., high mobility group box 1 (HMGB1) signaling, phosphatidylinositol 3-kinase (PI3K)/AKT pathway, epithelial mesenchymal transition, and heme and nicotinamide adenine dinucleotide (NAD) biosynthesis] were identified as potential mechanisms. These findings may hold significant implications for developing effective strategies to prevent and mitigate respiratory health risks arising from exposure to such airborne pollutants. However, due to certain limitations of the study, our results should be interpreted with caution.

11.
Nucleic Acids Res ; 50(21): 12019-12038, 2022 11 28.
Article in English | MEDLINE | ID: mdl-35425987

ABSTRACT

Although extended pluripotent stem cells (EPSCs) have the potential to form both embryonic and extraembryonic lineages, how their transcriptional regulatory mechanism differs from that of embryonic stem cells (ESCs) remains unclear. Here, we discovered that YY1 binds to specific open chromatin regions in EPSCs. Yy1 depletion in EPSCs leads to a gene expression pattern more similar to that of ESCs than control EPSCs. Moreover, Yy1 depletion triggers a series of epigenetic crosstalk activities, including changes in DNA methylation, histone modifications and high-order chromatin structures. Yy1 depletion in EPSCs disrupts the enhancer-promoter (EP) interactions of EPSC-specific genes, including Dnmt3l. Yy1 loss results in DNA hypomethylation and dramatically reduces the enrichment of H3K4me3 and H3K27ac on the promoters of EPSC-specific genes by upregulating the expression of Kdm5c and Hdac6 through facilitating the formation of CCCTC-binding factor (CTCF)-mediated EP interactions surrounding their loci. Furthermore, single-cell RNA sequencing (scRNA-seq) experiments revealed that YY1 is required for the derivation of extraembryonic endoderm (XEN)-like cells from EPSCs in vitro. Together, this study reveals that YY1 functions as a key regulator of multidimensional epigenetic crosstalk associated with extended pluripotency.


Subject(s)
Blastocyst , Epigenesis, Genetic , YY1 Transcription Factor , Chromatin/genetics , Chromatin/metabolism , Embryonic Stem Cells/metabolism , Promoter Regions, Genetic , YY1 Transcription Factor/metabolism , Mice , Animals , Blastocyst/cytology , Blastocyst/metabolism
12.
Sensors (Basel) ; 24(12)2024 Jun 14.
Article in English | MEDLINE | ID: mdl-38931647

ABSTRACT

In this paper, the kinematic models of the Strapdown Inertial Navigation System (SINS) and its errors on the SE(3) group in the Earth-Centered Inertial frame (ECI) are established. On the one hand, with the ECI frame being regarded as the reference, based on the joint representation of attitude and velocity on the SE(3) group, the dynamic of the local geographic coordinate system (n-frame) and the body coordinate system (b-frame) evolve on the differentiable manifold, respectively, and the high-order expansion of the Baker-Campbell-Haussdorff equation compensates for the non-commutative motion errors stimulated by strong maneuverability. On the other hand, the kinematics of the left- and right-invariant errors of the n-frame and the b-frame on the SE(3) group are separately derived, where the errors of the b-frame completely depend on inertial sensor errors, while the errors of the n-frame rely on position errors and velocity errors. In this way, the errors brought by the inconsistency of the reference coordinate system are tackled, and a novel attitude error definition is introduced to separate and decouple the factors affecting the dynamic of the n-frame errors and the b-frame errors for better attitude estimation. Through a turntable experiment and a car-mounted field experiment, the effectiveness of the proposed kinematic models in estimating attitude has been verified, with a remarkable improvement in yaw angle accuracy in the case of large initial misalignment angles, and the models developed have better robustness compared to the traditional SE(3) group-based model.

13.
Environ Sci Technol ; 57(21): 7978-7988, 2023 05 30.
Article in English | MEDLINE | ID: mdl-37162498

ABSTRACT

The inhalation exposure of pesticide applicators and residents who live close to pesticide-treated fields is a worldwide concern in public health. Quantitative assessment of exposure to pesticide inhalation health risk highlights the need to accurately assess the bioaccessibility rather than the total content in ambient air. Herein, we developed an in vitro method to estimate the inhalation bioaccessibility of emamectin benzoate and validated its applicability using a rat plasma pharmacokinetic bioassay. Emamectin benzoate was extracted using the Gamble solution, with an optimized solid-to-liquid ratio (1/250), extraction time (24 h), and agitation (200 rpm), which obtained in vitro inhalation bioaccessibility consistent with its inhalation bioavailability in vivo (32.33%). The margin of exposure (MOE) was used to assess inhalation exposure risk. The inhalation unit exposures to emamectin benzoate of applicators and residents were 11.05-28.04 and 0.02-0.04 ng/m3, respectively, varying markedly according to the methods of application, e.g., formulations and nozzles. The inhalation risk assessment using present application methods appeared to be acceptable; however, the MOE of emamectin benzoate might be overestimated by 32% without considering inhalation bioaccessibility. Collectively, our findings contribute insights into the assessment of pesticide inhalation exposure based on bioaccessibility and provide guidance for the safe application of pesticides.


Subject(s)
Pesticide Residues , Pesticides , Animals , Rats , Inhalation Exposure , Ivermectin/analysis , Pesticide Residues/analysis
14.
J Chem Phys ; 159(5)2023 Aug 07.
Article in English | MEDLINE | ID: mdl-37548304

ABSTRACT

Real-time monitoring and quantitative measurement of molecular exchange between different microdomains are useful to characterize the local dynamics in porous media and biomedical applications of magnetic resonance. Diffusion exchange spectroscopy (DEXSY) is a noninvasive technique for such measurements. However, its application is largely limited by the involved long acquisition time and complex parameter estimation. In this study, we introduce a physics-guided deep neural network that accelerates DEXSY acquisition in a data-driven manner. The proposed method combines sampling pattern optimization and physical parameter estimation into a unified framework. Comprehensive simulations and experiments based on a two-site exchange system are conducted to demonstrate this new sampling optimization method in terms of accuracy, repeatability, and efficiency. This general framework can be adapted for other molecular exchange magnetic resonance measurements.

15.
Mikrochim Acta ; 190(9): 351, 2023 08 15.
Article in English | MEDLINE | ID: mdl-37580613

ABSTRACT

Highly photoactive 3D nanoflower-like FeIn2S4/CdS heterostructures were synthesized by hydrothermal treatment and low-temperature cation exchange. The FeIn2S4/CdS displayed 14.5 times signal amplification in contrast to FeIn2S4 alone. It was applied as a photoactive substrate to construct a label-free photoelectrochemical (PEC) aptasensor for ultrasensitive determination of kanamycin (KAN). Under the optimal conditions, the constructed PEC aptasensor displayed a wide linear range (5.0 × 10-4 ~ 5.0 × 101 ng mL-1) and a low detection limit (S/N = 3) of 40.01 fg mL-1. This study provides some constructive insights for preparation of advanced photoactive materials and exhibits great potential for quantitative determination of antibiotics in foods and environmental samples.


Subject(s)
Aptamers, Nucleotide , Electrochemical Techniques , Kanamycin , Aptamers, Nucleotide/chemistry , Anti-Bacterial Agents
16.
Sensors (Basel) ; 23(5)2023 Mar 01.
Article in English | MEDLINE | ID: mdl-36904903

ABSTRACT

The development of inertial confinement fusion (ICF) experiments necessitates the diagnostic instrument to have multiple frames with a high spatial and temporal resolution for the two-dimensional detection of the hot spot at the implosion end of the ICF. The existing sampling two-dimensional imaging technology in the world has superior performance; however, its subsequent development requires a streak tube with large lateral magnification. In this work, an electron beam separation device was designed and developed for the first time. The device can be used without changing the structure of the streak tube. It can be combined directly with the corresponding device and matched with a special control circuit. Based on the original transverse magnification, 1.77 times the secondary amplification can be achieved, which is conducive to expanding the recording range of the technology. The experimental results showed that the static spatial resolution of the streak tube after the inclusion of the device can still reach 10 lp/mm.

17.
Chin J Traumatol ; 2023 Nov 23.
Article in English | MEDLINE | ID: mdl-38061929

ABSTRACT

PURPOSE: The study aimed to examine the pattern of motorization and the mortality rate related to road traffic crashes in Zunyi (a city in northern Guizhou province of China) from 2013 to 2022, and to identify the epidemiological characteristics of these crashes with to provide insights that could help improve road safety. METHODS: Data were obtained from the Zunyi traffic management data platform, and the mortality rates were calculated. We deployed various analytical methods, including descriptive analysis, Chi-square test or Fisher's exact test of categorical variable, circular distribution map analysis, and Rayleigh test to characterize the traits of road traffic crashes in the region. RESULTS: During the 10-year study period, 7488 people died due to road traffic accidents, with males accounting for 70.4% and females 29.6% (χ2 = 101.97, p < 0.001). The mortality rate increased from 7.80 deaths per 100,000 people in 2013 to 10.70 deaths per 100,000 people in 2016, but then decreased to 9.54 deaths per 100,000 people in 2019. A notable finding was that the death rate per 10,000 vehicles declined from 16.09 deaths per 10,000 vehicles in 2013 to 5.48 deaths per 10,000 vehicles in 2022. The study also found that vulnerable road users represented nearly half (48.76%) of all accident fatalities, and unlicensed or inexperienced driving contributed significantly to the occurrence of road traffic accidents. CONCLUSION: Although the number of road traffic accidents in Zunyi has decreased, there are still some critical issues that need to be addressed, particularly for vulnerable road users and unlicensed drivers. Our results highlight the need of targeted interventions to address the specific risk factors of road traffic crashes, particularly those affecting vulnerable road users and drivers without sufficient experience or license.

18.
J Am Chem Soc ; 144(18): 8389-8398, 2022 05 11.
Article in English | MEDLINE | ID: mdl-35482430

ABSTRACT

Enantioselective transformations of olefins are among the most important strategies for the asymmetric synthesis of organic compounds. Chemo-, diastereo-, and stereoselective control of reactions with internal acyclic alkenes for the construction of functionalized acyclic alkanes still remain a persistent challenge. Here, we report a palladium-catalyzed asymmetric regiodivergent Heck-type diarylation of internal acyclic alkenes. The 1,2-diarylation of two accessible acyclic alkenes, cinnamyl carbamates and enamides with diazonium salts and aromatic boronic acids, furnishes products containing vicinal stereogenic centers via the stereospecific formation of carbonyl coordination-assisted transient palladacycles. Moreover, the asymmetric migratory diarylation of enamides enables the formation of incontiguous stereocenters by an interrupted diastereoselective 1,3-chain-walking process. This protocol streamlines access to highly functionalized multisubstituted enantioenriched carbamates and amine derivatives which are embedded in the key biologically active motifs.


Subject(s)
Alkenes , Styrenes , Carbamates , Catalysis , Stereoisomerism
19.
Curr Issues Mol Biol ; 44(6): 2683-2694, 2022 Jun 10.
Article in English | MEDLINE | ID: mdl-35735624

ABSTRACT

Excessive reactive oxygen species (ROS), a highly reactive substance that contains oxygen, induced by ultraviolet A (UVA) cause oxidative damage to skin. We confirmed that hemin can catalyze the reaction of tyrosine (Tyr) and hydrogen peroxide (H2O2). Catalysis was found to effectively reduce or eliminate oxidative damage to cells induced by H2O2 or UVA. The scavenging effects of hemin for other free-radical ROS were also evaluated through pyrogallol autoxidation, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·)-scavenging assays, and phenanthroline-Fe2+ assays. The results show that a mixture of hemin and tyrosine exhibits strong scavenging activities for H2O2, superoxide anion (O2-·), DPPH·, and the hydroxyl radical (·OH). Furthermore, the inhibition of oxidative damage to human skin keratinocyte (HaCaT) cells induced by H2O2 or UVA was evaluated. The results show that catalysis can significantly reduce the ratio of cell apoptosis and death and inhibit the release of lactate dehydrogenase (LDH), as well as accumulation of malondialdehyde (MDA). Furthermore, the resistance to apoptosis was found to be enhanced. These results show that the mixture of hemin and tyrosine has a significantly protective effect against oxidative damage to HaCaT cells caused by UVA, suggesting it as a protective agent for combating UVA damage.

20.
Plant Cell Environ ; 45(12): 3492-3504, 2022 12.
Article in English | MEDLINE | ID: mdl-36130868

ABSTRACT

Heat stress (HS) caused by ambient high temperature poses a threat to plants. In the natural and agricultural environment, plants often encounter repeated and changeable HS. Moderate HS primes plants to establish a molecular 'thermomemory' that enables plants to withstand a later-and possibly more extreme-HS attack. Recent years, brassinosteroids (BRs) have been implicated in HS response, whereas the information is lacking on whether BRs signal transduction modulates thermomemory. Here, we uncover the positive role of BRs signalling in thermomemory of Arabidopsis thaliana. Heat priming induces de novo synthesis and nuclear accumulation of BRI1-Ethyl methyl sulfon-SUPPRESSOR (BES1), which is the key regulator of BRs signalling. BRs promote the accumulation of dephosphorylated BES1 during memory phase, and stoppage of BRs synthesis impairs dephosphorylation. During HS memory, BES1 is required to maintain sustained induction of HS memory genes and directly targets APX2 and HSFA3 for activation. In summary, our results reveal a BES1-required, BRs-enhanced transcriptional control module of thermomemory in Arabidopsis thaliana.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis/metabolism , Brassinosteroids/pharmacology , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Gene Expression Regulation, Plant , DNA-Binding Proteins/metabolism , Plants, Genetically Modified/metabolism
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