Tumor suppression in the absence of p53-mediated cell-cycle arrest, apoptosis, and senescence.

Cell-cycle arrest, apoptosis, and senescence are widely accepted as the major mechanisms by which p53 inhibits tumor formation. Nevertheless, it remains unclear whether they are the rate-limiting steps in tumor suppression. Here, we have generated mice bearing lysine to arginine mutations at one (p53(K117R)) or three (p53(3KR); K117R+K161R+K162R) of p53 acetylation sites. Although p53(K117R/K117R) cells are competent for p53-mediated cell-cycle arrest and senescence, but not apoptosis, all three of these processes are ablated in p53(3KR/3KR) cells. Surprisingly, unlike p53 null mice, which rapidly succumb to spontaneous thymic lymphomas, early-onset tumor formation does not occur in either p53(K117R/K117R) or p53(3KR/3KR) animals. Notably, p53(3KR) retains the ability to regulate energy metabolism and reactive oxygen species production. These findings underscore the crucial role of acetylation in differentially modulating p53 responses and suggest that unconventional activities of p53, such as metabolic regulation and antioxidant function, are critical for suppression of early-onset spontaneous tumorigenesis.

Spatial self-phase modulation excited by fractional-order linearly polarized vector fields.

Compared to the integer-order vector field, the fractional-order vector field has an additional degree of control freedom, which will bring rich photophysical properties and what we believe to be novel nonlinear optical phenomena. In this work, we theoretically and experimentally investigate the focusing, propagation, and spatial self-phase modulation (SSPM) of fractional-order linearly polarized vector fields (FLPVFs). It is shown that the weak focusing field of FLPVF exhibits an asymmetric intensity distribution. Intriguingly, its state of polarization (SoP) has a hybrid polarization distribution. When this focused FLPVF propagates to the far field in free space, its SoP degenerates into a localized linearly polarization distribution. However, after the focused FLPVF passes through an isotropic nonlinear Kerr medium, its SoP exhibits a hybrid polarization distribution. Additionally, unlike the self-diffraction intensity pattern of integer-order linearly polarized vector field (ILPVF) with a concentric multi-ring structure, the SSPM pattern of FLPVF is a symmetry broken self-diffraction intensity pattern. The presented work provides a nonlinear optics approach for manipulating both the SoP and intensity distributions of the light field.

Real-Time Cardiac Abnormality Monitoring and Nursing for Patient Using Electrocardiographic Signals.

INTRODUCTION: Cardiovascular disease nursing is a critical clinical application that necessitates real-time monitoring models. Previous models required the use of multi-lead signals and could not be customized as needed. Traditional methods relied on manually designed supervised algorithms, based on empirical experience, to identify waveform abnormalities and classify diseases, and were incapable of monitoring and alerting abnormalities in individual waveforms. METHODS: This research reconstructed the vector model for arbitrary leads using the phase space-time-delay method, enabling the model to arbitrarily combine signals as needed while possessing adaptive denoising capabilities. After employing automatically constructed machine learning algorithms and designing for rapid convergence, the model can identify abnormalities in individual waveforms and classify diseases, as well as detect and alert on abnormal waveforms. RESULT: Effective noise elimination was achieved, obtaining a higher degree of loss function fitting. After utilizing the algorithm in Section 3.1 to remove noise, the signal-to-noise ratio increased by 8.6%. A clipping algorithm was employed to identify waveforms significantly affected by external factors. Subsequently, a network model established by a generative algorithm was utilized. The accuracy for healthy patients reached 99.2%, while the accuracy for APB was 100%, for LBBB 99.32%, for RBBB 99.1%, and for P-wave peak 98.1%. CONCLUSION: By utilizing a three-dimensional model, detailed variations in electrocardiogram signals associated with different diseases can be observed. The clipping algorithm is effective in identifying perturbed and damaged waveforms. Automated neural networks can classify diseases and patient identities to facilitate precision nursing.

Adult classic Bartter syndrome: a case report with 5-year follow-up and literature review.

Bartter syndrome (BS) is a rare, inherited salt-losing renal tubular disorder characterized by secondary hyperaldosteronism, hypokalemia, hypochloremia, metabolic alkalosis, and low-to-normal blood pressure. Classic BS, or BS Type 3, the most common subtype in the Asian population, is caused by a molecular defect in ClC-Kb, a voltage-gated chloride channel in renal tubules, due to CLCNKB gene mutation. Because the onset of BS is more common in children than in adults, the diagnosis, treatment outcomes, genotype/phenotype association, and follow-up of adult-onset BS Type 3 are limited. This case report describes the findings in a 20-year-old man who was admitted with hypokalemic paralysis, with clinical manifestations were similar to those of Gitelman syndrome (GS); however, the patient was later diagnosed to have BS Type 3 through genetic testing (NM_000085.4 (CLCNKB): c.1052G>T). A literature review showed that no homozygous mutations have been reported to date. After 5 years of treatment and follow-up, we found that this genotype requires high levels of potassium and is prone to urinary protein and metabolic syndrome. Distinguishing adult-onset BS from GS is challenging in clinical practice. However, genetic diagnosis can help solve this problem effectively, and genotypes play a guiding role in treatment planning.

Antibody Responses to the SARS-CoV-2 Ancestral Strain and Omicron Variants in Moderna mRNA-1273 Vaccinated Active-Duty US Navy Sailors and Marines.

Omicron and its subvariants have steadily gained greater capability of immune escape compared to other variants of concern, resulting in an increased incidence of reinfections even among vaccinated individuals. We evaluated the antibody response to Omicron BA.1, BA.2, and BA.4/5 in US military members vaccinated with the primary 2-dose series of Moderna mRNA-1273 in a cross-sectional study. While nearly all vaccinated participants had sustained spike (S) IgG and neutralizing antibodies (ND50) to the ancestral strain, only 7.7% participants had detectable ND50 to Omicron BA.1 at 8 months postvaccination. The neutralizing antibody response to BA.2 and BA.5 was similarly reduced. The reduced antibody neutralization of Omicron correlated with the decreased antibody binding to the receptor-binding domain. The participants' seropositivity to the nuclear protein positively correlated with ND50. Our data emphasizes the need for continuous vigilance in monitoring for emerging variants and the need to identify potential alternative targets for vaccine design.

Magnetic Liposomes Infused with GPCR-Expressing Cell Membrane for Targeted Extraction Using Minimum Organic Solvent: An Investigative Study of Trace THC in Sewage.

Trace analysis of lipophilic substances in complex environmental, food, or biological matrices has proven to be a challenge, on account of their high susceptibility to adsorption by particulate matter and liquid-solid interfaces. For this purpose, liquid-liquid extraction (LLE) is often employed as the separation method, which uses water-immiscible organic solvents. As an alternative, magnetic solid-phase extraction (MSPE) allows for adsorption, separation, and recovery of analytes from large volumes of aqueous samples with minimum usage of organic solvents. However, the poor selectivity hampers its performance in various scenarios, especially in sewage samples where complicated and unpredictable interference exists, resulting in block of the active adsorption sites of the sorbent. To this end, we propose receptor-affinity MSPE employing magnetic liposomes decorated with cell membranes expressing G-protein-coupled receptor as the sorbents. Application of the novel sorbent CM@Lip@Fe infused with CB1 cannabinoid receptors was demonstrated for the targeted extraction and enrichment of tetrahydrocannabinol from sewage matrix. Thanks to the high affinity and molecular selectivity of the ligand-receptor interactions, a limit of quantitation of 5.17 ng/L was achieved coupled with HPLC-MS/MS in unfiltered raw sewage, featuring minimum usage of organic solvents, fivefold enhanced sensitivity, low sorbent dosage (75 mg/L of sewage), and high efficiency as major advantages over conventional LLE. This work establishes a framework for efficient separation of specific molecules from complex media, thus promising to extend and refine standard LLE as the clean-up procedure for trace analysis.

Maternal separation affects anxiety-like behavior beginning in adolescence and continuing through adulthood and related to Dnmt3a expression.

Early life stress, including maternal separation, is among one of the main causes of anxiety in adolescents. DNA methyltransferase 3A (Dnmt3a) is a key molecule that regulates DNA methylation and is found to be associated with anxiety-like behavior. It is not clear whether maternal separation affects anxiety levels in mice at different developmental stages or whether Dnmt3a plays a role in this process. Here, by using the open field test to explore the effect of maternal separation on anxiety-like behavior in mice of different ages, it was found that maternal separation could successfully induce anxiety-like behavior in adolescent mice, which continued through adulthood. By using Western blot, we found that the levels of Dnmt3a in the hippocampus and cortex showed different trends in maternal separation mice on postnatal day (P)17. Furthermore, by using immunostaining, we found that the expression levels of Dnmt3a in the cortex and hippocampus were significantly different and decreased to varying degrees with the age of mice, which was the reason for different trends. Our results provide an experimental basis for further development of anxiety/depression treatment programs more suitable for adolescence.NEW & NOTEWORTHY Most anxiety disorders begin in adolescence and continue through adulthood, and research on adolescent anxiety's pathogenesis and treatment options is insufficient. In this research, our results show that maternal separation can successfully induce anxiety-like behavior in adolescent mice that continues through adulthood, further accompanied by abnormal expression of Dnmt3a, which provides an experimental basis for further development of anxiety/depression treatment programs more suitable for adolescence.

Acetylation-regulated interaction between p53 and SET reveals a widespread regulatory mode.

Although lysine acetylation is now recognized as a general protein modification for both histones and non-histone proteins, the mechanisms of acetylation-mediated actions are not completely understood. Acetylation of the C-terminal domain (CTD) of p53 (also known as TP53) was an early example of non-histone protein acetylation and its precise role remains unclear. Lysine acetylation often creates binding sites for bromodomain-containing 'reader' proteins. Here we use a proteomic screen to identify the oncoprotein SET as a major cellular factor whose binding with p53 is dependent on CTD acetylation status. SET profoundly inhibits p53 transcriptional activity in unstressed cells, but SET-mediated repression is abolished by stress-induced acetylation of p53 CTD. Moreover, loss of the interaction with SET activates p53, resulting in tumour regression in mouse xenograft models. Notably, the acidic domain of SET acts as a 'reader' for the unacetylated CTD of p53 and this mechanism of acetylation-dependent regulation is widespread in nature. For example, acetylation of p53 also modulates its interactions with similar acidic domains found in other p53 regulators including VPRBP (also known as DCAF1), DAXX and PELP1 (refs. 7, 8, 9), and computational analysis of the proteome has identified numerous proteins with the potential to serve as acidic domain readers and lysine-rich ligands. Unlike bromodomain readers, which preferentially bind the acetylated forms of their cognate ligands, the acidic domain readers specifically recognize the unacetylated forms of their ligands. Finally, the acetylation-dependent regulation of p53 was further validated in vivo by using a knock-in mouse model expressing an acetylation-mimicking form of p53. These results reveal that acidic-domain-containing factors act as a class of acetylation-dependent regulators by targeting p53 and, potentially, other proteins.

[Angiodynamic and optical coupling analysis of skin tissue model under finite pressure].

The pulse amplitude of fingertip volume could be improved by selecting the vascular dense area and applying appropriate pressure above it. In view of this phenomenon, this paper used Comsol Multiphysics 5.6 (Comsol, Sweden), the finite element analysis software of multi-physical field coupling simulation, to establish the vascular tissue model of a single small artery in fingertips for simulation. Three dimensional Navier-Stokes equations were solved by finite element method, the velocity field and pressure distribution of blood were calculated, and the deformation of blood vessels and surrounding tissues was analyzed. Based on Lambert Beer's Law, the influence of the longitudinal compression displacement of the lateral light surface region and the tissue model on the light intensity signal is investigated. The results show that the light intensity signal amplitude could be increased and its peak value could be reduced by selecting the area with dense blood vessels. Applying deep pressure to the tissue increased the amplitude and peak of the signal. It is expected that the simulation results combined with the previous experimental experience could provide a feasible scheme for improving the quality of finger volume pulse signal.

Semiquantitative Visual Chiral Assay with a Pseudoenantiomeric Fluorescent Sensor Pair.

A new red-light-emitting fluorescent probe (R)-5 was synthesized. In the presence of Zn2+, this compound was found to exhibit good enantioselective fluorescence enhancement at λ = 655 nm when treated with a variety of amino acids in aqueous solution. This probe in combination with a green-light-emitting probe (S)-4 that has enantioselective fluorescence enhancement at λ = 505 nm has formed a pseudoenantiomeric sensor pair because of their opposite enantioselectivities. This sensor pair can simultaneously detect both enantiomers of a chiral amino acid at two very different wavelengths (Δ = 150 nm). It was used to visually and semiquantitatively determine the enantiomeric compositions of amino acids. For example, when a 1:1 mixture of (R)-5 and (S)-4 was treated with Zn(OAc)2 and histidine samples of 0-100% [d-His], the color of the mixtures changed from green to yellow, orange, and red under a UV lamp (365 nm), which allowed a quick quantification of [d-His]%. This is the first example of using fluorescence to visually quantify the enantiomeric composition of chiral compounds.

Ferroptosis as a p53-mediated activity during tumour suppression.

Although p53-mediated cell-cycle arrest, senescence and apoptosis serve as critical barriers to cancer development, emerging evidence suggests that the metabolic activities of p53 are also important. Here we show that p53 inhibits cystine uptake and sensitizes cells to ferroptosis, a non-apoptotic form of cell death, by repressing expression of SLC7A11, a key component of the cystine/glutamate antiporter. Notably, p53(3KR), an acetylation-defective mutant that fails to induce cell-cycle arrest, senescence and apoptosis, fully retains the ability to regulate SLC7A11 expression and induce ferroptosis upon reactive oxygen species (ROS)-induced stress. Analysis of mutant mice shows that these non-canonical p53 activities contribute to embryonic development and the lethality associated with loss of Mdm2. Moreover, SLC7A11 is highly expressed in human tumours, and its overexpression inhibits ROS-induced ferroptosis and abrogates p53(3KR)-mediated tumour growth suppression in xenograft models. Our findings uncover a new mode of tumour suppression based on p53 regulation of cystine metabolism, ROS responses and ferroptosis.

Ultrathin VSe2 Nanosheets with Fast Ion Diffusion and Robust Structural Stability for Rechargeable Zinc-Ion Battery Cathode.

The realizing of high-performance rechargeable aqueous zinc-ion batteries (ZIBs) with high energy density and long cycling life is promising but still challenging due to the lack of suitable layered cathode materials. The work reports the excellent zinc-ion storage performance as-observed in few-layered ultrathin VSe2 nanosheets with a two-step Zn2+ intercalation/de-intercalation mechanism verified by ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterizations. The VSe2 nanosheets exhibit a discharge plateau at 1.0-0.7 V, a specific capacity of 131.8 mAh g-1 (at 0.1 A g-1 ), and a high energy density of 107.3 Wh kg-1 (at a power density of 81.2 W kg-1 ). More importantly, outstanding cycle stability (capacity retention of 80.8% after 500 cycles) without any activation process is achieved. Such a prominent cyclic stability should be attributed to its fast Zn2+ diffusion kinetics (DZn 2+  ≈ 10-8 cm-2 s-1 ) and robust structural/crystalline stability. Density functional theory (DFT) calculation further reveals a strong metallic characteristic and optimal zinc-ion diffusion pathway with a hopping energy barrier of 0.91 eV. The present finding implies that 2D ultrathin VSe2 is a very promising cathode material in ZIBs with remarkable battery performance superior to other layered transitional metal dichalcogenides.

Development of a Sensitive and Rapid Recombinase Polymerase Amplification Assay for Detection of Anaplasma phagocytophilum.

Human granulocytic anaplasmosis (HGA) is a tick-borne disease caused by the obligate intracellular Gram-negative bacterium Anaplasma phagocytophilum The disease often presents with nonspecific symptoms with negative serology during the acute phase. Direct pathogen detection is the best approach for early confirmatory diagnosis. Over the years, PCR-based molecular detection methods have been developed, but optimal sensitivity is not achieved by conventional PCR while real-time PCR requires expensive and sophisticated instruments. To improve the sensitivity and also develop an assay that can be used in resource-limited areas, an isothermal DNA amplification assay based on recombinase polymerase amplification (RPA) was developed. To do this, we identified a 171-bp DNA sequence within multiple paralogous copies of msp2 within the genome of A. phagocytophilum Our novel RPA assay targeting this sequence has an analytical limit of detection of one genome equivalent copy of A. phagocytophilum and can reliably detect 125 bacteria/ml in human blood. A high level of specificity was demonstrated by the absence of nonspecific amplification using genomic DNA from human or DNA from other closely-related pathogenic bacteria, such as Anaplasma platys, Ehrlichia chaffeensis, Orientia tsutsugamushi, and Rickettsia rickettsii, etc. When applied to patient DNA extracted from whole blood, this new RPA assay was able to detect 100% of previously diagnosed A. phagocytophilum cases. The sensitivity and rapidness of this assay represents a major improvement for early diagnosis of A. phagocytophilum in human patients and suggest a role for better surveillance in its reservoirs or vectors, especially in remote regions where resources are limited.

Pravastatin alleviates intracellular calcium dysregulation induced by Interleukin-6 via the mitochondrial ROS pathway in adult ventricular myocytes.

Acute inflammation often contributes to the increased arrhythmogenesis in the cardiomyocytes. We investigated the protective effects of pravastatin on calcium disorders induced by acute administration of pro-inflammatory cytokines in isolated ventricular myocytes and its underlying mechanisms. Wild-type mice were intraperitoneally injected for five days with either pravastatin 20 mg/kg per day or an equal volume of normal saline. Cytosol Ca2+ handling was studied in freshly isolated ventricular myocytes after acute exposure of interleukin-6 (IL-6) (1 ng/ml) for 120 min by Ionoptix and confocal microscopy. Acute administration of clinically relevant concentrations of IL-6 disturbed calcium handling in ventricular myocytes, which presented as decreased amplitudes, prolonged decay times of Ca2+ transients, and reduced sarcoplasmic reticulum (SR) calcium stores. The frequency of spontaneous Ca2+ release, including calcium sparks and spontaneous calcium waves, was dramatically enhanced in the setting of IL-6. Notably, the pretreatment of pravastatin alleviated disturbed Ca2+ cycling, reduced spontaneous Ca2+ leakage induced by IL-6. Mitochondrial ROS pathway may constitute the underlying mechanism of the protective effects of pravastatin. Pravastatin protected the cardiomyocytes against calcium disorders induced by IL-6 via the mitochondrial ROS pathway, which suggests that pravastatin may represent a promising auxiliary therapeutic strategy for cardiac injury under acute inflammation.

Simultaneous Determination of Concentration and Enantiomeric Composition of Amino Acids in Aqueous Solution by Using a Tetrabromobinaphthyl Dialdehyde Probe.

3,3'-Diformyl-1,1'-bi-2-naphthol or its methoxymethyl-protected derivative is found to undergo a highly selective reaction with excess bromine in CH2 Cl2 at reflux to give the novel 5,5',6,6'-tetrabrominated product (S)- or (R)-2. The observed electrophilic substitution at the 5,5'-positons of an optically active binaphthyl compound is unprecedented. Unlike unbrominated 3,3'-diformyl-1,1'-bi-2-naphthol, which is not suitable for fluorescent recognition in water, compound (S)-2, in combination with Zn2+ , exhibits a highly enantioselective fluorescent response toward amino acids in aqueous solution (HEPES buffer, pH 7.4). It is further found that the condensation product of (R)-2 with tryptophan, (R)-3, shows dual-responsive emissions toward amino acids; the short wavelength (λ1 =350 nm) emission is sensitive to the concentration of the substrate regardless of the chiral configuration and the long wavelength (λ2 >500 nm) emission is highly enantioselective. Thus, the use of (R)-3 allows the simultaneous determination of the concentration and enantiomeric composition of an amino acid sample from one fluorescence measurement.

Acute administration of tumour necrosis factor-α induces spontaneous calcium release via the reactive oxygen species pathway in atrial myocytes.

Aims: The arrhythmogenic mechanisms of atrial fibrillation (AF) that are induced by acute inflammation, such as postoperative AF, are not well understood. We investigated the acute effects of tumour necrosis factor-α (TNF-α) that mimic acute inflammation on Ca2+ handling in isolated atrial myocytes and its underlying mechanisms. Methods and results: Cytosol Ca2+ handling and mitochondrial reactive oxygen species (ROS) production were studied in freshly isolated atrial myocytes of wild-type mice that were exposed to TNF-α (0.05 ng/mL) for 2 h by Ionoptix and confocal microscopy. The acute effects of TNF-α on Ca2+ handling were decreased amplitudes and prolonged decay times of Ca2+ transients in isolated atrial myocytes. A significant reduction in the sarcoplasmic reticulum (SR) Ca2+ content was detected in TNF-α treated cells, which was associated with increased spontaneous Ca2+ release events. In particular, physiological concentrations of TNF-α dramatically promoted the frequency of spontaneous Ca2+ waves and Ca2+ sparks, while the spark mass presented with reduced amplitudes and prolonged durations. The underlying mechanisms of pro-arrhythmic effects of TNF-α were further investigated. Acute exposure to TNF-α rapidly promoted mitochondrial ROS production that was correlated with the acute effect of TNF-α on Ca2+ handling, and enhanced the oxidation of calcium/calmodulin-dependent protein kinase II (CaMKII) and the phosphorylation of RyR2. However, the performance of ROS inhibitor, DL-Dithiothreitol (DTT), reversed Ca2+ handling disorders induced by TNF-α. Conclusion: Tumour necrosis factor-α rapidly increases spontaneous Ca2+ release and promotes atrial arrhythmogenesis via the ROS pathway, which suggests that antioxidant therapy is a promising strategy for acute inflammation related AF.

An Eight-Direction Scanning Detection Algorithm for the Mapping Robot Pathfinding in Unknown Indoor Environment.

Aiming at the problem of how to enable the mobile robot to navigate and traverse efficiently and safely in the unknown indoor environment and map the environment, an eight-direction scanning detection (eDSD) algorithm is proposed as a new pathfinding algorithm. Firstly, we use a laser-based SLAM (Simultaneous Localization and Mapping) algorithm to perform simultaneous localization and mapping to acquire the environment information around the robot. Then, according to the proposed algorithm, the 8 certain areas around the 8 directions which are developed from the robot's center point are analyzed in order to calculate the probabilistic path vector of each area. Considering the requirements of efficient traverse and obstacle avoidance in practical applications, the proposal can find the optimal local path in a short time. In addition to local pathfinding, the global pathfinding is also introduced for unknown environments of large-scale and complex structures to reduce the repeated traverse. The field experiments in three typical indoor environments demonstrate that deviation of the planned path from the ideal path can be kept to a low level in terms of the path length and total time consumption. It is confirmed that the proposed algorithm is highly adaptable and practical in various indoor environments.

Deletion of LR11 Attenuates Hypoxia-Induced Pulmonary Arterial Smooth Muscle Cell Proliferation With Medial Thickening in Mice.

OBJECTIVE: We aimed to determine whether LR11 (low-density lipoprotein receptor with 11 binding repeats) is a potential key regulator of smooth muscle cell (SMC) proliferation during the progression of hypoxia-induced medial thickening in mice and whether sLR11 (soluble LR11) can serve as a biomarker in patients with pulmonary arterial hypertension. APPROACH AND RESULTS: The role of LR11 in pulmonary arterial hypertension was investigated using mouse and cell models of induced hypoxia. The expression of LR11 and of hypoxia-inducible factor-1α was significantly increased in lung tissues from C57Bl/6 mice after 3 weeks of exposure to hypoxia compared with normoxia. Serum sLR11 levels were also increased. Physiological and histochemical analyses showed that increased right ventricular systolic pressure, right ventricular hypertrophy, and medial thickening induced under hypoxia in wild-type mice were attenuated in LR11(-/-) mice. The proliferation rates stimulated by hypoxia or platelet-derived growth factor-BB were attenuated in SMC derived from LR11(-/-) mice, compared with those from wild-type mice. Exogenous sLR11 protein increased the proliferation rates of SMC from wild-type mice. The expression of LR11 and hypoxia-inducible factor-1α was increased in cultured SMC under hypoxic conditions, and hypoxia-inducible factor-1α knockdown almost abolished the induction of LR11. Serum sLR11 levels were significantly higher in patients with, rather than without, pulmonary arterial hypertension. sLR11 levels positively correlated with pulmonary vascular resistance and mean pulmonary arterial pressure. CONCLUSIONS: LR11 regulated SMC proliferation during the progression of hypoxia-induced medial thickening in mice. The findings obtained from mice, together with those in humans, indicate that sLR11 could serve as a novel biomarker that reflects the pathophysiology of proliferating medial SMC in pulmonary arterial hypertension.

p53 Protein-mediated regulation of phosphoglycerate dehydrogenase (PHGDH) is crucial for the apoptotic response upon serine starvation.

Although p53 is frequently mutated in human cancers, about 80% of human melanomas retain wild-type p53. Here we report that PHGDH, the key metabolic enzyme that catalyzes the rate-limiting step of the serine biosynthesis pathway, is a target of p53 in human melanoma cells. p53 suppresses PHGDH expression and inhibits de novo serine biosynthesis. Notably, upon serine starvation, p53-mediated cell death is enhanced dramatically in response to Nutlin-3 treatment. Moreover, PHGDH has been found recently to be amplified frequently in human melanomas. We found that PHGDH overexpression significantly suppresses the apoptotic response, whereas RNAi-mediated knockdown of endogenous PHGDH promotes apoptosis under the same treatment. These results demonstrate an important role of p53 in regulating the serine biosynthesis pathway through suppressing PHGDH expression and reveal serine deprivation as a novel approach to sensitize p53-mediated apoptotic responses in human melanoma cells.

Preparation of amphiphilic poly(divinylbenzene-co-N-vinylpyrrolidone)-functionalized polydopamine magnetic nanoadsorbents for enrichment of synthetic cannabinoids in wastewater.

Concerns have been raised about synthetic cannabinoids (SCs), which are among the most often trafficked and used illegal substances. An analytical method that holds promise for determining illicit drug use in the general population is wastewater-based epidemiology (WBE). Unfortunately, the concentration of SCs in wastewater is often extremely low on account of their hydrophobic nature, thus presenting a significant obstacle to the accurate detection and quantification of SCs using WBE. In this study, we present novel magnetic nanomaterials as amphiphilic adsorbents for pretreatment of wastewater using magnetic solid phase extraction (MSPE). Polydopamine-modified Fe3O4 nanoparticles were used as the magnetic core and further functionalized with poly(divinylbenzene-N-vinylpyrrolidone). Coupled with UHPLC-MS/MS analysis, an analytical method to simultaneously detect nine SCs at trace-levels in wastewater was developed and validated, enriching 50 mL wastewater to 100 µL with limits of detection (LOD) being 0.005-0.5 ng L-1, limits of quantification (LOQ) being 0.01-1.0 ng L-1, recoveries ranging from 73.99 to 110.72%, and the intra- and inter-day precision's relative standard deviations less than 15%. In comparison to the time-consuming conventional column-based solid phase extraction, the entire MSPE procedure from sample pre-treatment to data acquisition could be finished in one hour, thus largely facilitating the WBE method for drug surveillance and control.