Visualizing Catalytic Dynamics of Single-Cu-Atom-Modified SnS2 in CO2 Electroreduction via Rapid Freeze-Quench Mössbauer Spectroscopy.

Effective design and engineering of catalysts for an optimal performance depend extensively on a profound understanding of the intricate catalytic dynamics under reaction conditions. In this work, we showcase rapid freeze-quench (RFQ) Mössbauer spectroscopy as a powerful technique for quantitatively monitoring the catalytic dynamics of single-Cu-atom-modified SnS2 (Cu1/SnS2) in the electrochemical CO2 reduction reaction (CO2RR). Utilizing the newly established RFQ 119Sn Mössbauer methodology, we clearly identified the dynamic transformation of Cu1/SnS2 to Cu1/SnS and Cu1/Sn during the CO2RR, resulting in an outstanding Faradaic efficiency for formate production (∼90.9%) with a partial current density of 158 mA cm-2. Results from operando Raman spectroscopy, operando attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), quasi in situ electron microscopy, and quasi in situ X-ray photoelectron spectroscopy (XPS) measurements indicate that the anchored single Cu atom in Cu1/SnS2 can accelerate the reduction of SnS with in situ formation of Cu1/Sn under CO2RR conditions, which effectively promote the generation of *CO2-/*OCHO intermediates. Theoretical calculations further support that in situ formed Cu1/Sn works as active sites catalyzing the CO2RR, which reduces the energy barrier for the CO2 activation and formation of the *OCHO intermediate, thereby facilitating the conversion of CO2 to formate. The results of this work provide a thorough understanding of the dynamic evolution of Sn-based catalytic sites in the CO2RR and shed light for engineering single atoms with an optimized catalytic performance. We anticipate that RFQ Mössbauer spectroscopy will emerge as an advanced spectroscopic technique for enabling a genuine visualization of catalytic dynamics across various reaction systems.

Neuroprotective effects of miRNA-326 knockout in neonatal hypoxic-ischemic brain damage mice via the δ-opioid receptor.

Hypoxic-ischemic brain damage (HIBD) in the perinatal period is an important cause of cerebral damage and long-term neurological sequelae, and can place much pressure on families and society. Our previous study demonstrated that miRNA-326 reduces neuronal apoptosis by up-regulating the δ-opioid receptor (DOR) under oxygen-glucose deprivation in vitro. In the present study, we aimed to explore the neuroprotective effects of the miRNA-326/DOR axis by inhibiting apoptosis in HIBD using neonatal miRNA-326 knockout mice. Neonatal C57BL/6 mice, neonatal miRNA-326 knockout mice, and neonatal miRNA-326 knockout mice intraperitoneally injected with the DOR inhibitor naltrindole were treated with hypoxic-ischemia (HI). Neurological deficit scores, magnetic resonance imaging, terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling, and Caspase-3, Bax, and B-cell lymphoma 2 (Bcl-2) expression were evaluated on day 2 after HI. Neurobehavioral analyses were performed on days 2 and 28 after HI. Additionally, the Morris water maze test was conducted on days 28. Compared with HI-treated neonatal C57BL/6 mice, HI-treated neonatal miRNA-326 knockout mice had higher neurological deficit scores, smaller cerebral infarction areas, and improved motor function, reaction ability, and long-term spatial learning and memory. These effects were likely the result of inhibiting apoptosis; the DOR inhibitor reversed these neuroprotective effects. Our findings indicate that miRNA-326 knockout plays a neuroprotective effect in neonatal HIBD by inhibiting apoptosis via the target gene DOR.

A COX2-targeting cancer-specific fluorescent probe for hydrogen sulfide detection in living cells, Caenorhabditis elegans, and zebrafish.

A novel cyclooxygenase-2 (COX-2) targeted H2S-activated cancer-specific fluorescent probe, namely, COX2-H2S, was designed and synthesized, with naphthalimide as the fluorophore and indomethacin as the targeting group. This H2S-sensing probe was developed to differentiate tumor cells from normal cells and was tested in living cells, Caenorhabditis elegans (C. elegans), and zebrafish. The probe could successfully be used for imaging endogenous and exogenous H2S in living cells, demonstrating high sensitivity and specificity and strong anti-interference. COX2-H2S had the ability to not only discern cancer cells from normal cells but also specifically recognize 9L/lacZ cells from other glioblastoma cells (U87-MG and LN229). It could also be successfully applied for the fluorescent live imaging of H2S in both C. elegans and zebrafish.

Chronic polystyrene microplastics exposure-induced changes in thick-shell mussel (Mytilus coruscus) metaorganism: A holistic perspective.

Microplastics have emerged as a significant global concern, particularly in marine ecosystems. While extensive research has focused on the toxicological effects of microplastics on marine animals and/or their associated microorganisms as two separate entities, the holistic perspective of the adaptability and fitness of a marine animal metaorganism-comprising the animal host and its microbiome-remains largely unexplored. In this study, mussel metaorganisms subjected chronic PS-MPs exposure experienced acute mortality but rapidly adapted. We investigated the response of innate immunity, digestive enzymes and their associated microbiomes to chronic PS-MPs exposure. We found that PS-MPs directly and indirectly interacted with the host and microbe within the exposure system. The adaptation was a joint effort between the physiological adjustments of mussel host and genetic adaptation of its microbiome. The mussel hosts exhibited increased antioxidant activity, denser gill filaments and increased immune cells, enhancing their innate immunity. Concurrently, the gill microbiome and the digestive gland microbiome respective selectively enriched for plastic-degrading bacteria and particulate organic matter-utilizing bacteria, facilitating the microbiome's adaptation. The microbial adaptation to chronic PS-MPs exposure altered the ecological roles of mussel microbiome, as evidenced by alterations in microbial interactions and nutrient cycling functions. These findings provided new insights into the ecotoxicological impact of microplastics on marine organisms from a metaorganism perspective.

Porous Organic Cage as an Efficient Platform for Industrial Radioactive Iodine Capture.

Herein, we firstly develop porous organic cage (POC) as an efficient platform for highly effective radioactive iodine capture under industrial operating conditions (typically ≥ 150 °C, ≤ 150 ppmv of I2). Due to the highly dispersed and readily accessible binding sites as well as sufficient accommodating space, the constructed NKPOC-DT-(I-)Me (NKPOC = Nankai porous organic cage) demonstrates a record-high I2 uptake capacity of 48.35 wt% and extraordinary adsorption capacity of unit ionic site (~1.62) at 150 °C and 150 ppmv of I2. The I2 capacity is 3.5, 1.6, and 1.3 times higher than industrial silver-based adsorbents Ag@MOR and benchmark materials of TGDM and 4F-iCOF-TpBpy-I- under the same conditions. Furthermore, NKPOC-DT-(I-)Me exhibits remarkable adsorption kinetics (k1 = 0.013 min-1), which is 1.2 and 1.6 times higher than TGDM and 4F-iCOF-TpBpy-I- under the identical conditions. NKPOC-DT-(I-)Me thus sets a new benchmark for industrial radioactive I2 adsorbents. This work not only provides a new insight for effectively enhancing the adsorption capacity of unit functional sites, but also advances POC as an efficient platform for radioiodine capture in industry.

Metal-Organic Framework-DNA Bio-Barcodes Amplified CRISPR/Cas12a Assay for Ultrasensitive Detection of Protein Biomarkers.

CRISPR/Cas12a shows excellent potential in disease diagnostics. However, insensitive signal conversion strategies hindered its application in detecting protein biomarkers. Here, we report a metal-organic framework (MOF)-based DNA bio-barcode integrated with the CRISPR/Cas12a system for ultrasensitive detection of protein biomarkers. In this work, zirconium-based MOF nanoparticles were comodified with antibodies and bio-barcode phosphorylated DNA as an efficient signal converter, which not only recognized the protein biomarker to form the sandwich complex but also released the bio-barcode DNA activators after MOF dissociation to activate the trans-cleavage activity of Cas12a. Due to the obvious advantages, including numerous loaded oligonucleotides, a convenient release process, and the nontoxic release reagent, this MOF-DNA bio-barcode strategy could amplify the CRISPR/Cas12a system to achieve simple and highly sensitive detection of tumor protein biomarkers with detection limits of 0.03 pg/mL (PSA) and 0.1 pg/mL (CEA), respectively. Furthermore, this platform could detect PSA directly in clinical serum samples, offering a powerful tool for early disease diagnosis.

Urolithin B alleviates Helicobacter pylori-induced inflammation and oxidative stress in mice.

BACKGROUND: Helicobacter pylori is one of the most common chronic bacterial infections. Active eradication of H. pylori infection is rare due to the fact that most infected patients are asymptomatic and the use of large amounts of antibiotics in eradication therapy leads to severe side effects. Urolithin B (UB) is an additional major intestinal metabolite of ellagic acid (EA), which has been shown to possess anti-inflammatory, antioxidant, and antiapoptotic biological activities. Preventing the incidence of H. pylori-related gastric disease and reducing the damage to the host by H. pylori is a current approach to control H. pylori infection. In this study, we explored the effect of UB on H. pylori infection. MATERIALS AND METHODS: The effects of UB on inflammation and oxidative stress induced by H. pylori in vivo and in vitro were investigated by qPCR, ELISA, HE staining, IHC staining, etc. RESULTS: UB reduced the adhesion and colonization of H. pylori and improved H. pylori-induced inflammation and oxidative stress in vivo and in vitro. Moreover, UB had better anti-inflammatory and antioxidant effects than clarithromycin (CLR) and metronidazole (MET). In addition to inhibiting the secretion of CagA, UB reduced tissue damage by H. pylori infection. CONCLUSIONS: UB was effective in improving damage caused by H. pylori.

STAT3-EphA7 axis contributes to the progression of esophageal squamous cell carcinoma.

BACKGROUND: Our previous study has revealed that EphA7 was upregulated in patient-derived esophageal squamous cell carcinoma (ESCC) xenografts with hyper-activated STAT3, but its mechanism was still unclear. MATERIALS AND METHODS: To assess the association between EphA7 and STAT3, western blotting, immunofluorescence, ChIP assay, and qRT-PCR were conducted. Truncated mutation and luciferase assay were performed to examine the promoter activity of EphA7. CCK-8 assay and colony formation were performed to assess the proliferation of ESCC. Cell-derived xenograft models were established to evaluate the effects of EphA7 on ESCC tumor growth. RNA-seq analyses were used to assess the effects of EphA7 on related signals. RESULTS: In this study, EphA7 was found upregulated in ESCC cell lines with high STAT3 activation, and immunofluorescence also showed that EphA7 was co-localized with phospho-STAT3 in ESCC cells. Interestingly, suppressing STAT3 activation by the STAT3 inhibitor Stattic markedly inhibited the protein expression of EphA7 in ESCC cells, in contrast, activation of STAT3 by IL-6 obviously upregulated the protein expression of EphA7. Moreover, the transcription of EphA7 was also mediated by the activation of STAT3 in ESCC cells, and the -2000∼-1500 region was identified as the key promoter of EphA7. Our results also indicated that EphA7 enhanced the cell proliferation of ESCC, and silence of EphA7 significantly suppressed ESCC tumor growth. Moreover, EphA7 silence markedly abolished STAT3 activation-derived cell proliferation of ESCC. Additionally, RNA-seq analyses indicated that several tumor-related signaling pathways were significantly changed after EphA7 downregulation in ESCC cells. CONCLUSION: Our results showed that the transcriptional expression of EphA7 was increased by activated STAT3, and the STAT3 signaling may act through EphA7 to promote the development of ESCC.

The relationship between physical activity and the severity of menopausal symptoms: a cross-sectional study.

OBJECTIVE: To investigate the relationship between physical activity and the severity of menopausal symptoms in middle-aged women in northwest China. METHODS: This was a cross-sectional online survey study. Using a snowball sampling method, 468 women aged 45 to 60 were recruited from northwest China and their demographic information was collected. The modified Kupperman Menopausal Index scale and International Physical Activity Questionnaire short form were used in this study. Random forest was used to rank the importance of variables and select the optimal combination. The direction and relative risk (odds ratio value) of selected variables were further explained with an ordinal logistic regression model. RESULTS: The prevalence of menopausal syndromes was 74.8% and more than one-half of the participants had moderate or severe symptoms (54.3%). The Mantel-Haenszel linear-by-linear chi-square test showed a strong and negative correlation between physical activity level and the severity of menopausal symptoms (P < 0.001). Random forest demonstrated that the physical activity level was the most significant variable associated with the severity of menopausal symptoms. Multiple random forest regressions showed that the out-of-bag error rate reaches the minimum when the top 4 variables (physical activity level, menopausal status, perceived health status, and parity) in the importance ranking form an optimal variable combination. Ordinal logistic regression analysis showed that a higher physical activity level and a satisfactory perceived health status might be protective factors for menopausal symptoms (odds ratio (OR) < 1, P < 0.001); whereas perimenopausal or postmenopausal status and 2 parities might be risk factors for menopausal symptoms (OR > 1, P < 0.001). CONCLUSIONS: There is a strong negative correlation between physical activity and the severity of menopausal symptoms. The results have a clinical implication that the menopausal symptoms may be improved by the moderate-to-high level physical activity in the lives of middle-aged women.

Metal Organic Framework-Based Bio-Barcode CRISPR/Cas12a Assay for Ultrasensitive Detection of MicroRNAs.

CRISPR/Cas12a has shown great potential in molecular diagnostics, but its application in sensing of microRNAs (miRNAs) was limited by sensitivity and complexity. Here, we have sensitively and conveniently detected microRNAs by reasonably integrating metal-organic frameworks (MOFs) based biobarcodes with CRISPR/Cas12a assay (designated as MBCA). In this work, DNA-functionalized Zr-MOFs were designed as the converter to convert and amplify each miRNA target into activators that can initiate the trans-cleavage activity of CRISPR/Cas12a to further amplify the signal. Such integration provides a universal strategy for sensitive detection of miRNAs. By tuning the complementary sequences modified on nanoprobes, this assay achieves subattomolar sensitivity for different miRNAs and was selective to single-based mismatches. With the proposed method, the expression of miR-21 in different cancer cells can be assessed, and breast cancer patients and healthy individuals can be differentiated by analyzing the target miRNAs extracted from serum samples, holding great potential in clinical diagnosis.

Salicylic acid biosynthesis is not from phenylalanine in Arabidopsis.

The phytohormone salicylic acid (SA) regulates biotic and abiotic stress responses in plants. Two distinct biosynthetic pathways for SA have been well documented in plants: the isochorismate (IC) pathway in the chloroplast and the phenylalanine ammonia-lyase (PAL) pathway in the cytosol. However, there has been no solid evidence that the PAL pathway contributes to SA biosynthesis. Here, we report that feeding Arabidopsis thaliana with Ring-13 C-labeled phenylalanine (13 C6 -Phe) resulted in incorporation of the 13 C label not into SA, but into its isomer 4-hydroxybenzoic acid (4-HBA) instead. We obtained similar results when feeding 13 C6 -Phe to the SA-deficient ics1 ics2 mutant and the SA-hyperaccumulating mutant s3h s5h. Notably, we detected 13 C6 -SA when 13 C6 -benzoic acid (BA) was provided, suggesting that SA can be synthesized from BA. Furthermore, despite the substantial accumulation of SA upon pathogen infection, we did not observe incorporation of 13 C label from Phe into SA. We also did not detect 13 C6 -SA in PAL-overexpressing lines in the kfb01 kfb02 kfb39 kfb50 background after being fed 13 C6 -Phe, although endogenous PAL levels were dramatically increased. Based on these combined results, we propose that SA biosynthesis is not from Phe in Arabidopsis. These results have important implications for our understanding of the SA biosynthetic pathway in land plants.

Making small molecules in plants: A chassis for synthetic biology-based production of plant natural products.

Plant natural products have been extensively exploited in food, medicine, flavor, cosmetic, renewable fuel, and other industrial sectors. Synthetic biology has recently emerged as a promising means for the cost-effective and sustainable production of natural products. Compared with engineering microbes for the production of plant natural products, the potential of plants as chassis for producing these compounds is underestimated, largely due to challenges encountered in engineering plants. Knowledge in plant engineering is instrumental for enabling the effective and efficient production of valuable phytochemicals in plants, and also paves the way for a more sustainable future agriculture. In this manuscript, we briefly recap the biosynthesis of plant natural products, focusing primarily on industrially important terpenoids, alkaloids, and phenylpropanoids. We further summarize the plant hosts and strategies that have been used to engineer the production of natural products. The challenges and opportunities of using plant synthetic biology to achieve rapid and scalable production of high-value plant natural products are also discussed.

Anti-tumour potential of PD-L1/PD-1 post-translational modifications.

The immune checkpoint programmed death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1) are biologically important immunosuppressive molecules, and the PD-L1/PD-1-mediated signalling pathway is currently considered one of the main mechanisms of tumour escape immune surveillance. PD-L1 is highly expressed on the cytomembrane of tumour cell and binds to PD-1 receptor of activated T cells. This interaction activates PD-L1/PD-1 downstream signal transduction, inhibiting T cells anti-tumour activity. Therefore, inhibitors of PD-L1/PD-1 activation, showing significant efficacy in some types of tumours, have been widely approved in clinical tumour therapy. Recent research on PD-L1/PD-1 signalling pathway regulation has shown post-translational modifications (PTMs) form of PD-L1 or PD-1, including glycosylation, ubiquitination, phosphorylation, and acetylation, which may play an important role in PD-L1/PD-1 signalling pathway regulation and anti-tumour function of T cells. In this review, we focused on PTMs of PD-L1/PD-1 research and potential applications in tumour immunotherapy.

Potential-Driven Restructuring of Cu Single Atoms to Nanoparticles for Boosting the Electrochemical Reduction of Nitrate to Ammonia.

Restructuring is ubiquitous in thermocatalysis and of pivotal importance to identify the real active site, yet it is less explored in electrocatalysis. Herein, by using operando X-ray absorption spectroscopy in conjunction with advanced electron microscopy, we reveal the restructuring of the as-synthesized Cu-N4 single-atom site to the nanoparticles of ∼5 nm during the electrochemical reduction of nitrate to ammonia, a green ammonia production route upon combined with the plasma-assisted oxidation of nitrogen. The reduction of Cu2+ to Cu+ and Cu0 and the subsequent aggregation of Cu0 single atoms is found to occur concurrently with the enhancement of the NH3 production rate, both of them are driven by the applied potential switching from 0.00 to -1.00 V versus RHE. The maximum production rate of ammonia reaches 4.5 mg cm-2 h-1 (12.5 molNH3 gCu-1 h-1) with a Faradaic efficiency of 84.7% at -1.00 V versus RHE, outperforming most of the other Cu catalysts reported previously. After electrolysis, the aggregated Cu nanoparticles are reversibly disintegrated into single atoms and then restored to the Cu-N4 structure upon being exposed to an ambient atmosphere, which masks the potential-induced restructuring during the reaction. The synchronous changes of the Cu0 percentage and the ammonia Faradaic efficiency with the applied potential suggests that the Cu nanoparticles are the genuine active sites for nitrate reduction to ammonia, which is corroborated with both the post-deposited Cu NP catalyst and density functional theory calculations.

Crystal structure of the plant feruloyl-coenzyme A monolignol transferase provides insights into the formation of monolignol ferulate conjugates.

Lignin is a highly complex phenolic polymer which is essential for plants, but also makes it difficult for industrial processing. Engineering lignin by introducing relatively labile linkages into the lignin backbone can render it more amenable to chemical depolymerization. It has been reported that introducing a feruloyl-coenzyme A monolignol transferase from Angelica sinensis (AsFMT) into poplar could incorporate monolignol ferulate conjugates (ML-FAs) into lignin polymers, suggesting a promising way to manipulate plants for readily deconstructing. FMT catalyzes a reaction between monolignols and feruloyl-CoA to produce ML-FAs and free CoA-SH. However, the mechanisms of substrate specificity and catalytic process of FMT remains poorly understood. Here we report the structure of AsFMT, which adopts a typical fold of BAHD acyltransferase family. Structural comparisons with other BAHD homologs reveal several unique structural features of AsFMT, different from those of the BAHD homologs. Further molecular docking studies showed that T375 in AsFMT may function as an oxyanion hole to stabilize the reaction intermediate and also proposed a role of H278 in the binding of the nucleophilic hydroxyl group of monolignols. Together, this study provides important structural insights into the reactions catalyzed by AsFMT and will shed light on its future application in lignin engineering.

Aptazyme-induced cascade amplification integrated with a volumetric bar-chart chip for highly sensitive detection of aflatoxin B1 and adenosine triphosphate.

A simple aptazyme-induced cascade signal amplification (denoted as ACSA) was integrated with a triple-channel volumetric bar-chart chip (TV-Chip) to visually quantitate aflatoxin B1 (AFB1) and adenosine triphosphate (ATP). Bifunctional aptazymes consisting of aptamers and G-quadruplex-forming sequences were modified on magnetic silica nanoparticles (MSNPs) to construct sensing probes. The recognition of aptamers and targets leads to the formation of hemin/G-quadruplex (hGQ) DNAzymes, which can mimic the horseradish peroxidase (HRP)-accelerated signal enhancement reaction, enabling the polymerization of dopamine and subsequent deposition of polydopamine (PDA) on the MSNP probes, thereby providing abundant anchor sites to covalently immobilize numerous 4-mercaptophenylboric acid (4-MPBA)-modified platinum nanoparticles (PtNPs) (MPt). As a result, this strategy possesses high sensitivity by introducing a large number of PtNPs into the TV-Chip. The detection limits of AFB1 and ATP with 0.075 pM and 0.818 pM, respectively, were easily achieved without any additional instruments. In addition, the detection results of AFB1-spiked food samples were in good agreement with the commercial AFB1 ELISA kit, which verified the accuracy and reliability of this method. The ACSA-based TV-Chip would show great promise for on-site and real-time visual quantitation of trace targets.

Influence of Early-Onset Peritonitis on Mortality and Clinical Outcomes in ESRD Patients with Diabetes Mellitus on Peritoneal Dialysis: A Retrospective Multicenter Study.

INTRODUCTION: The impact of early-onset peritonitis (EOP) on patients with diabetes undergoing peritoneal dialysis (PD) has not been adequately addressed. We therefore sought to investigate the effects of EOP on the therapeutic response to management and long-term prognostic outcomes in patients with diabetes undergoing PD. METHODS: For this retrospective cohort study, we analyzed the data for patients with end-stage renal disease, who were also suffering from diabetes mellitus and had undergone PD between January 1, 2013, and December 31, 2018. EOP was defined as the first episode of peritoneal dialysis-related peritonitis (PDAP) occurring within 12 months of PD initiation. All patients were divided into an EOP group and a later-onset peritonitis (LOP) group. Clinical data, treatment results, and outcomes were compared between groups. RESULTS: Ultimately, 202 patients were enrolled for the analysis. Compared to the EOP group, the LOP group had more Streptococcus (p = 0.033) and Pseudomonas (p = 0.048). Patients with diabetes in the EOP group were less likely to have PDAP-related death (OR 0.13, CI: 0.02-0.82, p = 0.030). Patients with diabetes in the EOP group were more likely to have multiple episodes of PDAP and had higher rates of technical failure and poorer patient survival than those in the LOP group, as indicated by Kaplan-Meier analysis (p = 0.019, p = 0.004, and p < 0.001). In the multivariate Cox proportional hazards model, EOP was a significant predictor for multiple PDAP (HR 4.20, CI: 1.48-11.96, p = 0.007), technical failure (HR 6.37, CI: 2.21-18.38, p = 0.001), and poorer patient survival (HR 3.09, CI: 1.45-6.58, p = 0.003). CONCLUSIONS: The occurrence of EOP is significantly associated with lower rates of PDAP-related death and poorer clinical outcomes in patients with diabetes undergoing PD.

Immunoenhancing Effects of Cyclina sinensis Pentadecapeptide through Modulation of Signaling Pathways in Mice with Cyclophosphamide-Induced Immunosuppression.

Our study aimed to investigate the immune-enhancing mechanism of the pentadecapeptide (RVAPEEHPVEGRYLV) from Cyclina sinensis (SCSP) in a cyclophosphamide (CTX)-induced murine model of immunosuppression. Our results showed that SCSP treatment significantly increased mouse body weight, immune organ indices, and the production of serum IL-6, IL-1ß, and tumor necrosis factor (TNF)-α in CTX-treated mice. In addition, SCSP treatment enhanced the proliferation of splenic lymphocytes and peritoneal macrophages, as well as phagocytosis of the latter in a dose-dependent manner. Moreover, SCSP elevated the phosphorylation levels of p38, ERK, JNK, PI3K and Akt, and up-regulated IKKα, IKKß, p50 NF-κB and p65 NF-κB protein levels, while down-regulating IκBα protein levels. Our results indicate that SCSP has immune-enhancing activities, and that it can activate the MAPK/NF-κB and PI3K/Akt pathways to enhance immunity in CTX-induced immunosuppressed mice.

Arabidopsis MYB4 plays dual roles in flavonoid biosynthesis.

Flavonoids are major secondary metabolites derived from the plant phenylpropanoid pathway that play important roles in plant development and also have benefits for human health. So-called MBW ternary complexes involving R2R3-MYB and basic helix-loop-helix (bHLH) transcription factors along with WD-repeat proteins have been reported to regulate expression of the biosynthetic genes in the flavonoid pathway. MYB4 and its closest homolog MYB7 have been suggested to function as repressors of phenylpropanoid metabolism. However, the detailed mechanism by which they act has not been fully elucidated. Here, we show that Arabidopsis thaliana MYB4 and its homologs MYB7 and MYB32 interact with the bHLH transcription factors TT8, GL3 and EGL3 and thereby interfere with the transcriptional activity of the MBW complexes. In addition, MYB4 can also inhibit flavonoid accumulation by repressing expression of the gene encoding Arogenate Dehydratase 6 (ADT6), which catalyzes the final step in the biosynthesis of phenylalanine, the precursor for flavonoid biosynthesis. MYB4 potentially represses not only the conventional ADT6 encoding the plastidial enzyme but also the alternative isoform encoding the cytosolic enzyme. We suggest that MYB4 plays dual roles in modulating the flavonoid biosynthetic pathway in Arabidopsis.

Arabidopsis SnRK1 negatively regulates phenylpropanoid metabolism via Kelch domain-containing F-box proteins.

Phenylpropanoid metabolism represents a substantial metabolic sink for photosynthetically fixed carbon. The evolutionarily conserved Sucrose Non-Fermenting Related Kinase 1 (SnRK1) is a major metabolic sensor that reprograms metabolism upon carbon deprivation. However, it is not clear if and how the SnRK1-mediated sugar signaling pathway controls phenylpropanoid metabolism. Here, we show that Arabidopsis SnRK1 negatively regulates phenylpropanoid biosynthesis via a group of Kelch domain-containing F-box (KFB) proteins that are responsible for the ubiquitination and degradation of phenylalanine ammonia lyase (PAL). Downregulation of AtSnRK1 significantly promoted the accumulation of soluble phenolics and lignin polymers and drastically increased PAL cellular accumulation but only slightly altered its transcription level. Co-expression of SnRK1α with PAL in Nicotiana benthamiana leaves resulted in the severe attenuation of the latter's protein level, but protein interaction assays suggested PAL is not a direct substrate of SnRK1. Furthermore, up or downregulation of AtSnRK1 positively affected KFBPALs gene expression, and energy starvation upregulated KFBPAL expression, which partially depends on AtSnRK1. Collectively, our study reveals that SnRK1 negatively regulates phenylpropanoid biosynthesis, and KFBPALs act as regulatory components of the SnRK1 signaling network, transcriptionally regulated by SnRK1 and subsequently mediate proteasomal degradation of PAL in response to the cellular carbon availability.