Transcriptomic-Proteomic Analysis Revealed the Regulatory Mechanism of Peanut in Response to Fusarium oxysporum.

Peanut Fusarium rot, which is widely observed in the main peanut-producing areas in China, has become a significant factor that has limited the yield and quality in recent years. It is highly urgent and significant to clarify the regulatory mechanism of peanuts in response to Fusarium oxysporum. In this study, transcriptome and proteome profiling were combined to provide new insights into the molecular mechanisms of peanut stems after F. oxysporums infection. A total of 3746 differentially expressed genes (DEGs) and 305 differentially expressed proteins (DEPs) were screened. The upregulated DEGs and DEPs were primarily enriched in flavonoid biosynthesis, circadian rhythm-plant, and plant-pathogen interaction pathways. Then, qRT-PCR analysis revealed that the expression levels of phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), and cinnamic acid-4-hydroxylase (C4H) genes increased after F. oxysporums infection. Moreover, the expressions of these genes varied in different peanut tissues. All the results revealed that many metabolic pathways in peanut were activated by improving key gene expressions and the contents of key enzymes, which play critical roles in preventing fungi infection. Importantly, this research provides the foundation of biological and chemical analysis for peanut disease resistance mechanisms.

A Magnetic Reduced Graphene Oxide Nanocomposite: Synthesis, Characterization, and Application for High-Efficiency Detoxification of Aflatoxin B1.

(1) Background: Safety problems associated with aflatoxin B1 (AFB1) contamination have always been a major threat to human health. Removing AFB1 through adsorption is considered an attractive remediation technique. (2) Methods: To produce an adsorbent with a high AFB1 adsorption efficiency, a magnetic reduced graphene oxide composite (Fe3O4@rGO) was synthesized using one-step hydrothermal fabrication. Then, the adsorbent was characterized using a series of techniques, such as SEM, TEM, XRD, FT-IR, VSM, and nitrogen adsorption-desorption analysis. Finally, the effects of this nanocomposite on the nutritional components of treated foods, such as vegetable oil and peanut milk, were also examined. (3) Results: The optimal synthesis conditions for Fe3O4@rGO were determined to be 200 °C for 6 h. The synthesis temperature significantly affected the adsorption properties of the prepared material due to its effect on the layered structure of graphene and the loading of Fe3O4 nanoparticles. The results of various characterizations illustrated that the surface of Fe3O4@rGO had a two-dimensional layered nanostructure with many folds and that Fe3O4 nanoparticles were distributed uniformly on the surface of the composite material. Moreover, the results of isotherm, kinetic, and thermodynamic analyses indicated that the adsorption of AFB1 by Fe3O4@rGO conformed to the Langmuir model, with a maximum adsorption capacity of 82.64 mg·g-1; the rapid and efficient adsorption of AFB1 occurred mainly through chemical adsorption via a spontaneous endothermic process. When applied to treat vegetable oil and peanut milk, the prepared material minimized the loss of nutrients and thus preserved food quality. (4) Conclusions: The above findings reveal a promising adsorbent, Fe3O4@rGO, with favorable properties for AFB1 adsorption and potential for food safety applications.

Phosphorylation Modification, Structural Characterization, Antioxidant and DNA Protection Capacities of Polysaccharides from Asarum Sieboldii Miq.

Polysaccharide from Asarum sieboldii Miq (ASP) was extracted and five phosphorylation polysaccharides with different degree of substitution were obtained, namely ASPP1, ASPP2, ASPP3, ASPP4, and ASPP5 (ASPPs). The physical and chemical structure and biological activities were studied. The results suggested that the carbohydrate and protein content were reduced while uronic acid was increased after phosphorylation modification. The molecular weight of ASPPs was significantly lower than that of ASP. ASPPs were acidic heteropolysaccharides mainly composed of galacturonic acid, galactose, glucose, fructose, and arabinose. The UV-vis spectrum indicated that the polysaccharides did not contain nucleic acid or protein after modification. The Fourier transform infrared spectrum demonstrated that ASPPs contained characteristic absorption peaks of P=O and P-O-C near 1270 and 980 cm-1 . ASPPs presented a triple helix conformation, but it was not presented in ASP. The scanning electron microscopy analysis showed that the surface topography and particle structure of ASP were different after modification. Compared with ASP, ASPPs enhanced the activity to scavenge DPPH and ABTS free radicals and possessed more protective ability to DNA oxidation caused by OH⋅, GS⋅, and AAPH free radicals. These results suggest that chemical modification is beneficial for the exploitation and utilization of natural polysaccharides.

Cathepsin V drives lung cancer progression by shaping the immunosuppressive environment and adhesion molecules cleavage.

Cathepsin V (CTSV) is a cysteine cathepsin protease that plays a crucial role in extracellular matrix degradation. CTSV is correlated with poor prognosis in various cancers, but the underlying mechanism remains elusive. Here, we observed that CSTV is upregulated in lung cancer and is a poor prognosis factor for lung cancer. CTSV acts as a driver in the metastasis of lung cancer both in vitro and in vivo. CTSV promotes lung cancer metastasis by downregulating adhesion molecules, including fibronectin, E-cadherin, and N-cadherin. Our data revealed that CTSV functions by mediating the fragmentation of fibronectin, E-cadherin, and N-cadherin in cleavage, remodeling the extracellular matrix (ECM). The rationally designed antibody targeting CTSV blocks its cleaving ability towards fibronectin, E-cadherin, and N-cadherin, suppressing migration and invasion. Furthermore, we found that CTSV expression is negatively correlated with immune cell infiltration and immune scores and inhibits T cell activity. Targeting CTSV with specific antibodies effectively suppressed lung cancer metastasis in a mouse model. Our study demonstrates the critical role of CTSV in the immunity and metastasis of lung cancer, suggesting that the CTSV-targeting approach is a promising strategy for lung cancer.

Andrographolide inhibits infectious bronchitis virus-induced apoptosis, pyroptosis, and inflammation.

BACKGROUND: Avian infectious bronchitis virus (IBV), a coronavirus, causes a huge economic loss to the poultry industry. Andrographolide (APL) is a compound with a variety of pharmacological properties, including antiviral and anti-inflammatory effects. In this study, APL was evaluated for antiviral activity by its anti-apoptotic, anti-pyroptosis, and anti-inflammatory effects. METHODS: The cytotoxicity of APL was determined by the MTT method. We investigated the therapeutic impact of APL on IBV through a plate assay. We explored that APL inhibited IBV-induced apoptosis, pyroptosis, and inflammation in HD11 cells by RT-qPCR and immunofluorescence. Also, it was verified in the clinical chicken embryo trial. RESULTS: We found that APL down-regulated apoptosis-related genes Caspase-3, Caspase-8, Caspase-9, Bax, Bid, and Bak, down-regulated pyroptosis gene DFNA5, and down-regulated inflammation-related genes (NF-κB, NLRP3, iNOS, TNF-α, and IL-1ß). In addition, APL reduced the reactive oxygen species (ROS) production in cells. Finally, clinical trials showed that APL inhibited IBV-induced apoptosis, pyroptosis, and inflammation, as well as reduced the mortality and malformation of chicken embryos. CONCLUSIONS: In this study, we delved into the antiviral properties of APL in the context of chicken macrophage (HD11) infection with IBV. Our findings confirm that andrographolide effectively inhibits apoptosis, pyroptosis, and inflammation by IBV infection. Furthermore, this inhibition was verified on chicken embryos in vivo. This inhibition suggests a substantial potential for APL as a therapeutic agent to mitigate the harmful effects of IBV on host cells.

Corrigendum: Self-assembling and pH-Responsive protein nanoparticle as potential platform for targeted tumor therapy.

[This corrects the article DOI: 10.3389/fmolb.2023.1172100.].

New insights into the antimicrobial action and protective therapeutic effect of tirapazamine towards Escherichia coli-infected mice.

OBJECTIVES: Escherichia coli is an important pathogen responsible for numerous cases of diarrhoea worldwide. The bioreductive agent tirapazamine (TPZ), which was clinically used to treat various types of cancers, has obvious antibacterial activity against E. coli strains. In the present study, we aimed to evaluate the protective therapeutic effects of TPZ in E. coli-infected mice and provide insights into its antimicrobial action mechanism. METHODS: The MIC and MBC tests, drug sensitivity test, crystal violet assay and proteomic analysis were used to detect the in vitro antibacterial activity of TPZ. The clinical symptoms of infected mice, tissue bacteria load, histopathological features and gut microbiota changes were regarded as indicators to evaluation the efficacy of TPZ in vivo. RESULTS: Interestingly, TPZ-induced the reversal of drug resistance in E. coli by regulating the expression of resistance-related genes, which may have an auxiliary role in the clinical treatment of drug-resistant bacterial infections. More importantly, the proteomics analysis showed that TPZ upregulated 53 proteins and downregulated 47 proteins in E. coli. Among these, the bacterial defence response-related proteins colicin M and colicin B, SOS response-related proteins RecA, UvrABC system protein A, and Holliday junction ATP-dependent DNA helicase RuvB were all significantly upregulated. The quorum sensing-related protein glutamate decarboxylase, ABC transporter-related protein glycerol-3-phosphate transporter polar-binding protein, and ABC transporter polar-binding protein YtfQ were significantly downregulated. The oxidoreductase activity-related proteins pyridine nucleotide-disulfide oxidoreductase, glutaredoxin 2 (Grx2), NAD(+)-dependent aldehyde reductase, and acetaldehyde dehydrogenase, which participate in the elimination of harmful oxygen free radicals in the oxidation-reduction process pathway, were also significantly downregulated. Moreover, TPZ improved the survival rate of infected mice; significantly reduced the bacteria load in the liver, spleen, and colon; and alleviated E. coli-associated pathological damages. The gut microbiota also changed in TPZ-treated mice, and these genera were considerably differentiated: Candidatus Arthromitus, Eubacterium coprostanoligenes group, Prevotellaceae UCG-001, Actinospica, and Bifidobacterium. CONCLUSIONS: TPZ may represent an effective and promising lead molecule for the development of antimicrobial agents for the treatment of E. coli infections.

Targeting the KRT16-vimentin axis for metastasis in lung cancer.

Lung cancer is the most diagnosed malignant cancer and the leading cause of cancer-related deaths worldwide, with advanced stage and metastasis being a major issue. The mechanism leading to metastasis is not yet understood. Here, we found that KRT16 is upregulated in metastatic lung cancer tissues and correlated with poor overall survival. Knockdown of KRT16 inhibits metastasis of lung cancer both in vitro and in vivo. Mechanistically, KRT16 interacts with vimentin, and depletion of KRT16 leads to downregulation of vimentin. KRT16 acquired its oncogenic ability by stabilizing vimentin, and vimentin is required for KRT16-driven metastasis. FBXO21 mediates the polyubiquitination and degradation of KRT16, and vimentin inhibits KRT16 ubiquitination and degradation by impairing its interaction with FBXO21. Significantly, IL-15 inhibits metastasis of lung cancer in a mouse model through upregulation of FBXO21, and the level of IL-15 in circulating serum was significantly higher in nonmetastatic lung cancer patients than in metastatic patients. Our findings indicate that targeting the FBXO21/KRT16/vimentin axis may benefit lung cancer patients with metastasis.

Antioxidant and DNA protecting activity of carboxymethylated polysaccharides from Cortex periplocae.

In this study, polysaccharide from Cortex periplocae (CPP) was modified and three carboxymethylation modification polysaccharides (CPPCs) were obtained, and their physicochemical characteristics and in vitro biological activities were investigated. Based on the ultraviolet-visible (UV-Vis) scan, CPPs (CPP and CPPCs) did not contain nucleic acids or proteins. However, the Fourier transform infrared (FTIR) spectrum showed a new absorption peak around 1731 cm-1. In addition, three absorption peaks near 1606, 1421, and 1326 cm-1 were enhanced after carboxymethylation modification. Based on UV-Vis scan, the maximum absorption wavelength of Congo Red + CPPs exhibited a red-shift compared to Congo Red meant CPPs had a triple helix conformation. Scanning electron microscopy (SEM) indicated that CPPCs exhibited more fragments and non-uniform-sized filiform than CPP. Thermal analysis showed that CPPCs degraded between the temperature 240 °C-350 °C and CPP in the 270 °C-350 °C. In addition, the antioxidant and DNA protecting activities of CPPCs were significantly enhanced compared to CPP. Overall, this study demonstrated the potential applications of CPPs in food and pharmaceutical industries.

Design, synthesis, antibacterial/antitumor activity and in vitro stability of novel cordycepin derivatives with unsaturated fatty acid chain.

To overcome the metabolic instability of cordycepin (adenosine deaminase (ADA) metabolic deamination and plasma degradation) and obtain better bioactivity, three novel kinds of cordycepin derivatives 1a-1c containing unsaturated fatty acids including linoleic acid, arachidonic acid and α-linolenic acid, respectively, were designed and synthesized. In terms of antibacterial activity, the synthesized compounds 1a and 1c showed enhanced activity than cordycepin in the tested bacterial strains. 1a-1c also exhibited enhanced antitumor activity against four cancer cell lines (human cervical cancer cell line HeLa, human non-small cell lung cancer cell line A549, human breast cancer cell line MCF-7, and human hepatoma cell line SMMC-7721) compared with cordycepin. Notably, 1a and 1b showed better antitumor activity even compared with positive control 5-Fluorouracil (5-FU) in HeLa, MCF-7 and SMMC-7721. The cell cycle assay indicated that when compared with cordycepin, 1a and 1b could significantly inhibit the cell propagation trapped in S and G2/M phases and increase the percentage of cells trapped in G0/G1 in HeLa and A549, which might provide a synergistic antitumor mechanism evidence different from cordycepin. Last but not the least, 1a and 1b displayed improved stability both in ADA solution and mouse plasma compared with cordycepin and 1a owns a solubility of 130 µg/mL in PBS. These results offer a novel insight into the primary structure and activity relationship of how the unsaturated fatty acid chain could affect the bioactivity of cordycepin, which also represents a series of cordycepin analogs with obviously improved bioactivity and enhanced stability, therefore promoting its druggable enhancement.

Self-assembling and pH-responsive protein nanoparticle as potential platform for targeted tumor therapy.

Frequent injections at high concentrations are often required for many therapeutic proteins due to their short in vivo half-life, which usually leads to unsatisfactory therapeutic outcomes, adverse side effects, high cost, and poor patient compliance. Herein we report a supramolecular strategy, self-assembling and pH regulated fusion protein to extend the in vivo half-life and tumor targeting ability of a therapeutically important protein trichosanthin (TCS). TCS was genetically fused to the N-terminus of a self-assembling protein, Sup35p prion domain (Sup35), to form a fusion protein of TCS-Sup35 that self-assembled into uniform spherical TCS-Sup35 nanoparticles (TCS-Sup35 NP) rather than classic nanofibrils. Importantly, due to the pH response ability, TCS-Sup35 NP well retained the bioactivity of TCS and possessed a 21.5-fold longer in vivo half-life than native TCS in a mouse model. As a result, in a tumor-bearing mouse model, TCS-Sup35 NP exhibited significantly improved tumor accumulation and antitumor activity without detectable systemic toxicity as compared with native TCS. These findings suggest that self-assembling and pH responding protein fusion may provide a new, simple, general, and effective solution to remarkably improve the pharmacological performance of therapeutic proteins with short circulation half-lives.

Roles of conserved active site residues in the IscS cysteine desulfurase reaction.

Escherichia coli cysteine desulfurase (CD), IscS, modifies basal metabolism by transferring sulphur (S) from L-cysteine to numerous cellular pathways, whereas NFS1, a human CD, is active only in the formation of the [Acp]2:[ISD11]2:[NFS1]2 complex. Despite the accumulation of red-coloured IscS in E. coli cells as a result of the deficiency of accessible iron, as revealed in our previous studies, the mechanism of the potential enzymatic reaction remains unclear. In this study, the N-terminus of IscS was fused with the C-terminus of NFS1, which was reported to be almost fully active as IscS and exhibits a pyridoxal 5'-phosphate (PLP) absorption peak at 395 nm. Moreover, SUMO-EH-IscS exhibited significant growth recovery and NADH-dehydrogenase I activity in the iscS mutant cells. Furthermore, through in vitro and in vivo experiments combined with high-performance liquid chromatography and ultra-performance liquid chromatography-tandem mass spectrometry, it was shown that the new absorption peaks of the IscS H104Q, IscS Q183E, IscS K206A, and IscS K206A&C328S variants at 340 and 350 nm may correspond to the enzyme reaction intermediates, Cys-ketimine and Cys-aldimine, respectively. However, after mutation of the conserved active-site residues, additional absorption peaks at 420 and 430 nm were associated with PLP migration in the active-site pocket. Additionally, the corresponding absorption peaks of Cys-quinonoid, Ala-ketimine, and Ala-aldimine intermediates in IscS were 510, 325, and 345 nm, respectively, as determined by site-directed mutagenesis and substrate/product-binding analyses during the CD reaction process. Notably, red IscS formed in vitro by incubating IscS variants (Q183E and K206A) with excess L-alanine and sulphide under aerobic conditions produced an absorption peak similar to the wild-type IscS, at 510 nm. Interestingly, site-directed mutation of IscS with hydrogen bonds to PLP at Asp180 and Gln183 resulted in a loss of enzymatic activity followed by an absorption peak consistent with NFS1 (420 nm). Furthermore, mutations at Asp180 or Lys206 inhibited the reaction of IscS in vitro with L-cysteine (substrate) and L-alanine (product). These results suggest that the conserved active site residues (His104, Asp180, and Gln183) and their hydrogen bond with PLP in the N-terminus of IscS play a key role in determining whether the L-cysteine substrate can enter the active-site pocket and regulate the enzymatic reaction process. Therefore, our findings provide a framework for evaluating the roles of conserved active-site residues, motifs, and domains in CDs.

Gastrointestinal perforation associated with novel antineoplastic agents: A real-world study based on the FDA Adverse Event Reporting System.

Purpose: Gastrointestinal perforation (GIP) is a fatal adverse event (AE). The AE of GIP induced by novel antineoplastic agents has attracted attention recently. We aimed to explore the AE signals of GIP related to novel antineoplastic agents comprehensively based on the FDA Adverse Event Reporting System (FAERS). Methods: The FAERS database containing 71 quarters of records was used for analysis. Reporting odds ratio (ROR), information component (IC), and empirical Bayesian geometric mean (EBGM) were utilized to evaluate the signals of GIP associated with novel antineoplastic drugs. Standardization of drug names was by employing MedEx-UIMA software and Python. Data analysis and visualization were performed using MySQL Workbench and R software. Results: After cleaning and handling the data, 5226 GIP cases were identified that were associated with new antineoplastic medications, where these agents were the main suspected contributors. A total of 37 novel antineoplastic drugs were detected with signals of GIP for ROR and IC. Only 22 drugs showed statistically significant signals for EBGM. We found the GIP signals of 22 novel antineoplastic drugs overlapped for the 3 indicators, including anti-vascular endothelial growth factor/vascular endothelial growth factor receptor, anti-endothelial growth factor receptor, immune checkpoint inhibitors, and so on. Conclusion: The potential risk of GIP associated with several novel antineoplastic agents was identified through data mining, which provided valuable information on the safety risks associated with GIP among these drugs. The potential threat of GIP should be recognized and managed properly when using these novel antineoplastic agents.

Effect of chlorantraniliprole on soil bacterial and fungal diversity and community structure.

Chlorantraniliprole (CAP) is an insecticide with low toxicity and high efficiency, which is widely used in agriculture in China. However, its potential ecological risks remain unknown. In this study, we investigated the impact of different CAP concentrations on bacterial and fungal communities in soil based on high-throughput sequencing. The results showed that CAP application had no significant effect on soil bacterial and fungal diversity, but altered the bacterial and fungal community structure. In particular, the soil bacterial and fungal community structure in the low CAP concentration treatment group exhibited large variability. Compared with 0 day, the phylum level of bacteria changed at 115 days, and fungi changed at 175 days, indicating that soil microbial community might have significant correlation with CAP degradation in soil. Correlation analysis between soil properties and microbial communities showed that TN, TP, and NO3-N were three key factors that significantly influenced microbial community structure. These results provide basic data for studying the effects of pesticides on ecosystem and potential remediation strategies of polluted soil.

Resveratrol-Loaded Dipalmitoylphosphatidylcholine Liposomal Large Porous Microparticle Inhalations for the Treatment of Bacterial Pneumonia Caused by Acinetobacter baumannii.

Background: Acinetobacter baumannii-mediated bacterial pneumonia is a common disease that is harmful to human health. Dipalmitoylphosphatidylcholine (DPPC) is the major lipid component of the pulmonary surfactant (PS) found in the alveolar space; the PS helps to keep surface tension low, which allows for improved oxygen delivery. Resveratrol (RE) is a phytoalexin found in plants that is released in response to injury or infection. The therapeutic effect of Re is limited due to its low solubility and bioavailability. In this study, we report pulmonary delivery of Re-loaded DPPC liposomal large porous microparticles (RDLPMs) for treatment of A. baumannii-induced pneumonia. Methods: Novel RDLPMs were prepared by rotary evaporation and a freeze-drying method in this study. RDLPMs were evaluated by the particle size, electric potential, in vitro release, and particle size distribution. A rat model of A. baumannii-mediated pneumonia was established and used for pharmacodynamic evaluations. Results: The Re-loaded DPPC liposomes (RDLs) consisted of Re/DPPC (1:3, mol/mol) and DPPC/cholesterol (3:1, w/w), with a hydration time of 15 minutes. The RDLs had a high encapsulation efficiency of 69.8% ± 1.6%, a mean size of 191.5 ± 4.5 nm, and a high zeta potential of 12.4 ± 1.5 mV. The RDLPMs were composed of mannitol/large porous microparticles/RDLs (1:4:2, w/w/w) and had a loading efficiency of 2.20% ± 0.24%. The RDLPMs had an aerodynamic diameter (2.73 ± 0.65 µm), a good fluidity (28.30° ± 6.13°), and demonstrated high lung deposition (fine particle fraction = 43.33%). Surprisingly, while penicillin showed better microbial inhibition than the RDLPMs and Re groups in vitro, the RDLPMs were more effective in vivo. Conclusion: The RDLPMs showed good powder properties for pulmonary delivery. The RDLPMs may inhibit the nuclear factor kappa-B pathway and downregulate the expression of cytokines downstream of tumor necrosis factor-α and interleukin-1ß. As well as, RDLPMs demonstrated some antibacterial properties against A. baumannii bacteria. Re, when delivered in RDLPMs as a dry powder inhaler, is a promising substitute for antibiotics in the treatment of A. baumannii pneumonia.

Developmental toxicity of TCBPA on the nervous and cardiovascular systems of zebrafish (Danio rerio): A combination of transcriptomic and metabolomics.

Tetrachlorobisphenol A (TCBPA), a widely used halogenated flame retardant, is frequently detected in environmental compartments and human samples. However, unknown developmental toxicity and mechanisms limit the entire understanding of its effects. In this study, zebrafish (Danio rerio) embryos were exposed to various concentrations of TCBPA while a combination of transcriptomics, behavioral and biochemical analyzes as well as metabolomics were applied to decipher its toxic effects and the potential mechanisms. We found that TCBPA could interfere with nervous and cardiovascular development through focal adhesion and extracellular matrix-receptor (ECM-receptor) interaction pathways through transcriptomic analysis. Behavioral and biochemical analysis results indicated abnormal swimming behavior of zebrafish larvae. Morphological observations revealed that TCBPA could cause the loss of head blood vessels. Metabolomic analysis showed that arginine-related metabolic pathways were one of the main pathways leading to TCBPA developmental toxicity. Our study demonstrated that by using omics, TCBPA was shown to have neurological and cardiovascular developmental toxicity and the underlying mechanisms were uncovered and major pathways identified.

Islet primary cilia motility controls insulin secretion.

Primary cilia are specialized cell-surface organelles that mediate sensory perception and, in contrast to motile cilia and flagella, are thought to lack motility function. Here, we show that primary cilia in human and mouse pancreatic islets exhibit movement that is required for glucose-dependent insulin secretion. Islet primary cilia contain motor proteins conserved from those found in classic motile cilia, and their three-dimensional motion is dynein-driven and dependent on adenosine 5'-triphosphate and glucose metabolism. Inhibition of cilia motion blocks beta cell calcium influx and insulin secretion. Human beta cells have enriched ciliary gene expression, and motile cilia genes are altered in type 2 diabetes. Our findings redefine primary cilia as dynamic structures having both sensory and motile function and establish that pancreatic islet cilia movement plays a regulatory role in insulin secretion.

ISCA2 deficiency leads to heme synthesis defects and impaired erythroid differentiation in K562 cells by indirect ROS-mediated IRP1 activation.

Iron­sulfur (Fe-S) clusters have been shown to play important roles in various cellular physiological process. Iron­sulfur cluster assembly 2 (ISCA2) is a vital component of the [4Fe-4S] cluster assembly machine. Several studies have shown that ISCA2 is highly expressed during erythroid differentiation. However, the role and specific regulatory mechanisms of ISCA2 in erythroid differentiation and erythroid cell growth remain unclear. RNA interference was used to deplete ISCA2 expression in human erythroid leukemia K562 cells. The proliferation, apoptosis, and erythroid differentiation ability of the cells were assessed. We show that knockdown of ISCA2 has profound effects on [4Fe-4S] cluster formation, diminishing mitochondrial respiratory chain complexes, leading to reactive oxygen species (ROS) accumulation and mitochondrial damage, inhibiting cell proliferation. Excessive ROS can inhibit the activity of cytoplasmic aconitase (ACO1) and promote ACO1, a bifunctional protein, to perform its iron-regulating protein 1(IRP1) function, thus inhibiting the expression of 5'-aminolevulinate synthase 2 (ALAS2), which is a key enzyme in heme synthesis. Deficiency of ISCA2 results in the accumulation of iron divalent. In addition, the combination of excessive ferrous iron and ROS may lead to damage of the ACO1 cluster and higher IRP1 function. In brief, ISCA2 deficiency inhibits heme synthesis and erythroid differentiation by double indirect downregulation of ALAS2 expression. We conclude that ISCA2 is essential for normal functioning of mitochondria, and is necessary for erythroid differentiation and cell proliferation.

Silencing suppressors of rice black-streaked dwarf virus and rice stripe virus hijack the 26S proteasome of Laodelphax striatellus to facilitate virus accumulation and transmission.

BACKGROUND: Rice black-streaked dwarf virus (RBSDV) is transmitted by small brown planthopper (Laodelphax striatellus [L. striatellus]) and causes devastating disease in rice. P9-1 has silencing suppression activity and is the key protein for viroplasm formation in RBSDV-infected plants and insects; however, its exact function is poorly understood. RESULTS: In this study, the P9-1 of RBSDV interacted with L. striatellus 26S proteasome subunit RPN8. RBSDV accumulation in L. striatellus increased after the 26S proteasome was disrupted by silencing the RPN8 expression. This finding indicated that L. striatellus 26S proteasome played a defense role against RBSDV infection by regulating RBSDV accumulation. Further investigations revealed that P9-1 could competitively bind to RPN8 with RPN7, thereby disrupting the assembly of 26S proteasome in L. striatellus and promoting the infection of RBSDV in insect vectors, and further affecting the transmission of the virus to rice by insect vectors. Similar to P9-1, rice stripe virus (RSV) NS2, a weak silencing suppressor, regulated virus accumulation and transmission by hijacking RPN8 to interfere with the function of 26S proteasome in L. striatellus. CONCLUSION: These results suggest that viruses promote their own infection via interfering with ubiquitination pathway of insect vectors, and this mechanism might be of universal importance. These findings provide a new insight into the mechanism of virus transmission in insect vectors. © 2022 Society of Chemical Industry.