Construction and analysis of competitive endogenous RNA networks and prognostic models associated with ovarian cancer based on the exoRBase database.

OBJECTIVE: To construct a competitive endogenous RNA (ceRNA) regulatory network in blood exosomes of patients with ovarian cancer (OC) using bioinformatics and explore its pathogenesis. METHODS: The exoRbase2.0 database was used to download blood exosome gene sequencing data from patients OC and normal controls and the expression profiles of exosomal mRNA, long non-coding RNA (lncRNA), and circular RNA (circRNA) were detected independently using R language for differential expression analysis. TargetScan and miRanda databases were combined for the prediction and differential expression of mRNA-binding microRNAs (miRNA). The miRcode and starBase databases were used to predict miRNAs that bind to differentially expressed lncRNAs and circRNAs repectively. The relevant mRNA, circRNA, lncRNA and their corresponding miRNA prediction data were imported into Cytoscape software for visualization of the ceRNA network. The R language and KEGG Orthology-based Annotation System (KOBAS) were used to execute and illustrate the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Hub genes were identified using The CytoHubba plugin. RESULTS: Thirty-one differentially expressed mRNAs, 17 differentially expressed lncRNAs, and 24 differentially expressed circRNAs were screened. Cytoscape software was used to construct the ceRNA network with nine mRNA nodes, two lncRNA nodes, eight circRNA nodes, and 51 miRNA nodes. Both GO and KEGG were focused on the Spliceosome pathway, indicating that spliceosomes are closely linked with the development of OC, while heterogenous nuclear ribonucleoprotein K and RNA binding motif protein X-linked genes were the top 10 score Hub genes screened by Cytoscape software, including two lncRNAs, four mRNAs, and four circRNAs. In patients with OC, the expression of eukaryotic translation initiation factor 4 gamma 2 (EIF4G2), SERPINE 1 mRNA binding protein 1 (SERBP1), ribosomal protein L15 (RPL15) and human leukocyte antigen complex P5 (HCP5) was significantly higher whereas that of testis expressed transcript, Y-linked 15 and DEAD-box helicase 3 Y-linked genes was lower compared to normal controls Immunocorrelation scores revealed that SERBP1 was significantly and negatively correlated with endothelial cells and CD4+ T cells and positively correlated with natural killer (NK) cells and macrophages, respectively; RPL15 was significantly positively correlated with macrophages and endothelial cells and negatively correlated with CD8+ T cells and uncharacterized cells, respectively. EIF4G2 was significantly and negatively correlated with endothelial cells and CD4+ T cells, and positively correlated with uncharacterized cells, respectively. Based on the survival data and the significant correlation characteristics derived from the multifactorial Cox analysis (P < 0.05), the survival prediction curves demonstrated that the prognostic factors associated with 3-year survival in patients with OC were The prognostic factors associated with survival were Macrophage, RPL15. CONCLUSION: This study successfully constructs a ceRNA regulatory network in blood exosomes of OV patients, which provides the specific targets for diagnosis and treatment of OC.

Biofilm Microenvironment Activated Antibiotic Adjuvant for Implant-Associated Infections by Systematic Iron Metabolism Interference.

Hematoma, a risk factor of implant-associated infections (IAIs), creates a Fe-rich environment following implantation, which proliferates the growth of pathogenic bacteria. Fe metabolism is a major vulnerability for pathogens and is crucial for several fundamental physiological processes. Herein, a deferiprone (DFP)-loaded layered double hydroxide (LDH)-based nanomedicine (DFP@Ga-LDH) that targets the Fe-rich environments of IAIs is reported. In response to acidic changes at the infection site, DFP@Ga-LDH systematically interferes with bacterial Fe metabolism via the substitution of Ga3+ and Fe scavenging by DFP. DFP@Ga-LDH effectively reverses the Fe/Ga ratio in Pseudomonas aeruginosa, causing comprehensive interference in various Fe-associated targets, including transcription and substance metabolism. In addition to its favorable antibacterial properties, DFP@Ga-LDH functions as a nano-adjuvant capable of delaying the emergence of antibiotic resistance. Accordingly, DFP@Ga-LDH is loaded with a siderophore antibiotic (cefiderocol, Cefi) to achieve the antibacterial nanodrug DFP@Ga-LDH-Cefi. Antimicrobial and biosafety efficacies of DFP@Ga-LDH-Cefi are validated using ex vivo human skin and mouse IAI models. The pivotal role of the hematoma-created Fe-rich environment of IAIs is highlighted, and a nanoplatform that efficiently interferes with bacterial Fe metabolism is developed. The findings of the study provide promising guidance for future research on the exploration of nano-adjuvants as antibacterial agents.

Transcatheter closure of post-myocardial infarction ventricular septal defect: A systematic review and single-arm meta-analysis.

Background: Ventricular septal defects (VSDs) are one of the mechanical complications of acute myocardial infarction (AMI). Because of the high risks of mortality and postoperative complications, a new alternative method is needed. With the development of interventional medicine, transcatheter closure has been increasingly performed for postmyocardial infarction ventricular septal defects (PMIVSDs). The aim of this study is to explore the feasibility and safety of transcatheter closure of PMIVSDs by meta-analysis. Methods: The included studies were mainly single-arm studies of transcatheter closure of PMIVSDs. We compared VSD size, device size, preoperative risk factors and interventions among PMIVSD patients. We analysed the transcatheter closure success rate, the 30-day mortality rate, and the incidence of residual shunts. Results: A total of 12 single-arm articles (284 patients) were included. The combined incidences of preoperative hypertension, hyperlipidaemia, and diabetes were 66% [95% CI 0.56-0.75], 54% [95% CI 0.40-0.68], and 33% [95% CI] 0.21-0.46], respectively. Multiple studies reported the combined incidences of preoperative PCI, IABP, and CABG, which were 46% [95% CI 0.15-0.80], 60% [95% CI 0.44-0.75], and 8% [95% CI 0.02-0.18]. Eleven studies reported the number of successful closures and the 30-day mortality rate; the success rate was 90% [95% CI 0.86-0.94], and the 30-day mortality rate reached 27% [95% CI 0.86-0.94]. Conclusion: For patients with PMIVSD, transcatheter closure in the acute phase can be used as a rescue measure, while in the chronic phase, it is more effective and has a lower mortality rate, but the effect of selection bias should be considered. Residual shunts are a long-term complication that have a high incidence and long-lasting effects on patients. More large, multicentre, randomized controlled trials are needed in the future to confirm the safety and reliability of transcatheter closure of PMIVSDs.

Application effect evaluation of hybrid biochemistry teaching model based on WeChat platform under the trend of COVID-19.

With WeChat platform as the carrier, we explored the effect of online and offline mixed teaching mode applied to Biochemistry teaching. One hundred and eighty-three students from the 4-year nursing major of Xinglin College of Nantong University in 2018 and 2019 were used as the observation group, using online and offline hybrid teaching methods, and 221 students majoring in 4-year nursing from Xinglin College of Nantong University in 2016 and 2017 were the control group, where the traditional classroom teaching method was adopted. The usual stage scores and final scores of the observation group were significantly higher than those of the control group (P < .01). The micro-lecture videos, animations, and periodic assessment methods of the WeChat platform under "Internet+" can greatly stimulate students' interest in learning, thereby significantly improving academic performance and autonomous learning ability.

The after-school sedentary behavior status among children and adolescents with intellectual disabilities.

Background: There is evidence that the after-school period plays an essential role in accumulating sedentary behavior (SB) among children and adolescents, as well as implementing potential interventions. However, relatively little is known regarding SB status of children and adolescents with intellectual disabilities (ID) during the after-school period. The purpose of this study was to investigate the total level and specific pattern of the after-school SB among children and adolescents with ID. Methods: The after-school SB status among 325 children and adolescents with ID was evaluated by the parent-reported Children's Leisure Activities Study Survey-Chinese edition questionnaire. Results: Parents of children and adolescents with ID reported approximately 204 min/day of after-school SB. Specifically, the longest time of the after-school period was spent performing the screen-based SB (84 mins/d). This was followed by recreational SB and educational SB (50 and 30 mins/d, respectively). The children aged 6-12 years old engaged more time in recreational SB than adolescents aged 16-18 years old (p < 0.05) during the after-school period. Further, the data indicated that 37.5% of children and adolescents with ID achieved the guideline limitation of 2-h-maximum screen-based SB during the after-school hour. Conclusion: Children and adolescents with ID spent a large portion of the after-school period in SB, particularly engaged in more time on after-school screen-based SB. Future efforts should focus on developing and implementing period-specific interventions designed to reduce after-school SB in the segment of this population.

Radiogenomics analysis reveals the associations of dynamic contrast-enhanced-MRI features with gene expression characteristics, PAM50 subtypes, and prognosis of breast cancer.

Background: To investigate reliable associations between dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) features and gene expression characteristics in breast cancer (BC) and to develop and validate classifiers for predicting PAM50 subtypes and prognosis from DCE-MRI non-invasively. Methods: Two radiogenomics cohorts with paired DCE-MRI and RNA-sequencing (RNA-seq) data were collected from local and public databases and divided into discovery (n = 174) and validation cohorts (n = 72). Six external datasets (n = 1,443) were used for prognostic validation. Spatial-temporal features of DCE-MRI were extracted, normalized properly, and associated with gene expression to identify the imaging features that can indicate subtypes and prognosis. Results: Expression of genes including RBP4, MYBL2, and LINC00993 correlated significantly with DCE-MRI features (q-value < 0.05). Importantly, genes in the cell cycle pathway exhibited a significant association with imaging features (p-value < 0.001). With eight imaging-associated genes (CHEK1, TTK, CDC45, BUB1B, PLK1, E2F1, CDC20, and CDC25A), we developed a radiogenomics prognostic signature that can distinguish BC outcomes in multiple datasets well. High expression of the signature indicated a poor prognosis (p-values < 0.01). Based on DCE-MRI features, we established classifiers to predict BC clinical receptors, PAM50 subtypes, and prognostic gene sets. The imaging-based machine learning classifiers performed well in the independent dataset (areas under the receiver operating characteristic curve (AUCs) of 0.8361, 0.809, 0.7742, and 0.7277 for estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2)-enriched, basal-like, and obtained radiogenomics signature). Furthermore, we developed a prognostic model directly using DCE-MRI features (p-value < 0.0001). Conclusions: Our results identified the DCE-MRI features that are robust and associated with the gene expression in BC and displayed the possibility of using the features to predict clinical receptors and PAM50 subtypes and to indicate BC prognosis.

Differences in community structure of gastrointestinal tract between Helicobacter pylori positive patients and negative patients with gastric cancer.

Gastric cancer is one of the most severe cancers, while the relationship between Helicobacter pylori (H. pylori) and gastric cancer are still in dispute, and little work has been done to explore the microbial diversity between H. pylori positive patients and negative patients. In the present work, a total of 43 gastric cancer patients and 10 healthy 53 participants were enrolled to compare the microbial differences in community structure in gastrointestinal tract between H. pylori positive patients and negative patients with gastric cancer. Our results indicated that the abundance and diversity of gastrointestinal microbiota was slight lower in gastric cancer patients than that in healthy participants especially in intestine, while the abundance of some potential pathogens, e.g. Streptococcus, Lactobacillus, Akkermansia and Halomones were higher in H. pylori positive patients than H. pylori negative patients. Therefore, our work suggests the various microbial diversity between H. pylori positive patients and H. pylori negative patients with gastric cancer, which contribute to deepen the understanding of the role of H. pylori in gastric carcinogenesis and progression.

Retrospective analysis of the preparation and application of immunotherapy in cancer treatment (Review).

Monoclonal antibody technology plays a vital role in biomedical and immunotherapy, which greatly promotes the study of the structure and function of genes and proteins. To date, monoclonal antibodies have gone through four stages: murine monoclonal antibody, chimeric monoclonal antibody, humanised monoclonal antibody and fully human monoclonal antibody; thousands of monoclonal antibodies have been used in the fields of biology and medicine, playing a special role in the pathogenesis, diagnosis and treatment of disease. In this review, we compare the advantages and disadvantages of hybridoma technology, phage display technology, ribosome display technology, transgenic mouse technology, single B cell monoclonal antibody generation technologies, and forecast the promising applications of these technologies in clinical medicine, disease diagnosis and tumour treatment.

Combination of an engineered Lactococcus lactis expressing CXCL12 with light-emitting diode yellow light as a treatment for scalded skin in mice.

Impaired wound closure is an increasingly crucial clinical challenge. Recently, wound healing has shifted towards innovative treatments that exploit nanotechnology, biomaterials, biologics and phototherapy. Here, we constructed an engineered MG1363-pMG36e-mCXCL12 strain with pMG36e plasmid encoding stromal cell-derived factor 1α (named CXCL12) and evaluated the synergistic effects of light-emitting diode (LED) yellow light and MG1363-pMG36e-mCXCL12 on scald wounds in mice. The results indicated that the combined treatment with LED yellow light with mCXCL12 delivering strain accelerated wound closure, tissue remodelling, re-epithelialization and hair follicle regeneration and inhibited over-inflammation oppositely in the central and surrounding wounds by macroscopic, histopathologic and immunohistochemistry parameters. Furthermore, combination therapy increased the epidermal growth factor and Ki67-positive cells and upregulated beta-catenin (ß-catenin), cellular-myelocytomatosis (c-Myc), wingless-type MMTV integration site family member 1 (Wnt1), Jagged 1, neurogenic locus notch homolog protein 1 (Notch 1) and hairy and enhancer of split 1 (Hes 1) protein levels of the Wnt and Notch signalling pathways. It also facilitated collagen fibrogenesis and deposition and improved the activities of hydroxyproline, superoxide dismutase and glutathione peroxidase in scalded granulation tissue, in addition to reducing the inflammatory factors interleukin 1 beta (IL-1ß) and tumour necrosis factor alpha (TNF-α). The combined treatment effectively reduced skin pathogens Ralstonia and Acinetobacter to further reduce the risk of infection. Overall, combination of LED yellow light and MG1363-pMG36e-mCXCL12 represents a potential strategy for the treatment of cutaneous wounds.

Regulation of ERα Stability and Estrogen Signaling in Breast Cancer by HOIL-1.

Estrogen receptor α (ERα) is the major driver for breast tumor carcinogenesis and progression, while ERα positive breast cancer is the major subtype in breast malignancies, which account for 70% breast cancers in patients. The success of endocrine therapy such as tamoxifen is one of the biggest breakthroughs in breast cancer treatments. However, the endocrine therapy resistance is a headache problem in breast cancer. Further mechanisms need to be identified to the effect of ERα signaling in controlling breast cancer progression and drug resistance. HOIL-1 was firstly identified as the ERα transcriptional co-activator in modulating estrogen signaling in breast cancer. In our current study, we showed that HOIL-1, which was elevated in breast cancer, related to good prognosis in ERα positive breast cancer, but correlated with poor outcome in endocrine-treated patients. HOIL-1 was required for ERα positive breast cancer proliferation and clone formation, which effect could be rescued by further ERα overexpression. Further mechanism studies showed that HOIL-1 is required for ERα signaling activity in breast cancer cells. HOIL-1 could interact with ERα in the cytosol and modulate ERα stability via inhibiting ERα K48-linked poly-ubiquitination. Thus, our study demonstrated a novel post-translational modification in ERα signaling, which could provide novel strategy for ERα-driven breast cancer therapy.

Aptamer-Functionalized Dendrimer Delivery of Plasmid-Encoding lncRNA MEG3 Enhances Gene Therapy in Castration-Resistant Prostate Cancer.

PURPOSE: The clinical management of patients with castration-resistant prostate cancer (CRPC) is difficult. However, novel treatment methods are gradually being introduced. Considering the adverse effects of traditional treatments, recent studies have investigated gene therapy as a method to combat CRPC; but, the application of long non-coding (lnc) RNA in gene therapy remains scarce, despite their promise. Therefore, it is imperative to develop a system that can efficiently deliver lncRNA for the treatment of CRPC. Here, we investigated the efficacy of a delivery system by introducing the plasmid-encoding tumor suppressor lncRNA MEG3 (pMEG3) in CRPC cells. MATERIALS AND METHODS: An EpDT3 aptamer-linked poly(amidoamine) (PAMAM) dendrimer targeting EpCAM was used to deliver pMEG3 in CRPC cells. The PAMAM-PEG-EpDT3/pMEG3 nanoparticles (NPs) were tested using in vitro cellular assays including cellular uptake, entry, and CCK-8 measurement, and tumor growth inhibition, histological assessment, and safety evaluations in in vivo animal models. RESULTS: The EpDT3 aptamer promoted endocytosis of PAMAM and PAMAM-PEG-EpDT3/pMEG3 NPs in CRPC cells. PAMAM-PEG-EpDT3/pMEG3 NPs exhibited a significant anti-CRPC effect, both in vivo and in vitro, when compared to that of unfunctionalized PAMAM-PEG/pMEG3 NPs. CONCLUSION: PAMAM-PEG-EpDT3/pMEG3 NPs can potentially improve gene therapy in CRPC cells.

Differences in pathologic characteristics between ductal carcinoma in situ (DCIS), DCIS with microinvasion and DCIS with invasive ductal carcinoma.

In order to further our understanding of pathologic features in various ductal carcinoma in situ (DCIS) related breast ductal cancers, including DCIS, DCIS with microinvasion (DCIS-Mi) and DCIS with invasive ductal carcinoma (DCIS-IDC), a retrospective study including 453 cases of DCIS, 88 cases of DCIS-Mi, and 269 cases of DCIS-IDC was conducted. Statistical analysis showed significant pathological differences were found in DCIS, DCIS-Mi, and DCIS-IDC. Compared with DCIS, DCIS-IDC was significantly more associated with high nuclear grade, large tumor size, high Ki67 index, and lymph node metastasis (all P<0.05). Higher expression of steroid receptors was shown in DCIS-IDC than in DCIS (all P<0.05), but the status of HER2 between the two groups was similar (P=0.269). Compared with DCIS, DCIS-Mi was significantly more associated with high nuclear grade, large tumor size, comedonecrosis, absence of steroid receptors, HER2 overexpression, and high Ki67 index (all P<0.05). These features remain consistently even when compared with DCIS-IDC. According to the immunohistochemistry surrogate classification, the dominant types of DCIS and DCIS-IDC were luminal types (luminal A and luminal B, respectively), while the dominant type of DCIS-Mi was HER2 overexpression. These findings suggest that DCIS-Mi represents a distinct entity, and DCIS with features including high nuclear grade, large tumor size, comedonecrosis, steroid receptors negativity, HER2 positivity, and high Ki67 expression was more likely to have microinvasion than DCIS without these features.

Dimethyloxaloylglycine-stimulated human bone marrow mesenchymal stem cell-derived exosomes enhance bone regeneration through angiogenesis by targeting the AKT/mTOR pathway.

BACKGROUND: Mesenchymal stem cell (MSC)-derived exosomes have been recognized as new candidate agents for treating critical-sized bone defects; they promote angiogenesis and may be an alternative to cell therapy. In this study, we evaluated whether exosomes derived from bone marrow-derived MSCs (BMSCs) preconditioned with a low dose of dimethyloxaloylglycine (DMOG), DMOG-MSC-Exos, exert superior proangiogenic activity in bone regeneration and the underlying mechanisms involved. METHODS: To investigate the effects of these exosomes, scratch wound healing, cell proliferation, and tube formation assays were performed in human umbilical vein endothelial cells (HUVECs). To test the effects in vivo, a critical-sized calvarial defect rat model was established. Eight weeks after the procedure, histological/histomorphometrical analysis was performed to measure bone regeneration, and micro-computerized tomography was used to measure bone regeneration and neovascularization. RESULTS: DMOG-MSC-Exos activated the AKT/mTOR pathway to stimulate angiogenesis in HUVECs. This contributed to bone regeneration and angiogenesis in the critical-sized calvarial defect rat model in vivo. CONCLUSIONS: Low doses of DMOG trigger exosomes to exert enhanced proangiogenic activity in cell-free therapeutic applications.

Exosomes Derived from Human Bone Marrow Mesenchymal Stem Cells Stimulated by Deferoxamine Accelerate Cutaneous Wound Healing by Promoting Angiogenesis.

The exosomes are derived from mesenchymal stem cells (MSCs) and may be potentially used as an alternative for cell therapy, for treating diabetic wounds, and aid in angiogenesis. This study, aimed to investigate whether exosomes originated from bone marrow-derived MSCs (BMSCs) preconditioned by deferoxamine (DFO-Exos) exhibited superior proangiogenic property in wound repair and to explore the underlying mechanisms involved. Human umbilical vein endothelial cells (HUVECs) were used for assays involving cell proliferation, scratch wound healing, and tube formation. To test the effects in vivo, streptozotocin-induced diabetic rats were established. Two weeks after the procedure, histological analysis was used to measure wound-healing effects, and the neovascularization was evaluated as well. Our findings demonstrated that DFO-Exos activate the PI3K/AKT signaling pathway via miR-126 mediated PTEN downregulation to stimulate angiogenesis in vitro. This contributed to enhanced wound healing and angiogenesis in streptozotocin-induced diabetic rats in vivo. Our results suggest that, in cell-free therapies, exosomes derived from DFO preconditioned stem cells manifest increased proangiogenic ability.

Curcumin improves age-related and surgically induced osteoarthritis by promoting autophagy in mice.

Reduced autophagy has been implied in chondrocyte death and osteoarthritis. Curcumin (Cur) owns therapeutic effect against osteoarthritis (OA) and enhances autophagy in various tumor cells. Whether the cartilage protection of curcumin is associated with autophagy promotion and the potential signaling pathway involved remains unclear. The present study aimed to investigate the role of autophagy in the anti-OA activity of curcumin using spontaneous and surgically induced OA mice model. Spontaneous and surgically induced OA mice model was established and treated with Cur. Articular cartilage destruction and proteoglycan loss were scored through Safranin O/Fast green staining. Apoptotic cell death was detected with TUNEL (terminal deoxynucleotidyl transferase-mediated dTUP-biotin nick end labeling assay) staining and Western blot for caspase-3, Bcl-2 associated X protein (Bax), and Bcl-2 (B-cell lymphoma-2). Light chain 3 (LC3) immunohistochemistry was used to evaluate autophagy. In vitro, primary chondrocytes were treated with interleukin 1 beta (IL-1ß) and Cur. Autophagy was inhibited using 3-methyladenine. Apoptosis and autophagy were detected using flow cytometry and Western blotting assay. Curcumin treatment enhanced autophagy, reduced apoptosis, and cartilage loss in both OA models. In vitro, curcumin treatment improved IL-1ß induced autophagy inhibition, cell viability decrease, and apoptosis. Mechanistically, in vivo studies suggested curcumin promoted autophagy through regulating Akt/mTOR pathway. In conclusion, our results demonstrate that curcumin-induced autophagy via Akt/mTOR signaling pathway contributes to the anti-OA effect of curcumin.

Production of a fungal furocoumarin by a polyketide synthase gene cluster confers the chemo-resistance of Neurospora crassa to the predation by fungivorous arthropods.

The formation of sexual fruiting bodies and production of polyketides are believed to be the most important strategies for fungal survival in environmental insults. In Neurospora crassa, the backbone gene of polyketide synthase gene cluster 6 (pks-6), which is expressed at lower level under vegetative growth, is highly expressed during perithecia development. Intriguingly, deletion of pks-6 does not affect perithecia maturation. How the expression of pks-6 correlates with fungal sexual development remains to be established. Here, we showed that overexpression of pks-6 results in an enhanced production of an insecticidal furocoumarin (neurosporin A). Deletion of pks-6, however, abolished neurosporin A biosynthesis. Moreover, the content of neurosporin A negatively associates with the food preference of fungivores, where the pks-6 knockout strain is more prone to be grazed by collembolans Sinella curviseta. Additionally, during vegetative growth, confrontation with Drosophila melanogaster also results in an enhanced expression of pks-6 and production of neurosporin A. Thus, high expression of pks-6 positively interrelates with the chemo-resistance of N. crassa to arthropod predation. Our findings suggest that pks-6 confers the production of insecticidal neurosporin A counteracting the feeding attack by arthropods during sexual development of N. crassa.

Regulation of Anticancer Styrylpyrone Biosynthesis in the Medicinal Mushroom Inonotus obliquus Requires Thioredoxin Mediated Transnitrosylation of S-nitrosoglutathione Reductase.

The medicinal macrofungus Inonotus obliquus widely utilized as folk medicine in Russia and Baltic countries is a source of phenylpropanoid-derived styrylpyrone polyphenols that can inhibit tumor proliferation. Insights into the regulatory machinery that controls I. obliquus styrylpyrone polyphenol biosynthesis will enable strategies to increase the production of these molecules. Here we show that Thioredoxin (Trx) mediated transnitrosylation of S-nitrosoglutathione reductase (GSNOR) underpins the regulation of styrylpyrone production, driven by nitric oxide (NO) synthesis triggered by P. morii coculture. NO accumulation results in the S-nitrosylation of PAL and 4CL required for the synthesis of precursor phenylpropanoids and styrylpyrone synthase (SPS), integral to the production of styrylpyrone, inhibiting their activities. These enzymes are targeted for denitrosylation by Trx proteins, which restore their activity. Further, this Trx S-nitrosothiol (SNO) reductase activity was potentiated following S-nitrosylation of Trx proteins at a non-catalytic cysteine (Cys) residue. Intriguingly, this process was counterbalanced by Trx denitrosylation, mediated by Trx-dependent transnitrosylation of GSNOR. Thus, unprecedented interplay between Trx and GSNOR oxidoreductases regulates the biosynthesis of styrylpyrone polyphenols in I. obliquus.

Reversible S-nitrosylation limits over synthesis of fungal styrylpyrone upon nitric oxide burst.

Nitric oxide (NO) is known to be involved in modulating production of styrylpyrone polyphenols in the basidiomycete Inonotus obliquus. However, it remains unknown how NO orchestrates fungal styrylpyrone biosynthesis. Here, we show that a transient NO burst correlated with an enhanced expression of phenylalanine ammonia lyase (PAL), 4-coumarate CoA ligase (4CL), and styrylpyrone synthase (SPS), the key enzymes involved in styrylpyrone biosynthesis, and subsequently an increased production of styrylpyrone polyphenols. In parallel, the NO burst also resulted in S-nitrosylation of PAL, 4CL, and SPS, which compromised their enzymatic activities mediating a post-translational feedback mechanism that keeps NO-dependent transcriptional activation in check. Moreover, dysfunction of thioredoxin reductase (TrxR) further increased the formation of S-nitrosylated proteins, implicating the significance of the Trx system in maintaining a low level of protein-nitrosothiols. Three thioredoxin-like proteins (TrxLs) from I. obliquus show in vitro denitrosylation potential toward S-nitrosylated proteins via trans-denitrosylation or mixed disulfide intermediates. Thus, S-nitrosylation triggered by the NO burst limits over production of fungal styrylpyrone polyphenols, and denitrosylation by TrxLs that act in concert with TrxR play a key role in maintaining redox balance and orchestrating catalytic activities of the enzymes engaged in styrylpyrone synthetic metabolism.

Correlation of nitric oxide produced by an inducible nitric oxide synthase-like protein with enhanced expression of the phenylpropanoid pathway in Inonotus obliquus cocultured with Phellinus morii.

Fungal interspecific interactions enhance biosynthesis of phenylpropanoid metabolites (PM), and production of nitric oxide (NO) is known to be involved in this process. However, it remains unknown which signaling pathway(s) or regulator(s) mediate fungal PM biosynthesis. In this study, we cocultured two white-rot fungi, Inonotus obliquus and Phellinus morii, to examine NO production, expression of the genes involved in phenylpropanoid metabolism and accumulation of phenylpropanoid-derived polyphenols by I. obliquus. Coculture of the two fungi caused an enhanced NO biosynthesis followed by increased transcription of the genes encoding phenylalanine ammonia lyase (PAL) and 4-coumarate CoA ligase (4CL), as well as an upregulated biosynthesis of styrylpyrone polyphenols in I. obliquus. Addition of the NO synthase (NOS) selective inhibitor aminoguanidine (AG) inhibited NO production by more than 90% followed by cease in transcription of PAL and 4Cl. Treatment of guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one did not affect NO production but suppressed transcription of PAL and 4CL and reduced accumulation of total phenolic constituents. Genome-wide analysis of I. obliquus revealed two genes encoding a constitutive and an inducible NOS-like protein, respectively (cNOSL and iNOSL). Coculture of the two fungi did not increase the expression of the cNOSL gene but triggered expression of the iNOSL gene. Cloned iNOSL from Escherichia coli shows higher activity in transferring L-arginine to NO, and this activity is lost upon AG addition. Thus, iNOSL is more responsible for NO production in I. obliquus and may act as an important regulator governing PM production during fungal interspecific interactions.