Photoswitchable dynamics and RNAi synergist with tailored interface and controlled release reprogramming tumor immunosuppressive niche.

Immunosuppressive tumor microenvironment (ITM) severely limited the efficacy of immunotherapy against triple-negative breast cancer (TNBC). Herein, Apt-LPR, a light-activatable photodynamic therapy (PDT)/RNAi immune synergy-enhancer was constructed by co-loading miR-34a and photosensitizers in cationic liposomes (in phase III clinical trial). Interestingly, the introduction of tumor-specific aptamers creates a special "Liposome-Aptamer-Target" interface, where the aptamers are initially in a "lying down" state but transform to "standing up" after target binding. The interfacing mechanism was elaborately revealed by computational and practical experiments. This unique interface endowed Apt-LPR with neutralized surface potential of cationic liposomes to reduce non-specific cytotoxicity, enhanced DNase resistance to protect aptamers, and preserved target-binding ability for selective drug delivery. Upon near-infrared irradiation, the generated reactive oxygen species would oxidize unsaturated phospholipids to destabilize both liposomes and lysosomes, realizing stepwise lysosomal escape of miR-34a for tumor cell apoptosis and downregulation of PD-L1 to suppress immune escape. Together, tumor-associated antigens released from PDT-damaged mitochondria and endoplasmic reticulum could activate the suppressive immune cells to establish an "immune hot" milieu. The collaborative immune-enhancing strategy effectively aroused systemic antitumor immunity and inhibited primary and distal tumor progression as well as lung metastasis in 4T1 xenografted mouse models. The photo-controlled drug release and specific tumor-targeting capabilities of Apt-LPR were also visualized in MDA-MB-231 xenografted zebrafish models. Therefore, this photoswitchable PDT/RNAi immune stimulator offered a powerful approach to reprogramming ITM and reinforcing cancer immunotherapy efficacy.

Emergency department clinical performance of ADVIA Centaur n-terminal prohormone of B-type natriuretic peptide assay.

BACKGROUND: Natriuretic peptide testing is guideline recommended as an aid to the diagnosis of heart failure (HF). We sought to evaluate the performance of the ADVIA Centaur (Siemens Healthcare Diagnostics, Tarrytown, NY) NT-proBNPII assay (PBNPII) in emergency department (ED) dyspneic patients. METHODS: Eligible patients presented to the ED with dyspnea, with their gold standard diagnosis determined by up to 3 cardiologists blinded to the PBNPII results. Patients were stratified into 3 groups based on PBNPII resultsa rule out group of NT-proBNP<300  pg/mL, an age-specific rule in group using cutoffs of 450, 900, and 1800 pg/mL, for <50, 50-75, and > 75 years respectively, and an intermediate cohort for results between the rule out and rule in groups. RESULTS: Of 3128 eligible patients, 1148 (36.7 %) were adjudicated as acute heart failure (AHF). The gold standard AHF diagnosis rate was 3.7, 24.3, and 67.2 % for patients with NTproBNPII in the negative, indeterminate, and positive groups, respectively. Overall likelihood ratios (LR) were 0.07 (95 % CI: 0.05,0.09), 0.55 (0.45,0.67), and 3.53 (3.26,3.83) for the same groups, respectively. Individual LR+for age dependent cutoffs were 5.01 (4.25,5.91), 3.71 (3.25,4.24), and 2.38 (2.10,2.69), respectively. NTproBNPII increased with increasing severity of HF when stratified by NYHA classification. CONCLUSIONS: The ADVIA Centaur PBNPII assay demonstrates acceptable clinical performance using the recommended single rule out and age dependent rule in cutoffs for an AHF diagnosis in dyspneic ED patients.

SCG2 Mediates HNSCC Progression With CCL2/TGFß1high M2 Macrophage Infiltration.

OBJECTIVES: This study aims to unravel the mechanisms underlying M2 macrophage polarization in head and neck squamous cell carcinoma (HNSCC), and identify potential therapeutic targets. MATERIALS AND METHODS: We conducted an integrated bioinformatic analysis using HNSCC bulk transcriptomes from TCGA and GEO databases to pinpoint critical factors influencing M2 macrophage polarization and tumor prognosis. The significance of these genes was validated in function analysis, single-cell transcriptome datasets, and in vitro experiments. Their mechanisms in modulating M2 macrophage polarization were further explored by gene knockdown, cell coculture, and other assays for quantification. RESULTS: We identified a novel prognostic signature of five genes associated with M2 macrophage infiltration, in which SCG2 emerged as a pivotal factor in M2 macrophage polarization in HNSCC. High expression of SCG2 in tumor patients correlated with poorer prognoses, and knocking down SCG2 reduced the proliferation and migration of HNSCC cells, disrupting M2 macrophage polarization. Furthermore, interference of SCG2 resulted in a significant decrease in the secretion of pro-tumor cytokines such as CCL2 and TGFß1. CONCLUSIONS: Our findings provide deeper insights into the pathogenesis of HNSCC and offer promising therapeutic targets for HNSCC, especially SCG2, to inhibit M2 macrophage polarization and modulate cytokine secretion.

Activation of Gs signaling in mouse enteroendocrine K-cells greatly improves obesity- and diabetes-related metabolic deficits.

Following a meal, glucagon-like peptide-1 (GLP1) and glucose-dependent insulinotropic polypeptide (GIP), the two major incretins promoting insulin release, are secreted from specialized enteroendocrine cells (L- and K-cells, respectively). Although GIP is the dominant incretin in humans, the detailed molecular mechanisms governing its release remain to be explored. GIP secretion is regulated by the activity of G protein-coupled receptors (GPCRs) expressed by K-cells. GPCRs couple to one or more specific classes of heterotrimeric G proteins. In the present study, we focused on the potential metabolic roles of K-cell Gs. First, we generated a mouse model that allowed us to selectively stimulate K-cell Gs signaling. Second, we generated a mouse strain harboring an inactivating mutation of Gnas, the gene encoding the alpha-subunit of Gs, selectively in K-cells. Metabolic phenotyping studies showed that acute or chronic stimulation of K-cell Gs signaling greatly improved impaired glucose homeostasis in obese mice and in a mouse model of type 2 diabetes, due to enhanced GIP secretion. In contrast, K-cell-specific Gnas knockout mice displayed markedly reduced plasma GIP levels. These data strongly suggest that strategies aimed at enhancing K-cell Gs signaling may prove useful for the treatment of diabetes and related metabolic diseases.

OSCC-derived EVs educate fibroblasts and remodel collagen landscape.

Cancer-associated myofibroblasts (mCAFs) represent a significant component of the tumor microenvironment due to their contributions to extracellular matrix (ECM) remodeling. The pro-tumor mechanisms of extracellular vesicles (EVs) by regulating mCAFs and related collagens remain poorly understood in oral squamous cell carcinoma (OSCC). In this study, through analysis of single-cell sequencing data and immunofluorescence staining, we confirmed the increased presence of mCAFs and enrichment of specific collagen types in OSCC tissues. Furthermore, we demonstrated that OSCC-derived EVs promote the transformation of fibroblasts into mCAFs, leading to tumor invasion. Proteomic analysis identified the presence of TGF-ß1 in EVs and revealed its role in inducing mCAFs via the TGF-ß1/Smad3 signaling pathway. Experiments in vivo confirmed that EVs, particularly those carrying TGF-ß1, trigger COL18high COL5high matrix deposition, thereby forming the pro-tumor ECM in OSCC. In summary, our investigation unveils the significant involvement of OSCC-derived EVs in orchestrating the differentiation of fibroblasts into mCAFs and modulating specific collagen types within the ECM. Therefore, this study provides a theoretical basis for targeting the EV-mediated TGF-ß1 signaling pathway as a potential therapeutic strategy for OSCC.

B Cells at the Core: Immune Mechanisms and Therapeutic Potentials in Periapical Lesions.

INTRODUCTION: Periapical lesions (PLs) are common inflammatory diseases primarily caused by microbial infections within root canals. These infections trigger complex immune responses in periapical tissues, with B lymphocytes playing dual roles: defending against pathogens while also contributing to tissue damage. This highlights the crucial role of B cells in the immunological processes of PLs. METHOD: A comprehensive review of the literature on B cells in PLs was conducted using PubMed, Web of Science, Scopus, and ScienceDirect databases. RESULTS: The review included 123 studies that examined the distribution and subtypes of B cells, their dual functions in PLs, and the potential applications of B-cell-related therapies in treating apical periodontitis. CONCLUSION: This review enhances our understanding of the complex immune mechanisms in PLs and aids in the development of new therapeutic approaches from a B-cell perspective.

Porphyromonas gingivalis Promotes Oral Squamous Cell Carcinoma Progression by Modulating Autophagy.

OBJECTIVES: Porphyromonas gingivalis (P. gingivalis) is a keystone periodontal pathogen associated with various gastro-intestinal tract cancers. However, whether P. gingivalis can promote oral squamous cell carcinoma (OSCC) and the underlying mechanism associated with such promotion remain unclear. MATERIALS AND METHODS: In this study, OSCC xenograft models were used to evaluate the effects of P. gingivalis on tumor progression. The functional studies were done on several OSCC cell lines in vitro. P. gingivalis-specific 16S rRNA fluorescent in situ hybridization (FISH) was used to test its prevalence in clinical samples. RESULTS: We found that P. gingivalis increased tumor volume and tumor growth in OSCC nude models. Functional studies demonstrated that P. gingivalis inhibited the apoptosis of OSCC cells by promoting cellular autophagy. P. gingivalis was more prevalent in FISH samples from patients with OSCC than from patients with leukoplakia or healthy subjects (70% vs. 47.2% vs. 33.3%, p = 0.045 and p < 0.001, respectively). CONCLUSION: These data suggest that P. gingivalis plays an accelerating role in OSCC progression and contributes to OSCC by enhancing the autophagy pathway to reduce carcinoma apoptosis.

Potential of solar photodegradation of antibiotics in shallow ditches: Kinetics, the role of dissolved organic matter and prediction models.

Shallow ditches, which generally receive livestock or domestic sewage, are widely distributed in rural and suburban areas, making them important sites for antibiotic exposure. Because of the easy penetration of solar irradiation, the photochemical reactions of antibiotics tend to be active in shallow ditches. This study investigated the photodegradation potential of 21 commonly used antibiotics belonging to five categories in a typical shallow ditch by conducting simulated solar irradiation experiments. The influence of dissolved organic matter (DOM) in ditch water on the photodegradation of antibiotics was analyzed, and a model based on DOM changes was established to predict the degradation behavior of antibiotics. The results indicated that the degradation rates of different varieties of antibiotics in ultrapure water and ditch water followed the trend of fluoroquinolones > tetracyclines > sulfonamides > macrolides > lincosamides. In ditch water, direct photodegradation and photooxidation mediated by 3DOM∗ played predominant roles in the antibiotic photodegradation, whereas the contributions of singlet oxygen (1O2) and hydroxyl radicals (·OH) varied significantly depending on the reactivity of the antibiotics. A simple and effective model was proposed for predicting the photodegradation process of antibiotics in ditch water based on the degree of DOM photobleaching determined by excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis. The prediction model was simplified by considering the similarity in photochemical properties within the same category of antibiotics and was validated by field tests. This study fills a critical research gap by evaluating the photodegradation of antibiotics in shallow ditches, thereby providing valuable insights into their fate and transport in shallow ditch water.

Strong Subseasonal Variability of Oxic Methane Production Challenges Methane Budgeting in Freshwater Lakes.

Methane (CH4) accumulation in the well-oxygenated lake epilimnion enhances the diffusive atmospheric CH4 emission. Both lateral transport and in situ oxic methane production (OMP) have been suggested as potential sources. While the latter has been recently supported by increasing evidence, quantifying the exact contribution of OMP to atmospheric emissions remains challenging. Based on a large high-resolution field data set collected during 2019-2020 in the deep stratified Lake Stechlin and on three-dimensional hydrodynamic modeling, we improved existing CH4 budgets by resolving each component of the mass balance model at a seasonal scale and therefore better constrained the residual OMP. All terms in our model showed a large temporal variability at scales from intraday to seasonal, and the modeled OMP was most sensitive to the surface CH4 flux estimates. Future efforts are needed to reduce the uncertainties in estimating OMP rates using the mass balance approach by increasing the frequency of atmospheric CH4 flux measurements.

Orientation-dependent CD45 inhibition with viral and engineered ligands.

CD45 is a cell surface phosphatase that shapes the T cell receptor signaling threshold but does not have a known ligand. A family of adenovirus proteins, including E3/49K, exploits CD45 to evade immunity by binding to the extracellular domain of CD45, resulting in the suppression of T cell signaling. We determined the cryo-EM structure of this complex and found that the E3/49K protein is composed of three immunoglobulin domains assembled as "beads on a string" that compel CD45 into a closely abutted dimer by cross-linking the CD45 D3 domain, leading to steric inhibition of its intracellular phosphatase activity. Inspired by the E3/49K mechanism, we engineered CD45 surrogate ligands that can fine-tune T cell activation by dimerizing CD45 into different orientations and proximities. The adenovirus E3/49K protein has taught us that, despite a lack of a known ligand, CD45 activity can be modulated by extracellular dimerizing ligands that perturb its phosphatase activity and alter T cell responses.

Locoregional event or dyssynchronous distant metastasis: clinicopathological and molecular analysis of contralateral axillary lymph node metastasis in breast cancer patients.

AIMS: Contralateral axillary lymph node metastasis (CAM) is a rare clinical condition in patients with breast cancer (BC). CAM can be either a locoregional event or a distant metastasis. Molecular application for clonal evolution in BC has not been reported in CAM cases. METHODS: We studied six patients with CAM with clinical, pathological and/or molecular evidence of distant metastasis; those patients had poor outcomes. RESULTS: Two cases with molecular analysis of paired primary and CAM established clonal evolution of the CAM with its corresponding primary with additional molecular alteration, increased tumour mutation burden, and copy number variations (CNVs) in the CAMs. Four cases containing alterations from genes potentially modulate chromatin organization, supporting chromatin and subsequent transcriptional signature changes are essential in CAM. Molecular analysis is critical to establish the connection between CAM and its primary counterpart. Distant CAM shows clonal evolution compared with its corresponding primary with additional molecular alterations, increased mutation burden and/or copy number variations. CONCLUSION: CAM should be evaluated individually and handled in a personalized fashion. Evidence of a true metastatic CAM can be supported by distant metastasis to other organs, specific morphological features and/or clonal evolution.

The Development and Application of KinomePro-DL: A Deep Learning Based Online Small Molecule Kinome Selectivity Profiling Prediction Platform.

Characterizing the kinome selectivity profiles of kinase inhibitors is essential in the early stages of novel small-molecule drug discovery. This characterization is critical for interpreting potential adverse events caused by off-target polypharmacology effects and provides unique pharmacological insights for drug repurposing development of existing kinase inhibitor drugs. However, experimental profiling of whole kinome selectivity is still time-consuming and resource-demanding. Here, we report a deep learning classification model using an in-house built data set of inhibitors against 191 well-representative kinases constructed based on a novel strategy by systematically cleaning and integrating six public data sets. This model, a multitask deep neural network, predicts the kinome selectivity profiles of compounds with novel structures. The model demonstrates excellent predictive performance, with auROC, prc-AUC, Accuracy, and Binary_cross_entropy of 0.95, 0.92, 0.90, and 0.37, respectively. It also performs well in a priori testing for inhibitors targeting different categories of proteins from internal compound collections, significantly improving over similar models on data sets from practical application scenarios. Integrated to subsequent machine learning-enhanced virtual screening workflow, novel CDK2 kinase inhibitors with potent kinase inhibitory activity and excellent kinome selectivity profiles are successfully identified. Additionally, we developed a free online web server, KinomePro-DL, to predict the kinome selectivity profiles and kinome-wide polypharmacology effects of small molecules (available on kinomepro-dl.pharmablock.com). Uniquely, our model allows users to quickly fine-tune it with their own training data sets, enhancing both prediction accuracy and robustness.

Single-stage resection of uterine fibroids and intravascular leiomyomatosis: a case report.

BACKGROUND: Uterine Fibroids (UFs) are common benign tumors in the female reproductive tract, but their progression to intravascular leiomyomatosis (IVL) is rare. Presently, there are few reports on single-stage resection of UFs and IVL. CASE PRESENTATION: A 47-year-old woman, G2P2, had been diagnosed multiple UFs four years ago and now developed heart failure. Imaging examinations revealed that UFs had invaded the right iliac vein and extended into the right atrium through the inferior vena cava. Through multidisciplinary collaboration and a single-stage resection, the patient has survived for over 24 months post-surgery, and her heart function has significantly improved compared to preoperative levels, with no recurrence of UFs observed. CONCLUSIONS: Single-stage resection of IVL and UF is feasible and advantageous for this case, and selecting the appropriate surgical approach is crucial.

Lonicera japonica Fermented by Lactobacillus plantarum Improve Multiple Patterns Driven Osteoporosis.

Osteoporosis (OP) represents a global health challenge. Certain functional food has the potential to mitigate OP. Honeysuckle (Lonicera japonica) solution has medicinal effects, such as anti-inflammatory and immune enhancement, and can be used in functional foods such as health drinks and functional snacks. The composition of honeysuckle changed significantly after fermentation, and 376 metabolites were enriched. In this study, we used dexamethasone to induce OP in the rat model. Research has confirmed the ability of FS (fermented Lonicera japonica solution) to enhance bone mineral density (BMD), repair bone microarchitectural damage, and increase blood calcium levels. Markers such as tartrate-resistant acid phosphatase-5b (TRACP-5b) and pro-inflammatory cytokines (TNF-α and IL-6) were notably decreased, whereas osteocalcin (OCN) levels increased after FS treatment. FS intervention in OP rats restored the abundance of 6 bacterial genera and the contents of 17 serum metabolites. The results of the Spearman correlation analysis showed that FS may alleviate OP by restoring the abundance of 6 bacterial genera and the contents of 17 serum metabolites, reducing osteoclast differentiation, promoting osteoblast differentiation, and reducing the inflammatory response. This study revealed that Lactobacillus plantarum-fermented honeysuckle alleviated OP through intestinal bacteria and serum metabolites and provided a theoretical basis for the development of related functional foods.

Photoinduction of Ferroptosis and cGAS-STING Activation by a H2S-Responsive Iridium(III) Complex for Cancer-Specific Therapy.

Triggering ferroptosis represents a promising anticancer therapeutic strategy, but the development of a selective ferroptosis inducer for cancer-specific therapy remains a great challenge. Herein, a H2S-responsive iridium(III) complex NA-Ir has been well-designed as a ferroptosis inducer. NA-Ir could selectively light up H2S-rich cancer cells, primarily localize in mitochondria, intercalate into mitochondrial DNA (mtDNA), and induce mtDNA damage, exhibiting higher anticancer activity under light irradiation. Mechanistic studies showed that NA-Ir-mediated PDT triggered lipid peroxidation and glutathione peroxidase 4 downregulation through ROS production and GSH depletion, resulting in ferroptosis through multiple pathways. Moreover, the intense mtDNA damage can activate the cyclic GMP-AMP synthase-stimulator of the interferon gene (cGAS-STING) pathway, leading to ferritinophagy and further ferroptosis. RNA-sequencing analysis showed that NA-Ir-mediated PDT mainly affects the expression of genes related to ferroptosis, autophagy, and cancer immunity. This study demonstrates the first cancer-specific example with ferroptosis and cGAS-STING activation, which provides a new strategy for multimodal synergistic therapy.

Ankrd1 regulates endogenous cardiac regeneration in mice by modulating cyclin D1.

Restoration of the expression of factors regulating neonatal heart regeneration in the adult heart can promote myocardial repair. Therefore, investigations of the regulatory factors that play key roles in neonatal heart regeneration are urgently needed for the development of cardiac regenerative therapies. In our previous study, we identified ankyrin repeat domain 1 (Ankrd1) through multiomics analysis in a neonatal mouse model of cardiac regeneration and hypothesized that Ankrd1 plays a regulatory role in neonatal heart regeneration. In the present study, we aimed to determine the role of Ankrd1 in neonatal heart regeneration and adult myocardial repair. Our findings confirmed that Ankrd1 could mediate cardiomyocyte proliferation and that Ankrd1 knockdown in cardiomyocytes inhibited myocardial regeneration after apical resection in neonatal mice. Furthermore, we found that cardiomyocyte-specific Ankrd1 overexpression promoted cardiac repair and cardiac function recovery after adult myocardial infarction (MI). Mechanistically, Ankrd1 could regulate the cell cycle of cardiomyocytes and significantly mediate cardiac regeneration, at least in part, through cyclin D1. Overall, our study demonstrates that Ankrd1 is an effective target for achieving cardiac repair after MI, providing new ideas for the treatment of ischemic heart disease in the future.

Genetically predicted the causal relationship between gut microbiota and the risk of polymyositis/dermatomyositis: a Mendelian randomization analysis.

Introduction: Observational studies suggest associations between gut microbiota and polymyositis (PM) and dermatomyositis (DM), but causal relationships are unclear. We investigate the causal effects of gut microbiota on PM and DM, providing insights hoping to provide insights for future treatment and prevention. Methods: Summary statistics of gut microbiota were obtained from a multi-ethnic Genome Wide Association Studies (GWAS) meta-analysis, including 119 taxa from 18,340 Europeans. PM/DM statistics were extracted from GWAS analyses. Mendelian randomization (MR) with IVW, MR-Egger, and weighted median methods was performed. Sensitivity analyses addressed heterogeneity and pleiotropy. Of the 119 bacterial genera studied, six showed causal links. Results: Alloprevotella (OR: 3.075, 95% CI: 1.127-8.386, p = 0.028), Ruminococcaceae UCG003 (OR: 4.219, 95% CI: 1.227-14.511, p = 0.022), Dialister (OR: 0.273, 95% CI: 0.077-0.974, p = 0.045) were associated with PM. Anaerotruncus (OR: 0.314, 95% CI: 0.112-0.882, p = 0.028), Ruminococcaceae UCG002 (OR: 2.439, 95% CI: 1.173-5.071, p = 0.017), Sutterella (OR: 3.392, 95% CI: 1.302-8.839, p = 0.012) were related to DM. Sensitivity analyses validated these associations. Discussion: We establish causal relationships between Ruminococcaceae, Sutterella, Anaerotruncus with DM, Alloprevotella, Ruminococcaceae UCG003, and Dialister with PM. Common microbiota, like Ruminococcaceae, have significant clinical implications. These findings open up greater possibilities for the gut microbiota to contribute to the development of PM/DM and for future monitoring of the gut microbiota in patients with PM/DM.

Weakly-supervised Depth Estimation and Image Deblurring via Dual-Pixel Sensors.

Dual-pixel (DP) imaging sensors are getting more popularly adopted by modern cameras. A DP camera captures a pair of images in a single snapshot by splitting each pixel in half. Several previous studies show how to recover depth information by treating the DP pair as an approximate stereo pair. However, dual-pixel disparity occurs only in image regions with defocus blur which is unlike classic stereo disparity. Heavy defocus blur in DP pairs affects the performance of depth estimation approaches based on matching. Therefore, we treat the blur removal and the depth estimation as a joint problem. We investigate the formation of the DP pair, which links the blur and depth information, rather than blindly removing the blur effect. We propose a mathematical DP model that can improve depth estimation by the blur. This exploration motivated us to propose our previous work, an end-to-end DDDNet (DP-based Depth and Deblur Network), which jointly estimates depth and restores the image in a supervised fashion. However, collecting the ground-truth (GT) depth map for the DP pair is challenging and limits the depth estimation potential of the DP sensor. Therefore, we propose an extension of the DDDNet, called WDDNet (Weakly-supervised Depth and Deblur Network), which includes an efficient reblur solver that does not require GT depth maps for training. To achieve this, we convert all-in-focus images into supervisory signals for unsupervised depth estimation in our WDDNet. We jointly estimate an all-in-focus image and a disparity map, then use a Reblur and Fstack module to regularize the disparity estimation and image restoration. We conducted extensive experiments on synthetic and real data to demonstrate the competitive performance of our method when compared to state-of-the-art (SOTA) supervised approaches. Index Terms-Dual-pixel Sensor, Weakly-supervised, Depth Estimation, Deblur and Reblu.

Regulatory mechanism of C4-dicarboxylates in cyclo (Phe-Pro) production.

Cyclo (Phe-Pro) (cFP), a cyclic dipeptide with notable antifungal, antibacterial, and antiviral properties, shows great promise for biological control of plant diseases. Produced as a byproduct by non-ribosomal peptide synthetases (NRPS), the regulatory mechanism of cFP biosynthesis remains unclear. In a screening test of 997 Tn5 mutants of Burkholderia seminalis strain R456, we identified eight mutants with enhanced antagonistic effects against Fusarium graminearum (Fg). Among these, mutant 88's culture filtrate contained cFP, confirmed through HPLC and LC-MS, which actively inhibited Fg. The gene disrupted in mutant 88 is part of the Dct transport system (Dct-A, -B, -D), responsible for C4-dicarboxylate transport. Knockout mutants of Dct genes exhibited higher cFP levels than the wild type, whereas complementary strains showed no significant difference. Additionally, the presence of exogenous C4-dicarboxylates reduced cFP production in wild type R456, indicating that these substrates negatively regulate cFP synthesis. Given that cFP synthesis is related to NRPS, we previously identified an NRPS cluster in R456, horizontally transferred from algae. Specifically, knocking out gene 2061 within this NRPS cluster significantly reduced cFP production. A Fur box binding site was predicted upstream of gene 2061, and yeast one-hybrid assays confirmed Fur protein binding, which increased with additional C4-dicarboxylates. Knockout of the Fur gene led to up-regulation of gene 2061 and increased cFP production, suggesting that C4-dicarboxylates suppress cFP synthesis by enhancing Fur-mediated repression of gene 2061.