Tricarboxylic Acid Cycle Research Articles

Slc25a21 in cisplatin-induced acute kidney injury: a new target for renal tubular epithelial protection by regulating mitochondrial metabolic homeostasis

Acute kidney injury (AKI) is a significant global health issue, which is often caused by cisplatin therapy and characterized by mitochondrial dysfunction. Restoring mitochondrial homeostasis in tubular cells could exert therapeutic effects. Here, we investigated Slc25a21, a mitochondrial carrier, as a potential target for AKI intervention. Renal Slc25a21 expression is negatively associated with kidney function in both AKI patients and cisplatin-induced murine models. Sustaining renal expression of Slc25a21 slowed down AKI progression by reducing cellular apoptosis, necroptosis, and the inflammatory response, likely through its regulation of 2-oxoadipate conversion. Slc25a21 is highly expressed in proximal tubular epithelial cells, and its down-regulation contributes to compromised mitochondrial biogenesis and integrity, as well as impaired oxidative phosphorylation. Mechanistically, reduced Slc25a21 in AKI disrupts mitochondrial 2-oxoadipate transport, affecting related metabolites influx and the tricarboxylic acid cycle. These findings demonstrate a previously unappreciated metabolic function of Slc25a21 in tubular cells, and suggest that targeting mitochondrial metabolic homeostasis by sustaining Slc25a21 expression could be a potential novel therapeutic strategy for AKI.

PFKFB3-dependent redox homeostasis and DNA repair support cell survival under EGFR-TKIs in non-small cell lung carcinoma

BackgroundThe efficacy of tyrosine kinase inhibitors (TKIs) targeting the EGFR is limited due to the persistence of drug-tolerant cell populations, leading to therapy resistance. Non-genetic mechanisms, such as metabolic rewiring, play a significant role in driving lung cancer cells into the drug-tolerant state, allowing them to persist under continuous drug treatment.MethodsOur study employed a comprehensive approach to examine the impact of the glycolytic regulator 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3) on the adaptivity of lung cancer cells to EGFR TKI therapies. We conducted metabolomics to trace glucose rerouting in response to PFKFB3 inhibition during TKI treatment. Live cell imaging and DCFDA oxidation were used to quantify levels of oxidation stress. Immunocytochemistry and Neutral Comet assay were employed to evaluate DNA integrity in response to therapy-driven oxidative stress.ResultsOur metabolic profiling revealed that PFKFB3 inhibition significantly alters the metabolic profile of TKI-treated cells. It limited glucose utilization in the polyol pathway, glycolysis, and TCA cycle, leading to a depletion of ATP levels. Furthermore, pharmacological inhibition of PFKFB3 overcome TKI-driven redox capacity by diminishing the expression of glutathione peroxidase 4 (GPX4), thereby exacerbating oxidative stress. Our study also unveiled a novel role of PFKFB3 in DNA oxidation and damage by controlling the expression of DNA-glycosylases involved in base excision repair. Consequently, PFKFB3 inhibition improved the cytotoxicity of EGFR-TKIs by facilitating ROS-dependent cell death.ConclusionsOur results suggest that PFKFB3 inhibition reduces glucose utilization and DNA damage repair, limiting the adaptivity of the cells to therapy-driven oxidative stress and DNA integrity insults. Inhibiting PFKFB3 can be an effective strategy to eradicate cancer cells surviving under EGFR TKI therapy before they enter the drug-resistant state. These findings may have potential implications in the development of new therapies for drug-resistant cancer treatment.

Comprehensive analysis of lysine lactylation and its potential biological significance in clear cell renal cell carcinoma

BackgroundClear cell renal cell carcinoma (ccRCC) is a common histological subtype of malignant renal neoplasm. Protein lysine lactylation (Kla) plays a crucial role in tumor metabolic reprogramming. However, little is known regarding the distribution and potential biological functions of Kla in ccRCC. This study aimed to systematically investigate the role of Kla in ccRCC.MethodsA total of 12 ccRCC samples were collected from 6 patients. Western blotting was performed to determine the trend of Kla-modified proteins in ccRCC. Liquid chromatography–tandem mass spectrometry was used to quantitatively analyze Kla in ccRCC. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein–protein interaction (PPI) network analyses were conducted to clarify the biological functions and interactional relationships of differentially lactylated proteins (DLPs).ResultsIn total, 239 DLPs, including 441 lactylated sites, were identified by comparing ccRCC tissues with adjacent normal tissues. Kla-related enzymes have a higher affinity for alanine than for other amino acid residues in ccRCC. Subcellular localization analysis revealed that most DLPs were localized in the cytoplasm and mitochondria. GO enrichment analysis showed that most of the DLPs were enriched in metabolism-associated biological processes, including the purine ribonucleotide, monocarboxylic acid, ribonucleoside triphosphate, purine nucleoside triphosphate, and ATP metabolic processes. KEGG analysis indicated that most DLPs were also enriched in metabolism-related pathways, including glycolysis, amino acid (valine, leucine, and isoleucine) degradation, pyruvate metabolism, fatty acid degradation, and the citrate cycle. The top 20 hub proteins were screened from the PPI network based on their degree ranks.ConclusionsThis study revealed the role of Kla in ccRCC, which will extend our understanding of the potential molecular mechanisms underlying ccRCC formation and progression. These key Kla-modified proteins may be promising therapeutic targets for the treatment of ccRCC. However, further molecular experiments are required to validate these findings.

Metabolomic analysis reveals an important role of sphingosine 1-phosphate in the development of HFMD due to EV-A71 infection.

Hand, foot, and mouth disease (HFMD) is a serious pediatric infectious disease that causes immeasurable physical and mental health burdens. Currently, there is a lack of information on the mechanisms of HFMD severity and early diagnosis. We performed metabolomic profiling of sera from 84 Enterovirus A71 (EV-A71) infections and 45 control individuals. Targeted metabolomics assays were employed to further validate some of the differential metabolic molecules. We identified significant molecular changes in the sera of HFMD patients compared to healthy controls (HCs). A total of 54, 60, 35, and 62 differential metabolites were screened between mild cases and HCs, severe cases and HCs, severe cases and mild cases, and among the three groups, respectively. These differential metabolites implicated dysregulation of the tricarboxylic acid cycle, alanine, aspartate, and glutamate metabolism, and valine, leucine, and isoleucine biosynthesis. The diagnostic panel based on some overlapped differential metabolites could effectively discriminate severe cases from mild cases with an AUC of 0.912 (95% CI: 0.85-0.97) using the logistic regression model. Next, we found the elevation of serum sphingosine 1-phosphate (S1P) level in EV-A71 infection mice, which was similar to clinical observation. Importantly, after blocking the release of S1P by MK571, the clinical symptoms and survival of mice were significantly improved, involving the reduction of leukocyte infiltration in infected brain tissues. Collectively, our data provided a landscape view of metabolic alterations in EV-A71 infected children and revealed regulating S1P metabolism was an exploitable therapeutic target against EV-A71 infection.

Momordicine-I suppresses head and neck cancer growth by modulating key metabolic pathways

One of the hallmarks of cancer is metabolic reprogramming which controls cellular homeostasis and therapy resistance. Here, we investigated the effect of momordicine-I (M-I), a key bioactive compound from Momordica charantia (bitter melon), on metabolic pathways in human head and neck cancer (HNC) cells and a mouse HNC tumorigenicity model. We found that M-I treatment on HNC cells significantly reduced the expression of key glycolytic molecules, SLC2A1 (GLUT-1), HK1, PFKP, PDK3, PKM, and LDHA at the mRNA and protein levels. We further observed reduced lactate accumulation, suggesting glycolysis was perturbed in M-I treated HNC cells. Metabolomic analyses confirmed a marked reduction in glycolytic and TCA cycle metabolites in M-I-treated cells. M-I treatment significantly downregulated mRNA and protein expression of essential enzymes involved in de novo lipogenesis, including ACLY, ACC1, FASN, SREBP1, and SCD1. Using shotgun lipidomics, we found a significant increase in lysophosphatidylcholine and phosphatidylcholine loss in M-I treated cells. Subsequently, we observed dysregulation of mitochondrial membrane potential and significant reduction of mitochondrial oxygen consumption after M-I treatment. We further observed M-I treatment induced autophagy, activated AMPK and inhibited mTOR and Akt signaling pathways and leading to apoptosis. However, blocking autophagy did not rescue the M-I-mediated alterations in lipogenesis, suggesting an independent mechanism of action. M-I treated mouse HNC MOC2 cell tumors displayed reduced Hk1, Pdk3, Fasn, and Acly expression. In conclusion, our study revealed that M-I inhibits glycolysis, lipid metabolism, induces autophagy in HNC cells and reduces tumor volume in mice. Therefore, M-I-mediated metabolic reprogramming of HNC has the potential for important therapeutic implications.Graphical

TCA cycle impairment leads to PIN2 internalization and degradation via reduced MAB4 level and ARA6 components in Arabidopsis roots

The mitochondrial pyruvate dehydrogenase complex (PDC) plays a crucial role in linking the glycolysis pathway and the tricarboxylic acid (TCA) cycle. Previously, we reported that a mutation of MAB1, encoding an E1β subunit of PDC, affects the abundance of auxin efflux carriers PIN-FORMED proteins (PINs) via reduced recycling and enhanced degradation in vacuoles. Here, we further analyzed the effects of TCA cycle inhibition on vesicle trafficking using both the mab1-1 mutant and 3-BP, a TCA cycle inhibitor. Pharmacological and genetic impairment of the TCA cycle induced the aggregated components of ARA6, which is a plant-unique RAB5 GTPase that mediates endosomal trafficking to the plasma membrane. In addition, MAB4, which is an NPH3-like protein that inhibits PIN internalization from the plasma membrane, was severely reduced in 3-BP-treated roots and mab1-1. Furthermore, TCA cycle impairment led to the accumulation of reactive oxygen species in root tips, and treatment with H2O2 reduced MAB4 levels while increasing the internalization of PIN2 from the plasma membrane, and aggregated ARA6-positive compartments. These results suggest that TCA cycle impairment targets PIN proteins for degradation in the vacuole by disrupting both the MAB4-mediated block of internalization and the ARA6-mediated endocytic pathway.

Renal phenotyping in a hypomorphic murine model of propionic aciduria reveals common pathomechanisms in organic acidurias

Mutations in the mitochondrial enzyme propionyl-CoA carboxylase (PCC) cause propionic aciduria (PA). Chronic kidney disease (CKD) is a known long-term complication. However, good metabolic control and standard therapy fail to prevent CKD. The pathophysiological mechanisms of CKD are unclear. We investigated the renal phenotype of a hypomorphic murine PA model (Pcca-/-(A138T)) to identify CKD-driving mechanisms. Pcca-/-(A138T) mice show elevated retention parameters and express markers of kidney damage progressing with time. Morphological assessment of the Pcca-/-(A138T) mouse kidneys indicated partial flattening of tubular epithelial cells and focal tubular-cystic dilation. We observed altered renal mitochondrial ultrastructure and mechanisms acting against oxidative stress were active. LC–MS/MS analysis confirmed disease-specific metabolic signatures and revealed disturbances in mitochondrial energy generation via the TCA cycle. Our investigations revealed altered mitochondrial networks shifted towards fission and a marked reduction of mitophagy. We observed a steep reduction of PGC-1-α, the key mediator modulating mitochondrial functions and a counter actor of mitochondrial fission. Our results suggest that impairment of mitochondrial homeostasis and quality control are involved in CKD development in PA. Therapeutic targeting of the identified pathways might help to ameliorate CKD in addition to the current treatment strategies.

Multiomics Analyses Reveal that Fatty Acid Metabolism and TCA Cycle Contribute to the Achievement of Functional Cure in Chronic Hepatitis B.

Peg-IFNα is one of the current therapeutic strategies for Hepatitis B virus (HBV) seroclearance. Nevertheless, the underlying mechanisms are not yet adequately understood. The objective of this study was to explore the potential mechanisms using multiomics approach. For the first time, we revealed the transcriptomic, proteomic, and metabolomic characterizations of Peg-IFNα-induced HBsAg seroclearance. We found that Peg-IFNα caused significant changes during the treatment. Patients who achieved HBsAg seroclearance were characterized as having decreased transcriptional activity of genes involved in fatty acid metabolism and the glycolysis/gluconeogenesis pathway, with up-regulated expression of fatty acid degradation-related proteins. Consistently, mitochondrial TCA cycle metabolites, including citric, isocitric, and malic acids, were significantly elevated in patients who achieved HBsAg seroclearance. We also observed up-regulated transcriptional activity of NK cell-mediated cytotoxicity, positive regulation of B cell activation, immunoglobulin production, and T cell receptor complex in functional-cured patients. Conversely, the metabolites associated with unsaturated fatty acid biosynthesis were increased in HBsAg persistent patients, and the transcriptional activity of immunoglobulin production and T cell receptor complex was down-regulated after 48 weeks of Peg-IFNα treatment. Our findings provided valuable resources to better understand the process of HBsAg seroclearance and shed new light on the pathways to facilitate higher functional cure rates for CHB.

An erythroid-specific lentiviral vector improves anemia and iron metabolism in a new model of XLSA.

X-linked sideroblastic anemia (XLSA) is a congenital anemia caused by mutations in ALAS2, a gene responsible for heme synthesis. Treatments are limited to pyridoxine supplements and blood transfusions, offering no definitive cure except for allogeneic hematopoietic stem cell transplantation, only accessible to a subset of patients. The absence of a suitable animal model has hindered the development of gene therapy research for this disease. We engineered a conditional Alas2-KO mouse model using tamoxifen administration or treatment with lipid nanoparticles (LNP) carrying Cre-mRNA and conjugated to an anti-CD117 antibody. Alas2-KOBM animals displayed a severe anemic phenotype characterized by ineffective erythropoiesis (IE), leading to low numbers of red blood cells (RBC), hemoglobin (Hb), and hematocrit (HCT). In particular, erythropoiesis in these animals showed expansion of polychromatic erythroid cells, characterized by reduced oxidative phosphorylation, mitochondria's function, and activity of key Tricarboxylic Acid (TCA) cycle enzymes. In contrast, glycolysis was increased in the unsuccessful attempt to extend cell survival despite mitochondrial dysfunction. The IE was associated with marked splenomegaly and low hepcidin levels, leading to iron accumulation in the liver, spleen, and bone marrow and the formation of ring sideroblasts. To investigate the potential of a gene therapy approach for XLSA, we developed a lentiviral vector (X-ALAS2-LV) to direct ALAS2 expression in erythroid cells. Infusion of BM cells with 0.6-1.4 copies of the X-ALAS2-LV in Alas2-KOBM mice improved CBC levels, tissue iron accumulation, and survival rates. These findings suggest our vector could be curative in XLSA patients.

Transcriptome Sequencing of Bacillus sp. TTMP20 and Analysis of the Effect of BDH Gene on Tetramethylpyrazine Synthesis.

Bacillus sp. TTMP20 has high tetramethylpyrazine (TTMP) yield. However, the mechanism of TTMP production in this strain is unclear at present, which limits the modification for strain TTMP20. In this study, key metabolic pathways related to TTMP synthesis were identified, which included glycolytic pathway, tricarboxylic acid cycle and nitrogen metabolism pathway. Moreover, transgenic Bacillus sp. TTMP20 with recombinant vector PHY-300PLK-BDH was constructed. 2,3-butanediol dehydrogenase gene (BDH) overexpression considerably reduced TTMP biosynthesis. This study will supply new insight into the regulation of TTMP biosynthesis at key enzyme gene level.

Non-Targeted Metabolomics Analysis of Small Molecular Metabolites in Refrigerated Goose Breast Meat

Poultry represents a rich source of multiple nutrients. Refrigeration is commonly employed for poultry preservation, although extended storage duration can adversely affect the meat quality. Current research on this topic has focused on the analysis of biochemical indices in chilled goose meat, with limited information on changes in metabolites that influence the quality of the meat during storage. This study used non-targeted metabolomics and the random forest algorithm to investigate metabolite changes in goose meat over an extended storage period. The results showed a significant change in the composition of the meat as the duration of storage increased, with the identification of 121 distinct metabolites. Further analysis identified 18 metabolites that could be used as indicators of the degradation of carbohydrates, amino acids, nucleotides, and lipids. These metabolites could be used as markers to monitor the deterioration process. These intermediate metabolites tended to be transformed into lower-level products involving pyruvate, acetyl coenzyme A, and fumaric acid, used in the tricarboxylic acid cycle, performing substance transformation. This comprehensive analysis of metabolites provides a valuable reference for monitoring the freshness of goose meat, potentially improving the safety of domestic poultry products.

Sugar Transport and Signaling in Shoot Branching

The source–sink relationship is critical for proper plant growth and development, particularly for vegetative axillary buds, whose activity shapes the branching pattern and ultimately the plant architecture. Once formed from axillary meristems, axillary buds remain dormant or become active to grow into new branches. This transition is notably driven by the regulation of the bud sink strength, which is reflected in the ability to unload, metabolize and store photoassimilates. Plants have so far developed two main mechanisms for unloading sugars (sucrose) towards sink organs, a symplasmic pathway and an apoplasmic pathway, but so far limited investigations have been reported about the modes of sugar uptake during the transition from the dormant to the active outgrowth state of the bud. The available data indicate that the switch from dormant bud to active outgrowing state, requires sugar and is shortly preceded by an increase in bud metabolic activity and a remobilization of the stem starch reserves in favor of growing buds. This activation of the bud sink strength is accompanied by an up-regulation of the main markers of apoplasmic unloading, such as sugar transporters (sucrose transporters—SUTs; sugar will eventually be exported transporters—SWEETs), sucrose hydrolyzing enzymes (cell wall invertase—CWINV) and sugar metabolic pathways (glycolysis/tricarboxylic cycle—TCA; oxidative pentose phosphate pathway—OPPP). As these results are limited to a few species, they are not sufficient to provide a complete and accurate picture of the mode(s) of sugar unloading toward axillary buds and deserve to be complemented by additional studies in a wide variety of plants using systems integration, combining genetic, molecular and immunolocalization approaches. Altogether, we discuss here how sugar is a systemic regulator of shoot branching, acting both as an energy-rich molecule and a signaling entity in the establishment of the bud sink strength.

The effects of different hormone combinations on the growth of Panax notoginseng anther callus based on metabolome analysis

Panax notoginseng saponins (PNS), the primary active components of Panax notoginseng (Burk.) F.H.Chen, a traditional and precious Chinese medicinal herb, are mainly derived from the roots of the plant. However, due to the long cultivation period and specific environmental requirements, the PNS supply is often limited. And, callus cultures of P. notoginseng, which grow rapidly, have short production cycles, and can be cultured under controlled conditions, provide a more efficient source for the quick acquisition of saponins. In this study, anthers of P. notoginseng were used as explants, and twelve hormone combinations were tested to induce callus formation. Eight kinds of hormone combinations successfully induced P. notoginseng anther callus. Among these, callus induced by combinations 5 and 7 had the highest saponin content, while those induced by combinations 1 and 3 exhibited the highest relative growth rates. Metabolomic analysis of these four callus types revealed that there were a total of 99 differential metabolites between combinations 5 and 7, 30 between combinations 1 and 3, 123 between combinations 3 and 7, and 116 between combinations 1 and 5. Further analysis showed that the tricarboxylic acid (TCA) cycle metabolites in callus induced by combinations 1 and 3 were significantly upregulated, with corresponding genes showing high expression levels, increased ATP accumulation, and low responses of the auxin response factor PnARF-3 and cytokinin response factor PnCRF-3. The abundance of metabolites in the PNS biosynthesis pathway in callus induced by combinations 5 and 7 increased significantly, with related genes showing high expression levels, increased IPP accumulation, and high responses of PnARF-3 and PnCRF-3. Overexpression of PnARF-3 and PnCRF-3 in callus induced by combination 3 promoted the production of IPP and saponins while reducing ATP production. In conclusion, different hormone combinations affect the distribution of Acetyl-CoA through PnARF-3 and PnCRF-3, resulting in the relative growth rate and saponin of P. notoginseng anther callus differences.

The Causal Association Between Blood Metabolites and Ovarian Cancer: Mendelian Randomization Study

Objective: Ovarian cancer is closely related to human metabolism, but the causal effect of serum metabolites on its occurrence and development is still unknown. Methods: Based on the publicly available Genome-Wide Association Studies (GWAS) abstract data set, this study used two-sample Mendelian randomization (MR) to determine the causal metabolites associated with ovarian cancer, and a comprehensive sensitivity analysis was used to verify the accuracy of the results. Finally, the metabolic pathway analysis of the causal metabolites that may affect the risk of ovarian cancer was carried out. Results: Based on the summary level of the GWAS data set, the MR method was first used to identify 17 metabolites that are highly correlated with the risk of ovarian cancer, 16 of which are related to ovarian cancer subtypes. Further sensitivity analysis excluded the influence of heterogeneity and horizontal pleiotropy, and confirmed the causal effects of 9 metabolites. Metabolic pathway analysis shows that tryptophan metabolic pathway may play a key role in invasive epithelial ovarian cancer, alanine, aspartic acid and glutamate metabolism, citrate cycle, glyoxylic acid and dicarboxylate Metabolism is closely related to mucinous ovarian cancer, and caffeine metabolism can affect the occurrence and development of low-grade potential ovarian cancer. Conclusion: This study comprehensively assessed the influence of blood metabolites on the risk of ovarian cancer and its different subtypes through genetic methods.

Microbiome and Metabolomics Reveal the Effect of Gut Microbiota on Liver Regeneration of Fatty Liver Disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is associated with impaired regenerative capacity and poor postoperative prognosis following hepatectomy. Previous research has highlighted the importance of the gut-liver axis in the physiological and pathological processes of the liver. However, the contribution of gut bacteria to the regeneration of livers with MAFLD and its metabolic regulatory mechanisms remain elusive. Partial hepatectomy (PHx) was performed on C57Bl/6J mice fed with high-fat diet (HFD) for 12 weeks. Pathological examination, immunohistochemistry, and qRT-PCR analysis were performed to assess the severity of steatosis and proliferative potential. The gut microbiome was examined by 16S rRNA gene sequencing and shotgun metagenomics, whereas liver metabolomics was analysed via untargeted and targeted metabolomics using liquid chromatography-tandem mass spectrometry (LC-MS). HFD-induced hepatic steatosis in mice led to impaired liver regeneration following PHx. The gut microbiota and liver metabolites were altered along with the liver regeneration process. Longitudinal time-series analysis revealed dynamic alterations in these data, whereas correlation analysis screened out bacterial candidates that potentially influence liver regeneration in MAFLD by modulating metabolic pathways. Among these bacteria, the dominant bacterium Akkermansia was selected for subsequent investigation. MAFLD mice gavaged with Akkermansia muciniphila (A.muciniphila) exhibited reduced liver lipid accumulation and accelerated liver regeneration, possibly through the regulation of the tricarboxylic acid (TCA) cycle. These data demonstrated the interplay between the gut microbiome, liver metabolomics, and liver regeneration in mice with MAFLD. A.muciniphila has the potential to serve as a clinical intervention agent to accelerate postoperative recovery in MAFLD. This work was supported by the Research Project of Jinan Microecological Biomedicine Shandong Laboratory [JNL-2022008B]; the Zhejiang Provincial Natural Science Foundation of China [LZ21H180001]; the Fundamental Research Funds for the Central Universities [No. 2022ZFJH003].

Study on the mechanism of lactic acid bacteria and their fermentation broth in alleviating hyperuricemia based on metabolomics and gut microbiota.

Hyperuricemia (HUA) is a metabolic disease caused by purine metabolism disorders in the body. Lactic acid bacteria (LAB) and their fermentation broth have the potential to alleviate hyperuricemia, but the potential mechanism of action is still unclear. The LAB with high inhibitory activity against xanthine oxidase (XOD) were screened out. Then the fermentation broth, fermentation supernatant and fermentation bacteria after fermentation of these LAB were administered into HUA mice, respectively. Lactobacillus reuteri NCUF203.1 and Lactobacillus brevis NCUF207.7, of which fermentation supernatant had high inhibitory activity against XOD, were screened out and administered into HUA mice. Among them, L. reuteri strain, L. reuteri fermentation broth, L. brevis fermentation broth and L. brevis fermentation supernatant could significantly reduce serum uric acid levels and inhibited the liver XOD activity in HUA mice. The GC-MS metabolomics analysis of colon contents showed that supplementation of these four substances could partially reverse the down-regulation of energy metabolism pathways such as ketone body metabolism, pyruvate metabolism and citric acid cycle in HUA mice. It could also regulate amino acid metabolism pathways such as alanine metabolism, arginine and proline metabolism, glycine and serine metabolism, and repair the disorders of amino acid metabolism caused by HUA. In addition, the intervention of L. brevis fermentation broth and L. brevis fermentation supernatant may also accelerate the catabolism of uric acid in the intestine by up-regulating the urea cycle pathway. Fecal 16S rRNA sequencing analysis showed that their intervention increased the diversity of gut microbiota in HUA mice and alleviated the gut microbiota dysregulation caused by HUA. These results indicated that the LAB and their fermentation broth may play a role in alleviating HUA by regulating intestinal metabolism and gut microbiota.

NMR-based metabolomics combined with metabolic pathway analysis reveals metabolic heterogeneity of colorectal cancer tissue at different anatomical locations and stages.

Colorectal cancer (CRC) still remains the leading cause of cancer death worldwide. This study aimed to profile the metabolic differences of colorectal cancer tissues (CCT) at different stages and sites, as compared with their distant noncancerous tissues (DNT), to investigate the temporal and spatial heterogeneities of metabolic characterization. Our NMR-based metabolomics fingerprinting revealed that many of the metabolite levels were significantly altered in CCT compared to DNT and esophageal cancer tissues, indicating deregulations of glucose metabolism, one-carbon metabolism, glutamine metabolism, amino acid metabolism, fatty acid metabolism, TCA cycle, choline metabolism, and so forth. A total of five biomarker metabolites, including glucose, glutamate, alanine, valine and histidine, were identified to distinguish between early and advanced stages of CCT. Metabolites that distinguish the different anatomical sites of CCT include glucose, glycerol, glutamine, inositol, succinate, and citrate. Those significant metabolic differences in CRC tissues at different pathological stages and sites suggested temporal and spatial heterogeneities of metabolic characterization in CCT, providing a metabolic foundation for further study on biofluid metabolism in CRC early detection.

Silicon-seed priming promotes seed germination under CA-induced autotoxicity by improving sucrose and respiratory metabolism in cucumber (Cucumis sativus L.)

Seed germination is one of the critical and sensitive stages of early plant growth, and its process is prevented by cinnamic acid (CA). Silicon (Si) plays a critical role in mitigating abiotic stresses and seed germination in plants, but little is known about its role in seed germination and physiology in CA-stressed cucumber. Here, we conducted experiments in the State Key Laboratory of Aridland Crop Science, Gansu Agricultural University from March to June 2021 to investigate the effects of Si-seed priming on growth, antioxidant capacity, sucrose mobilization and respiratory metabolism during germination under CA stress. Our results showed that seed soaking with Si (9 mmol/L) significantly reduced membrane lipid peroxidation and promoted post-germination growth of cucumber seeds under CA (2.0 mmol/L) stress. Si increased key enzyme activities in sucrose metabolism in CA-stressed seeds after germination, accelerating sucrose degradation and fructose synthesis. Si also enhanced the activities of key enzymes in the glycolytic pathway and pentose phosphate pathway in seeds, as well as in the post-germination tricarboxylic acid cycle, promoting glucose decomposition and ATP synthesis. Principal component analysis significantly separated the CK, Si, and CA + Si treatments from the CA treatment in the first principal component after 48 h of treatment. In addition, qRT-PCR analysis showed that Si induced overexpression of genes related to sucrose and respiratory metabolism in seeds treated with CA for 48 h. In conclusion, our findings provide evidence that Si priming may be an effective method to reverse CA inhibition of cucumber seeds, which effectively improve germination under CA stress by attenuating membrane lipid peroxidation and enhancing sucrose mobilization and respiratory metabolism in cucumber.

2-Methylbutyric acid functions as a potential antifungal fumigant by inhibiting Botrytis cinerea and inducing resistance to gray mold in cherry tomatoes

Botrytis cinerea causes gray mold disease on postharvest fruit, resulting in serious economic losses. Fumigation with natural volatile organic compounds can replace artificially synthesized fungicides to control postharvest fungal decay of agricultural products. The antifungal effects and potential mechanisms of microbial volatile compound 2-methylbutyric acid (2-MBA) against B. cinerea were investigated in this study. Results showed that 2-MBA inhibited mycelial growth and spores germination, altered mycelial morphology and reduced metabolic vitality of B. cinerea. Moreover, 2-MBA induced oxidative damage by stimulating ROS accumulation, increasing malondialdehyde levels, and decreasing the ratio of reduced/oxidized glutathione. Further studies indicated that 2-MBA reduced mitochondrial membrane potential, interfered TCA cycle by decreasing succinate dehydrogenase activity and ATP content, ultimately leading to decreased mitochondrial activity. In addition, key genes involved in botrydial biosynthesis and mycelial growth were down-regulated. 2-MBA controlled postharvest gray mold by inducing resistance to B. cinerea in cherry tomatoes. Taken together, 2-MBA is an effective and promising fumigant to control gray mold caused by B. cinerea.

Adaptations of Rice Seed Germination to Drought and Hypoxic Conditions: Molecular and Physiological Insights

Seed germination is crucial for plant survival, crop stand establishment, and achieving optimal grain yield. The main objective of this review is to explore the physiological and molecular mechanisms governing rice seed germination under aerobic (water stress) and anaerobic (hypoxic) conditions in direct-seeded rice (DSR) systems. Moreover, it discusses the recent genomic advancements and innovations to improve rice seed germination. Here, we discuss how coleoptile and mesocotyl elongation plays a vital role in anaerobic germination (AG) and the function of raised antioxidants, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in maintaining Reactive Oxygen Species (ROS), and malondialdehyde (MDA) homeostasis for stabilizing seed germination in water-scarce conditions. This study comprehensively highlights the functions and dynamics of phytohormones—GA (gibberellic acid) and ABA (abscisic acid)—key regulatory genes, transcription factors (TFs), key proteins, and regulatory metabolic pathways, including glycolysis, the pentose phosphate pathway (PPP), and the tricarboxylic acid cycle (TCA), in regulating seed germination under both conditions. Conventional agronomic and cultural practices, such as seed selection, seed priming, seed coating, and hardening, have proven to improve seed germination. Moreover, the utilization of molecular and novel approaches—such as clustered regularly interspaced short palindromic repeat (CRISPR-Cas9) mediated genome editing, marker-assisted selection (MAS), genome-wide associations studies (GWAS), single nucleotide polymorphisms (SNPs), multi-omics, RNA sequencing—combined with beneficial quantitative trait loci (QTLs) has expanded knowledge of crop genomics and inheritance. These advancements aid the development of specific traits for enhancing seed germination in DSR.