Expression Levels Of Key Enzymes Research Articles

Phenylpropanoid pathway mediated the defense response of ‘Korla’ fragrant pear against Alternaria alternata infection

Alternaria alternata has been found to be the dominating pathogenic fungus of harvested ‘Korla’ fragrant pear, and the resulting blackhead disease is a significant factor affecting the storage quality of pears. The present study explored the specific mechanisms by which the phenylpropanoid pathway mediates the defense response to A. alternata infection in pear fruit. In the A. alternata-inoculated group, the fruit exhibited increased activity and gene expression levels of key enzymes (PAL, C4H, and 4CL) as well as higher content of phenolic acids (trans-cinnamic acid, ferulic acid, caffeic acid, p-coumaric acid, and sinapic acid) and total phenol in the general phenylpropanoid pathway. In the mid-to-late storage period, the activity and gene expression levels of key enzymes in the lignin biosynthetic pathway (CCR and CAD) were suppressed, and the content of lignin monomers (sinapyl alcohol, coniferyl alcohol, and p-coumaryl alcohol) and lignin was reduced. Notably, the activity and gene expression levels of flavonoid biosynthetic pathway-related enzymes (CHS and CHI) as well as the content of various flavonoids (naringenin, apigenin, rutin, quercetin, and epicatechin) and total flavonoids continuously increased in response to A. alternata infection in the early to middle stages of storage but declined in the late storage period. In summary, the initial infection of A. alternata infection activated the stress response of pear fruit, particularly the phenylpropanoid–flavonoid branch pathway, to enhance the fruit’s defense against pathogens, but with the prolongation of the infestation time, the fruit could not continuously resist the invasion of pathogens, ultimately leading to the outbreak of disease. The present findings furnish a theoretical foundation further elucidating the interaction between ‘Korla’ fragrant pear and A. alternata and for developing an effective strategy to control the blackhead disease.

Light-Induced Nanobody-Mediated Targeted Protein Degradation for Metabolic Flux Control.

In metabolic engineering, increasing chemical production usually involves manipulating the expression levels of key enzymes. However, limited synthetic tools exist for modulating enzyme activity beyond the transcription level. Inspired by natural post-translational mechanisms, we present targeted enzyme degradation mediated by optically controlled nanobodies. We applied this method to a branched biosynthetic pathway, deoxyviolacein, and observed enhanced product specificity and yield. We then extend the biosynthesis pathway to violacein and show how simultaneous degradation of two target enzymes can further shift production profiles. Through the redirection of metabolic flux, we demonstrate how targeted enzyme degradation can be used to minimize unwanted intermediates and boost the formation of desired products.

Glutamine metabolism promotes human trophoblast cell invasion via COL1A1 mediated by PI3K-AKT pathway

Abnormal trophoblast invasion function is an important cause of recurrent spontaneous abortion (RSA). Recent research has revealed a connection between glutamine metabolism and RSA. However, the interplay between these three factors and their related mechanisms remains unclear. To address this issue, we collected villus tissues from 10 healthy women with induced abortion and from 10 women with RSA to detect glutamine metabolism. Then, the trophoblast cell line HTR-8/SVneo was used in vitro to explore the effect of glutamine metabolism on trophoblast cells invasion, which was tested by transwell assay. We found that the concentration of glutamine in the villi of the normal pregnancy group was significantly higher than that in the RSA group. Correspondingly, the expression levels of key enzymes involved in glutamine synthesis and catabolism, including glutamine synthetase and glutaminase, were significantly higher in the villi of the normal pregnancy group. Regarding trophoblast cells, glutamine markedly enhanced the proliferative and invasive abilities of HTR-8/SVneo cells. Additionally, collagen type I alpha 1 (COL1A1) was confirmed to be a downstream target of glutamine, and glutamine also activated the PI3K-AKT pathway in HTR-8/SVneo cells. These findings indicate that glutamine metabolism facilitates the invasion of trophoblasts by up-regulating COL1A1 expression through the activation of the PI3K-AKT pathway, but the specific mechanism of COL1A1 requires further study.

LncRNA TUG1 mediates microglial inflammatory activation by regulating glucose metabolic reprogramming

Microglia are natural immune cells in the central nervous system, and the activation of microglia is accompanied by a reprogramming of glucose metabolism. In our study, we investigated the role of long non-coding RNA taurine-upregulated gene 1 (TUG1) in regulating microglial glucose metabolism reprogramming and activation. BV2 cells were treated with Lipopolysaccharides (LPS)/Interferon-γ (IFN-γ) to establish a microglial activation model. The glycolysis inhibitor 2-Deoxy-D-glucose (2-DG) was used as a control. The expression levels of TUG1 mRNA and proinflammatory cytokines such as Interleukin-1β (IL-1β), Interleukin -6, and Tumor Necrosis Factor-α mRNA and anti-inflammatory cytokines such as IL-4, Arginase 1(Arg1), CD206, and Ym1 were detected by RT-qPCR. TUG1 was silenced using TUG1 siRNA and knocked out using CRISPR/Cas9. The mRNA and protein expression levels of key enzymes involved in glucose metabolism, such as Hexokinase2, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Lactate dehydrogenase, Glucose 6 phosphate dehydrogenase, and Pyruvate dehydrogenase (PDH), were determined by RT-qPCR and Western blotting. The glycolytic rate of microglial cells was measured using Seahorse. Differential metabolites were determined by metabolomics, and pathway enrichment was performed using these differential metabolites. Our findings revealed that the expression of TUG1 was elevated in proinflammatory-activated microglia and positively correlated with the levels of inflammatory factors. The expression of anti-inflammatory cytokines such as IL-4, Arg1, CD206, and Ym1 were decreased when induced with LPS/IFN-γ. However, this decrease was reversed by the treatment with 2-DG. Silencing of GAPDH led to an increase in the expression of TUG1 and inflammatory factors. TUG1 knockout (TUG1KO) inhibited the expression of glycolytic key enzymes and promoted the expression of oxidative phosphorylation key enzymes, shifting the metabolic profile of activated microglia from glycolysis to oxidative phosphorylation. Additionally, TUG1KO reduced the accumulation of metabolites, facilitating the restoration of the tricarboxylic acid cycle and enhancing oxidative phosphorylation in microglia. Furthermore, the downregulation of TUG1 was found to reduce the expression of both proinflammatory and anti-inflammatory cytokines under normal conditions. Interestingly, when induced with LPS/IFN-γ, TUG1 downregulation showed a potentially beneficial effect on microglia in terms of inflammation. Downregulation of TUG1 expression inhibits glycolysis and facilitates the shift of microglial glucose metabolism from glycolysis to oxidative phosphorylation, promoting their transformation towards an anti-inflammatory phenotype and exerting anti-inflammatory effects in BV2.

Enrichment of Flavonoids in Short-Germinated Black Soybeans (Glycine max L.) Induced by Slight Acid Treatment.

Exogenous abiotic stimulant treatments are a straightforward and effective method for enhancing secondary metabolites in plants. In this study, the response surface optimization method was used to optimize the conditions for enriching flavonoids in short-germinated black soybeans under a slight acid treatment, and the mechanism of flavonoid accumulation during black soybean germination was explored. The results show that the use of a 126.2 mM citric acid-sodium citrate buffer (pH 5.10) as a slight acid treatment resulted in the highest flavonoid content when the black soybeans were germinated for 24 h. Under these conditions, the isoflavonoid (glycitin, daidzein, and genistein) increased significantly, and the flavonoid content reached 2.32 mg/g FW. The microacidified germination treatment significantly increased the activities and relative gene expression levels of key enzymes involved in flavonoid metabolism (4-coumarate-CoA ligase and cinnamic acid 4-hydroxylase, etc.). However, the slight acid treatment inhibited the growth of the black soybeans and caused damage to their cells. This was evidenced by significantly higher levels of malondialdehyde, superoxide anion, and hydrogen peroxide compared to the control group. Furthermore, the antioxidant system in the short-germinated soybeans was activated by the slight acid treatment, leading to a significant increase in the activities and relative gene expression levels of catalase and peroxidase. The results above show that a slight acid treatment was beneficial in inducing the accumulation of flavonoids during the growth of black soybean sprouts. This lays a technical foundation for producing black soybean products that are rich in flavonoids.

β-Aminobutyric Acid Effectively Postpones Senescence of Strawberry Fruit by Regulating Metabolism of NO, H2S, Ascorbic Acid, and ABA

Current researchis focused on the influence of β-aminobutyric acid (BABA) on the metabolism of nitric oxide (NO), hydrogen sulfide (H2S), ascorbic acid, and abscisic acid (ABA) in strawberry fruit. The increases in ion leakage and malondialdehyde (MDA) concentration in strawberry fruit and the degradation of chlorophyll in the sepals of the fruit were markedly inhibited by BABA at 20 mM. BABA-immersed fruit exhibited lower activities and expressions of polygalacturonase (PG), pectinmethylesterase (PME), and ethylene biosynthetic enzymes compared to the control. Furthermore, BABA immersion evidently upgraded the metabolic levels of NO and H2S, including the enzymatic activities and intermediary contents of metabolites, which collectively enhanced the levels of endogenous NO and H2S contents in strawberry fruit. The high enzymatic activities and gene expressions of the AsA biosynthesis pathway jointly maintained AsA accumulation in the BABA-treated sample. The application of BABA led to a decrease in ABA concentration, which was associated with reduced activities and gene expression levels of key enzymes participating in ABA metabolism. Our experimental observations showed that immersion with BABA may be a highly promising means to delay senescence and reduce natural decay in strawberry fruit, and the alleviation in senescence using BABA may be attributed to the modulation of NO, H2S, AsA, and ABA metabolism.

LDHA and LDHB overexpression promoted the Warburg effect in malignantly transformed GES-1 cells induced by N-nitroso compounds.

N-nitroso compounds (NOCs) exposure is a major risk factor for the development of gastric cancer. However, the carcinogenic mechanisms by which NOCs induce gastric and other cancers, especially the NOCs-induced Warburg effect, have not been comprehensively studied. Lactate dehydrogenase (LDH), which has two subunits (LDHA and LDHB), plays an important role in the Warburg effect of tumor cells. Therefore, we hypothesized that LDHA and LDHB could promote Warburg effect in malignant transformed GES-1cells induced by Nmethyl-N'-nitro-N-nitrosoguanidine (MNNG). GES-1cells were exposed to 1μmol/L MNNG and cultured for 40 passages. During the culturing process, cell proliferation, migration, and soft agar colony formation significantly increased after 30 passages. Following MNNG exposure, lactate, LDH, glucose uptake, and the expression levels of key enzymes in glycolysis were significantly increased. Knocking down LDHA or LDHB alone reduced lactate secretion, inhibited cell viability, and impaired migratory capacities. Knocking down LDHA and LDHB together fully suppressed lactate secretion and effectively suppressed the malignant phenotype of cells transformed by long-term MNNG exposure. Finally, we demonstrated that overexpression of LDHA and LDHB promotes the malignant transformation of GES-1cells by enhancing the Warburg effect during long-term exposure to NOCs.

Highly efficient production of L-valine by multiplex metabolic engineering of Corynebacterium glutamicum

As a branched chain amino acid, L-valine is widely used in the medicine and feed sectors. In this study, a microbial cell factory for efficient production of L-valine was constructed by combining various metabolic engineering strategies. First, precursor supply for L-valine biosynthesis was enhanced by strengthening the glycolysis pathway and weakening the metabolic pathway of by-products. Subsequently, the key enzyme in the L-valine synthesis pathway, acetylhydroxylate synthase, was engineered by site-directed mutation to relieve the feedback inhibition of the engineered strain. Moreover, promoter engineering was used to optimize the gene expression level of key enzymes in L-valine biosynthetic pathway. Furthermore, cofactor engineering was adopted to change the cofactor preference of acetohydroxyacid isomeroreductase and branched-chain amino acid aminotransferase from NADPH to NADH. The engineered strain C. glutamicum K020 showed a significant increase in L-valine titer, yield and productivity in 5 L fed-batch bioreactor, up to 110 g/L, 0.51 g/g and 2.29 g/(L‧h), respectively.

Ishige okamurae Celluclast extract ameliorates non-alcoholic fatty liver in high-fructose diet-fed mice by modulation of lipid metabolism and gut microbiota composition.

Recently, a new mechanism has revealed that gut microbiota plays a pivotal role in metabolizing fructose to acetate that facilitates hepatic lipogenesis. Therefore, our study investigated the role of microbiome on abnormal lipid synthesis in the presence of fructose and identified attenuating effects of Ishige okamurae Celluclast extract (IOCE) against fructose-induced fatty liver. The results indicated that oral administration of IOCE (150 and 300mg/kg/day for 12 weeks) significantly reduced both gut microbiota-mediated and -non-mediated hepatic lipogenesis simultaneously triggered by fructose metabolism. IOCE reduced hepatic triglyceride accumulation and expression levels of key enzymes for glucolipid metabolism. In addition, IOCE regulated fatty acid synthesis, β-oxidation, and improved hepatic inflammation. Furthermore, IOCE inhibited direct fructose-to-acetate conversion and altered the compositions of gut microbiota. These findings suggest that IOCE might serve as a potential prebiotic dietary supplement by ameliorating fatty liver through dual regulation of classical lipogenic pathway and gut microbiota.

Full-length transcriptome analysis provides insights into flavonoid biosynthesis in Ranunculus japonicus.

Ranunculus japonicus Thunb. is a traditional Chinese herb. Plants in the genus Ranunculus are generally rich in flavonoids, which have antibacterial, anti-infective, and other pharmacological effects. However, owing to the lack of reference genomes, little is known about the flavonoid biosynthetic pathway in R. japonicus. In this study, PacBio isoform sequencing (PacBio iso-seq) and DNA nanoball sequencing (DNB-seq) were combined to build a full-length transcriptome database for three different tissues of R. japonicus. A total of 395,402 full-length transcripts were obtained, of which 308,474 were successfully annotated. A Kyoto Encyclopedia of Genes and Genomes analysis identified 29 differentially expressed genes encoding nine key enzymes for flavonoid biosynthesis. Correlation analysis indicated that flavanone 3-hydroxylase and flavonol synthase genes might have key roles in the accumulation of flavonoid substances in the different tissues of R. japonicus. The structures of chalcone synthase and chalcone isomerase enzymes were spatially modeled. Reverse-transcription quantitative PCR was used to verify gene expression levels of key enzymes associated with flavonoid biosynthesis. In addition, 22 MYB transcription factors involved in flavonoid biosynthesis and phenylpropanoid biosynthesis were discovered. The reliable transcriptomic data from this study provide genetic information about R. japonicus as well as insights into the molecular mechanism of flavonoid biosynthesis. The results also provide a basis for developing the medicinal value R. japonicus. This article is protected by copyright. All rights reserved.

The Ammonium/Nitrate Ratio Affects the Growth and Shikonin Accumulation in Arnebia euchroma

Nitrogen (N) strongly affects plant growth and metabolism. Although ammonium toxicity has been reported, the effects of nitrogen on shikonin biosynthesis remain obscure. In this study, we tested four different concentrations of NH4+ on Arnebia euchroma hairy roots (AEHR) to clarify the influence of NH4+ on the growth of AEHR and on shikonin accumulation in them and the possible mechanisms. The results showed that compared with the 0% NH4+ treatment (only nitrate as a nitrogen source), the 10% NH4+ treatment increased the fresh weight and the dry weight of AEHR and promoted the synthesis of shikonins. In contrast, the 20% NH4+ treatment started to show inhibition effects on the growth of and shikonin accumulation in AEHR, and the 30% NH4+ treatment exhibited the strongest inhibition effects. With an increased percentage of NH4+, the AEHR became shorter and thicker, with more branches. To further elucidate the mechanisms, we analyzed the time course of nitrogen assimilation, the gene expression level of key enzymes involved in shikonin biosynthesis pathway, and the content of various endogenous hormones in the presence of toxic NH4+ concentrations. The results indicated that auxin and cytokinin might regulate the growth and architecture of AEHR under NH4+ toxicity and revealed that the jasmonate level was reduced along with the inhibition of shikonin biosynthesis. This first comprehensive investigation of the effects of the ammonium/nitrate ratio on shikonin biosynthesis not only provides valuable data for optimizing the in vitro culture of A. euchroma and its shikonin production, but also suggests potential fertilizing strategies for its cultivation.

Differential roles of abscisic acid in maize roots in the adaptation to soil drought

AbstractMaize yield reduction occurs frequently due to soil drought. Abscisic acid (ABA) is an important hormonal signal indicating drought. However, it remains unclear about the specific roles of root ABA in the adaptation to soil drought in maize. This study applied five different soil water potentials (SWP), referring to maintaining SWP at −15, −30, −45, −60, and −75 kPa, respectively, and investigated the ABA content in roots and the activities and gene expression levels of key enzymes involved in the ABA biosynthesis, the leaf photosynthetic properties, root traits, and kernel yield. The results showed that maize root ABA content, the activities and gene expressions of key enzymes involved in the ABA biosynthesis were increased with the decrease of SWP. The leaf transpiration rate, and root dry weight, length, volume, surface area, and activity, and kernel yield of maize were increased first and then decreased with the severity of soil drying. The leaf photosynthetic rate was not significantly reduced with ABA accumulation at a low ABA content in roots. Root ABA content was significantly positively correlated with leaf transpiration efficiency and root activity when ABA content was relatively low (9.03–22.02 nmol g−1 DW), whereas root ABA content was negatively correlated with leaf photosynthetic rate, leaf transpiration efficiency, root volume, and root activity when ABA content was high (28.32–39.23 nmol g−1 DW). The results indicate that maize root ABA exhibit differential roles in the adaptation to soil drought, and can positively regulate the drought‐resistance of maize at an appropriate level.

Metabolomic Profiling of Lungs from Mice Reveals the Variability of Metabolites in Pneumocystis Infection and the Metabolic Abnormalities in BAFF-R-Deficient Mice.

The incidence of Pneumocystis pneumonia (PCP) in patients without human immunodeficiency virus (HIV) has been increasing. In this study, we aimed to investigate the metabolic changes in Pneumocystis infection and the metabolic abnormalities in B-cell-activating factor receptor (BAFF-R)-deficient mice with Pneumocystis infection. The important function of B cells during Pneumocystis infection is increasingly recognized. In this study, a Pneumocystis-infected mouse model was constructed in BAFF-R-/- mice and wild-type (WT) mice. Lungs of uninfected WT C57BL/6, WT Pneumocystis-infected, and BAFF-R-/- Pneumocystis-infected mice were used for metabolomic analyses to compare the metabolomic profiles among the groups, with the aim of exploring the metabolic influence of Pneumocystis infection and the influence of mature B-cell deficiency during infection. The results indicated that many metabolites, mainly lipids and lipid-like molecules, were dysregulated in Pneumocystis-infected WT mice compared with uninfected WT C57BL/6 mice. The data also demonstrated significant changes in tryptophan metabolism, and the expression levels of key enzymes of tryptophan metabolism, such as indoleamine 2,3-dioxygenase 1 (IDO1), were significantly upregulated. In addition, B-cell development and function might be associated with lipid metabolism. We found a lower level of alitretinoin and the abnormalities of fatty acid metabolism in BAFF-R-/- Pneumocystis-infected mice. The mRNA levels of enzymes associated with fatty acid metabolism in the lung were upregulated in BAFF-R-/- Pneumocystis-infected mice and positively correlated with the level of IL17A, thus suggesting that the abnormalities of fatty acid metabolism may be associated with greater inflammatory cell infiltration in the lung tissue of BAFF-R-/- Pneumocystis-infected mice compared with the WT Pneumocystis-infected mice. Our data revealed the variability of metabolites in Pneumocystis-infected mice, suggesting that the metabolism plays a vital role in the immune response to Pneumocystis infection.

Alanine-Dependent TCA Cycle Promotion Restores the Zhongshengmycin-Susceptibility in Xanthomonas oryzae.

Xanthomonas oryzae pv. oryzicola (Xoo) is a plant pathogenic bacterium that can cause rice bacterial blight disease, which results in a severe reduction in rice production. Antimicrobial-dependent microbial controlling is a useful way to control the spread and outbreak of plant pathogenic bacteria. However, the abuse and long-term use of antimicrobials also cause microbial antimicrobial resistance. As far as known, the mechanism of antimicrobial resistance in agricultural plant pathogenic bacteria still lacks prospecting. In this study, we explore the mechanism of Zhongshengmycin (ZSM)-resistance in Xoo by GC-MS-based metabolomic analysis. The results showed that the down-regulation of the TCA cycle was characteristic of antimicrobial resistance in Xoo, which was further demonstrated by the reduction of activity and gene expression levels of key enzymes in the TCA cycle. Furthermore, alanine was proven to reverse the ZSM resistance in Xoo by accelerating the TCA cycle in vivo. Our results are essential for understanding the mechanisms of ZSM resistance in Xoo and may provide new strategies for controlling this agricultural plant pathogen at the metabolic level.

Mitochondrial pyruvate carrier influences ganoderic acid biosynthesis in Ganoderma lucidum.

Mitochondrial pyruvate carriers (MPCs), located in the inner membrane of mitochondria, are essential carriers for pyruvate to enter mitochondria. MPCs regulate a wide range of intracellular metabolic processes, such as glycolysis, the tricarboxylic acid cycle (TCA cycle), fatty acid metabolism, and amino acid metabolism. However, the metabolic regulation of MPCs in macrofungi is poorly studied. We studied the role of MPCs in Ganoderma lucidum (GlMPC) on ganoderic acid (GA) biosynthesis regulation in G. lucidum. In this study, we found that the mitochondrial/cytoplasmic ratio of pyruvate was downregulated about 75% in GlMPC1- and GlMPC2-silenced transformants compared with wild type (WT). In addition, the GA content was 17.72mg/g and increased by approximately 50% in GlMPC1- and GlMPC2-silenced transformants compared with WT. By assaying the expression levels of three key enzymes and the enzyme activities of isocitrate dehydrogenase (IDH) and α-ketoglutarate dehydrogenase (α-KGDH) of the TCA cycle in GlMPC1- and GlMPC2-silenced transformants, it was found that the decrease in GlMPCs activity did not significantly downregulate the TCA cycle rate, and the enzyme activity of IDH increasedby 44% compared with WT. We then verified that fatty acid β-oxidation (FAO) supplements the TCA cycle by detecting the expression levels of key enzymes involved in FAO. The results showed that compared with WT, the GA content was 1.14mg/g and reduced by approximately 40% in co-silenced transformants. KEY POINTS: • GlMPCs affects the distribution of pyruvate between mitochondria and the cytoplasm. • Acetyl-CoA produced by FAO maintains the TCA cycle. • Acetyl-CoA produced by FAO promotes the accumulation of GA.

The BcLAE1 is involved in the regulation of ABA biosynthesis in Botrytis cinerea TB-31.

Abscisic acid (ABA), as a classic plant hormone, is a key factor in balancing the metabolism of endogenous plant hormones, and plays an important role in regulating the activation of mammalian innate immune cells and glucose homeostasis. Currently, Botrytis cinerea has been used for fermentation to produce ABA. However, the mechanism of the regulation of ABA biosynthesis in B. cinerea is still not fully understood. The putative methyltransferase LaeA/LAE1 is a global regulator involved in the biosynthesis of a variety of secondary metabolites in filamentous fungi. In this study, we demonstrated that BcLAE1 plays an important role in the regulation of ABA biosynthesis in B. cinerea TB-31 by knockout experiment. The deletion of Bclae1 caused a 95% reduction in ABA yields, accompanied by a decrease of the transcriptional level of the ABA synthesis gene cluster Bcaba1-4. Further RNA-seq analysis indicated that deletion of Bclae1 also affected the expression level of key enzymes of BOA and BOT in secondary metabolism, and accompanied by clustering regulatory features. Meanwhile, we found that BcLAE1 is involved in epigenetic regulation as a methyltransferase, with enhanced H3K9me3 modification and attenuated H3K4me2 modification in ΔBclae1 mutant, and this may be a strategy for BcLAE1 to regulate ABA synthesis.

Saturated Fatty Acid-Induced Impairment of Hepatic Lipid Metabolism Is Worsened by Prohibitin 1 Deficiency in Hepatocytes.

Obesity-associated nonalcoholic fatty liver disease (NAFLD) is characterized by excessive intrahepatic lipid accumulation. Despite the increasing prevalence of NAFLD and obesity, the pathogenesis of NAFLD has not yet been clearly elucidated. Prohibitin 1 (PHB1) is mainly expressed in the inner membrane of mitochondria and is known to play an important role in hepatocyte proliferation and lipid metabolism. In this study, we investigated how PHB1 affects lipid metabolism in murine hepatocytes. To reduce the expression of PHB1, Phb1 small interfering RNA was transfected into normal murine hepatocytes (AML12), and the cells were treated with the saturated fatty acid (SFA), palmitic acid (PA), for 24 h. When PHB1 was inhibited, the cell viability decreased by ∼20%, and it was found that it diminished further after PA treatment in both control and peroxisome proliferator-activated receptor gamma (Ppar-γ) knockdown cell groups. Examination of the mRNA expression levels of key enzymes involved in lipid metabolism revealed that PHB1 led to increased stearoyl-coenzyme A desaturase-1 (Scd1) mRNA levels, which leads to an increase in the synthesis of triglycerides (TGs). It also activates the endoplasmic reticulum (ER) stress response through upregulating C/EBP homologous protein (Chop) mRNA levels. PPAR-γ, which has been reported to be upregulated in NAFLD patients, also showed elevated expression. The expression of carnitine palmitoyltransferase 1A, which is involved in the conversion of excess intracellular SFA to fatty acid by catabolism, was downregulated in the PHB1-deficient group. Furthermore, TG synthesis was further promoted by a marked increase in SCD1 mRNA levels, which was further exacerbated by elevated Chop mRNA levels and Ppar-γ disruption. Taken together, PHB1 deficiency led to altered lipid metabolism, resulting in the increased intracellular lipid accumulation and ER stress. These cytotoxic effects were shown to be further exacerbated by excessive PA treatment.

Neonatal exposure of bisphenol A led to increased lipolysis of visceral adipose tissue in adult rats with DNA hypomethylation of Atgl being one of the possible underlying mechanisms

Accumulating evidence suggests the role of developmental exposure of bisphenol A (BPA) in metabolic disorders. However, the underlying mechanism remains unclear. Using a rat model, we investigated the neonatal exposure of BPA on lipid metabolism in adult and the underlying mechanisms. From postnatal day1(PND1) to PND10, male rats were exposed to BPA via daily subcutaneous injection with 10 µg/100 µL BPA (1.24–0.5 mg/kg body weight/day, a dose below the US-EPA LOAEL). After fasting for 8 h, adult rats aged 80 days showed elevated levels of serum free fatty acid (FFA), glycerol and glucose, and increased levels of FFA and glycerol in visceral adipose tissue. The expression levels of key enzymes of lipolysis, adipose triglyceride lipase (Atgl) and hormone-sensitive lipase (Hsl), were increased in visceral adipose tissue from BPA-exposed rats after fasting. On the other hand, transcription levels of lipogenic genes remained unchanged. Differentiation of visceral adipocyte in rats takes place neonatally. In our study, neonatal BPA exposure induced DNA hypomethylation of Atgl in visceral adipose tissue. In 3T3-L1 cell, administration of 10−7 mol/L BPA throughout the differentiation stage led to DNA hypomethylation and increased expression of Atgl. Our results suggest that neonatal exposure of BPA led to increased lipolysis of visceral adipose tissue in young adults, which will predispose individuals to multiple metabolic disorders. The DNA hypomethylation of Atgl might be one of the mechanisms underneath the long-lasting effect of neonatal BPA exposure.

Increased homocysteine regulated by androgen activates autophagy by suppressing the mammalian target of rapamycin pathway in the granulosa cells of polycystic ovary syndrome mice

ABSTRACT The purpose of this study was to explore the potential molecular mechanisms of excess homocysteine in relation to autophagic activity in the ovarian tissue of polycystic ovarian syndrome (PCOS) with hyperandrogenism.A PCOS model was constructed using ICR mice. ELISA was used to detect the Hcy levels in the serum and ovarian tissues of PCOS model. The expression level of key enzymes (Methionine synthase and Betaine-homocysteine methyltransferase, MTR and BHMT) in homocysteine metabolism and autophagy-related proteins were detected in ovarian tissues and mouse granulosa cells (mGCs) that were treated with homocysteine, androgen, autophagy inhibitors or BHMT-expressing plasmid by western blot and immunohistochemistry. Electron microscope experiments were used to evaluate autophagosomes in Hcy-treated mGCs. The prenatally androgenized (PNA) PCOS mouse model showed hyperhomocysteinemia and hyperandrogenism. Homocysteine levels displayed a significant increase, while its metabolic enzymes levels were significantly decreased in ovarian tissues of PCOS mice and dihydrotestosterone (DHT)-stimulated mGCs. The LC3II and Beclin1 expression levels were increased and the P62 and p-mTOR levels were decreased in vivo in ovarian tissue from the PCOS mice. The in vitro data were similarly with the in vivo by stimulation of mGCs with DHT or homocysteine. These effects could be diminished by the autophagy inhibitor (MHY1485), androgen receptor antagonists (ARN509) or BHMT-expressing plasmid. Androgen increases homocysteine concentration by downregulating the key enzymes in homocysteine metabolism. And then Hcy promotes GCs autophagy via the mTOR signal pathway.

Targeted lipidomics reveals phospholipids and lysophospholipids as biomarkers for evaluating community-acquired pneumonia.

BackgroundCommunity-acquired pneumonia (CAP) is often accompanied by changes in lipid metabolism. This study aimed to examine the changes in serum phospholipids (PLs) that may be useful for early disease stratification and as potential therapeutic targets in patients with CAP.MethodsSerum samples from 58 patients hospitalized with CAP and 11 control samples were collected during admission between January 2017 and October 2018. Targeted lipidomic analysis was used to determine the concentrations of phosphatidylcholine (PC), lysophosphatidylcholine (LPC), phosphatidylethanolamine (PE), and lysophosphatidylethanolamine (LPE). The Gene Expression Omnibus (GEO) database was used to evaluate the gene expression levels of key enzymes in the Lands cycle, and quantitative real-time polymerase chain reaction (qRT-PCR) was used for further verification.ResultsA significant decrease in LPC levels and an increase in PE levels, PC/LPC and PE/LPE ratios were observed in patients with CAP (P<0.05). The area under the curve (AUC) of PE serum concentrations combined with CURB-65 scores (confusion, uremia, respiratory rate, blood pressure, and age ≥65 years) was 0.848 for discriminating disease severity, which was significantly higher than the discriminating disease severity of CURB-65 (P<0.05). The efficiency of predicting 30-day mortality using PC, LPC, or PC/LPC ratio combined with CURB-65 scores (AUC =0.811, AUC =0.854, AUC =0.838, respectively) was better than CURB-65 alone (P<0.05). Gene expression analysis revealed the upregulation of LPC acyltransferase 2.ConclusionsLPC or PE serum levels as well as PC/LPC ratios combined with CURB-65 are effective biomarkers for predicting the disease severity and 30-day mortality of patients with CAP. Further investigations of phospholipid metabolism will improve our understanding and treatment of CAP.