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A series of 5-hydroxybenzofurans have been prepared by PIDA-mediated oxidation and coupling cyclization of β-dicarbonyl compounds and hydroquinones. The reaction functionalizes C(sp2)–H of hydroquinones directly with yields of target molecules up to 96%.

Supplementary materials, methods and figures

De novo nucleotide biosynthesis is essential for maintaining cellular nucleotide pools, the suppression of which leads to genome instability. The metabolic enzyme transketolase (TKT) in the nonoxidative branch of the pentose phosphate pathway (PPP) regulates ribose 5-phosphate (R5P) levels and de novo nucleotide biosynthesis. TKT is required for maintaining cell proliferation in human liver cancer cell lines, yet the role of TKT in liver injury and cancer initiation remains to be elucidated. In this study, we generated a liver-specific TKT knockout mouse strain by crossing TKTflox/flox mice with albumin-Cre mice. Loss of TKT in hepatocytes protected the liver from diethylnitrosamine (DEN)-induced DNA damage without altering DEN metabolism. DEN treatment of TKT-null liver increased levels of R5P and promoted de novo nucleotide synthesis. More importantly, supplementation of dNTPs in primary hepatocytes alleviated DEN-induced DNA damage, cell death, inflammatory response, and cell proliferation. Furthermore, DEN and high-fat diet (HFD)–induced liver carcinogenesis was reduced in TKTflox/floxAlb-Cre mice compared with control littermates. Mechanistically, loss of TKT in the liver increased apoptosis, reduced cell proliferation, decreased TNFα, IL6, and STAT3 levels, and alleviated DEN/HFD-induced hepatic steatosis and fibrosis. Together, our data identify a key role for TKT in promoting genome instability during liver injury and tumor initiation.Significance:These findings identify transketolase as a novel metabolic target to maintain genome stability and reduce liver carcinogenesis.

Transketolase (TKT), an enzyme in the non-oxidative branch of the pentose phosphate pathway (PPP), bi-directionally regulates the carbon flux between the PPP and glycolysis. Loss of TKT in adipose tissues decreased glycolysis, increased lipolysis and uncoupling protein-1 (UCP-1) expression, protecting mice from high-fat diet-induced obesity. However, the role of TKT in brown adipose tissue (BAT)-dependent glucose homeostasis under normal chow diet (NCD) remains to be elucidated. We found that TKT ablation increased levels of glucose transporter 4 (GLUT4), promoting glucose uptake and glycogen accumulation in BAT. Using the streptozotocin (STZ)-induced diabetic mouse model, we discovered that enhanced glucose uptake due to TKT deficiency in BAT contributed to decreasing blood glucose and weight loss, protecting mice from STZ-induced diabetes. Mechanistically, TKT deficiency decreased the level of thioredoxin-interacting protein (TXNIP), a known inhibitor for glucose transporter 4 (GLUT4), by decreasing NADPH and GSH levels and inducing oxidative stress in BAT. Therefore, our data reveal a new role of TKT in regulating the anti-diabetic function of BAT as well as glucose homeostasis.

A one-pot three-component reaction based on an oxidative dearomatization strategy has been performed to provide facile access to 5-hydroxyindole derivatives through a ZnI

Inflammatory bowel disease (IBD) has a close association with transketolase (TKT) that links glycolysis and the pentose phosphate pathway (PPP). However, how TKT functions in the intestinal epithelium remains to be elucidated. To address this question, we specifically delete TKT in intestinal epithelial cells (IECs). IEC TKT-deficient mice are growth retarded and suffer from spontaneous colitis. TKT ablation brings about striking alterations of the intestine, including extensive mucosal erosion, aberrant tight junctions, impaired barrier function, and increased inflammatory cell infiltration. Mechanistically, TKT deficiency significantly accumulates PPP metabolites and decreases glycolytic metabolites, thereby reducing ATP production, which results in excessive apoptosis and defective intestinal barrier. Therefore, our data demonstrate that TKT serves as an essential guardian of intestinal integrity and barrier function as well as a potential therapeutic target for intestinal disorders.

Deregulated metabolism is one of the characteristics of hepatocellular carcinoma. Sex hormone receptor signalling has been involved in the marked gender dimorphism of hepatocellular carcinoma pathogenesis. Oestrogen receptor (ER) has been reported to reduce the incidence of liver cancer. However, it remains unclear how oestrogen and ER regulate metabolic alterations in liver tumour cells. Our previous work revealed that ERα interacted with carbohydrate responsive element binding protein (ChREBP), which is a transcription factor promoting aerobic glycolysis and proliferation of hepatoma cells. Here, the data showed that ERα overexpression with E2 treatment reduced aerobic glycolysis and cell proliferation of hepatoma cells. In addition to modestly down‐regulating ChREBP transcription, ERα promoted ChREBP degradation. ERα co‐immunoprecipitated with both ChREBP‐α and ChREBP‐β, the two known subtypes of ChREBP. Although E2 promoted ERα to translocate to the nucleus, it did not change subcellular localization of ChREBP. In addition to interacting with ChREBP‐β and promoting its degradation, ERα decreased ChREBP‐α–induced ChREBP‐β transcription. Taken together, we confirmed an original role of ERα in suppressing aerobic glycolysis in liver cancer cells and elucidated the mechanism by which ERα and ChREBP‐α together regulated ChREBP‐β expression.

Cancer cells need to generate large amounts of glutathione (GSH) to buffer oxidative stress during tumor development. A rate-limiting step for GSH biosynthesis is cystine uptake via a cystine/glutamate antiporter Xc−. Xc− is a sodium-independent antiporter passively driven by concentration gradients from extracellular cystine and intracellular glutamate across the cell membrane. Increased uptake of cystine via Xc− in cancer cells increases the level of extracellular glutamate, which would subsequently restrain cystine uptake via Xc−. Cancer cells must therefore evolve a mechanism to overcome this negative feedback regulation. In this study, we report that glutamate transporters, in particular SLC1A1, are tightly intertwined with cystine uptake and GSH biosynthesis in lung cancer cells. Dysregulated SLC1A1, a sodium-dependent glutamate carrier, actively recycled extracellular glutamate into cells, which enhanced the efficiency of cystine uptake via Xc− and GSH biosynthesis as measured by stable isotope-assisted metabolomics. Conversely, depletion of glutamate transporter SLC1A1 increased extracellular glutamate, which inhibited cystine uptake, blocked GSH synthesis, and induced oxidative stress-mediated cell death or growth inhibition. Moreover, glutamate transporters were frequently upregulated in tissue samples of patients with non–small cell lung cancer. Taken together, active uptake of glutamate via SLC1A1 propels cystine uptake via Xc− for GSH biosynthesis in lung tumorigenesis. Significance: Cellular GSH in cancer cells is not only determined by upregulated Xc− but also by dysregulated glutamate transporters, which provide additional targets for therapeutic intervention.

Methionine restriction, a dietary regimen that protects against metabolic diseases and aging, represses cancer growth and improves cancer therapy. However, the response of different cancer cells to this nutritional manipulation is highly variable, and the molecular determinants of this heterogeneity remain poorly understood. Here we report that hepatocyte nuclear factor 4α (HNF4α) dictates the sensitivity of liver cancer to methionine restriction. We show that hepatic sulfur amino acid (SAA) metabolism is under transcriptional control of HNF4α. Knocking down HNF4α or SAA enzymes in HNF4α-positive epithelial liver cancer lines impairs SAA metabolism, increases resistance to methionine restriction or sorafenib, promotes epithelial-mesenchymal transition, and induces cell migration. Conversely, genetic or metabolic restoration of the transsulfuration pathway in SAA metabolism significantly alleviates the outcomes induced by HNF4α deficiency in liver cancer cells. Our study identifies HNF4α as a regulator of hepatic SAA metabolism that regulates the sensitivity of liver cancer to methionine restriction., The molecular determinants of differential responses of different cancer cells to methionine restriction are poorly understood. Here the authors show that hepatocyte nuclear factor 4α regulates sulfur amino acid metabolism and dictates the sensitivity of liver cancer to this dietary manipulation.

Obesity has recently become a prevalent health threat worldwide. Although emerging evidence has suggested a strong link between the pentose phosphate pathway (PPP) and obesity, the role of transketolase (TKT), an enzyme in the nonoxidative branch of the PPP that connects PPP and glycolysis, remains obscure in adipose tissues. In this study, we specifically deleted TKT in mouse adipocytes and found no obvious phenotype upon normal diet feeding. However, adipocyte TKT abrogation attenuated high-fat diet–induced obesity, reduced hepatic steatosis, improved glucose tolerance, alleviated insulin resistance, and increased energy expenditure. Mechanistically, TKT deficiency accumulated nonoxidative PPP metabolites and decreased glycolysis and pyruvate input into the mitochondria, leading to increased lipolytic enzyme gene expression and enhanced lipolysis, fatty acid oxidation, and mitochondrial respiration. Therefore, our data not only identify a novel role of TKT in regulating lipolysis and obesity but also suggest that limiting glucose-derived carbon into the mitochondria induces lipid catabolism and energy expenditure.

Transketolase (Tkt), an enzyme in pentose phosphate pathway, has been reported to regulate genome instability and cell survival in cancers. Yet, the role of Tkt after myocardial ischemic injury remains to be elucidated. Label-free proteomics revealed dramatic elevation of Tkt in murine hearts after myocardial infarction (MI). Lentivirus-mediated Tkt knockdown ameliorated cardiomyocyte apoptosis and preserved the systolic function after myocardial ischemic injury. In contrast, Tkt overexpression led to the opposite effects. Inducible conditional cardiomyocyte Tkt-knockout mice were generated, and cardiomyocyte-expressed Tkt was found to play an intrinsic role in the ischemic heart failure of these model mice. Furthermore, through luciferase assay and chromatin immunoprecipitation, Tkt was shown to be a direct target of transcription factor Krüppel-like factor 5 (Klf5). In cardiomyocytes under ischemic stress, Tkt redistributed into the nucleus. By binding with the full-length poly(ADP-ribose) polymerase 1 (Parp1), facilitating its cleavage, and activating apoptosis inducible factor (Aif) subsequently, nuclear Tkt demonstrated its non-metabolic functions. Overall, our study confirmed that elevated nuclear Tkt plays a noncanonical role in promoting cardiomyocyte apoptosis via the cleaved Parp1/Aif pathway, leading to the deterioration of cardiac dysfunction.

The liver is a metabolically active organ and is also 'tolerogenic', exhibiting sophisticated mechanisms of immune regulation that prevent pathogen attacks and tumorigenesis. How metabolism impacts the tumor microenvironment (TME) in hepatocellular carcinoma (HCC) remains understudied.We investigated the role of the metabolic regulator SIRT5 in HCC development by conducting metabolomic analysis, gene expression profiling, flow cytometry and immunohistochemistry analyses in oncogene-induced HCC mouse models and human HCC samples.We show that SIRT5 is downregulated in human primary HCC samples and that Sirt5 deficiency in mice synergizes with oncogenes to increase bile acid (BA) production, via hypersuccinylation and increased BA biosynthesis in the peroxisomes of hepatocytes. BAs act as a signaling mediator to stimulate their nuclear receptor and promote M2-like macrophage polarization, creating an immunosuppressive TME that favors tumor-initiating cells (TICs). Accordingly, high serum levels of taurocholic acid correlate with low SIRT5 expression and increased M2-like tumor-associated macrophages (TAMs) in HCC patient samples. Finally, administration of cholestyramine, a BA sequestrant and FDA-approved medication for hyperlipemia, reverses the effect of Sirt5 deficiency in promoting M2-like polarized TAMs and liver tumor growth.This study uncovers a novel function of SIRT5 in orchestrating BA metabolism to prevent tumor immune evasion and suppress HCC development. Our results also suggest a potential strategy of using clinically proven BA sequestrants for the treatment of patients with HCC, especially those with decreased SIRT5 and abnormally high BAs.Hepatocellular caricinoma (HCC) development is closely linked to metabolic dysregulation and an altered tumor microenvironment. Herein, we show that loss of the metabolic regulator Sirt5 promotes hepatocarcinogenesis, which is associated with abnormally elevated bile acids and subsequently an immunosuppressive microenvironment that favors HCC development. Targeting this mechanism could be a promising clinical strategy for HCC.

Obesity has recently become a prevalent health threat worldwide. Although emerging evidence has suggested a strong link between the pentose phosphate pathway (PPP) and obesity, the role of transketolase (TKT), an enzyme in the non-oxidative branch of the PPP which connects PPP and glycolysis, remains obscure in adipose tissues. In this study, we specifically delete TKT in mouse adipocytes and find no obvious phenotype upon normal diet feeding. However, adipocyte TKT abrogation attenuates high fat diet (HFD)-induced obesity, reduces hepatic steatosis, improves glucose tolerance, alleviates insulin resistance and increases energy expenditure. Mechanistically, TKT deficiency accumulates non-oxidative PPP metabolites, decreases glycolysis and pyruvate input into the mitochondria, leading to increased lipolytic enzyme gene expression and enhanced lipolysis, fatty acid oxidation and mitochondrial respiration. Therefore, our data not only identify a novel role of TKT in regulating lipolysis and obesity, but also suggest limiting glucose-derived carbon into the mitochondria induces lipid catabolism and energy expenditure.

Cancer cells need to generate large amounts of glutathione (GSH) to buffer oxidative stress during tumor development. A rate-limiting step for GSH biosynthesis is cystine uptake via a cystine/glutamate antiporter Xc

Migration and distribution of gas mixtures of hydrogen generated in severe accidents are related to thermal hydraulic behavior of the containment, which is a key issue for safety analysis. A series of experiments are conducted on a large-scale test facility, to study the effects of external cooling on stratification and mixing behavior of gas mixtures. Different concentration distributions are formed by changing injection conditions, including injection momentum, initial pressure and composition of gas mixtures. Results show that the increase of injection momentum or initial pressure will forming a more uniform distribution of helium, while the increase of hydrogen fraction of injection will promote stratification. During external cooling period, hydrogen concentration increases caused by condensation, and hydrogen stratification is weakened by natural circulation. The mixing behavior caused by natural circulation will be influenced by initial concentration distribution. The experimental data can be helpful for codes assessment.

Background & Aims The metabolic features and function of intratumoral regulatory T cells (Tregs) are ambiguous in colorectal cancer. Tumor-infiltrating Tregs are reprogrammed to exhibit high glucose-depleting properties and adapt to the glucose-restricted microenvironment. The glucose-responsive transcription factor MondoA is highly expressed in Tregs. However, the role of MondoA in colorectal cancer-infiltrating Tregs in response to glucose limitation remains to be elucidated. Methods We performed studies using mice, in which MondoA was conditionally deleted in Tregs, and human colorectal cancer tissues. Seahorse and other metabolic assays were used to assess Treg metabolism. To study the role of Tregs in antitumor immunity, we used a subcutaneous MC38 colorectal cancer model and induced colitis-associated colorectal cancer in mice by azoxymethane and dextran sodium sulfate. Results Our analysis of single-cell RNA sequencing data of patients with colorectal cancer revealed that intratumoral Tregs featured low activity of the MondoA–thioredoxin-interacting protein (TXNIP) axis and increased glucose uptake. Although MondoA-deficient Tregs were less immune suppressive and selectively promoted T-helper (Th) cell type 1 (Th1) responses in a subcutaneous MC38 tumor model, Treg-specific MondoA knockout mice were more susceptible to azoxymethane-DSS–induced colorectal cancer. Mechanistically, suppression of the MondoA-TXNIP axis promoted glucose uptake and glycolysis, induced hyperglycolytic Th17-like Tregs, which facilitated Th17 inflammation, promoted interleukin 17A-induced of CD8+ T-cell exhaustion, and drove colorectal carcinogenesis. Blockade of interleukin 17A reduced tumor progression and minimized the susceptibility of MondoA-deficient mice to colorectal carcinogenesis. Conclusions The MondoA-TXNIP axis is a critical metabolic regulator of Treg identity and function in the colorectal cancer microenvironment and a promising target for cancer therapy.

To analyze the process of a small-leak sodium–water reaction (SWR) in the secondary loop of the steam generator (SG) in sodium-cooled fast reactors (SFRs), a multi-module program is developed herein. This program is developed by evaluating the models of heat transfer tube self-wastage, target tube wastage, and hydrogen migration and dissolution, which are involved in the small-leak SWR accident caused by a heat transfer tube with leakage in a single-module SG. The developed program could be used to investigate the time of occurrence of the heat transfer tube self-wastage, adjacent tube wastage, and the response time of the hydrogen concentration detectors at different leakage rates. The program can further provide the reasonable positions of hydrogen concentration detectors. The results of this study provide a reference for designing the secondary loops of small-leak accident protection systems for SFRs.

The glucose-responsive transcription factor carbohydrate response element–binding protein (ChREBP) critically promotes aerobic glycolysis and cell proliferation in colorectal cancer cells. It has been reported that ubiquitination may be important in the regulation of ChREBP protein levels and activities. However, the ChREBP-specific E3 ligase and molecular mechanism of ChREBP ubiquitination remains unclear. Using database exploration and expression analysis, we found here that levels of the E3 ligase SMURF2 (Smad-ubiquitination regulatory factor 2) negatively correlate with those of ChREBP in cancer tissues and cell lines. We observed that SMURF2 interacts with ChREBP and promotes ChREBP ubiquitination and degradation via the proteasome pathway. Interestingly, ectopic SMURF2 expression not only decreased ChREBP levels but also reduced aerobic glycolysis, increased oxygen consumption, and decreased cell proliferation in colorectal cancer cells. Moreover, SMURF2 knockdown increased aerobic glycolysis, decreased oxygen consumption, and enhanced cell proliferation in these cells, mostly because of increased ChREBP accumulation. Furthermore, we identified Ser/Thr kinase AKT as an upstream suppressor of SMURF2 that protects ChREBP from ubiquitin-mediated degradation. Taken together, our results indicate that SMURF2 reduces aerobic glycolysis and cell proliferation by promoting ChREBP ubiquitination and degradation via the proteasome pathway in colorectal cancer cells. We conclude that the SMURF2–ChREBP interaction might represent a potential target for managing colorectal cancer.

De novo nucleotide biosynthesis is essential for maintaining cellular nucleotide pools, the suppression of which leads to genome instability. The metabolic enzyme transketolase (TKT) in the nonoxidative branch of the pentose phosphate pathway (PPP) regulates ribose 5-phosphate (R5P) levels and de novo nucleotide biosynthesis. TKT is required for maintaining cell proliferation in human liver cancer cell lines, yet the role of TKT in liver injury and cancer initiation remains to be elucidated. In this study, we generated a liver-specific TKT knockout mouse strain by crossing TKTflox/flox mice with albumin-Cre mice. Loss of TKT in hepatocytes protected the liver from diethylnitrosamine (DEN)-induced DNA damage without altering DEN metabolism. DEN treatment of TKT-null liver increased levels of R5P and promoted de novo nucleotide synthesis. More importantly, supplementation of dNTPs in primary hepatocytes alleviated DEN-induced DNA damage, cell death, inflammatory response, and cell proliferation. Furthermore, DEN and high-fat diet (HFD)–induced liver carcinogenesis was reduced in TKTflox/floxAlb-Cre mice compared with control littermates. Mechanistically, loss of TKT in the liver increased apoptosis, reduced cell proliferation, decreased TNFα, IL6, and STAT3 levels, and alleviated DEN/HFD-induced hepatic steatosis and fibrosis. Together, our data identify a key role for TKT in promoting genome instability during liver injury and tumor initiation. Significance: These findings identify transketolase as a novel metabolic target to maintain genome stability and reduce liver carcinogenesis.

A novel one-pot efficient synthesis of 2,5-dihydro-1H-benzo[c]azepines and 10,11-dihydro-5H-benzo[e]pyrrolo[1,2-a]azepines from α-amino acids and aromatic aldehydes containing an ortho-Michael acceptor is reported via decarboxylative annulations without metal catalysts in yields of 52-91%. Under microwave irradiation, this protocol provides rapid access to polycyclic ring systems (only 5 min in most cases).

A broad range of the title substrates reacts with proline, sarcosine or L-thioproline following a rapid microwave-assisted approach to provide 2,5-dihydro-1H-benzo[c]azepines in high yields.