Pyruvate Dehydrogenase E1 Subunit Research Articles

Enhancing intraneural revascularization following peripheral nerve injury through hypoxic Schwann-cell-derived exosomes: an insight into endothelial glycolysis

BackgroundEndothelial cell (EC)-driven intraneural revascularization (INRV) and Schwann cells-derived exosomes (SCs-Exos) both play crucial roles in peripheral nerve injury (PNI). However, the interplay between them remains unclear. We aimed to elucidate the effects and underlying mechanisms of SCs-Exos on INRV following PNI.ResultsWe found that GW4869 inhibited INRV, as well as that normoxic SCs-Exos (N-SCs-Exos) exhibited significant pro-INRV effects in vivo and in vitro that were potentiated by hypoxic SCs-Exos (H-SCs-Exos). Upregulation of glycolysis emerged as a pivotal factor for INRV after PNI, as evidenced by the observation that 3PO administration, a glycolytic inhibitor, inhibited the INRV process in vivo and in vitro. H-SCs-Exos more significantly enhanced extracellular acidification rate/oxygen consumption rate ratio, lactate production, and glycolytic gene expression while simultaneously suppressing acetyl-CoA production and pyruvate dehydrogenase E1 subunit alpha (PDH-E1α) expression than N-SCs-Exos both in vivo and in vitro. Furthermore, we determined that H-SCs-Exos were more enriched with miR-21-5p than N-SCs-Exos. Knockdown of miR-21-5p significantly attenuated the pro-glycolysis and pro-INRV effects of H-SCs-Exos. Mechanistically, miR-21-5p orchestrated EC metabolism in favor of glycolysis by targeting von Hippel-Lindau/hypoxia-inducible factor-1α and PDH-E1α, thereby enhancing hypoxia-inducible factor-1α-mediated glycolysis and inhibiting PDH-E1α-mediated oxidative phosphorylation.ConclusionThis study unveiled a novel intrinsic mechanism of pro-INRV after PNI, providing a promising therapeutic target for post-injury peripheral nerve regeneration and repair.Graphical

Novel Synonymous and Deep Intronic Variants Causing Primary and Secondary Pyruvate Dehydrogenase Complex Deficiency

Pyruvate dehydrogenase complex deficiency (PDCD) is a defect of aerobic carbohydrate metabolism that causes neurological disorders with varying degrees of severity. We report the clinical, biochemical, and molecular findings in patients with primary and secondary PDCD caused by novel atypical genetic variants. Whole-genome sequencing (WGS) identified the synonymous variants c.447A>G, p.(Lys149=) and c.570C>T, p.(Cys190=) in pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1), the deep intronic variants c.1023+2267G>A and c.1023+2302A>G in pyruvate dehydrogenase complex component X (PDHX), and c.185+15054G>A in thiamine pyrophosphokinase (TPK1). Analysis by Sanger and RNA sequencing of cDNA from patient blood and/or cultured fibroblasts showed that the synonymous variants in PDHA1 lead to aberrant splicing and skipping of exons 5 and 5-6 in one of the patients and transcripts lacking exon 6 in the other. The deep intronic variants in PDHX and TPK1 lead to insertion of intronic sequence in the corresponding transcripts. The splice defects in PDHA1 were more pronounced in cultured fibroblasts than in blood. Our findings expand the spectrum of pathogenic variants causing PDCD and highlight the importance of atypical variants leading to aberrant splicing. The severity of the splice defects and resulting biochemical dysfunction varied between tissues, stressing the importance of performing biochemical and transcript analysis in affected tissues. The two males with hemizygous synonymous PDHA1 variants have a mild phenotype and higher PDH enzyme activity than expected, which is consistent with aberrant but leaky splicing with a proportion of the transcripts remaining correctly spliced.

The BHLHE40‒PPM1F‒AMPK pathway regulates energy metabolism and is associated with the aggressiveness of endometrial cancer

BHLHE40 is a basic helix-loop-helix transcription factor that is involved in multiple cell activities including differentiation, cell cycle, and epithelial-to-mesenchymal transition. While there is growing evidence to support the functions of BHLHE40 in energy metabolism, little is known about the mechanism. In this study, we found that BHLHE40 expression was downregulated in cases of endometrial cancer of higher grade and advanced disease. Knockdown of BHLHE40 in endometrial cancer cells resulted in suppressed oxygen consumption and enhanced extracellular acidification. Suppressed pyruvate dehydrogenase (PDH) activity and enhanced lactated dehydrogenase (LDH) activity was observed in the knockdown cells. Knockdown of BHLHE40 also led to dephosphorylation of AMPKα Thr172 and enhanced phosphorylation of pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1) Ser293 and lactate dehydrogenase A (LDHA) Tyr10. These results suggested that BHLHE40 modulates PDH and LDH activity by regulating the phosphorylation status of PDHA1 and LDHA. We found that BHLHE40 enhanced AMPKα phosphorylation by directly suppressing the transcription of an AMPKα-specific phosphatase, PPM1F. Our immunohistochemical study showed that the expression of BHLHE40, PPM1F, and phosphorylated AMPKα correlated with the prognosis of endometrial cancer patients. Because AMPK is a central regulator of energy metabolism in cancer cells, targeting the BHLHE40‒PPM1F‒AMPK axis may represent a strategy to control cancer development.

Cuproptosis related gene PDHB is identified as a biomarker inversely associated with the progression of clear cell renal cell carcinoma

BackgroundCuproptosis is a newly discovered programmed cell death dependent on mitochondrial respiratory disorder induced by copper overload. Pyruvate dehydrogenase E1 subunit beta (PDHB) is one of the cuproptosis genesand is a nuclear-encoded pyruvate dehydrogenase, which catalyzes the conversion of pyruvate to acetyl coenzyme A. However, the mechanism of PDHB in clear cell renal cell carcinoma (ccRCC) remains unclear.MethodsWe used data from TCGA and GEO to assess the expression of PDHB in normal and tumor tissues. We further analyzed the relationship between PDHB and somatic mutations and immune infiltration. Finally, we preliminarily explored the impact of PDHB on ccRCC.ResultsThe expression level of PDHB was lower in tumor tissue compared with normal tissue. Meanwhile, the expression level of PDHB was also lower in high-grade tumors than low-grade tumors. PDHB is positively correlated with prognosis in ccRCC. Furthermore, PDHB may be associated with decreased risk of VHL, PBRM1 and KDM5C mutations. In 786-O cells, copper chloride could promote the expression of cuproptosis genes (DLAT, PDHB and FDX1) and inhibit cell growth. Last but not least, we found that PDHB could inhibit the proliferation and migration of ccRCC cells.ConclusionOur results demonstrated that PDHB could inhibit the proliferation, migration and invasion in ccRCC cells, which might be a prognostic predictor of ccRCC. Targeting this molecular might provide a new therapeutic strategy for patients with advanced ccRCC.

Beta-hydroxybutyrate regulation of metabolic stress responses to Staphylococcus aureusinfection in macrophages

Abstract Macrophages orchestrate the initiation, intensity, and duration of the inflammatory response induced during Staphylococcus aureusinfection. The pleiotropic role of macrophages is dictated by the capacity to adapt to different metabolic cues. During acute inflammation, macrophages are highly glycolytic; during resolution, these cells shift to oxidative metabolism. While glycolysis drives the expression of pro-inflammatory genes, oxidative phosphorylation leads to fatty acid oxidation and synthesis of ketone bodies, such as beta-hydroxybutyrate (BHB). Therefore, identifying the events that drive the shift from glycolytic to oxidative phosphorylation could provide clues for inflammation and homeostasis. If exogenous BHB influences macrophage responses to S. aureusinfection is not well understood. We hypothesize that BHB is a bridge between glycolysis and oxidative phosphorylation during S. aureusinfection. BHB increases mitochondrial respiration in S. aureus-infected immortalized bone-marrow-derived macrophages (iBMDM). During infection, treatment with BHB increased PDHA1(Pyruvate Dehydrogenase E1 Subunit Alpha 1) but decreased HK1 (Hexokinase 1) expression in iBMDMs. Furthermore, BHB decreased macrophage phagocytic capacity in S. aureusinfected peritoneal macrophages, indicating a decrease in glycolytic activity. Cumulatively, these findings suggest that BHB may cause a shift toward aerobic respiration and increase the anti-inflammatory capacity of macrophages. Therefore, exogenous BHB or ketogenic diets could be detrimental during S. aureusinfection by decreasing both antimicrobial effector functions and inflammatory responses. NIH R01 HL124159-09 The SyBBURE Searle Undergraduate Research Program

Dichloroacetic acid and rapamycin synergistically inhibit tumor progression.

Mammalian target of rapamycin (mTOR) controls cellular anabolism, and mTOR signaling is hyperactive in most cancer cells. As a result, inhibition of mTOR signaling benefits cancer patients. Rapamycin is a US Food and Drug Administration (FDA)-approved drug, a specific mTOR complex 1 (mTORC1) inhibitor, for the treatment of several different types of cancer. However, rapamycin is reported to inhibit cancer growth rather than induce apoptosis. Pyruvate dehydrogenase complex (PDHc) is the gatekeeper for mitochondrial pyruvate oxidation. PDHc inactivation has been observed in a number of cancer cells, and this alteration protects cancer cells from senescence and nicotinamide adenine dinucleotide (NAD+‍) exhaustion. In this paper, we describe our finding that rapamycin treatment promotes pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1) phosphorylation and leads to PDHc inactivation dependent on mTOR signaling inhibition in cells. This inactivation reduces the sensitivity of cancer cells' response to rapamycin. As a result, rebooting PDHc activity with dichloroacetic acid (DCA), a pyruvate dehydrogenase kinase (PDK) inhibitor, promotes cancer cells' susceptibility to rapamycin treatment in vitro and in vivo.

Abstract 4840: Dysregulation of mitochondrial function by PLK1-mediated PDHA1 phosphorylation promotes Cr(VI)-associated lung cancer progression

Abstract Hexavalent chromium (Cr(VI)), an class I environmental carcinogen, not only induces lung epithelial cell transformation but also promotes lung cancer progression by alterations of the cell cycle and cellular energy metabolism. Using Cr(VI)-transformed (CrT) bronchial epithelial cells (BEAS-2B) and parental BEAS-2B cells, we demonstrate that the level of polo-like kinase 1 (PLK1) is highly upregulated in CrT cells, which blocks mitochondrial function, and further promotes cell proliferation both in vitro and in vivo. Cells expressing a high level of PLK1 exhibited repressed mitochondrial activity due to defective modulation of pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1), which facilitates the carbon influx to TCA cycle via catalyzing pyruvate/Acetyl-CoA conversion. Mechanistically, we show that PDHA1 can be directly phosphorylated by PLK1 at T57, which triggers collapse of E1 and PDHA1 degradation via activation of mitophagy. These defects resulted in the inhibition of oxidative phosphorylation and reduction of mitochondrial reactive oxygen species (ROS) generation, eventually inhibiting mitochondrial-mediated apoptotic response. Defining the role of PLK1 in metabolic reprogramming in Cr(VI)-associated cancer progression may give us a new perspective and a target to inhibit Cr(VI)-induced cancer development. In addition, PLK1 inhibitors may be used to increase the chemo-sensitivity of cancer cells by restoring the normal function of mitochondria, thus alleviating the drug resistance caused by dysfunction and hyperpolarization of mitochondria. Citation Format: Qiongsi Zhang, Zhiguo Li, Xiongjian Rao, Derek B. Allison, Qi Qiao, Zhuangzhuang Zhang, Yifan Kong, Ruixin Wang, Teresa W. Fan, Richard M. Higashi, Andrew N. Lane, Xiaoqi Liu. Dysregulation of mitochondrial function by PLK1-mediated PDHA1 phosphorylation promotes Cr(VI)-associated lung cancer progression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4840.

Development and Evaluation of Recombinant B-Cell Multi-Epitopes of PDHA1 and GAPDH as Subunit Vaccines against Streptococcus iniae Infection in Flounder (Paralichthys olivaceus).

Streptococcus iniae is a severe Gram-positive pathogen that can infect a wide range of freshwater and marine fish species. In continuation of our earlier studies on the development of S. iniae vaccine candidates, pyruvate dehydrogenase E1 subunit alpha (PDHA1) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were highly efficacious in protecting flounder (Paralichthys olivaceus) against S. iniae. In the present study, to investigate the potential of multi-epitope vaccination strategy to prevent flounder against S. iniae infection, the liner B-cell epitopes of PDHA1 and GAPDH proteins were predicted using a bioinformatics approach and were identified by immunoassay, and recombinant B-cell multi-epitopes of PDHA1 and GAPDH (rMEPIP and rMEPIG) containing immunodominant epitope-concentrated domains were expressed in Escherichia coli BL21 (DE3) and were used as a subunit vaccine to immunize healthy flounder, while recombinant PDHA1 (rPDHA1), GAPDH (rGAPDH) and formalin-inactivated S. iniae (FKC) served as controls. Then, the immunoprotection efficacy of rMEPIP and rMEPIG was evaluated by determining the percentages of CD4-1+, CD4-2+, CD8β+ T lymphocytes and surface-IgM-positive (sIgM+) lymphocytes in peripheral blood leucocytes (PBLs), spleen leucocytes (SPLs) and head kidney leucocytes (HKLs), as well as total IgM, specific IgM, and relative percentage survival (RPS) post immunization, respectively. It was found that fish immunized with rPDHA1, rGAPDH, rMEPIP, rMEPIG and FKC showed significant increases in sIgM+, CD4-1+, CD4-2+, and CD8β+ lymphocytes and production of total IgM and specific IgM against S. iniae or recombinant proteins rPDHA1 and rGAPDH, which indicated the activation of humoral and cellular immune responses after vaccination. Moreover, RPS rate of the multi-epitope vaccine rMEPIP and rMEPIG groups reached 74.07% and 77.78%, higher than that of rPDHA1 and rGAPDH (62.96% and 66.67%) and KFC (48.15%). These results demonstrated that B-cell multi-epitope protein vaccination, rMEPIP and rMEPIG, could give a better protective effect against S. iniae infection, which provided a promising strategy to design the efficient vaccine in teleost fish.

PDHB-AS suppresses cervical cancer progression and cisplatin resistance via inhibition on Wnt/β-catenin pathway

Cervical cancer (CC) is the most prevalent gynecological malignancy occurring in the cervix. Long non-coding RNAs (lncRNAs) can act as oncogenes or anti-oncogenes in CC development. Here, we investigated the functional role and detailed mechanism of lncRNA pyruvate dehydrogenase E1 subunit beta antisense (PDHB-AS) in CC. At first, we found that PDHB-AS was significantly down-regulated in CC cells. Besides, overexpression of PDHB-AS repressed CC cell malignant behaviors. HKF-derived exosomes carried miR-4536-5p to CC cells and thereby inhibited PDHB-AS expression. Moreover, PDHB-AS inactivated the Wnt/β-catenin pathway via impeding the nuclear translocation of β-catenin in CC cells. In addition, miR-582-5p could bind with both PDHB-AS and Dickkopf-1 (DKK1). PDHB-AS recruited poly(A) binding protein cytoplasmic 1 (PABPC1) to inhibit Wnt7b expression. PDHB-AS interacted with RNA-binding motif protein X-linked (RBMX) to regulate cisplatin resistance in CC. Finally, we conducted in vivo experiments to confirm that HKF promoted CC tumor growth whereas PDHB-AS suppressed CC tumor growth. Collectively, PDHB-AS plays a tumor-suppressive role in the progression of CC, which suggests the therapeutic potential of PDHB-AS for CC.

A combined analysis of bulk and single-cell sequencing data reveals metabolic enzyme, pyruvate dehydrogenase E1 subunit beta (PDHB), as a prediction biomarker for the tumor immune response and immunotherapy

Pyruvate dehydrogenase E1 subunit beta (PDHB) is located in mitochondria and catalyzes the conversion of glucose-derived acetyl-CoA. The detailed roles of PDHB in human cancers is unclear. Here, through comprehensive bioinformatics analysis, we found that PDHB was aberrantly expressed in multiple human cancers and is associated with patients' clinical stage. The abnormal expression of PDHB was related to the prognostic values of cancers, such as kidney renal clear cell carcinoma (KIRC) and kidney renal papillary cell carcinoma (KIRP). The Wanderer database with clinical data from Cancer Genome Atlas (TCGA) showed a significant correlation between PDHB expression and the pathologic stage of KIRP patients. We also evaluated the mutation profiles of PDHB in pan-cancer, and showed its roles on the patients’ prognosis. At last, from several immunity algorithms, we demonstrated that the expression of PDHB was correlated with the infiltration of various immune cells in pan-cancer. Moreover, the aberrant PDHB had effects on the response to immune checkpoint inhibitors in cancer patients, such as anti-PD-1. Taken together, our study demonstrated the prognostic values of PDHB in pan-cancers. PDHB may be a potential molecular marker to predicting the immune response in cancer patients.

Genetic causes of isolated and severe fetal growth restriction in normal chromosomal microarray analysis.

To investigate the genetic burden in fetuses with isolated and severe fetal growth restriction (FGR) using Trio whole-exome sequencing (WES) with a normal chromosomal microarray. This retrospective study analyzed WES results of singleton fetuses with isolated and severe FGR, whose estimated fetal weight (EFW) was less than the third percentile by Hadlock formula, in a tertiary center between March 2016 and March 2022. Cases with abnormal chromosomal microarray analysis (CMA) and TORCH results were excluded. Fifty-one fetuses with isolated and severe FGR and negative CMA results underwent Trio-WES. Of all patients, eight (15.7%) were diagnosed with FGR at its early onset (<32 weeks) and showed pathogenic or likely pathogenic variants involving Nipped-B-like protein gene (NIPBL) (n= 3), fibroblast growth factor receptor 3 (n= 1), pyruvate dehydrogenase E1 subunit alpha 1 (n= 1), collagen, type I, alpha 1 (n= 1), superkiller viralicidic activity 2-like (n= 1), and chloride voltage-gated channel (CLCN5) (n= 1). De novo-generated variants were identified in five fetuses, of which two were novel, including c.6983C>A (p. Thr2328Lys) in NIPBL and c.934-1G>T in CLCN5. Genetic disorders involved Cornelia de Lange syndrome and metabolic and skeletal genetic diseases. The present study indicates that Trio-WES can improve effectivity of prenatal diagnoses for isolated and severe FGR in cases with normal CMA results, aiding prenatal genetic counseling and pregnancy management for FGR fetuses.

AP2α negatively regulates PDHA1 in cervical cancer cells to promote aggressive features and aerobic glycolysis in vitro and in vivo.

As a gate-keeper enzyme link, pyruvate dehydrogenase E1 subunit alpha (PDHA1) functions as a key regulator during glycolysis and the mitochondrial citric acid cycle, which has been reported in several tumors. Nevertheless, the effects of PDHA1 on biological behaviors and metabolism remain unclear in cervical cancer (CC) cells. The study aims to explore the PDHA1 effects on glucose metabolism in CC cells and its possible mechanism. We first determined the expression levels of PDHA1 and activating protein 2 alpha (AP2α) as a PDHA1 potential transcription factor. The effects of PDHA1 in vivo were evaluated through a subcutaneous xenograft mouse model. Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine (EdU) labeling assay, Transwell invasion assay, wound healing assay, Terminal deoxynucleotidyl transferase dUTP nick end labeling assay and flow cytometry were performed in CC cells. Oxygen consumption rate (OCR) levels were determined to reflect aerobic glycolysis level in gastric cancer cells. Reactive oxygen species (ROS) level was measured with 2', 7'-dichlorofluorescein diacetate kit. The relationship between PDHA1 and AP2α was examined by conducting chromatin immunoprecipitation assay and electrophoretic mobility shift assay. In CC tissues and cell lines, PDHA1 was downregulated, while AP2α was upregulated. Overexpression of PDHA1 remarkedly inhibited the proliferation, invasion and migration of CC cells, and tumor growth in vivo, as well as promoted OCR, apoptosis and ROS production. Moreover, AP2α directly bound to PDHA1 within suppressor of cytokine signaling 3 promoter region to negatively regulate PDHA1 expression level. What is more, PDHA1 knockdown could effectively reversed the AP2α silencing-mediated suppressive effects on cell proliferation, invasion, migration, and the promotive effects of AP2α knockdown on OCR, apoptosis and ROS production. Our findings demonstrate that AP2α negatively regulated PDHA1 via binding to PDHA1 gene promoter to promote malignant CC cell behaviors, which may provide a potential approach for CC therapeutics.

Open-chain thiamine analogues as potent inhibitors of thiamine pyrophosphate (TPP)-dependent enzymes.

A common approach to studying thiamine pyrophosphate (TPP)-dependent enzymes is by chemical inhibition with thiamine/TPP analogues which feature a neutral aromatic ring in place of the positive thiazolium ring of TPP. These are potent inhibitors but their preparation generally involves multiple synthetic steps to construct the central ring. We report efficient syntheses of novel, open-chain thiamine analogues which potently inhibit TPP-dependent enzymes and are predicted to share the same binding mode as TPP. We also report some open-chain analogues that inhibit pyruvate dehydrogenase E1-subunit (PDH E1) and are predicted to occupy additional pockets in the enzyme other than the TPP-binding pockets. This opens up new possibilities for increasing the affinity and selectivity of the analogues for PDH, which is an established anti-cancer target.

Reduced CircSMOC1 Level Promotes Metabolic Reprogramming via PTBP1 (Polypyrimidine Tract-Binding Protein) and miR-329-3p in Pulmonary Arterial Hypertension Rats.

Pulmonary arterial hypertension maintains rapid cell proliferation and vascular remodeling through metabolic reprogramming. Recent studies suggested that circRNAs play important role in pulmonary vascular remodeling and pulmonary arterial smooth muscle cells proliferation. However, the relationship between circRNA, cell proliferation, and metabolic reprogramming in pulmonary arterial hypertension has not been investigated. RNA-seq and qRT-PCR reveal the differential expression profile of circRNA in pulmonary arteries of pulmonary arterial hypertension rat models. Transfection was used to examine the effects of circSMOC1 on pulmonary artery smooth muscle cells, and the roles of circSMOC1 in vivo were investigated by adenoassociated virus. Mass spectrometry, RNA pull-down, RNA immunoprecipitation, and dual-luciferase reporter assay were performed to investigate the signaling pathway of circSMOC1 regulating the metabolic reprogramming. CircSMOC1 was significantly downregulated in pulmonary arteries of pulmonary arterial hypertension rats. CircSMOC1 knockdown promoted proliferation and migration and enhanced aerobic glycolysis of pulmonary artery smooth muscle cells. CircSMOC1 overexpression in vivo alleviates pulmonary vascular remodeling, right ventricular pressure, and right heart hypertrophy. In the nucleus, circSMOC1 directly binds to PTBP1 (polypyrimidine tract-binding protein), competitively inhibits the specific splicing of PKM (pyruvate kinase M) premRNA, resulting in the upregulation of PKM2 (pyruvate kinase M2), the key enzyme of aerobic glycolysis, to enhance glycolysis. In the cytoplasm, circSMOC1 acted as a miR-329-3p sponge, and its reduction in pulmonary arterial hypertension suppressed PDHB (pyruvate dehydrogenase E1 subunit beta) expression, leading to the impairment of mitochondrial oxidative phosphorylation. circSMOC1 is crucially involved in the metabolic reprogramming of pulmonary artery smooth muscle cells through PTBP1 and miR-329-3p to regulate pulmonary vascular remodeling in pulmonary arterial hypertension.

A Combined Analysis of Bulk and Single-Cell Sequencing Data Reveals Metabolic Enzyme, Pyruvate Dehydrogenase E1 Subunit Beta (PDHB), As a Prediction Biomarker for the Tumor Immune Response and Immunotherapy

A Combined Analysis of Bulk and Single-Cell Sequencing Data Reveals Metabolic Enzyme, Pyruvate Dehydrogenase E1 Subunit Beta (PDHB), As a Prediction Biomarker for the Tumor Immune Response and Immunotherapy

Exosomal miR-21-5p derived from cisplatin-resistant SKOV3 ovarian cancer cells promotes glycolysis and inhibits chemosensitivity of its progenitor SKOV3 cells by targeting PDHA1.

Ovarian cancer (OC) is a common reason for gynecologic cancer death. Standard treatments of OC consist of surgery and chemotherapy. However, chemoresistance should be considered. Exosomal miR-21-5p has been shown to regulate the chemosensitivity of cancer cells through regulating pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1). However, the role of miR-21-5p/PDHA1 in OC is unclear. The levels of miR-21-5p and PDHA1 in clinical samples and cells were investigated. Exosomes derived from SKOV3/cisplatin (SKOV3/DDP) cells (DDP-Exos) were isolated and used to treat SKOV3 cells to test DDP-Exos effects on SKOV3 cells. Extracellular acidification rateand oxygen consumption ratewere tested with a Seahorse analyzer. Cell apoptosis was analyzed by a flow cytometer. PDHA1 was overexpressed and miR-21-5p was silenced in SKOV3 cells to study the underlying mechanism of miR-21-5p in OC. Quantitative real-time PCRand immunoblots were applied to measure gene expression at mRNA and protein levels. The levels of PDHA1 in DDP-resistant SKOV3 or tumor tissues were significantly decreased while the levels of miR-21-5p were remarkably upregulated. miR-21-5p in DDP-Exos was sharply increased compared to that of Exos. Data also indicated that DDP-Exos treatment suppressed the sensitivity of SKOV3 cells to DDP and promoted cell viability and glycolysis of SKOV3 cells through inhibiting PDHA1 by exosomal miR-21-5p. miR-21-5p derived from DDP-resistant SKOV3 OC cells promotes glycolysis and inhibits chemosensitivity of its progenitor SKOV3 cells by targeting PDHA1. Our data highlights the important role of miR-21-5p/PDHA1 axis in OC and sheds light on new therapeutic development.

Anti-bacterial mechanism of the P-3 against Aeromonas hydrophila NJ-35 extracted from the Potentilla chinensis Ser. (Wei Ling Cai)

Potentilla chinesis Ser. (Wei Ling Cai) was a food for humans and animals in China, as well as a traditional Chinese herb recorded in “ZhonghuaBencao”. Aeromonas hydrophila NJ-35 (NJ-35) was a bacterial pathogen associated with high mortality rate in aquaculture. The purpose of the present work was to isolate and identify the anti-bacterial components against the NJ-35 from the extract of Wei Ling Cai, as well as explore the underlying anti-bacterial mechanism. The peak 3 was the most efficient anti-bacterial component in all collected peaks, and it was identified as (1R,2S,5R,6S)-2,6-bis(3-ethyl-4-hydroxy-5-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane (P-3) by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR). The minimum inhibition concentration (MIC) of P-3 against NJ-35 was 0.125 mg/mL. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) combined with NanoLC-ESI-MS/MS showed that, in the P-3-treated group, the proteins of phosphoglucomutase (PGM), pyruvate dehydrogenase E1 and alkyl hydroperoxide reductase subunit C (AhpC) were up-regulated, whereas, the porin and 30S ribosomal S3 were down-regulated. In addition, after the treatment of P-3, the activity of alkaline phosphatase (AKP) and the membrane permeability were increased (P < 0.01). The results of scanning electron microscope (SEM) showed that P-3 made the NJ-35 shriveled, sunken, and wrinkled. Taken together, these results suggested the P-3 might be a promising anti-bacterial agent for pharmacological research, and Wei Ling Cai could be a food-borne treatment for the A. hydrophila infection in aquaculture.

Lactic Acid Fermentation Is Required for NLRP3 Inflammasome Activation.

Activation of the Nod-like receptor 3 (NLRP3) inflammasome is important for activation of innate immune responses, but improper and excessive activation can cause inflammatory disease. We previously showed that glycolysis, a metabolic pathway that converts glucose into pyruvate, is essential for NLRP3 inflammasome activation in macrophages. Here, we investigated the role of metabolic pathways downstream glycolysis – lactic acid fermentation and pyruvate oxidation—in activation of the NLRP3 inflammasome. Using pharmacological or genetic approaches, we show that decreasing lactic acid fermentation by inhibiting lactate dehydrogenase reduced caspase-1 activation and IL-1β maturation in response to various NLRP3 inflammasome agonists such as nigericin, ATP, monosodium urate (MSU) crystals, or alum, indicating that lactic acid fermentation is required for NLRP3 inflammasome activation. Inhibition of lactate dehydrogenase with GSK2837808A reduced lactate production and activity of the NLRP3 inflammasome regulator, phosphorylated protein kinase R (PKR), but did not reduce the common trigger of NLRP3 inflammasome, potassium efflux, or reactive oxygen species (ROS) production. By contrast, decreasing the activity of pyruvate oxidation by depletion of either mitochondrial pyruvate carrier 2 (MPC2) or pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1) enhanced NLRP3 inflammasome activation, suggesting that inhibition of mitochondrial pyruvate transport enhanced lactic acid fermentation. Moreover, treatment with GSK2837808A reduced MSU-mediated peritonitis in mice, a disease model used for studying the consequences of NLRP3 inflammasome activation. Our results suggest that lactic acid fermentation is important for NLRP3 inflammasome activation, while pyruvate oxidation is not. Thus, reprograming pyruvate metabolism in mitochondria and in the cytoplasm should be considered as a novel strategy for the treatment of NLRP3 inflammasome-associated diseases.

Assessing the Thiamine Diphosphate Dependent Pyruvate Dehydrogenase E1 Subunit for Carboligation Reactions with Aliphatic Ketoacids.

The synthetic properties of the Thiamine diphosphate (ThDP)-dependent pyruvate dehydrogenase E1 subunit from Escherichia coli (EcPDH E1) was assessed for carboligation reactions with aliphatic ketoacids. Due to its role in metabolism, EcPDH E1 was previously characterised with respect to its biochemical properties, but it was never applied for synthetic purposes. Here, we show that EcPDH E1 is a promising biocatalyst for the production of chiral α-hydroxyketones. WT EcPDH E1 shows a 180–250-fold higher catalytic efficiency towards 2-oxobutyrate or pyruvate, respectively, in comparison to engineered transketolase variants from Geobacillus stearothermophilus (TKGST). Its broad active site cleft allows for the efficient conversion of both (R)- and (S)-configured α-hydroxyaldehydes, next to linear and branched aliphatic aldehydes as acceptor substrates under kinetically controlled conditions. The alternate, thermodynamically controlled self-reaction of aliphatic aldehydes was shown to be limited to low levels of conversion, which we propose to be due to their large hydration constants. Additionally, the thermodynamically controlled approach was demonstrated to suffer from a loss of stereoselectivity, which makes it unfeasible for aliphatic substrates.

LncRNA MEG3 promotes endoplasmic reticulum stress and suppresses proliferation and invasion of colorectal carcinoma cells through the MEG3/miR-103a-3p/PDHB ceRNA pathway.

LncRNA maternally expressed gene 3 (MEG3) is a potential prognostic and diagnostic biomarker in colorectal carcinoma (CC). However, its cellular functions and mechanism remain not fully uncovered. Relative expression of MEG3, miRNA (miR)-103a-3p, and pyruvate dehydrogenase E1 subunit beta (PDHB) was detected by RT-qPCR and western blotting. Cell proliferation was measured by CCK-8 assay, colony formation assay, and flow cytometry, as well as xenograft tumor assay. Transwell assay examined cell invasion. Endoplasmic reticulum (ER) stress was evaluated by western blotting. Dual-luciferase reporter assay and RNA immunoprecipitation determined the relationship between miR-103a-3p and MEG3 or PDHB. Expression of MEG3 was downregulated in human CC tumor tissues and cells (SW620 and HCT116), accompanied by higher miR-103a-3p and lower PDHB. Restoring MEG3 suppressed cell viability, colony formation ability, and invasion, arrested cell cycle, and induced apoptosis rate in SW620 and HCT116 cells, as well as promoted expression of ER stress-related proteins (GRP78, ATF6, CHOP, caspase-3, and caspase-9). Furthermore, MEG3 overexpression hindered tumor growth and facilitated ER stress in vivo. Molecularly, miR-103a-3p was a target of MEG3, and further targeted PDHB. Similarly, in function, blocking miR-103a-3p suppressed CC in vitro by affecting proliferation, invasion, and ER stress; in addition, restoring miR-103a-3p partially counteracted the suppressive role of MEG3 in CC cells. MEG3 sponged miR-103a-3p to suppress CC malignancy by inducing ER stress and inhibiting cell proliferation and invasion via upregulating PDHB, suggesting a novel MEG3/miR-103a-3p/PDHB ceRNA pathway.