Intracellular Adenosine Research Articles

Mitochondrial and Metabolic Dynamics of Endometrial Stromal Cells During the Endometrial Cycle.

The endometrial cycle in response to hormonal stimulation is essential for implantation. The female has endometrium that repeats this cycle through about half of a lifetime. The cycle includes three phases, proliferative, secretory, and menstrual, and each phase has distinct characteristics. The endometrial stromal cells (EnSCs) in each phase also have specialized characteristics, including cell cycle, morphologies, and cellular metabolic state. So we hypothesized that the cells in each phase have unique mitochondrial morphologies because they are generally linked to cellular metabolic state. To investigate the metabolic characteristics in each phase, we investigated the mitochondrial morphologies by transmission electron microscopy, oxygen consumption rate (OCR), and intracellular adenosine triphosphate (ATP) production. The decidualized EnSCs have shorter mitochondria than those in the proliferative phase. Besides, they also displayed distinct intracellular structural characteristics compared with the proliferative phase, such as ribosome-rich endoplasmic reticulum and increased formation of vesicles. OCR and luminescent ATP detection assay revealed that the basal respiration and ATP production in the decidualized EnSCs were lower than those in the proliferative phase. Thus, we concluded that morphological and intracellular structural changes were induced during the decidualization. Moreover, the decreased mitochondrial length was shown to correlate with decreased dependency on oxidative phosphorylation and ATP concentration in EnSCs.

The Effect of Chlorogenic Acid on Bacillus subtilis Based on Metabolomics.

Chlorogenic acid (CGA), a natural phenolic compound, is an important bioactive compound, and its antibacterial activity has been widely concerned, but its antibacterial mechanism remains largely unknown. Protein leakage and the solution exosmosis conductivity of Bacillus subtilis 24434 (B. subtilis) reportedly display no noticeable differences before and after CGA treatment. The bacterial cells treated with CGA displayed a consistently smooth surface under the electron microscope, indicating that CGA cannot directly disrupt bacterial membranes. However, CGA induced a significant decrease in the intracellular adenosine triphosphate (ATP) concentration, possibly by affecting the material and energy metabolism or cell-signaling transduction. Furthermore, metabolomic results indicated that CGA stress had a bacteriostatic effect by inducing the intracellular metabolic imbalance of the tricarboxylic acid (TCA) cycle and glycolysis, leading to metabolic disorder and death of B. subtilis. These findings improve the understanding of the complex action mechanisms of CGA antimicrobial activity and provide theoretical support for the application of CGA as a natural antibacterial agent.

Specific phosphodiesterase type-10 inhibitor, papaverine, added after the cooling period improves canine sperm quality

The use of chilled semen has gained increasing interest in canine reproductive services. The addition of phosphodiesterase (PDE) inhibitors that increase the intracellular cyclic adenosine monophosphate levels may improve sperm motility. The purpose of this study was to examine the quality of sperm under the effect of the specific PDE-10 inhibitor (papaverine) added after storage for 1, 2, and 3 days at 5 °C. The ejaculates were obtained from 5 healthy Beagle dogs by digital manipulation. After collection, ejaculates were pooled, extended and cooled at 5 °C during 3 days. Sperm parameters were tested 30 min after the addition of different papaverine (PA) concentrations: 0, 5, 10 and 20 µM. Sperm motility (CASA), viability (PI/FITC-PNA) and capacitation status (chlortetracycline assay) were evaluated. The results showed that the addition of PA has no effect on sperm samples at day 0. However, concentrations of 5 and 10 µM increased (p < .05) sperm motility kinetics and viability significantly compared to the control at day 1, day 2 and day 3 of cooling. The addition of 20 μM PA decreased (p < .05) sperm quality parameters significantly and increased the percentage of capacitated/acrosome-reacted spermatozoa. In conclusion, the addition of 5 and 10 μM PA concentrations after cooled storage improved canine sperm quality.

Effect of parathyroid hormone-related protein on intracellular calcium ion and cyclic adenosine monophosphate concentrations in cardiac fibroblasts.

ObjectiveThis study aimed to determine the effect of parathyroid hormone-related protein (PTHrP) on proliferation of cardiac fibroblasts (CFs) in primary cultures of neonatal Wistar rats.MethodsDifferent PTHrP concentrations were added to CFs of neonatal Wistar rats and the cells were grouped according to the concentrations added. A verapamil (VPL) group and a calcitriol (CAL) group were also established. Changes in cell proliferation and in cyclic adenosine monophosphate and calcium ion levels were identified and recorded.ResultsWe found that as the concentration of PTHrP increased, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT, a tetrazolium salt) colorimetric absorbance values (A values) decreased. These values in the PTHrP groups were significantly lower than those in the control group. MTT colorimetric A values and 3H-thymidine deoxyribose intake were lower in the VPL group, low-dose CAL group, and the PTHrP 10−7 mol/L group compared with the control group. However, MTT colorimetric A values and 3H-thymidine deoxyribose intake were higher in the high-dose CAL group than in the PTHrP 10−7 mol/L group. As PTHrP concentrations increased, intracellular cyclic adenosine monophosphate concentrations also increased.ConclusionPTHrp, VPL, and low-dose CAL inhibit proliferation of CFs, while high-dose CAL promotes proliferation of CFs.

Action mode of cranberry anthocyanin on physiological and morphological properties of Staphylococcus aureus and its application in cooked meat

This study researched the action mode of cranberry anthocyanin (CA) against Staphylococcus aureus and the effect of CA on the counts of S. aureus and the quantity of cooked meat during storage. The antibacterial effect was assessed by minimum inhibitory concentration (MIC) and survival populations of S. aureus strains after CA treatments. The changes in intracellular adenosine 5′-triphosphate (ATP) concentration, cell membrane potential, content of bacterial protein and cell morphology were analyzed to reveal possible action mode. Application potentials of CA as antimicrobial agent were assessed during storage of cooked pork and beef. The result showed that the MIC of CA against S. aureus strains was 5 mg/mL. Approximately 8 log CFU/mL of S. aureus strains can be completely inhibited after treatment with 2.0 MIC of CA for 0.5 h. Treatments of CA resulted in lower intracellular ATP and soluble protein levels, damaged membrane structure and leakage of cytoplasmic. Application of CA on cooked pork and beef caused a significant decrease in S. aureus counts and pH values, and color-darkening compared with control samples. These findings demonstrated that CA played an effective antimicrobial against S. aureus and had a potential as natural preservative to inhibit the growth of food pathogens.

Intracellular adenosine released from THP-1 differentiated human macrophages is involved in an autocrine control of Leishmania parasitic burden, mediated by adenosine A2A and A2B receptors

Leishmania infected macrophages have conditions to produce adenosine. Despite its known immunosuppressive effects, no studies have yet established whether adenosine alter Leishmania parasitic burden upon macrophage infection. This work aimed at investigating whether endogenous adenosine exerts an autocrine modulation of macrophage response towards Leishmania infection, identifying its origin and potential pharmacological targets for visceral leishmaniasis (VL), using THP-1 differentiated macrophages. Adenosine deaminase treatment of infected THP-1 cells reduced the parasitic burden (29.1 ± 2.2%, P < 0.05). Adenosine A2A and A2B receptor subtypes expression was confirmed by RT-qPCR and by immunocytochemistry and their blockade with selective adenosine A2A and A2B antagonists reduced the parasitic burden [14.5 ± 3.1% (P < 0.05) and 12.3 ± 3.1% (P < 0.05), respectively; and 24.9 ± 2.8% (P < 0.05), by the combination of the two antagonists)], suggesting that adenosine A2 receptors are tonically activated in infected THP-1 differentiated macrophages. The tonic activation of adenosine A2 receptors was dependent on the release of intracellular adenosine through equilibrative nucleoside transporters (ENT1/ENT2): NBTI or dipyridamole reduced (~25%) whereas, when ENTs were blocked, adenosine A2 receptor antagonists failed to reduce and A2 agonists increase parasitic burden. Effects of adenosine A2 receptors antagonists and ENT1/2 inhibitor were prevented by L-NAME, indicating that nitric oxide production inhibition prevents adenosine from increasing parasitic burden. Results suggest that intracellular adenosine, released through ENTs, elicits an autocrine increase in parasitic burden in THP-1 macrophages, through adenosine A2 receptors activation. These observations open the possibility to use well-established ENT inhibitors or adenosine A2 receptor antagonists as new therapeutic approaches in VL.

Cyclic AMP-hydrolyzing phosphodiesterase inhibitors potentiate statin-induced cancer cell death.

Dipyridamole, an antiplatelet drug, has been shown to synergize with statins to induce cancer cell-specific apoptosis. However, given the polypharmacology of dipyridamole, the mechanism by which it potentiates statin-induced apoptosis remains unclear. Here, we applied a pharmacological approach to identify the activity of dipyridamole specific to its synergistic anticancer interaction with statins. We evaluated compounds that phenocopy the individual activities of dipyridamole and assessed whether they could potentiate statin-induced cell death. Notably, we identified that a phosphodiesterase (PDE) inhibitor, cilostazol, and other compounds that increase intracellular cyclic adenosine monophosphate (cAMP) levels potentiate statin-induced apoptosis in acute myeloid leukemia and multiple myeloma cells. Additionally, we demonstrated that both dipyridamole and cilostazol further inhibit statin-induced activation of sterol regulatory element-binding protein 2, a known modulator of statin sensitivity, in a cAMP-independent manner. Taken together, our data support that PDE inhibitors such as dipyridamole and cilostazol can potentiate statin-induced apoptosis via a dual mechanism. Given that several PDE inhibitors are clinically approved for various indications, they are immediately available for testing in combination with statins for the treatment of hematological malignancies.

A nanoprobe based on molybdenum disulfide nanosheets and silver nanoclusters for imaging and quantification of intracellular adenosine triphosphate

Adenosine triphosphate (ATP), as a high-energy phosphate compound that stores and releases energy in living cells, has an irreplaceable role in many physiological processes and maintenance of biological functions, and can be used as an indicator of many diseases. In this work, a composite nanoprobe, silver nanocluster (AgNC) @ molybdenum disulfide (MoS2), was designed to achieve in situ fluorescence imaging and quantitative analysis of intracellular ATP in HeLa cells by fluorescence spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). The probe was constructed based on the adsorption of DNA-AgNCs by MoS2 nanosheets, and the DNA-AgNCs were prepared with the ATP aptamer as a template, whose fluorescence was initially quenched by MoS2. When the probe was incubated into the cells, intracellular ATP recognized the aptamer sequence and caused the DNA-AgNCs to fall off the MoS2 nanosheets, resulting in fluorescence recovery. Here, AgNCs not only acted as a fluorescence label for imaging, but also as an element tag for quantitative analysis of intracellular ATP with the detection of 107Ag by ICP-MS. The ATP in HeLa cells detected by this method was 24.6 ± 1.7 nmol L−1, which was in good agreement with the test result of the ATP test kit (20.4 ± 0.8 nmol L−1). The proposed method has potential application in medical clinical diagnosis and evaluation of the body’s metabolic level via fluorescence imaging and ICP-MS detection of intracellular ATP.

Does Cyclic ADP-Ribose (cADPR) Activate the Non-selective Cation Channel TRPM2?

TRPM2 is a non-selective, Ca2+-permeable cation channel widely expressed in immune cells. It is firmly established that the channel can be activated by intracellular adenosine 5′-diphosphoribose (ADPR). Until recent cryo-EM structures have exhibited an additional nucleotide binding site in the N-terminus of the channel, this activation was thought to occur via binding to a C-terminal domain of the channel that is highly homologous to the ADPR pyrophosphatase NudT9. Over the years it has been controversially discussed whether the Ca2+ mobilizing second messenger cyclic ADP ribose (cADPR) might also directly activate Ca2+ entry via TRPM2. Here we will review the status of this discussion.

Identification of Genes Associated with Sensitivity to Ultraviolet A (UVA) Irradiation by Transposon Mutagenesis of Vibrio parahaemolyticus

Ultraviolet (UV) irradiation is used to disinfect water and food and can be classified as UVA (detected at wavelengths 320–400 nm), UVB (280–320 nm), and UVC (&lt;280 nm). We developed a method for UVA sterilization of equipment with a UVA-light-emitting diode (LED); however, a high rate of fluence was needed to promote pathogen inactivation. The aim of this study was to identify genes associated with UVA sensitivity with the goal of improving UVA-LED-mediated bactericidal activity. We constructed a transposon-mutant library of Vibrio parahaemolyticus and selected six mutants with high sensitivity to UVA irradiation. Genes associated with this phenotype include F-type H+-transporting ATPases (atp), as well as those involved in general secretion (gsp), and ubiquinone and terpenoid-quinone biosynthesis (ubi). Gene complementation resulted in decreased sensitivity to UVA-LED. The atp mutants had lower intracellular adenosine triphosphate (ATP) concentrations than the wild-type treatment, with 20 mM L-serine resulting in elevated ATP concentrations and decreased sensitivity to UVA-LED. The gsp mutants exhibited high levels of extracellular protein transport and the ubi mutants exhibited significantly different intracellular concentrations of ubiquinone-8. Taken together, our results suggest that the protein products of the atp, gsp, and ubi genes may regulate sensitivity to UVA irradiation.

New Synthesized Galloyl‐RGD Inhibits Melanogenesis by Regulating the CREB and ERK Signaling Pathway in B16F10 Melanoma Cells

Gallic acid (3, 4, 5-trihydroxybenzoic acid) is a phytochemical derived from diverse herbs. It has been reported to have effective antifungal, antiviral and antioxidant activity. However, gallic acid exhibits low solubility and instability at high temperatures. In a previous study, in order to overcome these limitations, we synthesized galloyl-RGD by combining gallic acid with arginine, glycine and asparaginic acid (RGD peptide). This compound showed better thermal stability than gallic acid. In this study, we investigated the antimelanogenic effect of galloyl-RGD and the underlying mechanism for this effect. Galloyl-RGD markedly inhibited melanin content and tyrosinase activity in a concentration-dependent manner. We also found that galloyl-RGD decreased the levels of melanogenesis-related gene and protein. In addition, galloyl-RGD reduces intracellular cyclic adenosine monophosphate (cAMP) levels that leads to inhibition of cAMP-responsive element binding protein (CREB) phosphorylation and activates extracellular signal-regulated kinase (ERK) expression. These results indicate that CREB and ERK regulation by galloyl-RGD contributes to reduced melanin synthesis via degradation of microphthalmia-associated transcription factor. Therefore, galloyl-RGD can be potential candidate for application in cosmetic or pharmaceutical industry.

AMPK, Mitochondrial Function, and Cardiovascular Disease.

Adenosine monophosphate-activated protein kinase (AMPK) is in charge of numerous catabolic and anabolic signaling pathways to sustain appropriate intracellular adenosine triphosphate levels in response to energetic and/or cellular stress. In addition to its conventional roles as an intracellular energy switch or fuel gauge, emerging research has shown that AMPK is also a redox sensor and modulator, playing pivotal roles in maintaining cardiovascular processes and inhibiting disease progression. Pharmacological reagents, including statins, metformin, berberine, polyphenol, and resveratrol, all of which are widely used therapeutics for cardiovascular disorders, appear to deliver their protective/therapeutic effects partially via AMPK signaling modulation. The functions of AMPK during health and disease are far from clear. Accumulating studies have demonstrated crosstalk between AMPK and mitochondria, such as AMPK regulation of mitochondrial homeostasis and mitochondrial dysfunction causing abnormal AMPK activity. In this review, we begin with the description of AMPK structure and regulation, and then focus on the recent advances toward understanding how mitochondrial dysfunction controls AMPK and how AMPK, as a central mediator of the cellular response to energetic stress, maintains mitochondrial homeostasis. Finally, we systemically review how dysfunctional AMPK contributes to the initiation and progression of cardiovascular diseases via the impact on mitochondrial function.

Extracellular AMP Suppresses Endotoxemia-Induced Inflammation by Alleviating Neutrophil Activation

Intracellular adenosine monophosphate (AMP) is indispensable for cellular metabolic processes, and it is interconverted to ADP and/or ATP or activates AMP-activated protein kinase (AMPK). However, the specific biological function of extracellular AMP has not been identified. We evaluated the effect of extracellular AMP using in vivo and in vitro models of endotoxemia. We found that AMP inhibited inflammation and neutrophil activation in lipopolysaccharide (LPS)-induced endotoxemic mice. The effects of extracellular AMP were abolished by an adenosine 1 receptor (A1R) antagonist but were not influenced by inhibiting the conversion of AMP to adenosine (ADO), indicating that AMP inhibited inflammation by directly activating A1R. In addition, in vitro experiments using LPS-stimulated mouse neutrophils showed that AMP inhibited LPS-induced reactive oxygen species (ROS) production, degranulation, and cytokine production, while the effects were reversed by an A1R antagonist. Further research showed that AMP regulated LPS-stimulated neutrophil functions by inhibiting the p38 MAPK pathway. These findings were also confirmed in primary neutrophils derived from healthy human blood. Moreover, we collected serum samples from septic patients. We found that AMP levels were increased compared with those of healthy volunteers and that AMP levels were negatively correlated with disease severity. Together, these data provide evidence that extracellular AMP acts on A1R to suppress endotoxemia-induced inflammation by inhibiting neutrophil overactivation and that the p38 MAPK signaling pathway is involved.

Non-thermal plasma with metformin synergistically induces cell death via upregulating AMPK to suppress energy metabolism

Non-thermal plasma (NTP) has a selective killing effect on a variety of cancer cells in vivo and in vitro, and is considered a potential tumor therapy. In this study, we found that metformin, which has shown promising antitumor effects in previous studies, with NTP synergistically increased cell death including apoptosis in colon cancer cell lines via reducing mitochondrial oxidative phosphorylation and intracellular adenosine triphosphate exhausting cellular energy, mediated through activation of AMP-activated protein kinase (AMPK). Reactive oxygen species was revealed to modulate the activation of AMPK after NTP exposure. Considering the safety and wide clinical use of metformin, the combination of metformin and NTP showed great potential in cancer therapy.

Detrimental effects of temephos on male fertility: An in vitro study on a mouse model

The World Health Organization recommends temephos as a nonsystemic organophosphorus pesticide due to its low mammalian toxicity compared with other chemical compounds. Although several studies have reported that temephos may be toxic under certain conditions, little research effort has been made to evaluate its effects on mammalian fertility. Therefore, the present study was designed to evaluate the effect of temephos on sperm functions and male fertility. Initially, cauda epididymis from mouse spermatozoa was incubated with temephos (0, 0.1, 1, 10, and 100 μM). Then, sperm motility and motion kinematics, capacitation status, intracellular adenosine triphosphate level, lactate dehydrogenase level, protein kinase A (PKA) activity, and degree of tyrosine phosphorylation were analyzed. Finally, the rates of fertilization and early embryonic development were evaluated. Sperm motility and motion kinematics were found to be significantly altered in temephos groups. In addition, the acrosome reaction and capacitation significantly increased and decreased in the 100 μM temephos group, respectively. Intracellular adenosine triphosphate levels significantly decreased in the 1, 10, and 100 μM temephos groups compared with that in the control group. Moreover, PKA activity and tyrosine phosphorylation significantly decreased in most temephos groups. Further, the rates of fertilization and early embryonic development significantly decreased in all temephos groups. Taken together, it was determined that temephos had harmful effects on male fertility. Therefore, the reproductive toxicity of temephos should be considered before its use.

Salvianolic acid B regulates mitochondrial autophagy mediated by NIX to protect H9c2 cardiomyocytes from hypoxia/reoxygenation injury

The aim of this paper was to investigate whether the mechanism of salvianolic acid B in protecting H9 c2 cardiomyocytes from hypoxia/reoxygenation injury is related to the regulation of mitochondrial autophagy mediated by NIX. H9 c2 cardiomyocytes were cultured in vitro and divided into normal group, model group and salvianolic acid B group(50 μmol·L~(-1)). Hypoxia/reoxygenation injury model was established by hypoxia for 4 h and reoxygenation for 2 h. In normal group, high glucose DMEM medium was used for culture. Those in model group were cultured with DMEM medium without glucose and oxygen, and no drugs for hypoxia and reoxyge-nation. In salvianolic acid B group, salvianolic acid B prepared by glucose-free DMEM medium was added during hypoxia, and the other process was as same as the model group. The cell viability was evaluated by CCK-8 assay. The leakage of lactate dehydrogenase(LDH) was detected by microplate method. The levels of intracellular reactive oxygen species(ROS) and mitochondrial membrane potential(ΔΨm) were measured by chemical fluorescence method. The level of intracellular adenosine triphosphate(ATP) was mea-sured by fluorescein enzyme method. The autophagy related proteins LC3-Ⅰ, LC3-Ⅱ, apoptosis related protein cleaved caspase-3 and mitochondrial autophagy receptor protein NIX were detected by Western blot. As compared with the normal group, the activity of H9 c2 cardiomyocytes and ATP level were decreased(P&lt;0.05); LDH leakage and ROS production were increased(P&lt;0.01); ΔΨm was decreased(P&lt;0.01); LC3-Ⅱ/LC3-Ⅰ ratio, cleaved caspase-3 and NIX protein expression levels were increased(all P&lt;0.05) in the model group. As compared with the model group, the activity of cells and ΔΨm were significantly increased(P&lt;0.01); ATP level was increased(P&lt;0.05); LDH leakage and ROS generation were decreased(P&lt;0.01); LC3-Ⅱ/LC3-Ⅰ ratio was decreased(P&lt;0.01); cleaved caspase-3 and NIX expression levels were decreased(P&lt;0.05) in the salvianolic acid B group. The protective effect of salvianolic acid B on hypoxia/reoxygenation injury of H9 c2 cardiomyocytes may be associated with inhibiting mitochondrial auto-phagy. The specific mechanism may be related to inhibiting the activation of mitochondrial autophagy mediated by NIX, increasing ΔΨm, reducing ROS production, reducing the expression of cleaved caspase-3, LC3-Ⅱ, and increasing cell viability.

TOM40 Inhibits Ovarian Cancer Cell Growth by Modulating Mitochondrial Function Including Intracellular ATP and ROS Levels

TOM40 is a channel-forming subunit of translocase, which is essential for the movement of proteins into the mitochondria. We found that TOM40 was highly expressed in epithelial ovarian cancer (EOC) cells at both the transcriptional and translational levels; its expression increased significantly during the transformation from normal ovarian epithelial cells to EOC (p < 0.001), and TOM40 expression negatively correlated with disease-free survival (Hazard ratio = 1.79, 95% Confidence inerval 1.16–2.78, p = 0.009). TOM40 knockdown decreased proliferation in several EOC cell lines and reduced tumor burden in an in vivo xenograft mouse model. TOM40 expression positively correlated with intracellular adenosine triphosphate (ATP) levels. The low ATP and high reactive oxygen species (ROS) levels increased the activity of AMP-activated protein kinase (AMPK) in TOM40 knockdown EOC cells. However, AMPK activity did not correlate with declined cell growth in TOM40 knockdown EOC cells. We found that metformin, first-line therapy for type 2 diabetes, effectively inhibited the growth of EOC cell lines in an AMPK-independent manner by inhibiting mitochondria complex I. In conclusion, TOM40 positively correlated with mitochondrial activities, and its association enhances the proliferation of ovarian cancer. Also, metformin is an effective therapeutic option in TOM40 overexpressed ovarian cancer than normal ovarian epithelium.

Compartmentalization of adenosine metabolism in cancer cells and its modulation during acute hypoxia.

Extracellular adenosine mediates diverse anti-inflammatory, angiogenic and vasoactive effects, and has become an important therapeutic target for cancer, which has been translated into clinical trials. This study was designed to comprehensively assess adenosine metabolism in prostate and breast cancer cells. We identified cellular adenosine turnover as a complex cascade, comprising (1) the ectoenzymatic breakdown of ATP via sequential ecto-nucleotide pyrophosphatase/phosphodiesterase-1 (NPP1, officially known as ENPP1), ecto-5'-nucleotidase (CD73, also known as NT5E), and adenosine deaminase reactions, and ATP re-synthesis through a counteracting adenylate kinase and members of the nucleoside diphosphate kinase (NDPK, also known as NME/NM23) family; (2) the uptake of nucleotide-derived adenosine via equilibrative nucleoside transporters; and (3) the intracellular adenosine phosphorylation into ATP by adenosine kinase and other nucleotide kinases. The exposure of cancer cells to 1% O2 for 24 h triggered an ∼2-fold upregulation of CD73, without affecting nucleoside transporters, adenosine kinase activity and cellular ATP content. The ability of adenosine to inhibit the tumor-initiating potential of breast cancer cells via a receptor-independent mechanism was confirmed in vivo using a xenograft mouse model. The existence of redundant pathways controlling extracellular and intracellular adenosine provides a sufficient justification for reexamination of the current concepts of cellular purine homeostasis and signaling in cancer.This article has an associated First Person interview with the first author of the paper.

Activation of Adenosine Monophosphate-Activated Protein Kinase Reduces the Onset of Diet-Induced Hepatocellular Carcinoma in Mice.

The worldwide obesity and type 2 diabetes epidemics have led to an increase in nonalcoholic fatty liver disease (NAFLD). NAFLD covers a spectrum of hepatic pathologies ranging from simple steatosis to nonalcoholic steatohepatitis, characterized by fibrosis and hepatic inflammation. Nonalcoholic steatohepatitis predisposes to the onset of hepatocellular carcinoma (HCC). Here, we characterized the effect of a pharmacological activator of the intracellular energy sensor adenosine monophosphate–activated protein kinase (AMPK) on NAFLD progression in a mouse model. The compound stimulated fat oxidation by activating AMPK in both liver and skeletal muscle, as revealed by indirect calorimetry. This translated into an ameliorated hepatic steatosis and reduced fibrosis progression in mice fed a diet high in fat, cholesterol, and fructose for 20 weeks. Feeding mice this diet for 80 weeks caused the onset of HCC. The administration of the AMPK activator for 12 weeks significantly reduced tumor incidence and size. Conclusion: Pharmacological activation of AMPK reduces NAFLD progression to HCC in preclinical models.

Detection of ATP from “fluorescence” to “enhanced fluorescence” based on metal-enhanced fluorescence triggered by aptamer nanoswitch

Herein, we demonstrate a novel approach to detect intracellular adenosine triphosphate (ATP) from “fluorescence” to “enhanced fluorescence” by metal-enhanced fluorescence (MEF), which is an activatable means to amplify fluorescence signal. In the meantime, hybridization chain reaction (HCR) is employed to aggregate DNA on the substrate of MEF, and the length of generated DNA strands is controllable. ATP target molecules specifically bind to aptamer, which is designed as the recognition part of the nanoswitch, and the sticky ends are released. Then, HCR is triggered, bringing Cy7 modified on H1 and H2 close to the surface of gold nanobipyramids (AuNBPs) substrate. The fluorescence signal is amplified with the ATP concentration increasing owing to MEF. Thus, the strategy based on structure-switching aptamer triggering metal-enhanced fluorescence (SATMEF) for Cy7 is designed to detect ATP via “enhanced fluorescence” signals, and the maximum fluorescence enhancement by the approach of SATMEF reaches 5.63-fold. We applied this DNA nanoswitch for quantitative analysis to ATP, and the results show that the intensity of enhanced Cy7 fluorescence is positively correlated with the ATP concentration in the range of 0.2−10 μM, with a detection limit of 35 nM. We believe that the SATMEF for quantitative detection by signal from “fluorescence” to “enhanced fluorescence” provides a new approach for those fluorophores which are superior but difficult to be quenched to construct DNA nanoswitches.