Intracellular Reduction Research Articles

A new fluorescent oxaliplatin(iv) complex with EGFR-inhibiting properties for the treatment of drug-resistant cancer cells.

Platinum chemotherapy is part of every second anticancer treatment regimen. However, its application is limited by severe side effects and drug resistance. The combination of platinum-based chemotherapeutics with EGFR inhibitors has shown remarkable synergism in clinical treatment. To enhance the tolerability of this combination, we designed a novel multi-action oxaliplatin-based platinum(iv) complex with an EGFR-inhibiting moiety (KP2749). KP2749 releases two independent cytotoxic agents upon reduction: oxaliplatin and the EGFR inhibitor KP2187, which was selected for its strong intrinsic fluorescence that became quenched upon complexation to metal ions. In particular, KP2749 demonstrated high stability and specific KP2187 release, with quenched fluorescent properties in its intact form, facilitating the investigation of its intracellular reduction. Notably, by exploiting its fluorescence, we demonstrated that intact KP2749 itself exhibited EGFR-inhibitory properties. Furthermore, subsequent experiments indicated that our complex was able to overcome resistance to oxaliplatin and EGFR inhibitors in vitro and in xenograft models in vivo. These effects were not only based on EGFR inhibition and DNA damage, but also improved cellular drug uptake. Finally, in silico docking analysis confirmed that the intact KP2749 complex had EGFR-binding properties, which were different from free KP2187. Consequently, these data suggested that the coordination of EGFR inhibitors to metal cores (like platinum) allow the fine-tuning of their EGFR-targeting properties. In conclusion, this study not only presents a new potential anticancer drug but also offers a novel fluorescent tool to study the intracellular drug release kinetics of platinum(iv) complexes.

SIRT5 desuccinylating IDH2 to alleviate oxidative stress in bovine mammary epithelial cells induced by ammonia.

Ammonia can cause cells to produce a large amount of reactive oxygen species (ROS), leading to the oxidative stress of cells. As the main intracellular reductant, nicotinamide adenine dinucleotide phosphate (NADPH) plays a crucial role in maintaining reduced glutathione (GSH), helping to remove ROS and protect cells from oxidative damage. Our study demonstrated that SIRT5 desuccinylated isocitrate dehydrogenase 2 (IDH2) to enhance its activity, resulting in increased NADPH production. Furthermore, we observed that SIRT5 overexpression alleviated ammonia-induced high levels of ROS in bovine mammary epithelial cells. This effect was achieved by activating IDH2 through SIRT5, which increased NADPH production and GSH levels, thereby improving the antioxidant capacity to scavenge ROS and reduce the susceptibility of cell to ROS. In conclusion, our findings revealed a SIRT5-dependent mechanism that modulated intracellular NADPH homeostasis to attenuate ammonia-induced oxidative stress by enhancing IDH2 enzymatic activity.

Targeted intracellular delivery of molecular cargo to hypoxic human breast cancer stem cells.

Cancer stem cells (CSCs) drive tumorigenesis, are responsible for metastasis, and resist conventional therapies thus posing significant treatment challenges. CSCs reside in hypoxic tumor regions and therefore, effective therapies must target CSCs within this specific microenvironment. CSCs are characterized by limited distinguishable features, however, surface displayed phosphatidylserine (PS) appears to be characteristic of stem cells and offers a potential target. GlaS, a truncated coagulation protein that is internalized after binding PS, was investigated for intracellular delivery of molecular payloads to CSCs. Intracellular delivery via GlaS was enhanced in patient-derived CD44+ mammary CSCs under hypoxic conditions relative to physoxia or hyperoxia. In vivo, GlaS successfully targeted hypoxic tumor regions, and functional delivery of molecular cargo was confirmed using luciferin conjugated to GlaS via a disulfide linkage (GlaS-SS-luc), which releases luciferin upon intracellular glutathione reduction. Bioluminescence imaging demonstrated effective GlaS-mediated delivery of luciferin, a model drug, to CSCs in culture and in vivo. These findings offer the promise of directed delivery of therapeutic agents to intracellular targets in CSCs.

Pseudomonas aeruginosa-mediated cr(VI) bioremediation: mechanistic insights and future directions

Contamination of hexavalent chromium (Cr(VI)) is a major environmental issue since it has the ability to cause cancer and genetic mutations. Bioremediation techniques using Pseudomonas aeruginosa have emerged as potential methods to tackle this problem. This study offers a thorough examination of the underlying mechanisms and potential future paths in the process of P. aeruginosa-mediated Cr(VI) remediation. Herein, the strategies used by P. aeruginosa were examined for the removal of Cr(VI) via processes such as biosorption, intracellular reduction, and extracellular metabolism. In addition, the function of extracellular polymeric substances (EPS) in capturing and isolating Cr(VI) was studied and the possibility of using genetic engineering techniques to improve P. aeruginosa’s ability to remove Cr(VI) from the environment was explored. In addition, we investigate the difficulties related to the use of P. aeruginosa for Cr(VI) bioremediation, such as environmental conditions and the presence of other microorganisms, and suggest potential areas for further study. These include the development of bioremediation strategies using consortia of microorganisms and the incorporation of nanomaterials to improve the removal of Cr(VI). This study seeks to enhance the development of sustainable solutions for remediating Cr(VI) by integrating existing information and identifying future research directions, with a focus on employing P. aeruginosa.

Metformin Syncs CeO2 to Recover Intra- and Extra-Cellular ROS Homeostasis in Diabetic Wound Healing.

Excessive generation of reactive oxygen species (ROS) poses a huge obstacle to the healing process of diabetic wounds, resulting in chronic, non-healing wounds. While numerous anti-ROS therapeutics have been developed, satisfied intra- and extra- cellular ROS homeostasis is hard to be established in diabetic wounds. To address this issue, a nanoparticle via loading metformin and CeO2 into mesoporous silica (MSN@Met-CeO2) is designed and synthesized, which is then encapsulated within ROS-responsive hydrogel and shaped as microneedles (MNs) for better application in diabetic wounds. Interestingly, a unique metformin-cerium chelate (Ce· 3Metformin) is formed during the synthesis of MSN@Met-CeO2 MN, which significantly strengthened the inhibitory effect of metformin on mitochondrial complex I. With the presence of Ce· 3Metformin, MSN@Met-CeO2 MN performed a remarkable effect on intracellular mtROS reduction as well as extracellular ROS elimination, the latter is primarily accomplished through the dissociative CeO2 in MSN@Met-CeO2 MN. In the mouse diabetic wound model, MSN@Met-CeO2 MN exhibited a superior pro-healing effect with accelerated inflammation resolution and enhanced angiogenesis, thus highlighting its significant potential for clinical application.

Simultaneous Reduction and Methylation of Nanoparticulate Mercury: The Critical Role of Extracellular Electron Transfer.

Mercury nanoparticles are abundant in natural environments. Yet, understanding their contribution to global biogeochemical cycling of mercury remains elusive. Here, we show that microbial transformation of nanoparticulate divalent mercury can be an important source of elemental and methylmercury.Geobacter sulfurreducensPCA, a model bacterium predominant in anoxic environments (e.g., paddy soils), simultaneously reduces and methylates nanoparticulate Hg(II). Moreover, the relative prevalence of these two competing processes and the dominant transformation pathways differ markedly between nanoparticulate Hg(II) and its dissolved and bulk-sized counterparts. Notably, even when intracellular reduction of Hg(II) nanoparticles is constrained by cross-membrane transport (a rate-limiting step that also regulates methylation), the overall Hg(0) formation remains substantial due to extracellular electron transfer. With multiple lines of evidence based on microscopic and electrochemical analyses, gene knockout experiments, and theoretical calculations, we show that nanoparticulate Hg(II) is preferentially associated with c-type cytochromes on cell membranes and has a higher propensity for accepting electrons from the heme groups than adsorbed ionic Hg(II), which explains the surprisingly larger extent of reduction of nanoparticles than dissolved Hg(II) at relatively high mercury loadings. These findings have important implications for the assessment of global mercury budgets as well as the bioavailability of nanominerals and mineral nanoparticles.

Design and construction of an artificial labor-division consortium for phenanthrene degradation with three-functional modules

Polycyclic Aromatic Hydrocarbons (PAHs) are highly toxic organic pollutants. Phenanthrene often serves as a model compound for studying PAHs biodegradation. In this work, we firstly engineered Escherichia coli M01 containing seven phenanthrene degradation genes and combined it with existing engineered strains E. coli M2 and M3 to form an artificial three-bacteria consortium, named M0123, which exhibited a degradation ratio of 64.66% for 100 mg/L of phenanthrene over 8 days. Subsequently, we constructed engineered Pseudomonas putida KTRL02 which could produce 928.49 mg/L rhamnolipids and integrated it with M0123, forming a four-bacteria consortium with an impressive 81.62% phenanthrene degradation ratio. Assessment of extracellular adenosine levels during the degradation process indicated high cellular energy demand in the four-bacteria consortium. Then, we introduced Bacillus subtilis RH33, a riboflavin-producing strain, as an energy-supplying bacterium, to create a five-bacteria consortium, which exhibited an 88.19% degradation ratio for phenanthrene. The NADH/NAD+ ratio in the five-bacteria consortium during the degradation process was monitored, which was consistently higher than that of the four-bacteria consortium over the eight-day period, indicating a higher overall intracellular reduction capacity. Furthermore, the five-bacteria consortium displayed good tolerance to phenanthrene, even achieving a degradation ratio of 79.38% for 500 mg/L of phenanthrene. This study demonstrates that designing and constructing artificial consortia from the functional perspective and various angles can effectively enhance the degradation of phenanthrene after the addition of the energy-supplying bacterium. This study demonstrates that designing and constructing artificial labor-division consortia from the functional perspective and various angles can effectively enhance the degradation of phenanthrene.

Rethinking of phosphodiesterase 5 inhibition: the old, the new and the perspective in human health.

The phosphodiesterases type 5 (PDE5) are catalytic enzymes converting the second messenger cyclic guanosine monophosphate (cGMP) to 5' GMP. While intracellular cGMP reduction is associated with several detrimental effects, cGMP stabilization associates with numerous benefits. The PDE5 specific inhibitors, PDE5i, found their explosive fortune as first-line treatment for erectile dysfunction (ED), due to their powerful vasoactive properties. The favorable effect for ED emerged as side-effect when PDE5i were originally proposed for coronary artery disease (CAD). From that point on, the use of PDE5i captured the attention of researchers, clinicians, and companies. Indeed, PDE5-induced intracellular cGMP stabilization offers a range of therapeutic opportunities associated not only with vasoactive effects, but also with immune regulatory/anti-inflammatory actions. Chronic inflammation is acknowledged as the common link underlying most non-communicable diseases, including metabolic and cardiac diseases, autoimmune and neurodegenerative disorders, cancer. In this scenario, the clinical exploitation of PDE5i is undeniably beyond ED, representing a potential therapeutic tool in several human diseases. This review aims to overview the biological actions exerted by PDE5i, focusing on their ability as modulators of inflammation-related human diseases, with particular attention to inflammatory-related disorders, like cardiac diseases and cancer.

Elucidating the effect of levothyroxine and triiodothyronine on methylglyoxal derived stress.

Methylglyoxal (MG) is the most potent precursor during the formation of the advanced glycation end products (AGEs). MG-dependent glycative stress contributes to pathogenesis of diabetes, age-related disorders, and cancer. There is a great need to study the reduction process of glycative stress for effective management of metabolic disorders. From natural compounds to synthetic drugs, each element contributes to the reduction of glycative stress. Previously, it was established that the lowering of uric acid, low-density lipoprotein cholesterol, and urine albumin excretion rate, as well as reducing total oxidative stress, were all achieved more effectively with a levothyroxine regimen. Still, there is no such study found that supports the MG-dependent glycative stress reduction with thyroid hormone compound. Our study aims to investigate the effects of T3 and T4 on MG-dependent glycative stress. The antiglycation effect was assayed through NBT assay, DNPH assay, ELISA, and fluorescence spectrophotometer. The intracellular reduction in reactive oxygen species (ROS) has been estimated through confocal microscopy. The results revealed an effective reduction in the formation of AGEs adducts and intracellular ROS formation. The investigation concludes AGEs formation was suppressed using these compounds, although in vivo and rigorous clinical trials are required in order to verify these findings.

Unraveling the Peroxidase Activity in Peroxiredoxins: A Comprehensive Review of Mechanisms, Functions, and Biological Significance.

Peroxiredoxins (Prxs) are members of the antioxidant enzymes necessary for every living object in the three domains of life and play critical roles in controlling peroxide levels in cells. This comprehensive literature review aims to elucidate the peroxidase activity of Prxs, examining their roles and significance for organisms across various taxa. Ironically, the primary role of the Prxs is the peroxidase activity, which comprises the reduction of hydrogen peroxide and other organic hydroperoxides and decreases the risk of oxidative damage in the cells. The above enzymatic activity occurs through the reversible oxidation-reduction catalyzed by cysteine residues in the active site by forming sulfenic acid and reduction by intracellular reductants. Structurally and functionally, Prxs function as dimers or decamers and show different catalytic patterns according to their subfamilies or cellular compartments. Compared to the mechanisms of the other two subgroups of Prxs, including 2-Cys Prxs and atypical Prxs, the 1-Cys Prxs have monomer-dimer switch folding coupled with catalytic activity. In addition to their peroxidase activity, which is widely known, Prxs are becoming acknowledged to be involved in other signaling processes, including redox signaling and apoptosis. This aversion to oxidative stress and regulation by the cellular redox state places them at the heart of adaptive cellular responses to changes in the environment or manifestations of diseases. In conclusion, based on the data obtained and on furthering the knowledge of Prxs' structure and function, these enzymes may be classified as a diverse yet essential family of proteins that can effectively protect cells from the adverse effects of oxidative stress due to peroxidase activity. This indicates secondary interactions, summarized as peroxide detoxification or regulatory signaling, and identifies their applicability in multiple biological pathways. Such knowledge is valuable for enhancing the general comprehension of essential cellular functions and disclosing further therapeutic approaches to the diseases caused by the increased production of reactive oxygen species.

TRP14 is the rate-limiting enzyme for intracellular cystine reduction and regulates proteome cysteinylation

It has remained unknown how cells reduce cystine taken up from the extracellular space, which is a required step for further utilization of cysteine in key processes such as protein or glutathione synthesis. Here, we show that the thioredoxin-related protein of 14 kDa (TRP14, encoded by TXNDC17) is the rate-limiting enzyme for intracellular cystine reduction. When TRP14 is genetically knocked out, cysteine synthesis through the transsulfuration pathway becomes the major source of cysteine in human cells, and knockout of both pathways becomes lethal in C. elegans subjected to proteotoxic stress. TRP14 can also reduce cysteinyl moieties on proteins, rescuing their activities as here shown with cysteinylated peroxiredoxin 2. Txndc17 knockout mice were, surprisingly, protected in an acute pancreatitis model, concomitant with activation of Nrf2-driven antioxidant pathways and upregulation of transsulfuration. We conclude that TRP14 is the evolutionarily conserved enzyme principally responsible for intracellular cystine reduction in C. elegans, mice, and humans.

Extracellularly secreted cysteine derived from cystine regulates oxidative and electrophilic stress in HepG2 cells

While cysteine (CysSH) is known to be exported into the extracellular space, its biological significance is not well understood. The present study examined the movement of extracellular CysSH using stable isotope-labeled cystine (CysSSCys), which is transported into cells and reduced to CysSH. Exposure of HepG2 cells to 100 µM stable isotope-labeled CysSSCys resulted in 70 µM labeled CysSH in cell medium 1 h after CysSSCys exposure. When the cell medium was collected and incubated with either hydrogen peroxide (H2O2) or atmospheric electrophiles, such as 1,2-naphthoquinone, 1,4-naphthoquinone and 1,4-benzoquinone, CysSH in the cell medium was almost completely consumed. In contrast, extracellular levels of CysSH were unaltered during exposure of HepG2 cells to H2O2 for up to 2 h, suggesting redox cycling of CysSSCys/CysSH in the cell system. Experiments with and without changing cell medium containing CysSH from HepG2 cells revealed that oxidative and electrophilic modifications of cellular proteins, caused by exposure to H2O2 and 1,2-naphthoquinone, were significantly repressed by CysSH in the medium. We also examined participation of enzymes and/or antioxidants in intracellular reduction of CysSSCys to CysSH. These results provide new findings that extracellular CysSH derived from CysSSCys plays a role in the regulation of oxidative and electrophilic stress.

A near-infrared fluorescent probe with two-photon excitation for in situ imaging of NQO1 in human colorectum cancer tissue

Colorectum cancer has become one of the most fatal cancer diseases, in which NAD(P)H: quinone oxidoreductase 1 (NQO1) plays a role in intracellular free radical reduction and detoxification and has been linked to colorectum cancer and chemotherapy resistance. Therefore, rational design of optical probe for NQO1 detection is urgent for the early diagnosis of colorectum cancer. Herein, we have developed a novel two-photon fluorescent probe, WHFD, which is capable of selectively detecting of intracellular NQO1 with two-photon (TP) absorption (800 nm) and near-infrared emission (620 nm). Combination with a substantial Stokes shift (175 nm) and biocompatibility, we have assessed its suitability for in vivo imaging of endogenous NQO1 activities from HepG2 tumor-bearing live animals with high tissue penetration up to 300 μm. Particularly, we for the first time used the probe to image NQO1 activities from human colorectum cancer samples by using TP microscopy, and proving our probe possesses reliable diagnostic performance to directly in situ imaging of cancer biomarker and can clearly distinguish the boundary between human colorectum cancer tissue and their surrounding normal tissue, which shows great potential for the intraoperative navigation.

Promoting effects of aluminum addition on chlorophyll biosynthesis and growth of two cultured iron‐limited marine diatoms

AbstractAluminum (Al) may play a role in the ocean's capacity for absorbing atmospheric CO2 via influencing carbon fixation, export, and sequestration. Aluminum fertilization, especially in iron (Fe)‐limited high‐nutrient, low‐chlorophyll ocean regions, has been proposed as a potential CO2 removal strategy to mitigate global warming. However, how Al addition would influence the solubility and bioavailability of Fe as well as the physiology of Fe‐limited phytoplankton has not yet been examined. Here, we show that Al addition (20 and 100 nM) had little influence on the Fe solubility in surface seawater and decreased the Fe bio‐uptake by 11–22% in Fe‐limited diatom Thalassiosira weissflogii in Fe‐buffered media. On the other hand, the Al addition significantly increased the rate of chlorophyll biosynthesis by 45–60% for Fe‐limited T. weissflogii and 81–102% for Fe‐limited Thalassiosira pseudonana, as well as their cell size, cellular chlorophyll content, photosynthetic quantum efficiency (Fv/Fm) and growth rate. Under Fe‐sufficient conditions, the Al addition still led to an increased growth rate, though the beneficial effects of Al addition on chlorophyll biosynthesis were no longer apparent. These results suggest that Al may facilitate chlorophyll biosynthesis and benefit the photosynthetic efficiency and growth of Fe‐limited diatoms. We speculate that Al addition may enhance intracellular Fe use efficiency for chlorophyll biosynthesis by facilitating the superoxide‐mediated intracellular reduction of Fe(III) to Fe(II). Our study provides new evidence and support for the iron–aluminum hypothesis.

Conductive magnetic nanowires accelerated electron transfer between C1020 carbon steel and Desulfovibrio vulgaris biofilm

Microbial biofilms are behind microbiologically influenced corrosion (MIC). Sessile cells in biofilms are many times more concentrated volumetrically than planktonic cells in the bulk fluids, thus providing locally high concentrations of chemicals. More importantly, “electroactive” sessile cells in biofilms are capable of utilizing extracellularly supplied electrons (e.g., from elemental Fe) for intracellular reduction of an oxidant such as sulfate in energy metabolism. MIC directly caused by anaerobic biofilms is classified into two main types based on their mechanisms: extracellular electron transfer MIC (EET-MIC) and metabolite MIC (M-MIC). Sulfate-reducing bacteria (SRB) are notorious for their corrosivity. They can cause EET-MIC in carbon steel, but they can also secrete biogenic H2S to corrode other metals such as Cu directly via M-MIC. This study investigated the use of conductive magnetic nanowires as electron mediators to accelerate and thus identify EET-MIC of C1020 by Desulfovibrio vulgaris. The presence of 40 ppm (w/w) nanowires in ATCC 1249 culture medium at 37 °C resulted in 45 % higher weight loss and 57 % deeper corrosion pits after 7-day incubation. Electrochemical tests using linear polarization resistance and potentiodynamic polarization supported the weight loss data trend. These findings suggest that conductive magnetic nanowires can be employed to identify EET-MIC. The use of insoluble 2 μm long nanowires proved that the extracellular section of the electron transfer process is a bottleneck in SRB MIC of carbon steel.

Physiological and biochemical responses of Leersia hexandra Swartz to nickel stress: Insights into antioxidant defense mechanisms and metal detoxification strategies

Phytoremediation is widely considered as a cost-effective method for managing heavy metal soil pollution. Leersia hexandra Swartz shows a promising potential for the remediation of heavy metals pollution, including chromium (Cr), copper (Cu), and nickel (Ni). It is vital to understand the physiological and biochemical responses of L. hexandra to Ni stress to elucidate the mechanisms underlying Ni tolerance and accumulation. Here, we examined the metabolic and transcriptomic responses of L. hexandra exposed to 40 mg/L Ni for 24 h and 14 d. After 24-h Ni stress, gene expression of glutathione metabolic cycle (GSTF1, GSTU1 and MDAR4) and superoxide dismutase (SODCC2) was significantly increased in plant leaves. Furthermore, after 14-d Ni stress, the ascorbate peroxidase (APX7), superoxide dismutase (SODCP and SOD1), and catalase (CAT) gene expression was significantly upregulated, but that of glutathione metabolic cycle (EMB2360, GSTU1, GSTU6, GSH2, GPX6, and MDAR2) was downregulated. After 24-h Ni stress, the differentially expressed metabolites (DEMs) were mainly flavonoids (45%) and flavones (20%). However, after 14-d Ni stress, the DEMs were mainly carbohydrates and their derivatives (34%), amino acids and derivatives (15%), and organic acids and derivatives (8%). Results suggest that L. hexandra adopt distinct time-dependent antioxidant and metal detoxification strategies likely associated with intracellular reduction–oxidation balance. Novel insights into the molecular mechanisms responsible for Ni tolerance in plants are presented.

Evaluation of serum thioredoxin as a hepatocellular carcinoma diagnostic marker

BackgroundHepatocellular carcinoma (HCC) is one of the most prevalent and fatal malignancies worldwide. Following an increase in reactive oxygen species (ROS), cancer cells enter an oxidative stress state. As a result, these cells experience an increase in antioxidant activity to counteract oxidative stress. The thioredoxin (TRX) system is a ubiquitous mammalian antioxidant system that neutralizes ROS and maintains intracellular reduction oxidation (redox) balance, which is essential for HCC growth. However, the role of TRX protein in HCC remains largely unknown. Hence, we aimed to assess the diagnostic utility of serum TRX in patients with HCC. A total of 50 patients were consecutively recruited in this observational study. They were classified into three groups: an HCC group (25 patients), a cirrhosis group (15 patients with liver cirrhosis on top of chronic HCV infection), and a control group (10 healthy individuals). Serum TRX levels were measured using ELISA.ResultsHigher serum TRX levels were detected in the HCC group than in the cirrhosis and control groups (140.96 ± 12.70 vs 88.33 ± 10.34 vs 73.10 ± 13.22 ng/mL, respectively; P < 0.001). TRX was independently associated with the presence of HCC (P < 0.001). Regarding the detection of HCC, TRX at a cut-off value of 114 ng/mL had superior diagnostic performance to AFP with an AUC of 1.000, sensitivity of 100%, and specificity of 100%, whereas AFP at a cut-off value of 20.5 ng/mL had an AUC of 1.000, sensitivity of 100%, and specificity of 47%.ConclusionThioredoxin has the potential to be an HCC diagnostic marker. The clinical significance of thioredoxin in HCC requires further investigation.

Inhibition of Protein Disulfide Isomerase Attenuates Osteoclast Differentiation and Function via the Readjustment of Cellular Redox State in Postmenopausal Osteoporosis.

Due to the accumulation of reactive oxygen species (ROS) and heightened activity of osteoclasts, postmenopausal osteoporosis could cause severe pathological bone destruction. Protein disulfide isomerase (PDI), an endoplasmic prototypic thiol isomerase, plays a central role in affecting cellular redox state. To test whether suppression of PDI could inhibit osteoclastogenesis through cellular redox regulation, bioinformatics network analysis was performed on the causative genes, followed by biological validation on the osteoclastogenesis in vitro and ovariectomy (OVX) mice model in vivo. The analysis identified PDI as one of gene targets for postmenopausal osteoporosis, which was positively expressed during osteoclastogenesis. Therefore, PDI expression inhibitor and chaperone activity inhibitor were used to verify the effects of PDI inhibitors on osteoclastogenesis. Results demonstrated that PDI inhibitors could reduce osteoclast number and inhibit resorption function via suppression on osteoclast marker genes. The mechanisms behind the scenes were the PDI inhibitors-caused intracellular ROS reduction via enhancement of the antioxidant system. Micro-CT and histological results indicated PDI inhibitors could effectively alleviate or even prevent bone loss in OVX mice. In conclusion, our findings unveiled the suppressive effects of PDI inhibitors on osteoclastogenesis by reducing intracellular ROS, providing new therapeutic options for postmenopausal osteoporosis.

Inhibitory effect of trans-tiliroside on very low-density lipoprotein secretion in HepG2 cells and mouse liver

An acylated flavonol glycoside, trans-tiliroside (1), is found in certain parts of different herbs, including the seeds of Rosa canina (Rosaceae). Previous studies on compound 1 have focused on triglyceride (TG) metabolism, including its anti-obesity and intracellular TG reduction effects. In the present study, the effects of compound 1 on cholesterol (CHO) metabolism were investigated using human hepatocellular carcinoma-derived HepG2 cells and mice. Compound 1 decreased CHO secretion in HepG2 cells, which was enhanced by mevalonate in a concentration-dependent manner and decreased the secretion of apoprotein B (apoB)-100, a marker of very low-density lipoprotein (VLDL). Compound 1 also inhibited the activity of microsomal triglyceride transfer proteins, which mediate VLDL formation from cholesterol and triglycerides in the liver. In vivo, compound 1 inhibited the accumulation of Triton WR-1339-induced TG in the blood of fasted mice and maintained low levels of apoB-100. These results suggest that compound 1 inhibits the secretion of CHO as VLDL from the liver and has the potential for use for the prevention of dyslipidemia.Graphical abstract

Implication of amino acid metabolism and cell surface integrity for the thermotolerance mechanism in the thermally adapted acetic acid bacterium Acetobacter pasteurianus TH-3.

Acetobacter pasteurianus, an industrial vinegar-producing strain, is suffered by fermentation stress such as fermentation heat and/or high concentrations of acetic acid. By an experimental evolution approach, we have obtained a stress-tolerant strain, exhibiting significantly increased growth and acetic acid fermentation ability at higher temperatures. In this study, we report that only the three gene mutations of ones accumulated during the adaptation process, ansP, dctD, and glnD, were sufficient to reproduce the increased thermotolerance of A. pasteurianus. These mutations resulted in cell envelope modification, including increased phospholipid and lipopolysaccharide synthesis, increased respiratory activity, and cell size reduction. The phenotypic changes may cooperatively work to make the adapted cell thermotolerant by enhancing cell surface integrity, nutrient or oxygen availability, and energy generation.