scholarly journals Prebiotics Inhibit Proteolysis by Gut Bacteria in a Host Diet-Dependent Manner: a Three-Stage Continuous In Vitro Gut Model Experiment

2020 ◽  
Vol 86 (10) ◽  
Author(s):  
Xuedan Wang ◽  
Glenn R. Gibson ◽  
Manuela Sailer ◽  
Stephan Theis ◽  
Robert A. Rastall
Keyword(s):  
Dietary Protein ◽  
Health Benefit ◽  
Distal Colon ◽  
High Protein ◽  
Model Systems ◽  
Dependent Manner ◽  
Bacterial Fermentation ◽  
Protein Levels

ABSTRACT Dietary protein residue can result in microbial generation of various toxic metabolites in the gut, such as ammonia. A prebiotic is “a substrate that is selectively utilised by host microorganisms conferring a health benefit” (G. R. Gibson, R. Hutkins, M. E. Sanders, S. L. Prescott, et al., Nat Rev Gastroenterol Hepatol 14:491–502, 2017, https://doi.org/10.1038/nrgastro.2017.75). Prebiotics are carbohydrates that may have the potential to reverse the harmful effects of gut bacterial protein fermentation. Three-stage continuous colonic model systems were inoculated with fecal samples from omnivore and vegetarian volunteers. Casein (equivalent to 105 g protein consumption per day) was used within the systems as a protein source. Two different doses of inulin-type fructans (Synergy1) were later added (equivalent to 10 g per day in vivo and 15 g per day) to assess whether this influenced protein fermentation. Bacteria were enumerated by fluorescence in situ hybridization with flow cytometry. Metabolites from bacterial fermentation (short-chain fatty acid [SCFA], ammonia, phenol, indole, and p-cresol) were monitored to further analyze proteolysis and the prebiotic effect. A significantly higher number of bifidobacteria was observed with the addition of inulin together with reduction of Desulfovibrio spp. Furthermore, metabolites from protein fermentation, such as branched-chain fatty acids (BCFA) and ammonia, were significantly lowered with Synergy1. Production of p-cresol varied among donors, as we recognized four high producing models and two low producing models. Prebiotic addition reduced its production only in vegetarian high p-cresol producers. IMPORTANCE Dietary protein levels are generally higher in Western populations than in the world average. We challenged three-stage continuous colonic model systems containing high protein levels and confirmed the production of potentially harmful metabolites from proteolysis, especially replicates of the transverse and distal colon. Fermentations of proteins with a prebiotic supplementation resulted in a change in the human gut microbiota and inhibited the production of some proteolytic metabolites. Moreover, we observed both bacterial and metabolic differences between fecal bacteria from omnivore donors and vegetarian donors. Proteins with prebiotic supplementation showed higher Bacteroides spp. and inhibited Clostridium cluster IX in omnivore models, while in vegetarian modes, Clostridium cluster IX was higher and Bacteroides spp. lower with high protein plus prebiotic supplementation. Synergy1 addition inhibited p-cresol production in vegetarian high p-cresol-producing models while the inhibitory effect was not seen in omnivore models.

scholarly journals Mn Inhibits GSH Synthesis via Downregulation of Neuronal EAAC1 and Astrocytic xCT to Cause Oxidative Damage in the Striatum of Mice

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xinxin Yang ◽  
Haibo Yang ◽  
Fengdi Wu ◽  
Zhipeng Qi ◽  
Jiashuo Li ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Dependent Manner ◽  
Protein Levels ◽  
Key Factor ◽  
Protein Sulfhydryl ◽  
Mrna And Protein Expression ◽  
The Brain

Excessive manganese (Mn) can accumulate in the striatum of the brain following overexposure. Oxidative stress is a well-recognized mechanism in Mn-induced neurotoxicity. It has been proven that glutathione (GSH) depletion is a key factor in oxidative damage during Mn exposure. However, no study has focused on the dysfunction of GSH synthesis-induced oxidative stress in the brain during Mn exposure. The objective of the present study was to explore the mechanism of Mn disruption of GSH synthesis via EAAC1 and xCT in vitro and in vivo. Primary neurons and astrocytes were cultured and treated with different doses of Mn to observe the state of cells and levels of GSH and reactive oxygen species (ROS) and measure mRNA and protein expression of EAAC1 and xCT. Mice were randomly divided into seven groups, which received saline, 12.5, 25, and 50 mg/kg MnCl2, 500 mg/kg AAH (EAAC1 inhibitor) + 50 mg/kg MnCl2, 75 mg/kg SSZ (xCT inhibitor) + 50 mg/kg MnCl2, and 100 mg/kg NAC (GSH rescuer) + 50 mg/kg MnCl2 once daily for two weeks. Then, levels of EAAC1, xCT, ROS, GSH, malondialdehyde (MDA), protein sulfhydryl, carbonyl, 8-hydroxy-2-deoxyguanosine (8-OHdG), and morphological and ultrastructural features in the striatum of mice were measured. Mn reduced protein levels, mRNA expression, and immunofluorescence intensity of EAAC1 and xCT. Mn also decreased the level of GSH, sulfhydryl, and increased ROS, MDA, 8-OHdG, and carbonyl in a dose-dependent manner. Injury-related pathological and ultrastructure changes in the striatum of mice were significantly present. In conclusion, excessive exposure to Mn disrupts GSH synthesis through inhibition of EAAC1 and xCT to trigger oxidative damage in the striatum.

scholarly journals Protective Effects of Scolopendra Water Extract on Trimethyltin-Induced Hippocampal Neurodegeneration and Seizures in Mice

2019 ◽  
Vol 9 (12) ◽  
pp. 369
Author(s):  
Yun-Soo Seo ◽  
Mary Jasmin Ang ◽  
Byeong Cheol Moon ◽  
Hyo Seon Kim ◽  
Goya Choi ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Primary Cultures ◽  
Water Extract ◽  
Model Systems ◽  
Inflammatory Factor ◽  
Dependent Manner ◽  
Protective Effects ◽  
Cell Degeneration

Trimethyltin (TMT) is an organotin compound with potent neurotoxic action characterized by neuronal degeneration in the hippocampus. This study evaluated the protective effects of a Scolopendra water extract (SWE) against TMT intoxication in hippocampal neurons, using both in vitro and in vivo model systems. Specifically, we examined the actions of SWE on TMT- (5 mM) induced cytotoxicity in primary cultures of mouse hippocampal neurons (7 days in vitro) and the effects of SWE on hippocampal degeneration in adult TMT- (2.6 mg/kg, intraperitoneal) treated C57BL/6 mice. We found that SWE pretreatment (0–100 μg/mL) significantly reduced TMT-induced cytotoxicity in cultured hippocampal neurons in a dose-dependent manner, as determined by lactate dehydrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assays. Additionally, this study showed that perioral administration of SWE (5 mg/kg), from −6 to 0 days before TMT injection, significantly attenuated hippocampal cell degeneration and seizures in adult mice. Furthermore, quantitative analysis of Iba-1 (Allograft inflammatory factor 1)- and GFAP (Glial fibrillary acidic protein)-immunostained cells revealed a significant reduction in the levels of Iba-1- and GFAP-positive cell bodies in the dentate gyrus (DG) of mice treated with SWE prior to TMT injection. These data indicated that SWE pretreatment significantly protected the hippocampus against the massive activation of microglia and astrocytes elicited by TMT. In addition, our data showed that the SWE-induced reduction of immune cell activation was linked to a significant reduction in cell death and a significant improvement in TMT-induced seizure behavior. Thus, we conclude that SWE ameliorated the detrimental effects of TMT toxicity on hippocampal neurons, both in vivo and in vitro. Altogether, our findings hint at a promising pharmacotherapeutic use of SWE in hippocampal degeneration and dysfunction.

scholarly journals Advanced oxidation protein products downregulate CYP1A2 and CYP3A4 expression and activity via the NF-κB-mediated signaling pathway in vitro and in vivo

2021 ◽  
Author(s):  
Tianrong Xun ◽  
Zhufen Lin ◽  
Xiaokang Wang ◽  
Xia Zhan ◽  
Haixing Feng ◽  
...  
Keyword(s):  
Liver Microsomes ◽  
Advanced Oxidation ◽  
Uremic Toxins ◽  
Uremic Toxin ◽  
Dependent Manner ◽  
Advanced Oxidation Protein Products ◽  
Protein Levels ◽  
Cyp3a4 Expression

AbstractUremic toxin accumulation is one possible reason for alterations in hepatic drug metabolism in patients with chronic kidney disease (CKD). However, the types of uremic toxins and underlying mechanisms are poorly understood. In this study, we report the role of advanced oxidation protein products (AOPPs), a modified protein uremic toxin, in the downregulation of cytochromes P450 1A2 (CYP1A2) and P450 3A4 (CYP3A4) expression levels and activities. We found that AOPP accumulation in plasma in a rat CKD model was associated with decreased protein levels of CYP1A2 and CYP3A4. CYP1A2 and CYP3A4 metabolites (acetaminophen and 6β-hydroxytestosterone, respectively,) in liver microsomes were also significantly decreased. In human hepatocytes, AOPPs significantly decreased CYP1A2 and CYP3A4 protein levels in a dose- and time-dependent manner and downregulated their activities; however, bovine serum albumin (BSA), a synthetic precursor of AOPPs, had no effect on these parameters. The effect of AOPPs was associated with upregulation of p-IKKα/β, p-IκBα, p-NF-κB, and inflammatory cytokines protein levels and increases in p-IKKα/β/IKKα, p-IκBα/IκBα, and p-NF-κB/NF-κB phosphorylation ratios. Further, NF-kB pathway inhibitors BAY-117082 and PDTC abolished the downregulatory effects of AOPPs. These findings suggest that AOPPs downregulate CYP1A2 and CYP3A4 expression and activities by increasing inflammatory cytokine production and stimulating NF-κB-mediated signaling. Protein uremic toxins, such as AOPPs, may modify the nonrenal clearance of drugs in patients with CKD by influencing metabolic enzymes.

Acetylation of GATA-1 Is Required for Chromatin Occupancy.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1179-1179 ◽  
Author(s):  
Janine M. Lamonica ◽  
Christopher R. Vakoc ◽  
Gerd A. Blobel
Keyword(s):  
Protein Interactions ◽  
Dependent Manner ◽  
Protein Levels ◽  
Defective Mutant ◽  
Cellular Target ◽  
Stable Association ◽  
Peptide Affinity

Abstract All three hematopoietic GATA transcription factors GATA-1, GATA-2, and GATA-3 are acetylated, although the in vivo role of this modification remains unclear. It has been proposed that acetylation of GATA-1 increases its affinity for DNA in vitro, although this finding has not been observed by others. To study the role of GATA-1 acetylation, we examined the functions of an acetylation-defective mutant of GATA-1 in maturing erythroid cells. We found that removal of the acetylation sites in GATA-1 largely abrogates its biological activity but does not impair its nuclear localization, steady state protein levels, or its ability to bind naked GATA elements in vitro. However, chromatin immunoprecipitation (ChIP) experiments revealed that mutant GATA-1 was dramatically impaired in binding to its cellular target sites in vivo, including genes that are normally activated (α- and β-globin, EKLF, FOG-1, Band3, and AHSP) and repressed (GATA-2 and c-kit) by GATA-1. Together, these results suggest that acetylation is required for GATA-1 chromatin occupancy. These findings point to a novel function for transcription factor acetylation, perhaps by facilitating protein interactions required for stable association with chromatin templates in vivo. To identify proteins that interact with acetylated GATA-1, we performed peptide affinity chromatography using acetylated GATA-1 peptides. Using this technique coupled with mass spectrometry, several proteins that bind to GATA-1 peptides in an acetylation-dependent manner were identified. The identified proteins contain known acetyl-lysine binding modules (bromodomains) consistent with their binding properties. The in vivo role of these proteins with regard to GATA-1 function is being examined and will be discussed.

scholarly journals Effect of dietary protein level on in vivo and in vitro vitamin A esterase activity in the chick

1967 ◽  
Vol 21 (3) ◽  
pp. 565-581 ◽  
Author(s):  
I. Nir ◽  
I. Bruckental ◽  
I. Ascarelli ◽  
A. Bondi
Keyword(s):  
Vitamin A ◽  
Oral Dose ◽  
Dietary Protein ◽  
Protein Level ◽  
Blood Stream ◽  
Duodenal Mucosa ◽  
Protein Levels ◽  
Temporary Decrease

1. The efficiency of absorption of and liver storage from a single oral dose of 10000 i.u. vitamin A palmitate decreased in chicks reared on a diet containing 10% protein as compared to the efficiency in chicks reared on a diet in which the protein level was adequate. When the chicks were given orally an equivalent dose of vitamin A alcohol, the absorption was equally efficient at both dietary protein levels.2. The vitamin A alcohol content of this intestine, plasma and liver of chicks dosed with vitamin A palmitate was decreased by protein restriction. The physiological change responsible for this decrease seems to be the lowering of the hydrolysing activity for vitamin A palmitate in pancreas and in the duodenal mucosa.3. The importance of the enzymic step in the absorption of an oral dose of vitamin A palmitate is shown by the finding that protein malnutrition reduced only slightly the final liver stores when vitamin A in its different forms (palmitate, acetate or alcohol) was injected directly into the blood stream.4. The uptake of injected vitamin A from the blood was much delayed when the vitamin was injected as palmitate, i.e. the ester of a long-chain fatty acid, instead of the acetate ester of the free alcohol.5. When vitamin A was injected, the liver content did not rise continuously with time, but showed a temporary decrease after a certain period. The phenomenon was apparently due to changes in the rate of the two inverse processes of uptake of the vitamin by the liver and liberation from it.

scholarly journals The fate of methylmercury through the formation of bismethylmercury sulfide as an intermediate in mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yumi Abiko ◽  
Yusuke Katayama ◽  
Wenyang Zhao ◽  
Sawako Horai ◽  
Kenji Sakurai ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Intraperitoneal Administration ◽  
Distal Colon ◽  
The Body ◽  
Gas Chromatography Mass Spectrometry ◽  
Dependent Manner ◽  
Free System ◽  
A Cell

AbstractA previous study by our group indicated that methylmercury (MeHg) is biotransformed to bismethylmercury sulfide [(MeHg)2S)] by interaction with reactive sulfur species (RSS) produced in the body. In the present study, we explored the transformation of MeHg to (MeHg)2S in the gut and the subsequent fate of (MeHg)2S in vitro and in vivo. An ex vivo experiment suggested the possibility of the extracellular transformation of MeHg to (MeHg)2S in the distal colon, and accordingly, the MeHg sulfur adduct was detected in the intestinal contents and feces of mice administered MeHg, suggesting that (MeHg)2S is formed through reactions between MeHg and RSS in the gut. In a cell-free system, we found that (MeHg)2S undergoes degradation in a time-dependent manner, resulting in the formation of mercury sulfide and dimethylmercury (DMeHg), as determined by X-ray diffraction and gas chromatography/mass spectrometry, respectively. We also identified DMeHg in the expiration after the intraperitoneal administration of (MeHg)2S to mice. Thus, our present study identified a new fate of MeHg through (MeHg)2S as an intermediate, which leads to conversion of volatile DMeHg in the body.

scholarly journals Pregnenolone sulfate regulates prolactin production in the rat pituitary

2016 ◽  
Vol 230 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Eun-Jin Kang ◽  
So-Hye Hong ◽  
Jae-Eon Lee ◽  
Seung Chul Kim ◽  
Hoe-Saeng Yang ◽  
...  
Keyword(s):  
Target Genes ◽  
Mapk Signaling ◽  
Dependent Manner ◽  
Pregnenolone Sulfate ◽  
Protein Levels ◽  
Rat Pituitary ◽  
Pituitary Prolactin ◽  
Gh3 Cell

Pregnenolone sulfate (PS) is a neuroactive steroid hormone produced in the brain. In this study, the effects of PS on synthesis and secretion of rat pituitary prolactin (PRL) were examined. To accomplish this, GH3 rat pituitary adenoma cells were treated with PS, which showed significantly increased mRNA and protein levels of PRL compared with the control. The mechanism of action responsible for the effects of PS on PRL synthesis and secretion was investigated by pretreating cells with inhibitors of traditional PRL- or the PS-related signaling pathway. PS-stimulated PRL transcription was significantly reduced by inhibitors of PKA, PKC and MAPK, but unchanged by GABAAR and NMDAR inhibitors. Western blotting analysis revealed that the total ERK1/2 level was upregulated in a time-dependent manner following PS treatment. An approximate 10% increase in GH3 cell proliferation was also observed in response to PS relative to the control. In the animal study, levels of PRL in the pituitary and in serum were elevated by PS. PS-stimulated PRL synthesis was also found to be associated with decreased expression of PRL target genes such as GNRH1, FSHB and LHB. These findings show that PS upregulates PRL synthesis and secretion in vivo and in vitro via MAPK signaling, suggesting that it has the potential for use as a therapeutic hormone to treat PRL-related disorders such as hypoprolactinemia and low milk supply.

scholarly journals Identification of a region on hypoxia-inducible-factor prolyl 4-hydroxylases that determines their specificity for the oxygen degradation domains

2007 ◽  
Vol 408 (2) ◽  
pp. 231-240 ◽  
Author(s):  
Diego Villar ◽  
Alicia Vara-Vega ◽  
Manuel O. Landázuri ◽  
Luis Del Peso
Keyword(s):  
Transcription Factors ◽  
Tertiary Structure ◽  
Hypoxia Inducible Factor ◽  
Domain Swapping ◽  
Dependent Manner ◽  
Low Oxygen ◽  
Protein Levels ◽  
The Stability

HIFs [hypoxia-inducible (transcription) factors] are essential for the induction of an adaptive gene expression programme under low oxygen partial pressure. The activity of these transcription factors is mainly determined by the stability of the HIFα subunit, which is regulated, in an oxygen-dependent manner, by a family of three prolyl 4-hydroxylases [EGLN1–EGLN3 (EGL nine homologues 1–3)]. HIFα contains two, N- and C-terminal, independent ODDs (oxygen-dependent degradation domains), namely NODD and CODD, that, upon hydroxylation by the EGLNs, target HIFα for proteasomal degradation. In vitro studies indicate that each EGLN shows a differential preference for ODDs, However, the sequence determinants for such specificity are unknown. In the present study we showed that whereas EGLN1 and EGLN2 acted upon any of these ODDs to regulate HIF1α protein levels and activity in vivo, EGLN3 only acted on the CODD. With the aim of identifying the region within EGLNs responsible for their differential substrate preference, we investigated the activity and binding pattern of different EGLN deletions and chimaeric constructs generated by domain swapping between EGLN1 and EGLN3. These studies revealed a region of 97 residues that was sufficient to confer the characteristic substrate binding observed for each EGLN. Within this region, we identified the minimal sequence (EGLN1 residues 236–252) involved in substrate discrimination. Importantly, mapping of these sequences on the EGLN1 tertiary structure indicates that substrate specificity is determined by a region relatively remote from the catalytic site.

Identification of aldo-keto reductase (AKR7A1) and glutathione S-transferase pi (GSTP1) as novel renal damage biomarkers following exposure to mercury

2018 ◽  
Vol 37 (10) ◽  
pp. 1025-1036 ◽  
Author(s):  
Y-J Shin ◽  
K-A Kim ◽  
E-S Kim ◽  
J-H Kim ◽  
H-S Kim ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Dependent Manner ◽  
Clinical Markers ◽  
Sprague Dawley ◽  
Glutathione S Transferase ◽  
Protein Levels ◽  
Kidney Proximal Tubular Cells ◽  
New Biomarkers

The kidney is one of the main targets for toxicity induced by xenobiotics. Sensitive detection of early impairment is critical to assess chemical-associated renal toxicity. The aim of this study was to identify potential nephrotoxic biomarkers in rat kidney tissues after exposure to mercury (Hg), a representative nephrotoxicant, and to evaluate these new biomarkers employing in vivo and in vitro systems. Mercuric chloride was administered orally to Sprague-Dawley rats for 2 weeks. Proteomic analysis revealed that aldo-keto reductase (AKR7A1) and glutathione S-transferase pi (GSTP1) were significantly elevated in kidney after Hg exposure. While the levels of conventional nephrotoxic clinical markers including blood urea nitrogen and serum creatinine were not elevated, the mRNA and protein levels of AKR7A1 and GSTP1 were increased upon Hg exposure in a dose-dependent manner. The increases in AKR7A1 and GSTP1 were also observed in rat kidneys after an extended exposure for 6 weeks to low-dose Hg. In in vitro rat kidney proximal tubular cells, changes in AKR7A1 and GSTP1 levels correlated well with the extent of cytotoxicity induced by Hg, cadmium, or cisplatin. AKR7A1 and GSTP1 were identified as new candidates for Hg-induced nephrotoxicity, suggesting that these biomarkers have potential for evaluating or predicting nephrotoxicity.

scholarly journals NSun2 promotes cell migration through methylating autotaxin mRNA

2020 ◽  
Vol 295 (52) ◽  
pp. 18134-18147
Author(s):  
Xin Xu ◽  
Yihua Zhang ◽  
Junjie Zhang ◽  
Xiaotian Zhang
Keyword(s):  
Cell Migration ◽  
Biological Effects ◽  
Mrna Translation ◽  
Glioma Cell Line ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Protein Levels ◽  
Key Factor

NSun2 is an RNA methyltransferase introducing 5-methylcytosine into tRNAs, mRNAs, and noncoding RNAs, thereby influencing the levels or function of these RNAs. Autotaxin (ATX) is a secreted glycoprotein and is recognized as a key factor in converting lysophosphatidylcholine into lysophosphatidic acid (LPA). The ATX-LPA axis exerts multiple biological effects in cell survival, migration, proliferation, and differentiation. Here, we show that NSun2 is involved in the regulation of cell migration through methylating ATX mRNA. In the human glioma cell line U87, knockdown of NSun2 decreased ATX protein levels, whereas overexpression of NSun2 elevated ATX protein levels. However, neither overexpression nor knockdown of NSun2 altered ATX mRNA levels. Further studies revealed that NSun2 methylated the 3′-UTR of ATX mRNA at cytosine 2756 in vitro and in vivo. Methylation by NSun2 enhanced ATX mRNA translation. In addition, NSun2-mediated 5-methylcytosine methylation promoted the export of ATX mRNA from nucleus to cytoplasm in an ALYREF-dependent manner. Knockdown of NSun2 suppressed the migration of U87 cells, which was rescued by the addition of LPA. In summary, we identify NSun2-mediated methylation of ATX mRNA as a novel mechanism in the regulation of ATX.

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