scholarly journals Intestinal P Glycoprotein Acts as a Natural Defense Mechanism against Listeria monocytogenes

2004 ◽  
Vol 72 (7) ◽  
pp. 3849-3854 ◽  
Author(s):  
Brien L. Neudeck ◽  
Jennifer M. Loeb ◽  
Nancy G. Faith ◽  
Charles J. Czuprynski
Keyword(s):  
Listeria Monocytogenes ◽  
Defense Mechanism ◽  
Transepithelial Transport ◽  
Bacterial Invasion ◽  
Wild Type ◽  
In Vivo Experiments ◽  
Natural Defense ◽  
P Glycoprotein

ABSTRACT Mechanisms by which the intestinal epithelium resists invasion by food-borne pathogens such as Listeria monocytogenes are an evolving area of research. Intestinal P glycoprotein is well known to limit the absorption of xenobiotics and is believed to act as a cytotoxic defense mechanism. The aim of this study was to determine if intestinal P glycoprotein is involved in host defense against L. monocytogenes. Caco-2 cells and a P-glycoprotein-overexpressing subclone (Caco-2/MDR) were employed in addition to mdr1a−/− mice and wild-type controls. In vitro invasion assays and in vivo experiments were employed to measure bacterial invasion and dissemination. In addition, L. monocytogenes proteins were labeled with [35S]methionine, and the transepithelial transport across Caco-2 monolayers was characterized in both directions. Overexpression of P glycoprotein in Caco-2/MDR cells led to increased resistance to L. monocytogenes invasion, whereas P-glycoprotein inhibition led to increased invasion. Flux of [35S]methionine-labeled L. monocytogenes proteins was significantly greater in the basolateral-to-apical direction than in the apical-to-basolateral direction, indicating dependence on an apically located efflux transporter. Moreover, inhibiting P glycoprotein reduced the basolateral-to-apical flux of the proteins. Early dissemination of L. monocytogenes from the gastrointestinal tract was significantly greater in the mdr1a−/− mice than in wild-type controls. Expression and function of intestinal P glycoprotein is an important determinant in resistance to early invasion of L. monocytogenes.

scholarly journals Differential effect of anesthetics on mucociliary clearance in vivo in mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kyle S. Feldman ◽  
Eunwon Kim ◽  
Michael J. Czachowski ◽  
Yijen Wu ◽  
Cecilia W. Lo ◽  
...  
Keyword(s):  
Mucociliary Clearance ◽  
Defense Mechanism ◽  
Ex Vivo ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Wild Type ◽  
Sulfur Colloid ◽  
Ct System

AbstractRespiratory mucociliary clearance (MCC) is a key defense mechanism that functions to entrap and transport inhaled pollutants, particulates, and pathogens away from the lungs. Previous work has identified a number of anesthetics to have cilia depressive effects in vitro. Wild-type C57BL/6 J mice received intra-tracheal installation of 99mTc-Sulfur colloid, and were imaged using a dual-modality SPECT/CT system at 0 and 6 h to measure baseline MCC (n = 8). Mice were challenged for one hour with inhalational 1.5% isoflurane, or intraperitoneal ketamine (100 mg/kg)/xylazine (20 mg/kg), ketamine (0.5 mg/kg)/dexmedetomidine (50 mg/kg), fentanyl (0.2 mg/kg)/1.5% isoflurane, propofol (120 mg/Kg), or fentanyl/midazolam/dexmedetomidine (0.025 mg/kg/2.5 mg/kg/0.25 mg/kg) prior to MCC assessment. The baseline MCC was 6.4%, and was significantly reduced to 3.7% (p = 0.04) and 3.0% (p = 0.01) by ketamine/xylazine and ketamine/dexmedetomidine challenge respectively. Importantly, combinations of drugs containing fentanyl, and propofol in isolation did not significantly depress MCC. Although no change in cilia length or percent ciliation was expected, we tried to correlate ex-vivo tracheal cilia ciliary beat frequency and cilia-generated flow velocities with MCC and found no correlation. Our results indicate that anesthetics containing ketamine (ketamine/xylazine and ketamine/dexmedetomidine) significantly depress MCC, while combinations containing fentanyl (fentanyl/isoflurane, fentanyl/midazolam/dexmedetomidine) and propofol do not. Our method for assessing MCC is reproducible and has utility for studying the effects of other drug combinations.

scholarly journals Entrectinib, a TRK/ROS1 inhibitor with anti-CNS tumor activity: differentiation from other inhibitors in its class due to weak interaction with P-glycoprotein

2020 ◽  
Vol 22 (6) ◽  
pp. 819-829 ◽  
Author(s):  
Holger Fischer ◽  
Mohammed Ullah ◽  
Cecile C de la Cruz ◽  
Thomas Hunsaker ◽  
Claudia Senn ◽  
...  
Keyword(s):  
Steady State ◽  
Lipid Membrane ◽  
Kinase Inhibitor ◽  
Ex Vivo ◽  
Intracranial Tumor ◽  
Brain Penetration ◽  
In Vivo Experiments ◽  
P Glycoprotein

Abstract Background Studies evaluating the CNS penetration of a novel tyrosine kinase inhibitor, entrectinib, proved challenging, particularly due to discrepancies across earlier experiments regarding P-glycoprotein (P-gp) interaction and brain distribution. To address this question, we used a novel “apical efflux ratio” (AP-ER) model to assess P-gp interaction with entrectinib, crizotinib, and larotrectinib, and compared their brain-penetration properties. Methods AP-ER was designed to calculate P-gp interaction with the 3 drugs in vitro using P-gp–overexpressing cells. Brain penetration was studied in rat plasma, brain, and cerebrospinal fluid (CSF) samples after intravenous drug infusion. Unbound brain concentrations were estimated through kinetic lipid membrane binding assays and ex vivo experiments, while the antitumor activity of entrectinib was evaluated in a clinically relevant setting using an intracranial tumor mouse model. Results Entrectinib showed lower AP-ER (1.1–1.15) than crizotinib and larotrectinib (≥2.8). Despite not reaching steady-state brain exposures in rats after 6 hours, entrectinib presented a more favorable CSF-to-unbound concentration in plasma (CSF/Cu,p) ratio (>0.2) than crizotinib and larotrectinib at steady state (both: CSF/Cu,p ~0.03). In vivo experiments validated the AP-ER approach. Entrectinib treatment resulted in strong tumor inhibition and full survival benefit in the intracranial tumor model at clinically relevant systemic exposures. Conclusions Entrectinib, unlike crizotinib and larotrectinib, is a weak P-gp substrate that can sustain CNS exposure based on our novel in vitro and in vivo experiments. This is consistent with the observed preclinical and clinical efficacy of entrectinib in neurotrophic tropomyosin receptor kinase (NTRK) and ROS1 fusion-positive CNS tumors and secondary CNS metastases.

scholarly journals Regulatory Functions of Serine-46-Phosphorylated HPr in Lactococcus lactis

2001 ◽  
Vol 183 (11) ◽  
pp. 3391-3398 ◽  
Author(s):  
Vicente Monedero ◽  
Oscar P. Kuipers ◽  
Emmanuel Jamet ◽  
Josef Deutscher
Keyword(s):  
Lactococcus Lactis ◽  
Inhibitory Effect ◽  
Wild Type ◽  
Phosphotransferase System ◽  
Inducer Exclusion ◽  
Gram Positive Bacteria ◽  
In Vivo Experiments ◽  
Regulatory Functions

ABSTRACT In most low-G+C gram-positive bacteria, the phosphoryl carrier protein HPr of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) becomes phosphorylated at Ser-46. This ATP-dependent reaction is catalyzed by the bifunctional HPr kinase/P-Ser-HPr phosphatase. We found that serine-phosphorylated HPr (P-Ser-HPr) of Lactococcus lactis participates not only in carbon catabolite repression of an operon encoding a β-glucoside-specific EII and a 6-P-β-glucosidase but also in inducer exclusion of the non-PTS carbohydrates maltose and ribose. In a wild-type strain, transport of these non-PTS carbohydrates is strongly inhibited by the presence of glucose, whereas in a ptsH1 mutant, in which Ser-46 of HPr is replaced with an alanine, glucose had lost its inhibitory effect. In vitro experiments carried out with L. lactis vesicles had suggested that P-Ser-HPr is also implicated in inducer expulsion of nonmetabolizable homologues of PTS sugars, such as methylβ-d-thiogalactoside (TMG) and 2-deoxy-d-glucose (2-DG). In vivo experiments with theptsH1 mutant established that P-Ser-HPr is not necessary for inducer expulsion. Glucose-activated 2-DG expulsion occurred at similar rates in wild-type and ptsH1 mutant strains, whereas TMG expulsion was slowed in the ptsH1 mutant. It therefore seems that P-Ser-HPr is not essential for inducer expulsion but that in certain cases it can play an indirect role in this regulatory process.

scholarly journals Asthenozoospermia in Mice with Targeted Deletion of the Sperm Mitochondrion-Associated Cysteine-Rich Protein (Smcp) Gene

2002 ◽  
Vol 22 (9) ◽  
pp. 3046-3052 ◽  
Author(s):  
Karim Nayernia ◽  
Ibrahim M. Adham ◽  
Elke Burkhardt-Göttges ◽  
Jürgen Neesen ◽  
Mandy Rieche ◽  
...  
Keyword(s):  
Semen Analysis ◽  
Computer Assisted ◽  
Microscopical Examination ◽  
Structural Protein ◽  
Wild Type ◽  
Vitro Fertilization ◽  
In Vivo Experiments ◽  
Cysteine Rich Protein

ABSTRACT The sperm mitochondria-associated cysteine-rich protein (SMCP) is a cysteine- and proline-rich structural protein that is closely associated with the keratinous capsules of sperm mitochondria in the mitochondrial sheath surrounding the outer dense fibers and axoneme. To investigate the function of SMCP, we generated mice with a targeted disruption of the gene Smcp by homologous recombination. Homozygous mutant males on a mixed genetic background (C57BL/6J × 129/Sv) are fully fertile, while they are infertile on the 129/Sv background, although spermatogenesis and mating are normal. Homozygous Smcp−/− female mice are fertile on both genetic backgrounds. Electron microscopical examination demonstrated normal structures of sperm head, mitochondria, and tail. In vivo experiments with sperm of Smcp−/− 129/Sv mice revealed that the migration of spermatozoa from the uterus into the oviduct is reduced. This result is supported by the observation that sperm motility as determined by the computer-assisted semen analysis system (CASA) is significantly affected as compared to wild-type spermatozoa. In vitro fertilization assays showed that Smcp-deficient spermatozoa are able to bind to the oocyte but that the number of fertilized eggs is reduced by more than threefold relative to the wild-type control. However, removal of the zona pellucida resulted in an unaffected sperm-egg fusion which was monitored by the presence of pronuclei and generation of blastocyts. These results indicate that the infertility of the male Smcp−/− mice on the 129/Sv background is due to reduced motility of the spermatozoa and decreased capability of the spermatozoa to penetrate oocytes.

scholarly journals Recombinant Listeria monocytogenes Expressing a Cell Wall-Associated Listeriolysin O Is Weakly Virulent but Immunogenic

2009 ◽  
Vol 77 (10) ◽  
pp. 4371-4382 ◽  
Author(s):  
Javier A. Carrero ◽  
Boris Calderon ◽  
Hector Vivanco-Cid ◽  
Emil R. Unanue
Keyword(s):  
Listeria Monocytogenes ◽  
Listeriolysin O ◽  
Wild Type ◽  
Positive Bacterium ◽  
Cell Responses ◽  
A Cell ◽  
Weakly Virulent

ABSTRACT Listeriolysin O (LLO) is an essential virulence factor for the gram-positive bacterium Listeria monocytogenes. Our goal was to determine if altering the topology of LLO would alter the virulence and toxicity of L. monocytogenes in vivo. A recombinant strain was generated that expressed a surface-associated LLO (sLLO) variant secreted at 40-fold-lower levels than the wild type. In culture, the sLLO strain grew in macrophages, translocated to the cytosol, and induced cell death. However, the sLLO strain showed decreased infectivity, reduced lymphocyte apoptosis, and decreased virulence despite a normal in vitro phenotype. Thus, the topology of LLO in L. monocytogenes was a factor in the pathogenesis of the infection and points to a role of LLO secretion during in vivo infection. The sLLO strain was cleared by severe combined immunodeficient (SCID) mice. Despite the attenuation of virulence, the sLLO strain was immunogenic and capable of eliciting protective T-cell responses.

A new adenylyl cyclase, putative disease-resistance RPP13-like protein 3, participates in abscisic acid-mediated resistance to heat stress in maize

2020 ◽  
Author(s):  
Hao Yang ◽  
Yulong Zhao ◽  
Ning Chen ◽  
Yanpei Liu ◽  
Shaoyu Yang ◽  
...  
Keyword(s):  
Heat Stress ◽  
Disease Resistance ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Wild Type ◽  
In Vivo Experiments ◽  
In The Wild ◽  
Shock Proteins

Abstract In plants, 3´,5´-cyclic adenosine monophosphate (cAMP) is an important second messenger with varied functions; however, only a few adenylyl cyclases (ACs) that synthesize cAMP have been identified. Moreover, the biological roles of ACs/cAMP in response to stress remain largely unclear. In this study, we used quantitative proteomics techniques to identify a maize heat-induced putative disease-resistance RPP13-like protein 3 (ZmRPP13-LK3), which has three conserved catalytic AC centres. The AC activity of ZmRPP13-LK3 was confirmed by in vitro enzyme activity analysis, in vivo RNAi experiments, and functional complementation in the E. coli cyaA mutant. ZmRPP13-LK3 is located in the mitochondria. The results of in vitro and in vivo experiments indicated that ZmRPP13-LK3 interacts with ZmABC2, a possible cAMP exporter. Under heat stress, the concentrations of ZmRPP13-LK3 and cAMP in the ABA-deficient mutant vp5 were significantly less than those in the wild-type, and treatment with ABA and an ABA inhibitor affected ZmRPP13-LK3 expression in the wild-type. Application of 8-Br-cAMP, a cAMP analogue, increased heat-induced expression of heat-shock proteins in wild-type plants and alleviated heat-activated oxidative stress. Taken together, our results indicate that ZmRPP13-LK3, a new AC, can catalyse ATP for the production of cAMP and may be involved in ABA-regulated heat resistance.

scholarly journals Intestinal P-glycoprotein Expression is Multimodally Regulated by Intestinal Ischemia-Reperfusion

2014 ◽  
Vol 17 (2) ◽  
pp. 266 ◽  
Author(s):  
Yusuke Terada ◽  
Jiro Ogura ◽  
Takashi Tsujimoto ◽  
Kaori Kuwayama ◽  
Takahiro Koizumi ◽  
...  
Keyword(s):  
Intestinal Ischemia ◽  
Ischemia Reperfusion ◽  
Tacrolimus Concentration ◽  
Glycoprotein P ◽  
In Vivo Experiments ◽  
P Glycoprotein ◽  
Blood Tacrolimus Concentration ◽  
Intestinal Ischemia Reperfusion

Purpose. Reactive oxygen species (ROS) have multiple physiological effects that are amount-dependent. ROS are one of the causes of intestinal ischemia-reperfusion (I/R) injury. In this study, we investigated whether the amount of ROS and the degree of intestinal I/R injury affect the expression level of P-glycoprotein (P-gp). Methods. We used hydrogen peroxide (H2O2) as ROS in in vitro experiments. Intestinal I/R model rats, which were subjected 15-min ischemia (I/R-15), were used in in vivo experiments. Results. P-gp expression in Caco-2 cells was increased in response to 1 µM of H2O2 but decreased upon exposure to 10 mM of H2O2. We previously reported that P-gp expression is decreased after intestinal I/R with 30-min ischemia (I/R-30), which time a large amount of ROS is generated. I/R-15 induced slightly less mucosal and oxidative injury than did I/R-30. P-gp expression in the jejunum was increased at 1 h after I/R-15, and ileal paracellular permeability was increased. The blood concentration of tacrolimus, a P-gp substrate, was lower during 0-20 min but was higher during 40-90 min post-administration compared with that in the sham-operated rats. P-gp expression in the ileum was decreased at 6 h after I/R-15, due to abnormal localization of P-gp, resulting in a high blood tacrolimus concentration in rats reperfused for 6 h. Conclusions. ROS multimodally regulate P-gp expression depending on its amount. This is important for understanding the pattern of P-gp expression after intestinal I/R. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

scholarly journals Listeria monocytogenes PerR Mutants Display a Small-Colony Phenotype, Increased Sensitivity to Hydrogen Peroxide, and Significantly Reduced Murine Virulence

2005 ◽  
Vol 71 (12) ◽  
pp. 8314-8322 ◽  
Author(s):  
Rosemarie Rea ◽  
Colin Hill ◽  
Cormac G. M. Gahan
Keyword(s):  
Listeria Monocytogenes ◽  
High Frequency ◽  
Transcriptional Analysis ◽  
Wild Type ◽  
Large Colony ◽  
In The Wild ◽  
Increased Sensitivity ◽  
Small Colony

ABSTRACT Deletion of perR in Listeria monocytogenes results in a small-colony phenotype (ΔperR sm) that is slow growing and exhibits increased sensitivity to H2O2. At a relatively high frequency, large-colony variants (ΔperR lg) arise, which are more resistant to H2O2 than the wild-type and ultimately dominate the culture. Transcriptional analysis revealed that the kat gene (catalase) is up-regulated in both types of mutants and that the highest level is apparent in ΔperR sm mutants, demonstrating PerR regulation of this gene. Overexpression of the catalase gene in the wild-type background resulted in a slower-growing strain with a smaller colony size similar to that of ΔperR sm. By combining a bioinformatic approach with experimental evidence, other PerR-regulated genes were identified, including fur, lmo0641, fri, lmo1604, hemA, and trxB. The transcriptional profile of these genes in both mutant backgrounds was similar to that of catalase in that a higher level of expression was observed in ΔperR sm than in the wild type or ΔperR lg. Murine studies revealed that the virulence potential of the ΔperR sm mutant is substantially reduced compared to that of the wild-type and ΔperR lg strains. Collectively, the data demonstrate that the ΔperR sm mutant represents the true phenotype associated with the absence of PerR, which is linked to overexpression of regulated genes that negatively affect bacterial homeostasis both in vitro and in vivo. A subsequent secondary mutation occurred at a high frequency, which resulted in phenotypic reversion to a large-colony phenotype with increased fitness that may have obstructed the analysis of the role of PerR in the physiology of the bacterial cell.

Characterization Of In Vitro Hdm2 E3 Ubiquitin Ligase-Mediated p53 Ubiquitination

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4903-4903
Author(s):  
Bradley B Brasher ◽  
Eduardo Guillen ◽  
Ivan Tomasic ◽  
Carsten Schwerdtfeger ◽  
Francesco D Melandri
Keyword(s):  
Transcriptional Activation ◽  
Cell Function ◽  
Ring Finger ◽  
Ubiquitin Ligases ◽  
Wild Type ◽  
Western Blots ◽  
Hematopoietic Stem ◽  
In Vivo Experiments

Abstract Double minute 2 protein (Mdm2, Hdm2 in humans) is a RING-finger Ubiquitin E3 Ligase that acts as a major regulator of the tumor suppressor protein p53. Mdm2 inhibits p53 -mediated cell cycle arrest and apoptosis by binding its transcriptional activation domain. The ligase activity of Mdm2 is responsible for the ubiquitination and subsequent proteasomal degradation of p53. Mdm2 also regulates its own intracellular levels by auto-ubiquitination, and can be SUMOylated, which reportedly decreases autoubiquitination activity but increases activity toward p53. Imbalances in the p53 pathway are frequently associated with hematologic disease states. Loss of p53 function is a driving force in leukemia and lymphoma in humans and mice, while increased p53 activity can inhibit hematopoietic stem cell function and contribute to myelodysplasia. Thus, careful control of p53 activity is critical for homeostasis. Most of our understanding of p53 function in hematopoiesis is derived from in vivo experiments using genetically modified mice (Pant V., et al, Blood. 2012; 120:5118-27). While this is a powerful system for elucidating genetic pathways that influence p53 activity, there is still much to learn about the mechanisms of p53 regulation at the enzymatic level. To facilitate studies in this area, we purified recombinant Hdm2 and p53 from E.coli and developed gel-based assays to monitor both autoubiquitination and ubiquitination of protein substrates. We observed rapid autoubiquitination of Hdm2 using both wild-type and lysine-less (K0) ubiquitin, though reactions containing the former generated significantly higher molecular weight Hdm2-ubiquitin adducts. Hdm2 ubiquitination of p53 produced a discrete, ladder-like banding pattern on Western Blots regardless of whether wild-type or K0 ubiquitin was included in the reaction. This suggests that the principal product of this defined Hdm2-p53 reaction is multi-monoubiquitinated p53, as opposed to p53 modified with polyubiquitin chains. Reactions using an alternative substrate yielded different results. Hdm2 ubiquitination of Angiocidin/S5a protein generated a large smeary pattern on Western Blots instead of discrete bands. This is consistent with the Hdm2-catalyzed polyubiquitination of S5a, demonstrating that ubiquitin ligases are capable of generating different in vitro ubiquitination patterns that are dependent on the substrate utilized in the assay. These results suggest that care must be taken in experimental designs, particularly with respect to substrate and assay read out. Finally, recombinant UBE4B was included in Mdm2/p53 reactions to test the recently reported E4-ligase activity of this enzyme. Ultimately these reagents should prove useful for fully defined, in vitro studies investigating the interactions between p53 and the ubiquitin ligases and deubiquitinases that modify it in normal and diseased cellular states. Disclosures: Brasher: Boston Biochem Inc: Employment. Guillen:Boston Biochem Inc: Employment. Tomasic:Boston Biochem Inc: Employment. Schwerdtfeger:Boston Biochem Inc: Employment. Melandri:Boston Biochem Inc: Employment.

scholarly journals Listeria monocytogenes Infection in Caspase-11-Deficient Mice

2002 ◽  
Vol 70 (5) ◽  
pp. 2657-2664 ◽  
Author(s):  
Nicolas J. Mueller ◽  
Robert A. Wilkinson ◽  
Jay A. Fishman
Keyword(s):  
Immune Response ◽  
Listeria Monocytogenes ◽  
Survival Rates ◽  
Intraperitoneal Administration ◽  
Cytokine Signaling ◽  
Wild Type ◽  
Alternative Pathways ◽  
Similar Survival

ABSTRACT Caspase-11 (Cas11) is a cysteine protease involved in programmed cell death and cytokine maturation. Through activation of Cas1 (interleukin-1β [IL-1β]-converting enzyme), Cas11 is directly involved in the maturation of IL-1β and IL-18. Apoptosis is mediated through Cas3. Given the role of apoptosis and cytokine signaling during the innate immune response in intracellular infection, we examined Cas11-deficient (Cas11−/−) mice during infection with Listeria monocytogenes. Cas11−/− and wild-type C57BL/6 mice were equally susceptible to intravenous infection with L. monocytogenes, resulting in similar bacterial burdens in tissue and similar survival rates. By contrast, enhanced susceptibility was observed in control mice on a mixed genetic 129/C57BL/DBA2 background. Cas11−/− and wild-type mice infected with Listeria had similar hepatic microabscess formation in terms of histologic appearance, size, and number. Apoptosis of L. monocytogenes-infected hepatocytes in vivo and in vitro in primary culture was not altered by the absence of Cas11. Serum IL-18 and IL-1β levels were similar in Cas11−/− mice and controls. Endotoxin (lipopolysaccharide [LPS])-challenged Cas11−/− mice were deficient in the production of gamma interferon. IL-1β responses in Cas11−/− were normal with intravenous administration of LPS but decreased with intraperitoneal administration. Our findings suggest that Cas11 deficiency does not impair the immune response to infection with L. monocytogenes. Apoptosis and maturation of IL-18 and IL-1β were normal despite Cas11 deficiency. LPS-induced proinflammatory pathways are altered by the absence of Cas11. While Cas11-mediated Cas1 and Cas3 activation is crucial for cytokine maturation and apoptosis during inflammation, alternative pathways allow normal inflammatory and apoptotic responses during infection with L. monocytogenes.

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