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Scientific Reports Feb 2024While antibiotic resistance poses a threat from both Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), GNB pose a more imminent public health hazard...
While antibiotic resistance poses a threat from both Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), GNB pose a more imminent public health hazard globally. GNB are a threat to growing antibiotic resistance because of the complex makeup of the membrane. The AcrAB-TolC efflux pump is a known resistance mechanism of Escherichia coli (E. coli) cells. This study utilized molecular dynamics modeling to visualize some of the changes occurring at a molecular level when airborne bacteria are exposed to stress and antibiotics. This study was conducted to build upon previous experimental research showing that there is an increase in antibiotic resistance and efflux pump activity when exposed to aerosolization. AcrB and AcrAB-TolC proteins were simulated under standard and increased pressure to compare the effect of aerosolization on the binding to the three different antibiotics (puromycin (PUY), ampicillin (AMP) and sulfamethoxazole-trimethoprim (SXT)) to the AcrB binding site. Analysis such as root-mean-square deviation of atomic positions and root-mean-square fluctuation, the opening of TolC, and the significant molecular mechanics with generalized Born and surface area solvation (MM-GBSA) scores associated with specific ligands were recorded. Resistance in experimental data indicated a relationship between the docking scores and some ligand-protein interactions. Results showed that there was more flexibility in the proteins within simulations conducted under standard pressure for the AcrB protein and the full tripartite complex AcrAB-TolC, showing that increased pressure causes more rigidity. MM-GBSA scores, used to calculate the free energy of ligand-protein binding, did not show a significant change, but interestingly, the strongest MM-GBSA scores were for ligands that moved to another binding pocket and did not result in resistance or opening of the efflux pump. However, the ligand moved from the binding site and did not cause the opening of TolC to increase significantly, whereas PUY and AMP were bound to the binding site for the duration of all simulations. AMP ligands under increased pressure showed the largest change in opening of the TolC efflux pump and aligns with experimental data showing E. coli cells had the most resistance to AMP after aerosolization. These results, in addition to other real-time changes such as OM proteins and mutations of targets within the cell, could be used to delineate and mitigate antibiotic resistance mechanisms.
Topics: Escherichia coli; Anti-Bacterial Agents; Escherichia coli Proteins; Membrane Transport Proteins; Molecular Dynamics Simulation; Ligands; Bacterial Outer Membrane Proteins; Multidrug Resistance-Associated Proteins; Carrier Proteins
PubMed: 38302495
DOI: 10.1038/s41598-024-52536-z -
Circulation Research Feb 2024The sympathoadrenergic system and its major effector PKA (protein kinase A) are activated to maintain cardiac output coping with physiological or pathological stressors....
BACKGROUND
The sympathoadrenergic system and its major effector PKA (protein kinase A) are activated to maintain cardiac output coping with physiological or pathological stressors. If and how PKA plays a role in physiological cardiac hypertrophy (PhCH) and pathological CH (PaCH) are not clear.
METHODS
Transgenic mouse models expressing the PKA inhibition domain (PKAi) of PKA inhibition peptide alpha (PKIalpha)-green fluorescence protein (GFP) fusion protein (PKAi-GFP) in a cardiac-specific and inducible manner (cPKAi) were used to determine the roles of PKA in physiological CH during postnatal growth or induced by swimming, and in PaCH induced by transaortic constriction (TAC) or augmented Ca influx. Kinase profiling was used to determine cPKAi specificity. Echocardiography was used to determine cardiac morphology and function. Western blotting and immunostaining were used to measure protein abundance and phosphorylation. Protein synthesis was assessed by puromycin incorporation and protein degradation by measuring protein ubiquitination and proteasome activity. Neonatal rat cardiomyocytes (NRCMs) infected with AdGFP (GFP adenovirus) or AdPKAi-GFP (PKAi-GFP adenovirus) were used to determine the effects and mechanisms of cPKAi on myocyte hypertrophy. rAAV9.PKAi-GFP was used to treat TAC mice.
RESULTS
(1) cPKAi delayed postnatal cardiac growth and blunted exercise-induced PhCH; (2) PKA was activated in hearts after TAC due to activated sympathoadrenergic system, the loss of endogenous PKIα (PKA inhibition peptide α), and the stimulation by noncanonical PKA activators; (3) cPKAi ameliorated PaCH induced by TAC and increased Ca influxes and blunted neonatal rat cardiomyocyte hypertrophy by isoproterenol and phenylephrine; (4) cPKAi prevented TAC-induced protein synthesis by inhibiting mTOR (mammalian target of rapamycin) signaling through reducing Akt (protein kinase B) activity, but enhancing inhibitory GSK-3α (glycogen synthase kinase-3α) and GSK-3β signals; (5) cPKAi reduced protein degradation by the ubiquitin-proteasome system via decreasing RPN6 phosphorylation; (6) cPKAi increased the expression of antihypertrophic atrial natriuretic peptide (ANP); (7) cPKAi ameliorated established PaCH and improved animal survival.
CONCLUSIONS
Cardiomyocyte PKA is a master regulator of PhCH and PaCH through regulating protein synthesis and degradation. cPKAi can be a novel approach to treat PaCH.
Topics: Mice; Rats; Animals; Proteasome Endopeptidase Complex; Cyclic AMP-Dependent Protein Kinases; Glycogen Synthase Kinase 3 beta; Cardiomegaly; Myocytes, Cardiac; Mice, Transgenic; Peptides; Mammals
PubMed: 38275112
DOI: 10.1161/CIRCRESAHA.123.322729 -
Frontiers in Chemistry 2023Microbial secondary metabolites have shown promise as a source of novel antimicrobial agents. In this study, we aimed to isolate, characterize, and evaluate the...
Microbial secondary metabolites have shown promise as a source of novel antimicrobial agents. In this study, we aimed to isolate, characterize, and evaluate the antimicrobial activity of compound from a novel strain MS38. The objective was to identify a potential bioactive compound with broad-spectrum antimicrobial properties. The isolated strain MS38 on starch casein agar was characterized using morphological, physiological, and molecular identification techniques. The compound was obtained from the fermented broth through extraction with n-butanol and further purification using silica gel column chromatography and high-performance liquid chromatography (HPLC). Structural elucidation was conducted using Ultraviolet (UV), Infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS) techniques. The antimicrobial activity was evaluated using the agar well diffusion method and the microplate Alamar blue assay (MABA). The isolated strain MS38 was identified as novel based on morphological characteristics and confirmed by 16S sequences analysis and MALDI-TOF MS. The compound obtained from the fermented broth exhibited substantial antimicrobial activity against a variety of pathogenic bacteria and fungi. Structural analysis revealed a complex chemical structure with characteristic functional groups indicative of potential antimicrobial properties. The compound demonstrated strong activity against both Gram-positive ( Spp.) and Gram-negative ( and ) bacteria, as well as fungi, including and . This study successfully isolated and characterized a bioactive compound from a novel MS38. The compound exhibited significant antimicrobial activity against a range of pathogenic microorganisms. These findings underscore the importance of exploring microbial biodiversity for the discovery of novel antimicrobial agents. This study contributes to the growing knowledge of microbial secondary metabolites with potential therapeutic value.
PubMed: 38264123
DOI: 10.3389/fchem.2023.1326328 -
BioRxiv : the Preprint Server For... Jan 2024There is tremendous interest in the production of recombinant proteins, particularly bispecific antibodies and antibody-drug conjugates for research and therapeutic use....
There is tremendous interest in the production of recombinant proteins, particularly bispecific antibodies and antibody-drug conjugates for research and therapeutic use. Here, we demonstrate a highly versatile plasmid system that allows rapid generation of stable Expi293 cell pools by episomal retention of transfected DNA. By linking protein expression to puromycin resistance though an attenuated internal ribosome entry site, we achieve stable cell pools producing proteins of interest. In addition, split intein-split puromycin-mediated selection of two separate protein expression cassettes allows the stable production of bispecific antibody-like molecules or antibodies with distinct C-terminal heavy chain modifications, such as an antigen on one chain and a sortase tag on the other chain. We also use this novel expression system to generate stable Expi293 cell pools that secrete sortase A Δ59 variant Srt4M. Using these reagents, we prepared a site-specific drug-to-antibody ratio of 1 antibody-siRNA conjugate. We anticipate the simple, robust, and rapid stable protein expression systems described here being useful for a wide variety of applications.
PubMed: 38260603
DOI: 10.1101/2024.01.03.574076 -
Blood Advances Mar 2024Mechanisms of proteostasis in anucleate circulating platelets are unknown and may regulate platelet function. We investigated the hypothesis that plasma-borne growth...
Mechanisms of proteostasis in anucleate circulating platelets are unknown and may regulate platelet function. We investigated the hypothesis that plasma-borne growth factors/hormones (GFHs) maintain constitutive translation in circulating platelets to facilitate reactivity. Bio-orthogonal noncanonical amino acid tagging (BONCAT) coupled with liquid chromatography-tandem mass spectrometry analysis revealed constitutive translation of a broad-spectrum translatome in human platelets dependent upon plasma or GFH exposure, and in murine circulation. Freshly isolated platelets from plasma showed homeostatic activation of translation-initiation signaling pathways: phosphorylation of p38/ERK upstream kinases, essential intermediate MNK1/2, and effectors eIF4E/4E-BP1. Plasma starvation led to loss of pathway phosphorylation, but it was fully restored with 5-minute stimulation by plasma or GFHs. Cycloheximide or puromycin infusion suppressed ex vivo platelet GpIIb/IIIa activation and P-selectin exposure with low thrombin concentrations and low-to-saturating concentrations of adenosine 5'-diphosphate (ADP) or thromboxane analog but not convulxin. ADP-induced thromboxane generation was blunted by translation inhibition, and secondary-wave aggregation was inhibited in a thromboxane-dependent manner. Intravenously administered puromycin reduced injury-induced clot size in cremaster muscle arterioles, and delayed primary hemostasis after tail tip amputation but did not delay neither final hemostasis after subsequent rebleeds, nor final hemostasis after jugular vein puncture. In contrast, these mice were protected from injury-induced arterial thrombosis and thrombin-induced pulmonary thromboembolism (PE), and adoptive transfer of translation-inhibited platelets into untreated mice inhibited arterial thrombosis and PE. Thus, constitutive plasma GFH-driven translation regulates platelet G protein-coupled receptor reactivity to balance hemostasis and thrombotic potential.
Topics: Mice; Humans; Animals; Platelet Aggregation; Thrombin; Thrombosis; Thromboxanes; Puromycin
PubMed: 38163324
DOI: 10.1182/bloodadvances.2023011734 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Dec 2023With the rapid development of gene editing technology, the study of spermatogonial stem cells (SSCs) holds great significance in understanding spermatogenesis and its...
With the rapid development of gene editing technology, the study of spermatogonial stem cells (SSCs) holds great significance in understanding spermatogenesis and its regulatory mechanism, developing transgenic animals, gene therapy, infertility treatment and protecting rare species. Biogenesis of lysosome-related organelles complex 1 subunit 1 () is believed to have anti-brucella potential. Exploring the impack of on goat SSCs not only helps investigate the ability of to promote SSCs proliferation, but also provides a cytological basis for disease-resistant breeding research. In this study, a overexpression vector was constructed by homologous recombination. The overexpression cell line of goat spermatogonial stem cells was successfully constructed by lentivirus packaging, transfection and puromycin screening. The overexpression efficiency of was found to be 18 times higher using real time quantitative PCR (RT-qPCR). Furthermore, the results from cell growth curve analysis, flow cytometry for cell cycle detection, and 5-ethynyl-2'-deoxyuridine (EdU) staining showed that significantly increased the proliferation activity of goat SSCs. The results of RT-qPCR, immunofluorescence staining and Western blotting analyses revealed up-regulation of proliferation-related genes (, , ), and , a key gene regulating the proliferation of spermatogonial stem cells. These findings strongly suggest that the proliferative ability of goat SSCs can be enhanced through the EIF2S3Y/ERK pathway. In summary, this study successfully created a goat spermatogonial stem cell overexpression cell line, which exhibited improved proliferation ability. This research laid the groundwork for exploring the regulatory role of in goat spermatogonia and provided a cell platform for further study into the biological function of . These findings also establish a foundation for breeding overexpressing goats.
Topics: Animals; Male; Goats; Stem Cells; Spermatogonia; Cell Proliferation; Flow Cytometry; Testis
PubMed: 38147990
DOI: 10.13345/j.cjb.230570 -
BioRxiv : the Preprint Server For... Dec 2023Protein synthesis is a core cellular process, necessary throughout the complex lifecycle of parasites, thus specific translation inhibitors would be a valuable class of...
Protein synthesis is a core cellular process, necessary throughout the complex lifecycle of parasites, thus specific translation inhibitors would be a valuable class of antimalarial drugs, capable of both treating symptomatic infections in the blood and providing chemoprotection by targeting the initial parasite population in the liver, preventing both human disease and parasite transmission back to the mosquito host. As increasing numbers of antiplasmodial compounds are identified that converge mechanistically at inhibition of cytoplasmic translation, regardless of molecular target or mechanism, it would be useful to gain deeper understanding of how their effectiveness as liver stage translation inhibitors relates to their chemoprotective potential. Here, we probed that relationship using the -HepG2 liver stage infection model. Using o-propargyl puromycin-based labeling of the nascent proteome in infected HepG2 monolayers coupled with automated confocal feedback microscopy to generate unbiased, single parasite image sets of liver stage translation, we determined translation inhibition EC for five compounds, encompassing parasite-specific aminoacyl tRNA synthetase inhibitors, compounds targeting the ribosome in both host and parasite, as well as DDD107498, which targets eEF2, and is a leading antimalarial candidate compound being clinically developed as cabamiquine. Compounds were then tested at equivalent effective concentrations to compare the parasite response to, and recovery from, a brief period of translation inhibition in early schizogony, with parasites followed up to 120 hours post-infection to assess liver stage antiplasmodial effects of the treatment. Our data conclusively show that translation inhibition efficacy does not determine a translation inhibitor's antiplasmodial efficacy. DDD107498 was the least effective translation inhibitor, yet exerted the strongest antimalarial effects at both 5x- and 10x EC concentrations. We show compound-specific heterogeneity in single parasite and population responses to translation inhibitor treatment, with no single metric strongly correlated to release of hepatic merozoites for all compound, demonstrate that DDD107498 is capable of exerting antiplasmodial effects on translationally arrested liver stage parasites, and uncover unexpected growth dynamics during the liver stage. Our results demonstrate that translation inhibition efficacy cannot function as a proxy for antiplasmodial effectiveness, and highlight the importance of exploring the ultimate, as well as proximate, mechanisms of action of these compounds on liver stage parasites.
PubMed: 38106175
DOI: 10.1101/2023.12.07.570699 -
Liver Cancer Dec 2023Complete resection is the only possible treatment for cholangiocarcinoma in the extrahepatic biliary tree (eCCA), although current imaging modalities are limited in...
INTRODUCTION
Complete resection is the only possible treatment for cholangiocarcinoma in the extrahepatic biliary tree (eCCA), although current imaging modalities are limited in their ability to accurately diagnose longitudinal spread. We aimed to develop fluorescence imaging techniques for real-time identification of eCCA using an enzyme-activatable probe, which emits fluorescence immediately after activation by a cancer-specific enzyme.
METHODS
Using lysates and small tissue fragments collected from surgically resected specimens, we selected the most specific probe for eCCA from among 800 enzyme-activatable probes. The selected probe was directly sprayed onto resected specimens and fluorescence images were acquired; these images were evaluated for diagnostic accuracy. We also comprehensively searched for enzymes that could activate the probe, then compared their expression levels in cancer and non-cancer tissues.
RESULTS
Analyses of 19 samples (four cancer lysates, seven non-cancer lysates, and eight bile samples) and 54 tissue fragments (13 cancer tissues and 41 non-cancer tissues) revealed that PM-2MeSiR was the most specific fluorophore for eCCA. Fluorescence images of 7 patients were obtained; these images enabled rapid identification of cancerous regions, which closely matched histopathology findings in 4 patients. Puromycin-sensitive aminopeptidase was identified as the enzyme that might activate the probe, and its expression was upregulated in eCCA.
CONCLUSION
Fluorescence imaging with PM-2MeSiR, which may be activated by puromycin-sensitive aminopeptidase, yielded generally high accuracy. This technique may be useful for real-time identification of the spread of eCCA during surgery and endoscopic examinations.
PubMed: 38058421
DOI: 10.1159/000530645 -
Journal of Experimental & Clinical... Dec 2023Colorectal cancer (CRC) is one of the most common malignancies and is characterized by reprogrammed metabolism. Ferroptosis, a programmed cell death dependent on iron,...
BACKGROUND
Colorectal cancer (CRC) is one of the most common malignancies and is characterized by reprogrammed metabolism. Ferroptosis, a programmed cell death dependent on iron, has emerged as a promising strategy for CRC treatment. Although small nucleolar RNAs are extensively involved in carcinogenesis, it is unclear if they regulate ferroptosis during CRC pathogenesis.
METHODS
The dysregulated snoRNAs were identified using published sequencing data of CRC tissues. The expression of the candidate snoRNAs, host gene and target gene were assessed by real-time quantitative PCR (RT-qPCR), fluorescence in situ hybridization (FISH), immunohistochemistry (IHC) and western blots. The biological function of critical molecules was investigated using in vitro and in vivo strategies including Cell Counting Kit-8 (CCK8), colony formation assay, flow cytometry, Fe/Fe, GSH/GSSG and the xenograft mice models. The ribosomal activities were determined by polysome profiling and O-propargyl-puromycin (OP-Puro) assay. The proteomics was conducted to clarify the downstream targets and the underlying mechanisms were validated by IHC, Pearson correlation analysis, protein stability and rescue assays. The clinical significance of the snoRNA was explored using the Cox proportional hazard model, receiver operating characteristic (ROC) and survival analysis.
RESULTS
Here, we investigated the SNORA56, which was elevated in CRC tissues and plasma, and correlated with CRC prognosis. SNORA56 deficiency in CRC impaired proliferation and triggered ferroptosis, resulting in reduced tumorigenesis. Mechanistically, SNORA56 mediated the pseudouridylation of 28 S rRNA at the U1664 site and promoted the translation of the catalytic subunit of glutamate cysteine ligase (GCLC), an indispensable rate-limiting enzyme in the biosynthesis of glutathione, which can inhibit ferroptosis by suppressing lipid peroxidation.
CONCLUSIONS
Therefore, the SNORA56/28S rRNA/GCLC axis stimulates CRC progression by inhibiting the accumulation of cellular peroxides, and it may provide biomarker and therapeutic applications in CRC.
Topics: Animals; Humans; Mice; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Ferroptosis; Glutamate-Cysteine Ligase; In Situ Hybridization, Fluorescence; RNA, Ribosomal; RNA, Small Nuclear
PubMed: 38049865
DOI: 10.1186/s13046-023-02906-8 -
Nephrology, Dialysis, Transplantation :... Jun 2024Glucocorticoids are the treatment of choice for proteinuric patients with minimal change disease (MCD) and primary focal segmental glomerulosclerosis (FSGS)....
BACKGROUND
Glucocorticoids are the treatment of choice for proteinuric patients with minimal change disease (MCD) and primary focal segmental glomerulosclerosis (FSGS). Immunosuppressive as well as direct effects on podocytes are believed to mediate their actions. In this study, we analyzed the anti-proteinuric effects of inhibition of the glucocorticoid receptor (GR) in glomerular epithelial cells, including podocytes.
METHODS
We employed genetic and pharmacological approaches to inhibit the GR. Genetically, we used Pax8-Cre/GRfl/fl mice to specifically inactivate the GR in kidney epithelial cells. Pharmacologically, we utilized a glucocorticoid antagonist called mifepristone.
RESULTS
Genetic inactivation of GR, specifically in kidney epithelial cells, using Pax8-Cre/GRfl/fl mice, ameliorated proteinuria following protein overload. We further tested the effects of pharmacological GR inhibition in three models and species: the puromycin aminonucleoside-induced nephrosis model in rats, the protein overload model in mice and the inducible transgenic NTR/MTZ zebrafish larvae with specific and reversible podocyte injury. In all three models, both pharmacological GR activation and inhibition consistently and significantly ameliorated proteinuria. Additionally, we translated our findings to humans, where three nephrotic adult patients with MCD or primary FSGS with contraindications or insufficient responses to corticosteroids were treated with mifepristone. This treatment resulted in a clinically relevant reduction of proteinuria.
CONCLUSIONS
Thus, across multiple species and proteinuria models, both genetic and pharmacological GR inhibition was at least as effective as pronounced GR activation. While the mechanism remains perplexing, GR inhibition may be a novel and targeted therapeutic approach to treat glomerular proteinuria potentially bypassing adverse actions of steroids.
Topics: Animals; Receptors, Glucocorticoid; Mice; Proteinuria; Humans; Rats; Podocytes; Zebrafish; Male; Mifepristone; Disease Models, Animal; Glomerulosclerosis, Focal Segmental; Female; Kidney Diseases; Puromycin Aminonucleoside; Hormone Antagonists; Nephrosis, Lipoid; Mice, Inbred C57BL; Mice, Transgenic
PubMed: 38037533
DOI: 10.1093/ndt/gfad254