scholarly journals Structure-guided disruption of pseudopilus tip inhibits Type II secretion in Pseudomonas aeruginosa

2018 ◽  
Author(s):  
Zongchao Jia ◽  
Yichen Zhang ◽  
Frederick Faucher ◽  
Wenwen Zhang ◽  
Shu Wang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Function Analysis ◽  
Type Ii Secretion ◽  
Type Ii ◽  
Core Complex ◽  
Wide Range ◽  
Interaction Interface ◽  
And Function

Pseudomonas aeruginosa utilizes the Type II secretion system (T2SS) to translocate a wide range of large, structured protein virulence factors through the periplasm to the extracellular environment for infection. In the T2SS, five pseudopilins assemble into the pseudopilus that acts as a piston to extrude exoproteins out of cells. Through structure determination of the pseudopilin complexes of XcpVWX and XcpVW and function analysis, we have confirmed that two minor pseudopilins, XcpV and XcpW, constitute a core complex indispensable to the pseudopilus tip. The absence of either XcpV or -W resulted in the non-functional T2SS. Our small-angle X-ray scattering experiment for the first time revealed the architecture of the entire pseudopilus tip and established the working model. Based on the interaction interface of complexes, we have developed inhibitory peptides. The structure-based peptides not only disrupted of the XcpVW core complex and the entire pseudopilus tip in vitro but also inhibited the T2SS in vivo. More importantly, these peptides effectively reduced the virulence of P. aeruginosa towards Caenorhabditis elegans.

scholarly journals hPSC-Derived Enteric Ganglioids Model Human ENS Development and Function

2022 ◽  
Author(s):  
Homa Majd ◽  
Ryan M Samuel ◽  
Jonathan T Ramirez ◽  
Ali Kalantari ◽  
Kevin Barber ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Xenograft Model ◽  
Developmental Relationships ◽  
Drug Candidates ◽  
Effective Strategies ◽  
Wide Range ◽  
Functional Features ◽  
And Function

The enteric nervous system (ENS) plays a central role in gut physiology and mediating the crosstalk between the gastrointestinal (GI) tract and other organs. The human ENS has remained elusive, highlighting the need for an in vitro modeling and mapping blueprint. Here we map out the developmental and functional features of the human ENS, by establishing robust and scalable 2D ENS cultures and 3D enteric ganglioids from human pluripotent stem cells (hPSCs). These models recapitulate the remarkable neuronal and glial diversity found in primary tissue and enable comprehensive molecular analyses that uncover functional and developmental relationships within these lineages. As a salient example of the power of this system, we performed in-depth characterization of enteric nitrergic neurons (NO neurons) which are implicated in a wide range of GI motility disorders. We conducted an unbiased screen and identified drug candidates that modulate the activity of NO neurons and demonstrated their potential in promoting motility in mouse colonic tissue ex vivo. We established a high-throughput strategy to define the developmental programs involved in NO neuron specification and discovered that PDGFR inhibition boosts the induction of NO neurons in enteric ganglioids. Transplantation of these ganglioids in the colon of NO neuron-deficient mice results in extensive tissue engraftment, providing a xenograft model for the study of human ENS in vivo and the development of cell-based therapies for neurodegenerative GI disorders. These studies provide a framework for deciphering fundamental features of the human ENS and designing effective strategies to treat enteric neuropathies.  

scholarly journals Role of Exosomes in Islet Transplantation

2021 ◽  
Vol 12 ◽  
Author(s):  
Jordan Mattke ◽  
Srividya Vasu ◽  
Carly M. Darden ◽  
Kenjiro Kumano ◽  
Michael C. Lawrence ◽  
...  
Keyword(s):  
Islet Transplantation ◽  
Graft Function ◽  
Pancreatic Islet Transplantation ◽  
Complex Molecules ◽  
Wide Range ◽  
And Function ◽  
Antigen Presenting

Exosomes are known for their ability to transport nucleic acid, lipid, and protein molecules, which allows for communication between cells and tissues. The cargo of the exosomes can have a variety of effects on a wide range of targets to mediate biological function. Pancreatic islet transplantation is a minimally invasive cell replacement therapy to prevent or reverse diabetes mellitus and is currently performed in patients with uncontrolled type 1 diabetes or chronic pancreatitis. Exosomes have become a focus in the field of islet transplantation for the study of diagnostic markers of islet cell viability and function. A growing list of miRNAs identified from exosomes collected during the process of isolating islets can be used as diagnostic biomarkers of islet stress and damage, leading to a better understanding of critical steps of the isolation procedure that can be improved to increase islet yield and quality. Exosomes have also been implicated as a possible contributor to islet graft rejection following transplantation, as they carry donor major histocompatibility complex molecules, which are then processed by recipient antigen-presenting cells and sensed by the recipient immune cells. Exosomes may find their way into the therapeutic realm of islet transplantation, as exosomes isolated from mesenchymal stem cells have shown promising results in early studies that have seen increased viability and functionality of isolated and grafted islets in vitro as well as in vivo. With the study of exosomes still in its infancy, continued research on the role of exosomes in islet transplantation will be paramount to understanding beta cell regeneration and improving long-term graft function.

scholarly journals In vivo activity of human-simulated regimens of imipenem alone and in combination with relebactam against Pseudomonas aeruginosa in the murine thigh infection model

2020 ◽  
Author(s):  
Sergio Reyes ◽  
Kamilia Abdelraouf ◽  
David P Nicolau
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clinical Utility ◽  
Infection Model ◽  
Treatment Groups ◽  
Log Reduction ◽  
Wide Range ◽  
To Receive ◽  
Inhibitor Combination

Abstract Background Imipenem/relebactam is a carbapenem/β-lactamase inhibitor combination with in vitro activity against Pseudomonas aeruginosa and Enterobacterales, including KPC producers. Objectives To provide translational data to support the clinical utility of the imipenem/relebactam 500/250 mg q6h regimen using a human-simulated regimen (HSR) of imipenem/relebactam, compared with imipenem alone, against a phenotypically and genotypically diverse population of P. aeruginosa. Methods Twenty-nine P. aeruginosa isolates, including KPC (n = 6), PDC (n = 9), PAO (n = 4), GES (n = 5) and VIM (n = 1) producers, were used for the in vivo efficacy studies. Neutropenic mice were thigh-inoculated and randomized to receive HSRs of either imipenem 500 mg q6h, imipenem 1 g q8h, imipenem/relebactam 500/250 mg q6h or saline. Results Twenty-seven of the 29 isolates examined were imipenem resistant, with 24/29 isolates showing imipenem MICs of ≥32 mg/L. The addition of relebactam decreased the MICs up to 64-fold; imipenem/relebactam MICs ranged from 0.25 to >32 mg/L. Efficacies of the imipenem monotherapies and the imipenem/relebactam therapy were comparable for the two imipenem-susceptible organisms. Among the imipenem-resistant isolates, an increased mean growth was observed in the imipenem 500 mg q6h HSR and 1 g q8h HSR treatment groups of 1.31 ± 1.01 and 0.18 ± 1.67 log10 cfu/thigh, respectively. In contrast, a ≥2 log reduction in bacterial density was observed in 27/29 (93%) of the imipenem-resistant isolates subjected to imipenem/relebactam 500/250 mg q6h HSR. Conclusions The imipenem/relebactam 500/250 mg q6h HSR demonstrated superior in vivo activity compared with the conventionally employed imipenem regimens against MDR P. aeruginosa over a wide range of imipenem/relebactam MICs.

scholarly journals A peptide targeting an interaction interface disrupts the dopamine D1‐D2 receptor heteromer to block signaling and function in vitro and in vivo: effective selective antagonism

2014 ◽  
Vol 28 (11) ◽  
pp. 4806-4820 ◽  
Author(s):  
Ahmed Hasbi ◽  
Melissa L. Perreault ◽  
Maurice Y. F. Shen ◽  
Lucia Zhang ◽  
Ryan To ◽  
...  
Keyword(s):  
D2 Receptor ◽  
Interaction Interface ◽  
And Function ◽  
Peptide Targeting

Three Types of Hereditary Antiterombin III Deficiency

1979 ◽  
Author(s):  
I. Nagy ◽  
H. Losonczy
Keyword(s):  
Antithrombin Iii ◽  
Clinical Signs ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Basic Activity ◽  
At Iii ◽  
And Function

The authors detected in the last seven years 15 patients with hereditary antithrombin III/AT III/ abnormality. All of them had typical clinical signs of recurrent arterious and venous thromboembolie. The abnormality inherited as an autosomal trait. Three types of the abnormality could be observed. In Type I both quantity and function of AT III were extremely decreased. In type II AT III is normal in quantity but abnormal in function. In Type III AT III is quantitatively normal and also its function seems normal as far as its basic activity is concerned /activity measured in absence of heparin/, but its abnormality becomes manifest in the presence of heparin in vitro/and also in vivo/. 5 of the patients belonged to Type I, 4 to Type II and 6 to Type III. In 60 examined family members of the 15 patients an abnormal AT III could be observed in 44, clinical signs in 23.The examination of AT III activity in the presence of a given amount of heparin ia of great importance in recognition of the different types of antithrombin III abnormalities.

scholarly journals Non-Canonical G-quadruplexes cause the hCEB1 minisatellite instability in Saccharomyces cerevisiae

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Aurèle Piazza ◽  
Xiaojie Cui ◽  
Michael Adrian ◽  
Frédéric Samazan ◽  
Brahim Heddi ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Structure Function ◽  
Genomic Instability ◽  
Function Analysis ◽  
Structural Features ◽  
Detectable Effect ◽  
Definition Of ◽  
And Function

G-quadruplexes (G4) are polymorphic four-stranded structures formed by certain G-rich nucleic acids in vitro, but the sequence and structural features dictating their formation and function in vivo remains uncertain. Here we report a structure-function analysis of the complex hCEB1 G4-forming sequence. We isolated four G4 conformations in vitro, all of which bear unusual structural features: Form 1 bears a V-shaped loop and a snapback guanine; Form 2 contains a terminal G-triad; Form 3 bears a zero-nucleotide loop; and Form 4 is a zero-nucleotide loop monomer or an interlocked dimer. In vivo, Form 1 and Form 2 differently account for 2/3rd of the genomic instability of hCEB1 in two G4-stabilizing conditions. Form 3 and an unidentified form contribute to the remaining instability, while Form 4 has no detectable effect. This work underscores the structural polymorphisms originated from a single highly G-rich sequence and demonstrates the existence of non-canonical G4s in cells, thus broadening the definition of G4-forming sequences.

scholarly journals In Vitro and In Vivo Assessment of the Efficacy of Bromoageliferin, an Alkaloid Isolated from the Sponge Agelas dilatata, against Pseudomonas aeruginosa

Marine Drugs ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 326
Author(s):  
Dawrin Pech-Puch ◽  
Mar Pérez-Povedano ◽  
Marta Martinez-Guitian ◽  
Cristina Lasarte-Monterrubio ◽  
Juan Carlos Vázquez-Ucha ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Carboxylic Acid ◽  
Galleria Mellonella ◽  
Biological Activities ◽  
Marine Sponges ◽  
In Vitro Assays ◽  
Significant Activity ◽  
Wide Range

The pyrrole-imidazoles, a group of alkaloids commonly found in marine sponges belonging to the genus Agelas, display a wide range of biological activities. Herein, we report the first chemical study of the secondary metabolites of the sponge A. dilatata from the coastal area of the Yucatan Peninsula (Mexico). In this study, we isolated eight known alkaloids from an organic extract of the sponge. We used NMR and MS analysis and comparison with existing databases to characterize the alkaloids: ageliferin (1), bromoageliferin (2), dibromoageliferin (3), sceptrin (4), nakamuric acid (5), 4-bromo-1H-pyrrole-2-carboxylic acid (6), 4,5-dibromopyrrole-2-carboxylic acid (7) and 3,7-dimethylisoguanine (8). We also evaluated, for the first time, the activity of these alkaloids against the most problematic multidrug-resistant (MDR) pathogens, i.e., the Gram-negative bacteria Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii. Bromoageliferin (2) displayed significant activity against P. aeruginosa. Comparison of the antibacterial activity of ageliferins 1–3 (of similar structure) against P. aeruginosa revealed some relationship between structure and activity. Furthermore, in in vitro assays, 2 inhibited growth and biofilm production in clinical strains of P. aeruginosa. Moreover, 2 increased the survival time in an in vivo Galleria mellonella model of infection. The findings confirm bromoageliferin (2) as a potential lead for designing new antibacterial drugs.

scholarly journals Signaling roles of phosphoinositides in the retina

2020 ◽  
pp. jlr.TR120000806 ◽  
Author(s):  
Raju V. S. Rajala
Keyword(s):  
Cell Types ◽  
Cellular Functions ◽  
Parent Molecule ◽  
Phosphoinositide Signaling ◽  
Wide Range ◽  
The Many ◽  
And Function ◽  
Different Cell Types

The field of phosphoinositide signaling has expanded significantly in recent years. Phosphoinositides (PIs) are universal signaling molecules that directly interact with membrane proteins or with cytosolic proteins containing domains that directly bind phosphoinositides and are recruited to cell membranes. Through the activities of PI kinases and PI phosphatases, seven distinct phosphoinositide lipid molecules are formed from the parent molecule phosphatidylinositol. PI signals regulate a wide range of cellular functions, including cytoskeletal assembly, membrane binding and fusion, ciliogenesis, vesicular transport, and signal transduction. Given the many excellent reviews on phosphoinositide kinases, phosphoinositide phosphatases, and PIs in general, in this review, we discuss recent studies and advances in PI lipid signaling in the retina. We specifically focus on PI lipids from vertebrate (e.g. bovine, rat, mice, toad, and zebrafish) and invertebrate (e.g. drosophila, horseshoe crab, and squid) retinas. We also discuss the importance of PIs revealed from animal models and human diseases, and methods to study PI levels both in vitro and in vivo. We propose that future studies should investigate the function and mechanism of activation of PI-modifying enzymes/phosphatases and further unravel PI regulation and function in the different cell types of the retina.

scholarly journals In vivo structure of the Legionella type II secretion system by electron cryotomography

2019 ◽  
Author(s):  
Debnath Ghosal ◽  
Ki Woo Kim ◽  
Huaixin Zheng ◽  
Mohammed Kaplan ◽  
Joseph P. Vogel ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Cell Envelope ◽  
Secretion System ◽  
Type Ii Secretion ◽  
Type Ii ◽  
Type Iv ◽  
Type Ii Secretion System ◽  
Wide Range ◽  
Electron Cryotomography

AbstractThe type II secretion system (T2SS) is a multi-protein envelope-spanning assembly that translocates a wide range of virulence factors, enzymes and effectors through the outer membrane (OM) of many Gram-negative bacteria. Here, using electron cryotomography and subtomogram averaging methods, we present the first in situ structure of an intact T2SS, imaged within the human pathogen Legionella pneumophila. Although the T2SS has only limited sequence and component homology with the evolutionarily-related Type IV pilus (T4P) system, we show that their overall architectures are remarkably similar. Despite similarities, there are also differences, including for instance that the T2SS-ATPase complex is usually present but disengaged from the inner membrane, the T2SS has a much longer periplasmic vestibule, and it has a short-lived flexible pseudopilus. Placing atomic models of the components into our ECT map produced a complete architectural model of the intact T2SS that provides new insights into the structure and function of its components, its position within the cell envelope, and the interactions between its different subcomplexes. Overall, these structural results strongly support the piston model for substrate extrusion.

scholarly journals Type II Secretion System of Pseudomonas aeruginosa: In Vivo Evidence of a Significant Role in Death Due to Lung Infection

2011 ◽  
Vol 203 (10) ◽  
pp. 1369-1377 ◽  
Author(s):  
Jeevan Jyot ◽  
Viviane Balloy ◽  
Gregory Jouvion ◽  
Amrisha Verma ◽  
Lhousseine Touqui ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Significant Role ◽  
Lung Infection ◽  
Secretion System ◽  
Type Ii Secretion ◽  
Type Ii ◽  
Type Ii Secretion System
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