LRRK2 deficiency induced mitochondrial Ca2+ efflux inhibition can be rescued by Na+/Ca2+/Li+ exchanger upregulation

Chemotherapeutics tumor resistance is a principal reason for treatment failure, and clinical and experimental data indicate that multidrug transporters such as ATP-binding cassette (ABC) B1 and ABCG2 play a leading role by preventing cytotoxic intracellular drug concentrations. Functional efflux inhibition of existing chemotherapeutics by these pumps continues to present a promising approach for treatment. A contributing factor to the failure of existing inhibitors in clinical applications is limited understanding of specific substrate/inhibitor/pump interactions. We have identified selective efflux inhibitors by profiling multiple ABC transporters against a library of small molecules to find molecular probes to further explore such interactions. In our primary screening protocol using JC-1 as a dual-pump fluorescent reporter substrate, we identified a piperazine-substituted pyrazolo[1,5-a]pyrimidine substructure with promise for selective efflux inhibition. As a result of a focused structure-activity relationship (SAR)–driven chemistry effort, we describe compound 1 (CID44640177), an efflux inhibitor with selectivity toward ABCG2 over ABCB1. Compound 1 is also shown to potentiate the activity of mitoxantrone in vitro as well as preliminarily in vivo in an ABCG2-overexpressing tumor model. At least two analogues significantly reduce tumor size in combination with the chemotherapeutic topotecan. To our knowledge, low nanomolar chemoreversal activity coupled with direct evidence of efflux inhibition for ABCG2 is unprecedented.

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Effect of Efflux Inhibition on Brain Uptake of Itraconazole in Mice Infected withCryptococcus neoformans

Drug Metabolism and Disposition ◽

10.1124/dmd.31.3.319 ◽

2003 ◽

Vol 31 (3) ◽

pp. 319-325 ◽

Cited By ~ 23

Author(s):

Frédéric Imbert ◽

Méryam Jardin ◽

Christine Fernandez ◽

Jean Charles Gantier ◽

Françoise Dromer ◽

...

Keyword(s):

Brain Uptake ◽

Efflux Inhibition

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Breaking the permeability barrier ofEscherichia coliby controlled hyperporination of the outer membrane.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01882-16 ◽

2016 ◽

pp. AAC.01882-16 ◽

Cited By ~ 30

Author(s):

Ganesh Krishnamoorthy ◽

David Wolloscheck ◽

Jon W. Weeks ◽

Cameron Croft ◽

Valentin V. Rybenkov ◽

...

Keyword(s):

Outer Membrane ◽

Antibacterial Agents ◽

Efflux Transporters ◽

Permeability Barrier ◽

Gram Negative Bacteria ◽

Active Efflux ◽

Efflux Inhibition ◽

Membrane Barrier ◽

Inhibitory Activities ◽

Synergistic Relationship

In Gram-negative bacteria, a synergistic relationship between slow passive uptake of antibiotics across the outer membrane and active efflux transporters creates a permeability barrier, which efficiently reduces effective concentrations of antibiotics in cells and hence, their activities. To analyze the relative contributions of the active efflux and the passive barrier in activities of antibiotics, we constructedEscherichia colistrains with controllable permeability of the outer membrane. The strains express a large pore that does not discriminate compounds based on their hydrophilicity and sensitizes cells to a variety of antibacterial agents. We found that efficacies of antibiotics in these strains are specifically affected by either active efflux, slow uptake, or both, and reflect differences in the properties of the outer membrane barrier, repertoire of efflux pumps and inhibitory activities of antibiotics. Our results identify antibiotics which are the best candidates for potentiation of activities through efflux inhibition and permeabilization of the outer membrane.

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CD36 Is Significantly Correlated with Adipophilin in Human Carotid Lesions and Inversely Correlated with Plasma ApoAI

Journal of Biomedicine and Biotechnology ◽

10.1155/2008/813236 ◽

2008 ◽

Vol 2008 ◽

pp. 1-8 ◽

Cited By ~ 5

Author(s):

Sophie Collot-Teixeira ◽

Calypso Barbatis ◽

Florence Bultelle ◽

Michael Koutouzis ◽

Gerard Pasterkamp ◽

...

Keyword(s):

Cholesterol Efflux ◽

Mrna Levels ◽

Gene Expressions ◽

Atherosclerotic Lesions ◽

Cd36 Expression ◽

Atherosclerotic Plaque Formation ◽

Protein Expressions ◽

Efflux Inhibition ◽

Plasma Marker ◽

Human Carotid

OxLDL uptake and cholesterol efflux inhibition in macrophages play a key role in atherosclerotic plaque formation, rupture, and thrombotic ischemia. This study investigates genes implicated in OxLDL uptake (CD36, SRA), cholesterol efflux inhibition (adipophilin, ADFP), and inflammatory recruitments of leukocytes (IL-8) in plaque lesion areas (PLAs) compared to nonplaque lesion areas NPLAs) in human carotid endarterectomy specimens. Gene and protein expressions were assayed using quantitative PCR and quantitative immunohistochemistry. Pearson tests were used to investigate potential correlation between (a) different gene expressions and (b) gene expression and patient's plasma constituents. CD36, SRA, ADFP, and IL-8 were shown to be significantly more expressed in PLA compared to NPLA. In PLA, a significant correlation was observed between CD36, SRA, ADFP, and IL-8 mRNA levels. Moreover, CD36 expression level was significantly inversely correlated to plasma marker ApoAI. The above investigated genes/proteins may play a key role in the maturation of atherosclerotic lesions.

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Fluorescent substrates for flow cytometric evaluation of efflux inhibition in ABCB1, ABCC1, and ABCG2 transporters

Analytical Biochemistry ◽

10.1016/j.ab.2013.02.018 ◽

2013 ◽

Vol 437 (1) ◽

pp. 77-87 ◽

Cited By ~ 40

Author(s):

J. Jacob Strouse ◽

Irena Ivnitski-Steele ◽

Anna Waller ◽

Susan M. Young ◽

Dominique Perez ◽

...

Keyword(s):

Flow Cytometric ◽

Efflux Inhibition ◽

Flow Cytometric Evaluation

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Molecular mechanisms of ceftazidime resistance in Pseudomonas aeruginosa isolates from canine and human infections

Veterinární Medicína ◽

10.17221/64/2010-vetmed ◽

2010 ◽

Vol 55 (No. 4) ◽

pp. 172-182 ◽

Cited By ~ 5

Author(s):

S-J Du ◽

H-C Kuo ◽

C-H Cheng ◽

ACY Fei ◽

H-W Wei ◽

...

Keyword(s):

Molecular Mechanisms ◽

Antimicrobial Agents ◽

Bloodstream Infections ◽

Beta Lactamase ◽

Efflux System ◽

Human Patient ◽

Minimal Inhibitory Concentrations ◽

Class A ◽

Efflux Inhibition ◽

Human Infections

Sixty-six clinical P. aeruginosa isolates, 17 obtained from canine otitis specimens and 49 received from human patients with bloodstream infections, were collected between February 2007 and January 2008. The minimal inhibitory concentrations (MICs) of the antimicrobial agents of these isolates were determined. Multidrug resistance was common, with 23 (34.8%) isolates found to be ceftazidime resistant. To explore the mechanisms of ceftazidime resistance, PCR analyses were performed to detect drug-resistance genes. The prevalence rate of Ambler class A, B, and D β-lactamase genes were obtained, with blaTEM-1 100%, blaPSE-1 100%, blaOXA-2 96.2%, blaSHV-18 91.3%, blaOXA-17 78.3%, blaVIM-3 26.1%, blaOXA-10 21.7% and blaSHV-1 8.7%. An efflux inhibition assay with the PAβN compound was conducted. The ceftazidime resistance isolates were also tested by RT-qPCR to determine the mRNA expression levels of the oprM and ampC genes. Five (21.7%) of the ceftazidime resistance isolates appeared to overactivate the OprM efflux system. The ampD, ampE, and ampR genes and the ampC-ampR intergenic region were subsequently amplified and sequenced. Five (21.7%) of the ceftazidime resistance isolates from humans and canines had a point mutation in AmpR (Asp135-Asn, n = 3; Als194-Ser, n = 2), which induces AmpC overproduction from 10- to 80-fold. This study first reported ceftazidime resistance in P. aeruginosa from canine otitis specimens, which are closely related to ESBLs (50%), including the overproduction of AmpC (25%) and the OprM efflux system (25%). The ESBLs (100%) played an important role in all ceftazidime resistance isolates from humans, and either AmpC (21.1%) or OprM (21.1%) might be overexpressed within the same isolate. A human patient isolate (H307B) showed simultaneous expression of ESBLs, the OprM efflux system, and AmpC overproduction.

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