A Small Molecule Inhibitor of Pex3–Pex19 Interaction Disrupts Glycosome Biogenesis and Causes Lethality in Trypanosoma brucei

Trypanosomatid parasites, including Trypanosoma and Leishmania, are infectious zoonotic agents for a number of severe diseases such as African sleeping sickness and American trypanosomiasis (Chagas disease) that affect millions of people, mostly in the emergent world. The glycosome is a specialized member of the peroxisome family of organelles found in trypanosomatids. These organelles compartmentalize essential enzymes of the glycolytic pathway, making them a prime target for drugs that can kill these organisms by interfering with either their biochemical functions or their formation. Glycosome biogenesis, like peroxisome biogenesis, is controlled by a group of proteins called peroxins (Pex). Pex3 is an early acting peroxin that docks Pex19, the receptor for peroxisomal membrane proteins, to initiate biogenesis of peroxisomes from the endoplasmic reticulum. Identification of Pex3 as the essential master regulator of glycosome biogenesis has implications in developing small molecule inhibitors that can impede Pex3–Pex19 interaction. Low amino acid sequence conservation between trypanosomatid Pex3 and human Pex3 (HsPex3) would aid in the identification of small molecule inhibitors that selectively interfere with the trypanosomatid Pex3–Pex19 interaction. We tested a library of pharmacologically active compounds in a modified yeast two-hybrid assay and identified a compound that preferentially inhibited the interaction of Trypanosoma brucei Pex3 and Pex19 versus HsPex3 and Pex19. Addition of this compound to either the insect or bloodstream form of T. brucei disrupted glycosome biogenesis, leading to mislocalization of glycosomal enzymes to the cytosol and lethality for the parasite. Our results show that preferential disruption of trypanosomal Pex3 function by small molecule inhibitors could help in the accelerated development of drugs for the treatment of trypanosomiases.

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KIF15 nanomechanics and kinesin inhibitors, with implications for cancer chemotherapeutics

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1801242115 ◽

2018 ◽

Vol 115 (20) ◽

pp. E4613-E4622 ◽

Cited By ~ 19

Author(s):

Bojan Milic ◽

Anirban Chakraborty ◽

Kyuho Han ◽

Michael C. Bassik ◽

Steven M. Block

Keyword(s):

Cancer Cell ◽

Small Molecule ◽

Single Molecule ◽

Small Molecule Inhibitors ◽

Cancer Cell Growth ◽

Combination Drug ◽

Cancer Chemotherapeutics ◽

Development Of Resistance ◽

Molecule Inhibitor ◽

Mechanochemical Cycle

Eg5, a mitotic kinesin, has been a target for anticancer drug development. Clinical trials of small-molecule inhibitors of Eg5 have been stymied by the development of resistance, attributable to mitotic rescue by a different endogenous kinesin, KIF15. Compared with Eg5, relatively little is known about the properties of the KIF15 motor. Here, we employed single-molecule optical-trapping techniques to define the KIF15 mechanochemical cycle. We also studied the inhibitory effects of KIF15-IN-1, an uncharacterized, commercially available, small-molecule inhibitor, on KIF15 motility. To explore the complementary behaviors of KIF15 and Eg5, we also scored the effects of small-molecule inhibitors on admixtures of both motors, using both a microtubule (MT)-gliding assay and an assay for cancer cell viability. We found that (i) KIF15 motility differs significantly from Eg5; (ii) KIF15-IN-1 is a potent inhibitor of KIF15 motility; (iii) MT gliding powered by KIF15 and Eg5 only ceases when both motors are inhibited; and (iv) pairing KIF15-IN-1 with Eg5 inhibitors synergistically reduces cancer cell growth. Taken together, our results lend support to the notion that a combination drug therapy employing both inhibitors may be a viable strategy for overcoming chemotherapeutic resistance.

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A Target-Based High Throughput Screen Yields Trypanosoma brucei Hexokinase Small Molecule Inhibitors with Antiparasitic Activity

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0000659 ◽

2010 ◽

Vol 4 (4) ◽

pp. e659 ◽

Cited By ~ 37

Author(s):

Elizabeth R. Sharlow ◽

Todd A. Lyda ◽

Heidi C. Dodson ◽

Gabriela Mustata ◽

Meredith T. Morris ◽

...

Keyword(s):

Trypanosoma Brucei ◽

Small Molecule ◽

High Throughput ◽

Small Molecule Inhibitors ◽

High Throughput Screen ◽

Antiparasitic Activity

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Nanomolar Inhibitors ofTrypanosoma bruceiRNA Triphosphatase

mBio ◽

10.1128/mbio.00058-16 ◽

2016 ◽

Vol 7 (1) ◽

Cited By ~ 7

Author(s):

Paul Smith ◽

C. Kiong Ho ◽

Yuko Takagi ◽

Hakim Djaballah ◽

Stewart Shuman

Keyword(s):

Drug Discovery ◽

Trypanosoma Brucei ◽

Small Molecule ◽

Active Sites ◽

Small Molecule Inhibitors ◽

Chemical Space ◽

Antiviral Drug ◽

Mrna Capping ◽

Rna Triphosphatase ◽

Triphosphate Tunnel Metalloenzyme

ABSTRACTEukaryal taxa differ with respect to the structure and mechanism of the RNA triphosphatase (RTPase) component of the mRNA capping apparatus. Protozoa, fungi, and certain DNA viruses have a metal-dependent RTPase that belongs to the triphosphate tunnel metalloenzyme (TTM) superfamily. Because the structures, active sites, and chemical mechanisms of the TTM-type RTPases differ from those of mammalian RTPases, the TTM RTPases are potential targets for antiprotozoal, antifungal, and antiviral drug discovery. Here, we employed RNA interference (RNAi) knockdown methods to show thatTrypanosoma bruceiRTPase Cet1 (TbCet1) is necessary for proliferation of procyclic cells in culture. We then conducted a high-throughput biochemical screen for small-molecule inhibitors of the phosphohydrolase activity of TbCet1. We identified several classes of chemicals—including chlorogenic acids, phenolic glycopyranosides, flavonoids, and other phenolics—that inhibit TbCet1 with nanomolar to low-micromolar 50% inhibitory concentrations (IC50s). We confirmed the activity of these compounds, and tested various analogs thereof, by direct manual assays of TbCet1 phosphohydrolase activity. The most potent nanomolar inhibitors included tetracaffeoylquinic acid, 5-galloylgalloylquinic acid, pentagalloylglucose, rosmarinic acid, and miquelianin. TbCet1 inhibitors were less active (or inactive) against the orthologous TTM-type RTPases of mimivirus, baculovirus, and budding yeast (Saccharomyces cerevisiae). Our results affirm that a TTM RTPase is subject to potent inhibition by small molecules, with the caveat that parallel screens against TTM RTPases from multiple different pathogens may be required to fully probe the chemical space of TTM inhibition.IMPORTANCEThe stark differences between the structure and mechanism of the RNA triphosphatase (RTPase) component of the mRNA capping apparatus in pathogenic protozoa, fungi, and viruses and those of their metazoan hosts highlight RTPase as a target for anti-infective drug discovery. Protozoan, fungal, and DNA virus RTPases belong to the triphosphate tunnel metalloenzyme family. This study shows that a protozoan RTPase, TbCet1 fromTrypanosoma brucei, is essential for growth of the parasite in culture and identifies, viain vitroscreening of chemical libraries, several classes of potent small-molecule inhibitors of TbCet1 phosphohydrolase activity.

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A Study on Dexing Copper-Molybdenum Flotation Separation with a New Low- Molecule Inhibitor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.396-398.867 ◽

2011 ◽

Vol 396-398 ◽

pp. 867-871

Author(s):

Xing Jin Liao ◽

Xiao Mu

Keyword(s):

Small Molecule ◽

Small Molecule Inhibitors ◽

Paper Study ◽

Test Results ◽

Single Factor ◽

Separation Technology ◽

High Consumption ◽

Molecule Inhibitor ◽

Low Efficiency ◽

Low Consumption

The inhibitor was high consumption of low-efficiency of depressant in the separation of copper- molybdenum is bottleneck, which restricts the improvement of the Cu-Mo separation technology. This paper study the Dexing copper-molybdenum flotation separation by using a new small molecule inhibitors named pseudothiohydantoin(DLC) and single-factor experiments were employed to confirmed the system of reagent. Test results indicate that DLC can make a high inhibit effect with a low consumption. Eventually, use close circuit tests to verify the inhibitor’s ability and the technical indexes such as the grade of Mo concentrate 26.17% and the recovery 89.83% are obtained by use of one time of roughing, one time of scavenging and two times of cleaning.

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Neutralization of B-Cell Activating Factor (BAFF) by Belimumab Reinforces Small Molecule Inhibitor Treatment in Chronic Lymphocytic Leukemia

Cancers ◽

10.3390/cancers12102725 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2725

Author(s):

Claudia Tandler ◽

Moritz Schmidt ◽

Jonas S. Heitmann ◽

Julia Hierold ◽

Jonas Schmidt ◽

...

Keyword(s):

Chronic Lymphocytic Leukemia ◽

B Cell ◽

Small Molecule ◽

Small Molecule Inhibitors ◽

Small Molecule Inhibitor ◽

Lymphocytic Leukemia ◽

Term Survival ◽

B Cell Activating Factor ◽

Molecule Inhibitor ◽

Inhibitor Treatment

The introduction of idelalisib, ibrutinib and venetoclax for treatment of chronic lymphocytic leukemia (CLL) has greatly improved long term survival of patients. However, many patients do not achieve complete remission and suffer from development of resistance upon treatment with these small molecule inhibitors. Here we report that the TNF family member B-cell activating factor (BAFF) mediates resistance of CLL cells to idelalisib, ibrutinib and venetoclax by sustaining survival and preventing apoptosis of the malignant B cells as revealed by analysis of cellular ATP levels and mitochondrial membrane integrity as well as caspase activation, respectively. As BAFF also plays a prominent role in autoimmune diseases, the BAFF-neutralizing antibody belimumab was developed and approved for treatment of systemic lupus erythematosus (SLE). When we employed belimumab in the context of CLL treatment with idelalisib, ibrutinib and venetoclax, BAFF neutralization was found to significantly increase the sensitivity of the leukemic cells to all three small molecule inhibitors. Notably, BAFF neutralization proved to be beneficial independently of clinical stage according to Binet and Rai or IgVH mutational status. Our results identify drug repurposing of belimumab for neutralization of BAFF to complement small molecule inhibitor treatment as a promising therapeutic approach in CLL that is presently undergoing clinical evaluation.

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