Screening of a Focused Ubiquitin-Proteasome Pathway Inhibitor Library Identifies Small Molecules as Novel Modulators of Botulinum Neurotoxin Type A Toxicity.

Botulinum neurotoxins (BoNTs) are known as the most potent bacterial toxins, which can cause potentially deadly disease botulism. BoNT Serotype A (BoNT/A) is the most studied serotype as it is responsible for most human botulism cases, and its formulations are extensively utilized in clinics for therapeutic and cosmetic applications. BoNT/A has the longest-lasting effect in neurons compared to other serotypes, and there has been high interest in understanding how BoNT/A manages to escape protein degradation machinery in neurons for months. Recent work demonstrated that an E3 ligase, HECTD2, leads to efficient ubiquitination of the BoNT/A Light Chain (A/LC); however, the dominant activity of a deubiquitinase (DUB), VCIP135, inhibits the degradation of the enzymatic component. Another DUB, USP9X, was also identified as a potential indirect contributor to A/LC degradation. In this study, we screened a focused ubiquitin-proteasome pathway inhibitor library, including VCIP135 and USP9X inhibitors, and identified ten potential lead compounds affecting BoNT/A mediated SNAP-25 cleavage in neurons in pre-intoxication conditions. We then tested the dose-dependent effects of the compounds and their potential toxic effects in cells. A subset of the lead compounds demonstrated efficacy on the stability and ubiquitination of A/LC in cells. Three of the compounds, WP1130 (degrasyn), PR-619, and Celastrol, further demonstrated efficacy against BoNT/A holotoxin in an in vitro post-intoxication model. Excitingly, PR-619 and WP1130 are known inhibitors of VCIP135 and USP9X, respectively. Modulation of BoNT turnover in cells by small molecules can potentially lead to the development of effective countermeasures against botulism

Supplementary data for the article: Selaković, Z.; Soloveva, V.; Gharaibeh, D. N.; Wells, J.; Šegan, S.; Panchal, R. G.; Šolaja, B. A. Anti-Ebola Activity of Diazachrysene Small Molecules. ACS Infectious Diseases 2016, 1 (6), 264–271. https://doi.org/10.1021/acsinfecdis.5b00028

Supporting information for: [https://doi.org/10.1021/acsinfecdis.5b00028]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2035

A high-content imaging assay for the quantification of the Burkholderia pseudomallei induced multinucleated giant cell (MNGC) phenotype in murine macrophages

BACKGROUND: Burkholderia pseudomallei (Bp), a Gram-negative, motile, facultative intracellular bacterium is the causative agent of melioidosis in humans and animals. The Bp genome encodes a repertoire of virulence factors, including the cluster 3 type III secretion system (T3SS-3), the cluster 1 type VI secretion system (T6SS-1), and the intracellular motility protein BimA, that enable the pathogen to invade both phagocytic and non-phagocytic cells. A unique hallmark of Bp infection both in vitro and in vivo is its ability to induce cell-to-cell fusion of macrophages to form multinucleated giant cells (MNGCs), which to date are semi-quantitatively reported following visual inspection. RESULTS: In this study we report the development of an automated high-content image acquisition and analysis assay to quantitate the Bp induced MNGC phenotype. Validation of the assay was performed using T6SS-1 (∆hcp1) and T3SS-3 (∆bsaZ) mutants of Bp that have been previously reported to exhibit defects in their ability to induce MNGCs. Finally, screening of a focused small molecule library identified several Histone Deacetylase (HDAC) inhibitors that inhibited Bp-induced MNGC formation of macrophages. CONCLUSIONS: We have successfully developed an automated HCI assay to quantitate MNGCs induced by Bp in macrophages. This assay was then used to characterize the phenotype of the Bp mutants for their ability to induce MNGC formation and identify small molecules that interfere with this process. Successful application of chemical genetics and functional reverse genetics siRNA approaches in the MNGC assay will help gain a better understanding of the molecular targets and cellular mechanisms responsible for the MNGC phenotype induced by Bp, by other bacteria such as Mycobacterium tuberculosis, or by exogenously added cytokines

Supplementary data for the article: Selaković, Z.; Soloveva, V.; Gharaibeh, D. N.; Wells, J.; Šegan, S.; Panchal, R. G.; Šolaja, B. A. Anti-Ebola Activity of Diazachrysene Small Molecules. ACS Infectious Diseases 2016, 1 (6), 264–271. https://doi.org/10.1021/acsinfecdis.5b00028

Supporting information for: [https://doi.org/10.1021/acsinfecdis.5b00028]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2035

A Limited Structural Modification Results in a Significantly More Efficacious Diazachrysene-Based Filovirus Inhibitor

Ebola (EBOV) and Marburg (MARV) filoviruses are highly infectious pathogens causing deadly hemorrhagic fever in humans and non-human primates. Promising vaccine candidates providing immunity against filoviruses have been reported. However, the sporadic nature and swift progression of filovirus disease underlines the need for the development of small molecule therapeutics providing immediate antiviral effects. Herein we describe a brief structural exploration of two previously reported diazachrysene (DAAC)-based EBOV inhibitors. Specifically, three analogs were prepared to examine how slight substituent modifications would affect inhibitory efficacy and inhibitor-mediated toxicity during not only EBOV, but also MARV cellular infection. Of the three analogs, one was highly efficacious, providing IC50 values of 0.696 mu M +/- 0.13 mu M and 2.76 mu M +/- 0.21 mu M against EBOV and MARV infection, respectively, with little or no associated cellular toxicity. Overall, the structure-activity and structure-toxicity results from this study provide a framework for the future development of DAAC-based filovirus inhibitors that will be both active and non-toxic in vivo

Induced IL-10 Splice Altering Approach to Antiviral Drug Discovery

Ebola virus causes an acute hemorrhagic fever lethal in primates and rodents. The contribution of host immune factors to pathogenesis has yet to be determined and may reveal efficacious targets for potential treatment. In this study, we show that the interleukin (IL)-10 signaling pathway modulates Ebola pathogenesis. IL-10 [superscript - / -] mice and wild-type mice receiving antisense targeting IL-10 signaling via disrupting expression through aberrant splice altering were resistant to ebola virus infection. IL-10 [superscript - / -] mice exhibited reduced viral titers, pathology, and levels of IL-2, IL-6, keratinocyte-derived chemokine (KC), and macrophage inflammatory protein-1 α and increased interferon (IFN)-γ relative to infected wild-type mice. Furthermore, antibody depletion studies in IL-10 [superscript - / -] mice suggest a requirement for natural killer cells and IFN-γ for protection. Together, these data demonstrate that resistance to ebola infection is regulated by IL-10 and can be targeted in a prophylactic manner to protect against lethal hemorrhagic virus challenge

High-throughput screen using a single-cell tyrosine phosphatase assay reveals biologically active inhibitors of tyrosine phosphatase CD45

Many cellular signaling events are regulated by tyrosine phosphorylation and mediated by the opposing actions of protein tyrosine kinases and phosphatases. Protein tyrosine phosphatases are emerging as drug targets, but poor cell permeability of inhibitors has limited the development of drugs targeting these enzymes [Tautz L, et al. (2006) Expert Opin Ther Targets 10:157–177]. Here we developed a method to monitor tyrosine phosphatase activity at the single-cell level and applied it to the identification of cell-permeable inhibitors. The method takes advantage of the fluorogenic properties of phosphorylated coumaryl amino propionic acid (pCAP), an analog of phosphotyrosine, which can be incorporated into peptides. Once delivered into cells, pCAP peptides were dephosphorylated by protein tyrosine phosphatases, and the resulting cell fluorescence could be monitored by flow cytometry and high-content imaging. The robustness and sensitivity of the assay was validated using peptides preferentially dephosphorylated by CD45 and T-cell tyrosine phosphatase and available inhibitors of these two enzymes. The assay was applied to high-throughput screening for inhibitors of CD45, an important target for autoimmunity and infectious diseases [Hermiston ML, et al. (2003) Annu Rev Immunol 21:107–137]. We identified four CD45 inhibitors that showed activity in T cells and macrophages. These results indicate that our assay can be applied to primary screening for inhibitors of CD45 and of other protein tyrosine phosphatases to increase the yield of biologically active inhibitors

Supplementary data for article: Opsenica, I.; Burnett, J. C.; Gussio, R.; Opsenica, D. M.; Todorović, N.; Lanteri, C. A.; Sciotti, R. J.; Gettayacamin, M.; Basilico, N.; Taramelli, D.; et al. A Chemotype That Inhibits Three Unrelated Pathogenic Targets: The Botulinum Neurotoxin Serotype A Light Chain, P. Falciparum Malaria, and the Ebola Filovirus. Journal of Medicinal Chemistry 2011, 54 (5), 1157–1169. https://doi.org/10.1021/jm100938u

Supporting information for: [https://doi.org/10.1021/jm100938u]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1157