Biology subjects

Ballatore, C.

Publications and source records attributed to Ballatore, C..

5 recordsLinked to original sources

bioRxiv2025

Structure-Activity Relationship and Target Investigation of Thiophen-2-yl-Pyrimidines against Schistosoma species

Chemotherapeutic options for schistosomiasis, a prevalent infectious disease of poverty, are limited to just one drug, praziquantel (PZQ), and alternatives are needed. Our previous studies identified thiophen-2-yl pyrimidines (TPPs), which are structurally derived from microtubule (MT)-active phenylpyrimidines, as potent paralytics of Schistosoma mansoni. Although relatively non-toxic to mammalian cells, the progenitor compound, 3, had poor aqueous solubility and was lipophilic potentially hindering preclinical advancement. To address these issues and expand on the structure-activity and structure-property relationships, 43 new TPP analogs were designed and synthesized, their lipophilicity calculated (cLogP), and their anti-schistosomal activity evaluated in culture. This effort yielded compound 38, which possessed an oxetane-containing amine moiety at C5, and an ortho, ortho-difluoroaniline at C6 of the TPP scaffold. Compared to 3, compound 38 had better aqueous solubility (46 vs. < 0.5 {micro}M) and decreased lipophilicity (logP calc. 4.48 vs. 6.81), with toxicity CC50 values > 20 {micro}M against three mammalian cell lines. Further, paralytic potency, as measured by the EC50 value for adult S. mansoni motility, was increased 14.5-fold (538 vs. 37 nM), and plasma half-life (t1/2) was improved 3-fold, from 0.48 to 1.51 h for a 40% loss in maximum plasma concentration (Cmax). In washout experiments, 38 produced a sustained paralysis of both juvenile and adult S. mansoni, possibly suggesting a broader in vitro efficacy spectrum compared to PZQ, which is inactive against the juvenile parasite. Also, the two other medically important species, Schistosoma haematobium and Schistosoma japonicum, were susceptible to 38. Finally, to identify potential protein targets, we synthesized a TPP photoaffinity labeling (PAL) probe that labeled several S. mansoni proteins by SDS-PAGE fluorescence analysis, although, notably, not tubulin, suggesting that the antischistosomal activity of 38 is a function of engaging other targets. Future work with the TPP series will aim to decrease toxicity further while improving PK properties to better support in vivo efficacy testing.

microbiology↗

bioRxiv2025

Photoaffinity labeling of protein targets in a complex metazoan: proof-of-concept using a probe for Schistosoma mansoni tubulin

Treatment of schistosomiasis, a prevalent neglected tropical disease, relies precariously on a single drug. The discovery and development of alternative anti-schistosomal small molecules most often relies on phenotypic (whole-organism) screening, whereas target- or "protein-first"-based discovery options are hampered by a paucity of genetic interrogation strategies and a complex biology. Here, we demonstrate the application of photoaffinity labeling (PAL) as a chemical biology strategy to probe protein target-ligand interactions in the schistosome. Using a triazolopyrimidine (TPD) probe that binds tubulin, we established a PAL workflow with living Schistosoma mansoni worms. The probe elicited deleterious phenotypic responses consistent with the TPD series and, upon UV light activation, covalently labeled tubulin as identified by proteomics. Specific concentration-dependent engagement of tubulin was confirmed using a photostable competitor TPD. When applied directly to worm lysates, the PAL workflow produced non-specific labeling, suggesting that the conformation of the protein target is important for ligand binding. The successful application of PAL for a metazoan is, to our knowledge, novel, and the platform should prove generally applicable to identifying potential drug targets, and exploring protein-ligand interactions, in schistosomes and other organisms.

cell biology↗

bioRxiv2023

Structure-Activity Relationships, Tolerability and Efficacy of Microtubule-Active 1,2,4-Triazolopyrimidines as Potential Candidates to Treat Human African Trypanosomiasis

Tubulin and microtubules (MTs) are potential protein targets to treat parasitic infections and our previous studies have shown that the triazolopyrimidine (TPD) class of MT- active compounds hold promise as antitrypanosomal agents. MT-targeting TPDs include structurally related but functionally diverse congeners that interact with mammalian tubulin at either one or two distinct interfacial binding sites; namely, the seventh and vinca sites, which are found within or between ,{beta}-tubulin heterodimers, respectively. Evaluation of the activity of 123 TPD congeners against cultured Trypanosoma brucei enabled a robust quantitative structure-activity relationship (QSAR) model and the prioritization of two congeners for in vivo pharmacokinetics (PK), tolerability and efficacy studies. Treatment of T. brucei-infected mice with tolerable doses of TPDs 3 and 4 significantly decreased blood parasitemia within 24 h. Further, two once-weekly doses of 4 at 10 mg/kg significantly extended the survival of infected mice relative to infected animals treated with vehicle. Further optimization of dosing and/or the dosing schedule of these CNS-active TPDs may provide alternative treatments for human African trypanosomiasis.

microbiology↗

bioRxiv2021

The Prolyl-tRNA Synthetase Inhibitor Halofuginone Inhibits SARS-CoV-2 Infection

Summary ParagraphWe identify the prolyl-tRNA synthetase (PRS) inhibitor halofuginone1, a compound in clinical trials for anti-fibrotic and anti-inflammatory applications2, as a potent inhibitor of SARS-CoV-2 infection and replication. The interaction of SARS-CoV-2 spike protein with cell surface heparan sulfate (HS) promotes viral entry3. We find that halofuginone reduces HS biosynthesis, thereby reducing spike protein binding, SARS-CoV-2 pseudotyped virus, and authentic SARS-CoV-2 infection. Halofuginone also potently suppresses SARS-CoV-2 replication post-entry and is 1,000-fold more potent than Remdesivir4. Inhibition of HS biosynthesis and SARS-CoV-2 infection depends on specific inhibition of PRS, possibly due to translational suppression of proline-rich proteins. We find that pp1a and pp1ab polyproteins of SARS-CoV-2, as well as several HS proteoglycans, are proline-rich, which may make them particularly vulnerable to halofuginones translational suppression. Halofuginone is orally bioavailable, has been evaluated in a phase I clinical trial in humans and distributes to SARS-CoV-2 target organs, including the lung, making it a near-term clinical trial candidate for the treatment of COVID-19.

microbiology↗

bioRxiv2019

Pharmacological inhibition of the heart of glass (HEG1)-Krev interaction trapped protein 1 (KRIT1) protein complex increases Kruppel-like Factors 4 and 2 (KLF4/2) expression in endothelial cells

The Kruppel-like Factors 4 and 2 (KLF4/2) are transcription factors and master regulators of endothelial cells (ECs) phenotype and homeostasis. KLF4/2 are important blood-flow-responsive genes within ECs that differentially regulate the expression of factors that confer anti-inflammatory, antithrombotic, and antiproliferative effects in ECs. Genetic inactivation of endothelial KRIT1 (Krev interaction trapped protein 1) or HEG1 (Heart of glass) lead to upregulation of KLF4/2 expression levels. Furthermore, increased expression of thrombomodulin (THBD) and suppression of thrombospondin (THBS1) was ascribed to elevation of KLF4/2 as a result of loss of endothelial KRIT1. Here, we developed a high-throughput screening assay to identify inhibitors of the HEG1-KRIT1 interaction and identified, HEG1-KRIT1 inhibitor 1 (HKi1), as a promising hit inhibitor. The crystal structure of HKi1 bound to the KRIT1 FERM domain confirmed the primary screening results and ultimately led to the identification of a fragment-like inhibitor (HKi3), which occupies the HEG1 pocket producing comparable activity. These findings suggest that these inhibitors block the interaction by competing with the HEG1 for binding to KRIT1 FERM domain. Moreover, our results demonstrate that HKi3 upregulates KLF4/2 gene expression in two types of human ECs. These results reveal that acute pharmacological inhibition of the HEG1-KRIT1 interaction rapidly induces expression of KLF4/2 and their important transcriptional targets thrombomodulin and thrombospondin.

biochemistry↗