Lead compound | EPFL Graph Search

A lead compound (ˈliːd, i.e. a "leading" compound, not to be confused with various compounds of the metallic element lead) in drug discovery is a chemical compound that has pharmacological or biological activity likely to be therapeutically useful, but may nevertheless have suboptimal structure that requires modification to fit better to the target; lead drugs offer the prospect of being followed by back-up compounds. Its chemical structure serves as a starting point for chemical modifications in order to improve potency, selectivity, or pharmacokinetic parameters. Furthermore, newly invented pharmacologically active moieties may have poor druglikeness and may require chemical modification to become drug-like enough to be tested biologically or clinically. Terminology Lead compounds are sometimes called developmental candidates. This is because the discovery and selection of lead compounds occurs prior to preclinical and clinical developmen

The chromatin remodeller Chd7 and the calcium ATPase Serca2 - adding new facets to the role of Notch in Hematopoiesis and T-ALL

Monique Coersmeyer

Project I: Chd7 Deficiency does not affect N1-driven T-ALL Induction and Maintenance nor impair Hematopoiesis Notch1 has been shown to be a key driver in pediatric T-cell acute lymphobastic leukemia (T-ALL). Previous work in the lab identified the chromatin-remodeling enzyme Chd7 to be highly over-expressed in aggressive versus pre-malignant disease. The aim of this project was to study if Chd7 is required during T-ALL initiation and disease maintenance as well as to characterize its role in the hematopoietic system under physiological and stress conditions. Therefore, Chd7 cKO animals were crossed with the MxCre deleter to ablate Chd7 specifically in BM progenitors. Chd7 deficiency did not induce any overt phenotype in the hematopoietic system, when studied under âsteadyâ state or stress conditions. In addition, Chd7 proved to be dispensable in the initiation and maintenance of murine and human Notch1-driven T-ALL. Therefore, we can rule out a role of Chd7 during late-stage leukemogenesis in Notch1-induced murine and human T-ALL. Project II: Serca2, a putative drug target to fight Notch1-driven T cell acute lymphoblastic leukemia, and its role in Hematopoiesis The Notch signalling pathway represents a bona fide drug target. We and Roti et al. performed a chemical compound screen and identified Cyclopiazonic acid (CPA) as potent Notch inhibitor. Biological target of this compound is the Sarco/Endoplasmic Reticulum ATPase2 (Serca2) that is involved in calcium homeostasis within the cell. Recently, it was shown that Serca2 regulates Notch1 (N1) receptor maturation and inhibition of Serca ATPases, using thapsigargin, blocks T-ALL progression in xenografts (Roti et al., 2013). The putative global effects of Serca2 inhibition on hematopoiesis have, however, not been addressed in this study. Aim of this study was to characterize the function of Serca2 in the hematopoietic system. Therefore, we crossed Serca2 cKO with MxCre to ablate Serca2 function in BM progenitors. Serca2 haploinsufficiency did not lead to any overt phenotype under physiological or competitive conditions. In contrast, Serca2ÎMxCre chimeras showed (i) impaired long-term reconstitution capacity upon transplantation, (ii) a severe reduction of total BM, splenic and thymic cellularity and (iii) an enrichment of KLS cells, the cell pool that contains HSCs. Mature lineages were highly apoptotic, while KLS were not majorly affected by apoptosis, resided predominantly in G0 phase of the cell cycle, exhibited slower cycling kinetics and were functionally impaired as they formed less and smaller colony forming units in vitro. Deregulated calcium levels can lead to an accumulation of unfolded proteins in the ER. In order to resolve ER stress, the cell activates the unfolded protein response (UPR). In case of unresolved ER stress, however, the cell undergoes apoptosis. We demonstrate that mature hematopoietic lineages up-regulate UPR-associated and pro-apoptotic genes, while KLS cells, in contrast, show unperturbed expression of these genes. In addition, we performed in vitro experiments, inhibiting Serca function in Lin- BM cells via thapsigargin (TH) treatment. TH induced severe apoptosis in the overall cell population, while KLS accumulated and were blocked in the G0 phase, closely mimicking Serca2 LOF in vivo. We therefore question the therapeutic approach of targeting Serca2 in N1-driven T-ALL due to severe side effects induced by Serca2 inactivation in the BM.

EPFL2015

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis, Characterization, and Evaluation

Sandrine Gerber, Céline Marie Anne Journot, Laura Camille Louise Nicolle

There is an increasing interest in cationic polymers as important constituents of non-viral gene delivery vectors. In the present study, we developed a versatile synthetic route for the production of covalent polymeric conjugates consisting of water-soluble depolymerized chitosan (dCS; MW 6–9 kDa) and low molecular weight polyethylenimine (PEI; 2.5 kDa linear, 1.8 kDa branched). dCSPEI derivatives were evaluated based on their physicochemical properties, including purity, covalent bonding, solubility in aqueous media, ability for DNA condensation, and colloidal stability of the resulting polyplexes. They were complexed with non-integrating DNA vectors coding for reporter genes by simple admixing and assessed in vitro using liver-derived HuH-7 cells for their transfection efficiency and cytotoxicity. Using a rational screening cascade, a lead compound was selected (dCS-Suc-LPEI-14) displaying the best balance of biocompatibility, cytotoxicity, and transfection efficiency. Scale-up and in vivo evaluation in wild-type mice allowed for a direct comparison with a commercially available non-viral delivery vector (in vivo-jetPEI). Hepatic expression of the reporter gene luciferase resulted in liver-specific bioluminescence, upon intrabiliary infusion of the chitosanbased polyplexes, which exceeded the signal of the in vivo jetPEI reference formulation by a factor of 10. We conclude that the novel chitosan-derivative dCS-Suc-LPEI-14 shows promise and potential as an efficient polymeric conjugate for non-viral in vivo gene therapy

2021

New optical tools for non-invasive imaging and quantification of glucose and nicotinamide riboside in living cells and animals

Aleksandra Konovalova

Glucose is one of the most important metabolites that plays a key role in living organisms, as it is the primary energy source. Glucose metabolism is also an integral part in the pathogenesis of diabetes and cancer. Despite this tremendous impact of glucose, there are no tools for imaging of glucose uptake non-invasively and in a real-time manner working in both living cells and animals without utilization of hazardous radiation and suitable for convenient preclinical use. The first part of this thesis is describing the development of a probe for imaging glucose uptake based on a highly sensitive and versatile bioluminescence technique. We set a goal to design a probe, which should be reliable, robust, easy to use and simply represent the glucose uptake in both living cells and animals. In addition the synthesis of the probe should be straightforward and high-yielding. This part of the thesis is composed of two projects utilizing different approaches to the probe design and probeâs mechanism of action. The first project was based on the Staudinger Ligation for imaging of glucose uptake by modifying the glucose molecule with an azide moiety and using luciferin caged with a reactive phosphine as a counter-partner for the assay. The second project describes the development of a cleavable disulfide glucose-conjugate probe. For the first project we aimed to synthesize a library of glucose pro bioluminescent probes, validate them in a cell-free and cell-based assay and identify the hit compound. Then we proved the GLUT-specificity of the uptake of our hit compound in living cells and animals. The robust and reproducible assay method for measurement of glucose uptake was established. The probe was applied for imaging of antidiabetic drugsâ influence on glucose uptake. We have also demonstrated its superior properties over 2-NBDG that is currently the most used probe in preclinical research. However, the probe utilized in the second project namely cleavable disulfide glucose conjugate probe was not so sensitive as glucose-azide. Nevertheless, we showed a successful application of this probe for imaging of glucose uptake in living cells and animals. The second part of this thesis describes the design and evaluation of the bioluminescent probe for imaging of nicotinamide riboside (NR) uptake. NR is a recently discovered NAD+ precursor that is naturally present in cow's milk. Despite its importance in modern research and a high potential as a new medicine for treatment of various types of diseases, including diabetes, there are no tools to visualize NR uptake in preclinical research. Also, there is a lack of knowledge on where and how NR can be absorbed in mammals. Here we established the Staudinger Ligation-based approach to develop an imaging tool for NR uptake. After the successful synthesis of azido-nicotinamide riboside molecule, we demonstrated its specificity and utility for imaging in living cells and animals. Findings described in this part cover not only the imaging of NR uptake, but also the possibility of existence of specific NR transporter in mammalian cells, which has not been discovered and described yet.

EPFL2016