Cible thérapeutique | EPFL Graph Search

Une cible thérapeutique est un élément quelconque d'un organisme auquel se fixe prioritairement une entité modifiant son comportement, tel qu'un ligand endogène, un médicament ou une drogue. Un exemple de cible thérapeutique courante sont les protéines et les acides nucléiques. La définition dépend du contexte et peut référer à la cible d'un médicament, la cible d'une hormone (comme l'insuline), ou la cible de stimulus externe. Le principe est que la cible est "touchée" par un signal et qu'ainsi sa fonction et son attitude sont changées. Les cibles biologiques sont souvent des protéines telles que des enzymes, des canaux ioniques et des récepteurs, des facteurs cellulaires impliqués dans la réplication virale. Mécanisme Le stimulus externe se lie à la cible. L'interaction entre la cible et la substance peut être :

non-covalente
covalente réversible
covalente non-réversible

Notes et références Catégorie:Pharmacologie Catégorie:Protéine

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

De novo identification of lipid II binding lipopeptides with antibacterial activity against vancomycin-resistant bacteria

Inmaculada Rentero Rebollo

Creative strategies for identifying new antibiotics are essential to addressing the looming threat of a post-antibiotic era. We here report the use of a targeted peptide phage display screen as a means of generating novel antimicrobial lipopeptides. Specifically, a library of phage displayed bicyclic peptides was screened against a biomolecular target based on the bacterial cell wall precursor lipid II. In doing so we identified unique lipid II binding peptides that upon lipidation were found to be active against a range of Gram-positive bacteria including clinically relevant strains of vancomycin resistant bacteria. Optimization of the peptide sequence led to variants with enhanced antibacterial activity and reduced hemolytic activity. Biochemical experiments further confirm a lipid II mediated mode of action for these new-to-nature antibacterial lipopeptides.

Royal Soc Chemistry2017

Targeting the oncogenic signaling of the transcription factor STAT3 with potent and selective monobody inhibitors

Grégory La Sala

Many targeted cancer therapies fail to improve the overall survival of patients. Limitations involve low drug selectivity and the rapid development of resistance. Moreover, the majority of oncogenic drivers presently remain considered as undruggable as these proteins often lack well-defined binding pockets able to fit small molecular antagonists. The need for novel strategies to expand the number of druggable targets thus appears crucial. STAT3 is a transcription factor that is constitutively active in a majority of solid and hematological tumors. It is considered a central target for cancer therapies, as it induces the transcription of genes essential for tumor proliferation, including anti-apoptotic genes, cell cycle regulators and angiogenic factors. Therefore, the inhibition of STAT3 represents a promising therapeutic strategy. However, the targeting of STAT3 still remains a formidable challenge due to the sparse number of chemical probes able to bind to non-enzymes. The engineering of protein binders could overcome many of the challenges in developing STAT3 antagonists. While most common approaches to preclude STAT3 activation consist in either inhibiting its phosphorylation by upstream tyrosine kinases with clinically-approved drugs, or in preventing the SH2 domain-dependent STAT3 dimerization using pre-clinical small molecule probes, the targeting of other STAT3 domains, such as its Coiled-coil or N-terminal domains, has not been thoroughly investigated. Our lab uses small engineered antibody mimics derived from a fibronectin type 3 scaffold (termed monobodies) capable of high affinity and selective binding. In addition, their small size (~10 kDa) and lack of disulfide bonds makes them promising candidates for intracellular antagonistic use. In this work, we selected several monobodies using phage and yeast display that bind to previously untargeted domains of STAT3 with low nanomolar affinities. The monobodies MS3-6 and MS3-N3, binding to the Coiled-coil and N-terminal domain of STAT3 respectively, showed high selectivity to STAT3 as compared to other STAT family members and other unrelated proteins. Additionally, the monobodies strongly inhibited the transcriptional activity of STAT3 in luciferase reporter assays, reduced mRNA levels of STAT3 downstream genes in human lung cancer cells, decreased STAT3 phosphorylation levels upon IL-22 stimulation and interfered with STAT3 nuclear translocation. Notably, the precise blockade of these previously untargeted key domains using monobodies provide new insights into the STAT3 signaling and expand the current strategies to preclude its activity. Altogether, we have developed the first selective monobody inhibitors against a transcription factor implicated in cancer and inflammatory diseases, and used them as biochemical tools to further characterize a poorly understood alternative IL-22R signaling axis involved in STAT3-driven human disorders such as colitis and psoriasis.

EPFL2020