849 research outputs found
Abstract IA06: Leveraging genome-wide CRISPR screens and synthetic lethal interactions for novel cancer therapeutics
No full textAbstract
Forward genetic screens with CRISPR-Cas9 genome editing enable high-resolution detection of genetic vulnerabilities in cancer cells. We conducted genome-wide CRISPR-Cas9 screens in RNF43 mutant pancreatic ductal adenocarcinoma (PDAC) cells, which rely on Wnt signaling for proliferation, and discovered a unique requirement for a Wnt signaling circuit engaging FZD5, one of the ten Frizzled receptors encoded in the human genome. Our results uncover an underappreciated level of context dependent specificity at the Wnt receptor level. We further derived a panel of recombinant antibodies that reports the expression of nine FZD proteins and confirm that FZD5 functional specificity cannot be explained by protein expression patterns. Antibodies that specifically bind FZD5 and FZD8 also robustly inhibited the growth of RNF43 mutant PDAC cells grown in vitro and as xenografts in vivo, providing strong orthogonal support for the functional specificity observed genetically. Proliferation of a patient-derived PDAC cell line harboring a RNF43 variant previously associated with PDAC was also selectively inhibited by the FZD5 antibodies, further demonstrating their use as a potential targeted therapy. Highlighting the potential generalizability of these findings, beyond PDAC, tumor organoid cultures from colorectal carcinoma patients that carried RNF43 mutations were also sensitive to the FZD5 antibodies. Our results provide the first example of how CRIPSR-based genetic screens can be leveraged to identify and validate cell surface targets for antibody development and cancer therapy.
Citation Format: Stephane Angers. Leveraging genome-wide CRISPR screens and synthetic lethal interactions for novel cancer therapeutics [abstract]. In: Proceedings of the AACR Precision Medicine Series: Opportunities and Challenges of Exploiting Synthetic Lethality in Cancer; Jan 4-7, 2017; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2017;16(10 Suppl):Abstract nr IA06.</jats:p
Vers une conceptualisation cognitive de l’architecture\ud des competences
No full textL’objectif de cette recherche consiste a examiner les conditions d’obtention d’un\ud
avantage concurrentiel pour une firme multi-activites. Nous proposons un\ud
renouvellement des outils de diagnostic en exploitant les théories emergentes du\ud
Modele des Ressources et Competences (MRC) et de l’approche cognitive des\ud
organisations.\ud
Alors que les theories traditionnelles des determinants de la performance des firmes\ud
multi-activites examinent la problematique du point de vue de l’alignement de la\ud
strategie et de la structure de la firme avec les circonstances d’un environnement\ud
exogene, l’approche cognitive pose l’environnement comme endogene, produit d’une\ud
mise en acte par l’entreprise de son univers. Dans une telle perspective, la coherence\ud
strategique de la firme se substitue e l’alignement avec l’environnement comme\ud
determinant premier de la performance. Le concept d’architecture des competences\ud
dont nous proposons une conceptualisation cognitive permet l’articulation entre les\ud
deux theories.\ud
La validite de notre construction theorique est testee via l’examen de trois cas de\ud
groupes industriels diversifies: Alpha, Delta et Gamma. Chaque cas est analyse sous\ud
l’angle des trois cadres theoriques (contingence, configurationnisme, architecture des\ud
competences). L’objectif de la recherche est d’evaluer la pertinence de notre\ud
construction conceptuelle, comparativement aux modeles etablis. L’analyse des cas\ud
indique que notre theorie de la cohérence strategique permet un diagnostic plus fin\ud
que les autres approches analytiques dans les situations complexes, pour lesquelles les\ud
leviers de performance sont causalement ambigus et difficilement reperables par les\ud
methodes etablies
The Social Doctrine of Bishop Charles Freppel and the School of Angers
No full textDegree awarded: Ph.D. Church History. The Catholic University of AmericaThe encyclical Rerum novarum, published in 1891 by Pope Leo XIII, is considered the cornerstone of modern Catholic social thought. In the years prior to its release a lively debate occurred throughout the Catholic world about the appropriate response of the Church to the realities of modern industrialized economies. This study examines one perspective in this discussion, largely represented by the thought of Bishop Charles Freppel of Angers (1827 - 1891). Freppel was the leader of the School of Angers, a group whose distinctive feature was its general distrust of state intervention as a resolution to the social question. In addition to his two decades as bishop of Angers, Freppel was also a deputy in the Chamber of Deputies from 1880 until his death in 1891. He thus serves as an interesting figure of study, offering insights into both the internal debates within the Catholic Church regarding the social question and the delicate question of the relationship between Church and State in the French Third Republic. Two collections of Freppel's works form the basis for the majority of this study: the first contains his homilies and pastoral letters as bishop, the second his speeches as deputy. In addition to Freppel, the broader social doctrine of the School of Angers will be considered by examining the thought of proponents such as Charles Perin and Claudio Jannet, and the primary periodical that presented this view. The proceedings of social congresses, especially those held in Liege and Angers in 1890, will also be examined as representative of diverging models of social Catholicism. Some important issues of disagreement included the relationship between justice and charity, and the role of state intervention in resolving the social question. A central theme that emerges is the manner in which the political context of the French Third Republic played a pivotal role in shaping the thought of Freppel and the School of Angers throughout the study. Finally, the minor but discernible influence of the School of Angers on Rerum novarum will be considered.Made available in DSpace on 2012-06-01T16:44:05Z (GMT). No. of bitstreams: 1
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Leveraging FZD Receptor Antibodies to Understand and Precisely Activate Wnt/β-Catenin Signalling Pathway for Neural Patterning in hPSC
No full textThe Wnt/β-catenin signaling plays diverse roles in embryonic development and tissue homeostasis. Its complexity arises from 19 Wnt proteins, 10 Frizzled (FZD) receptors, and multiple co-receptors, each with distinct spatiotemporal expression. Additionally, tissue-specific transcriptional programs enable β-catenin to drive context-dependent cellular responses. In neural development, Wnt/β-catenin activation is crucial for anterior-posterior (AP) patterning. Current human pluripotent stem cell (hPSC) differentiation protocols use GSK3α/β inhibitors to activate β-catenin signalling and posteriorize neural progenitors. However, GSK3α/β are pleiotropic kinases involved in multiple signaling pathways, and because their inhibition occurs downstream in the signaling cascade, it bypasses potential opportunities for specificity or regulation at the receptor level. Additionally, the specific roles of individual FZD receptors in AP patterning are poorly understood. Recently, the Angers lab has developed synthetic antibodies that can selectively bind to each of the ten FZD receptors and engineered an antibody-based agonists modality that can cluster FZD and LRP5/6 receptors to activate Wnt/β-catenin signalling with complete specificity. I hypothesize that using these FZD-LRP5/6 agonists (FLAg) for ventral midbrain (VM) patterning will enhance spatiotemporal control of Wnt signaling and improve dopaminergic (DA) neuron differentiation from hPSC. In the first project, I characterized the cell surface expression of FZD receptor in neural progenitors with different regional identities and found that FZD5 was upregulated in anterior progenitors. Using a FZD5-specific FLAg, I efficiently activated Wnt/β-catenin signaling to guide these progenitors toward a midbrain fate, generating functional DA neurons that rescued locomotor deficits in a Parkinson’s disease (PD) rat model. In the second project, I designed a genome-wide CRISPR screen using FZD5 as a phenotypic marker to identify regulators of posterior patterning under Wnt stimulation. UBE3B emerged as a key mediator, induced upon neural induction and showing enhanced ligase activity via DVL2 activation. Biochemical analyses revealed that UBE3B ubiquitinates CDK1, a critical cell cycle regulator that also shapes the epigenetic landscape in hPSC differentiation, suggesting a novel Wnt-regulated mechanism during AP patterning. Overall, this thesis leverages newly engineered Wnt receptor antibodies to gain insights into FZD receptor function, identify regulators of Wnt-driven neural patterning, and provide an alternative to GSK3α/β inhibitors in hPSC differentiation.Ph.D
Rich Dad Poor Dad: An Entrepreneurial Approach to the Teaching of Business French
No full textUS higher education has focused on the development of new cadres of employees to the near exclusion of entrepreneurship as a career path. In this article, the authors describe an entrepreneurial approach to the teaching of Business French. The senior author served as the course instructor while the junior author was a student who completed the course. To provide an entry into the world of global entrepreneurship, the senior author selected the French translation of Robert Kiyosaki’s Rich Dad Poor Dad. In parallel with the reading of Rich Dad, students completed a series of entrepreneurial course activities. Selected activities are described from the perspectives of both authors. The article ends with students’ feelings about (1) entrepreneurship, (2) future career plans, (3) the theme of the course, and (4) the use of Kiyosaki’s Rich Dad Poor Dad
Wnt signaling inhibition confers induced synthetic lethality to PARP inhibitors
No full textAbstract Despite considerable efforts, therapeutic strategies targeting the Wnt pathway are still not clinically available. The pervasive role of Wnt‐βcatenin signaling for the control of stem cells during normal tissue homeostasis makes the on‐target toxicity of available therapeutic grade molecules an important limitation preventing their clinical introduction. The article in this issue of EMBO Molecular Medicine by Kaur et al (2021) reveals that treatment of Wnt‐addicted cancer cells with inhibitors of Wnt signaling induces a state of BRCAness leading to hypersensitivity to PARP inhibitors. This is a new example of induced synthetic lethality that could pave the way for new indications for PARP inhibitors or may contribute to the long‐awaited clinical introduction of therapeutic agents targeting the Wnt pathway
Proteomic analyses of protein complexes in the Wnt pathway
No full textMultiple screens performed in Drosophila, Caenorhabditis elegans, Xenopus, and zebrafish have identified dozens of proteins participating in Wnt signal transduction. Epistasis experiments, enhancer and suppres-sor screens, and protein–protein interaction techniques have also been efficient at finding new pathway members, connecting proteins together, and establishing the architectural framework of how the Wnt signaling pathway functions. In the last few years, spectacular technological breakthroughs in the field of mass spectrometry have allowed the study of proteins and peptides with unprecedented sensitivity and accuracy. Recently, we have developed methods to study the Wnt pathway using mass spectrometry by studying the composition of protein complexes isolated from mammalian cells. In addition to identifying novel proteins acting in this pathway, this approach is providing information about the supramolecular organization of the protein complexes in the pathway and how the individual proteins are activated and regulated. This chapter details the experimental procedure that we developed to study mammalian pro-tein complexes using a gel-free mass spectrometry approach
Abstract A38: Genome-wide CRISPR-Cas9 screens reveal modulators of temozolomide sensitivity in glioblastoma
No full textAbstract
Glioblastoma (GBM) is a prevalent and highly lethal form of primary brain tumour. Presently, median survival time for GBM patients is only 15 months and thus improved treatment methods are in great need. Treatment of GBM consists of surgery, radiotherapy and the chemotherapeutic agent temozolomide (TMZ). Unfortunately, many GBMs are refractory to TMZ and most others ultimately develop resistance leading to localized disease recurrence and brain tumor invasion. With the aim of identifying new therapeutic targets for GBM we performed genome-wide CRISPR-Cas9 screens to identify genes that modulate TMZ sensitivity in GBM. The TKO library of single-guide RNAs (gRNAs) targeting over 89,000 exons in 17,232 human genes was used to screen a panel of 5 patient-derived human GBM stem cell (GSC) lines. GSCs treated with DMSO were grown in parallel with GSCs treated with either a lethal, or sub-lethal dose of TMZ. Next-generation sequencing was used to identify gRNAs that were increased/decreased in abundance in TMZ treated pools of cells.
Positive selection screening revealed that loss of key components of the mismatch repair pathway–MLH1, MSH2, MSH6 and PMS2 confers resistance to lethal doses of TMZ, as has previously been observed in GBM patients. Negative selection screening using sub-lethal doses of TMZ showed that loss of a conserved set of 15 genes that conferred TMZ hypersensitivity in four MGMT-negative GSC lines while the lone MGMT-positive GSC line in our set had a completely different set of hypersensitivity genes. Functional annotation revealed enrichment for genes involved in multiple DNA repair pathways, most prominently Fanconi Anemia and interstrand cross-link repair. Further studies validated that deletion of either member of the MCM8/9 helicase complex sensitizes GBM cells to TMZ and characterized the previously undescribed gene ZC3H7A which was revealed to be a cytoplasmic, stress-granule associated protein. In addition, our results revealed that in drug resistant MGMT expressing GSCs, TMZ resistance can be restored via the PARP inhibitor ABT-888.
In conclusion, our results have identified a core set of genes that can be targeted to increase sensitivity to the chemotherapeutic agent TMZ responsive GBMs and elucidated opportunities for restoring TMZ sensitivity in resistant GBMs. These genes, many of which are targetable enzymes represent promising therapeutic targets for increasing efficacy of chemotherapy and decreasing lethality in GBM.
Citation Format: Graham MacLeod, Nishani Rajakulendran, Traver Hart, Helen Yu, Peter B. Dirks, Stephane Angers. Genome-wide CRISPR-Cas9 screens reveal modulators of temozolomide sensitivity in glioblastoma [abstract]. In: Proceedings of the AACR Precision Medicine Series: Opportunities and Challenges of Exploiting Synthetic Lethality in Cancer; Jan 4-7, 2017; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2017;16(10 Suppl):Abstract nr A38.</jats:p
Der pyrrhonische Philosoph : Komödie in drei Akten ; Text erstellt nach der Ausgabe Angers, 1761
No full textLa comédie "Le Philosophe Pyrrhonien" a été publiée en 1761 à Angers, dans le nord de la France. L’auteur de l’oeuvre est Monsieur Martin, professeur au collège de Château-Gontier. Avec sa pièce de théâtre, Martin veut réfuter le scepticisme du philosophe grec Pyrrhon (~360 - ~270 av. J.-C.) et faire connaître à son public la théorie de la connaissance et l’éthique d’Aristote. L’ouvrage, publié à l’apogée des Lumières, est donc aussi -sous une forme voilée- un témoignage des débats philosophiques de son époque.The comedy "Le Philosophe Pyrrhonien" was published in Angers (Northern France) in 1761. Its author, Monsieur Martin, was a teacher at the Collège in Château-Gontier. The play aims to refute the scepticism of the Greek philosopher Pyrrho (~360 - ~270 BC) and to introduce the audience to Aristotle’s epistemology and ethics. Published at the height of the French Enlightenment, the work is thus also a testimony to the philosophical debates of its time - albeit in veiled form.Die Komödie "Le Philosophe Pyrrhonien" wurde im Jahre 1761 im nordfranzösischen Angers veröffentlicht. Der Autor des Werks war Monsieur Martin, Lehrer am Collège in Château-Gontier. Mit seinem Theaterstück will Martin den Skeptizismus des griechischen Philosophen Pyrrho (~360 – ~270 v. Chr.) widerlegen und seinem Publikum die Erkenntnistheorie und die Ethik des Aristoteles nahebringen. Das auf dem Höhepunkt der französischen Aufklärung erschienene Werk ist somit auch -freilich in verhüllter Form- ein Zeugnis der philosophischen Debatten seiner Zeit
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