37 episodes
Oncologie cellulaire et moléculaire - Hugues de Thé Collège de France
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- Education
L'oncologie est l'approche biologique de la transformation cancéreuse des cellules. Née il y a environ deux cents ans, avec des approches morphologiques, elle a connu une accélération brutale depuis quelques décennies, avec la découverte du répertoire des anomalies génétiques – le plus souvent acquises – qui déclenchent la maladie. De nombreuses autres branches de la biologie (épigénétique, immunologie, biologie cellulaire, interactions cellulaires...) sont venues enrichir la discipline. Les premières années d'enseignement de la chaire ont été consacrées à une approche historique, partant du rôle des virus, de celui du contrôle de l'expression génétique par des « gènes maîtres », jusqu'aux liens entre hormones et cancers. Les dernières années, nous avons traité les rapports entre cancers et différenciation ou cancer et sénescence, une forme de réponse cellulaire au stress impliqué dans la défense contre la transformation cancéreuse, comme dans la réponse thérapeutique. Nous entamons maintenant un nouveau cycle dédié à une étude renouvelée du mode d'action cellulaire et moléculaire des agents anti-cancéreux conventionnels ou historiques. Ces questions sont centrales pour la compréhension de la réponse aux différents traitements utilisés en clinique.
Recherche
L'un des fils conducteurs de notre activité de recherche est l'exploration des bases cellulaires à la réponse aux traitements anticancéreux chez l'homme. Le modèle de prédilection étudié par l'équipe est une forme rare de leucémie, liée à une anomalie génétique simple et associée à l'extrême sensibilité à des agents thérapeutiques dépourvus d'activité dans d'autres formes de cancers : une hormone (acide rétinoïque) et un toxique (l'oxyde d'arsenic). Nous avons pu montrer que ces deux agents ciblent directement la protéine à l'origine du déclenchement de cette forme particulière de leucémie et induisent la dégradation de cette protéine maîtresse. Les mécanismes biochimiques et cellulaires associés à la réponse thérapeutique ont été caractérisés. Élucider les bases moléculaires de la réponse thérapeutique nous semble essentiel, car sans compréhension fine des mécanismes, il n'y a pas d'optimisation possible. Nous étudions également les bases biologiques de l'activité de l'actinomycine D, et plus généralement celles des antibiotiques anticancéreux.
Ces études nous ont conduits à nous intéresser à des sous-domaines du noyau cellulaire, les corps nucléaires PML, qui sont associés à la réponse au stress et à la sénescence. L'équipe de recherche, avec V. Lallemand-Breitenbach, directeur de recherche Inserm, cherche à élucider la formation, le rôle biochimique et physiologique de ces domaines dans des situations normales ou pathologiques (voir site du CIRB).
Biographie
Né le 18 janvier 1959, à Marseille.
Hugues de Thé a bénéficié d'une double formation médicale et scientifique. Il explore les relations entre transcription des gènes, architecture du noyau et développement des cancers. Après la découverte d'un récepteur à l'acide rétinoïque et du premier élément de réponse à cette hormone lors de sa thèse dans le laboratoire de Pierre Tiollais à l'Institut Pasteur, il a apporté une contribution clef à la caractérisation de PML/RARA, le gène à l'origine de la leucémie aiguë promyélocytaire (LAP).
Il s'est depuis entièrement consacré à la compréhension de l'action de la protéine synthétisée par ce gène, montrant que PML/RARA exerce des effets dominants négatifs aussi bien sur la régulation de la transcription que sur l'organisation des corps nucléaires PML. Il a montré que les deux médicaments actifs dans la LAP, l'arsenic et l'acide rétinoïque, induisent tous deux la dégradation de la protéine PML/RARA, l'arsenic ciblant sa partie PML et l'acide rétinoïque sa partie RARA.
Utilisant des modèles animaux de ce
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Conférence - Tony Hunter : Noncanonical Protein Phosphorylation – Is Histidine Phosphorylation Used as a Reversible Regulatory Mechanism?
Hugues de Thé
Collège de France
Oncologie cellulaire et moléculaire
Année 2023-2024
Exploring the World of Protein Post-translational Modifications
Conférence - Tony Hunter : Noncanonical Protein Phosphorylation – Is Histidine Phosphorylation Used as a Reversible Regulatory Mechanism?
Tony Hunter
Salk Institute, La Jolla, California, USA
Résumé
Protein phosphorylation is not restricted to serine, threonine and tyrosine, but can occur on six other amino acids, including histidine. In this lecture, I will discuss what is known about non-canonical protein phosphorylation, focusing on our recent work developing new tools to study histidine phosphorylation in cells and tissues, and their use to investigate the possible roles of histidine phosphorylation in liver cancer, pediatric neuroblastoma, breast cancer and pancreatic cancer.
Histidine phosphorylation of proteins was discovered in 1962, before tyrosine phosphorylation, but much less is known about this PTM because phosphohistidine is chemically very labile and therefore hard to study. We set out to investigate histidine phosphorylation over thirty years ago but were stymied by the lack of key reagents. Because anti-phosphotyrosine antibodies have been so useful in studying tyrosine phosphorylation, we set out to develop anti-pHis antibodies, using chemically stable pHis analogues as antigens. We were successful in generating rabbit monoclonal antibodies selective for the 1-pHis and 3-pHis isoforms of phosphohistidine (pHis), using synthetic peptides containing the 1-Tza and 3-pTza pHis analogues as antigens, respectively. We have carried out structural studies of these mAbs bound to their cognate pTza peptide, which reveal how these mAbs achieve isoform specificity, and we have recently used these structures to engineer a higher affinity anti-3-pHis mAb. We have also exploited these mAbs to survey the pHis phosphoproteome, using mass spectrometry to identify novel sites of histidine phosphorylation and new pHis-containing proteins, which we are exploring.
I will go on to describe how we have utilized these mAbs to investigate roles for histidine phosphorylation in cancer, showing that elevated histidine phosphorylation is a potential driver of hepatocellular carcinoma and pediatric neuroblastoma. Finally, I will discuss ongoing work investigating a role for histidine phosphorylation in triple negative breast cancer and pancreatic cancer, and, in particular, a possible role for histidine phosphorylation in the formation and function of invadopodia structures in neuroblastoma cell invasiveness. -
Conférence - Tony Hunter : Crosstalk between Post-translational Modifications: The Role of Ptm Crosstalk in Protein Degradation
Hugues de Thé
Collège de France
Oncologie cellulaire et moléculaire
Année 2023-2024
Exploring the World of Protein Post-translational Modifications
Conférence - Tony Hunter : Crosstalk between Post-translational Modifications: The Role of Ptm Crosstalk in Protein Degradation
Tony Hunter
Salk Institute, La Jolla, California, USA
Résumé
In this lecture I will discuss the role of PTMs in increasing proteome complexity, why this is important for organisms with genomes of limited protein-coding capacity, and how the combinatorial use of PTMs on a single protein molecule can diversify signal outputs. I will go on to discuss examples of crosstalk between different PTMs in the context of transcriptional regulation mediated by posttranslational modifications of histone tails, and how different PTMs can be used to tag proteins for inducible degradation by the ubiquitin-proteasome system (UPS).
The modification of proteins by ubiquitin and ubiquitin-like proteins, such as SUMO, is second only to phosphorylation in terms of the number of sites modified in the mammalian proteome. I will discuss the versatility of ubiquitylation as a regulatory mechanism, and will review the different classes of ubiquitin ligases, deubiquitylating enzymes and ubiquitin binding domains, and the different members of the ubiquitin-like protein family, such as SUMO.
I will go on to discuss the discovery of RING finger E3 ubiquitin ligases, and, to illustrate their roles in PTM crosstalk, describe our own work on the c-Cbl RING domain protein as a phosphotyrosine-dependent E3 ubiquitin ligase that targets activated receptor tyrosine kinases, and the RNF4 RING domain protein as a SUMO-dependent E3 ubiquitin ligase (STUbL) that is critical in the DNA damage response.
I will end with a description of how we used a budding yeast genetic screen to discover that the RNF4 E3 ligase plays a role in quality control of RNA polymerase III complex assembly, and discuss recent follow up mouse experiments on RNA polymerase III disease mutations that cause a fatal human neurogenerative disease, that could potentially be treated with a sumoylation pathway inhibitor. -
Conférence - Tony Hunter : Post-translational Modifications of Proteins – Why Nature Chose Phosphate to Modify Proteins
Hugues de Thé
Collège de France
Oncologie cellulaire et moléculaire
Année 2023-2024
Exploring the World of Protein Post-translational Modifications
Conférence - Tony Hunter : Post-translational Modifications of Proteins – Why Nature Chose Phosphate to Modify Proteins
Tony Hunter
Salk Institute, La Jolla, California, USA
Résumé
This lecture will provide an introduction to the world of post-translational modifications (PTMs) of proteins. Chemical modifications of protein surfaces serves as a mechanism to increase proteome diversity. More than 400 different PTMs are known, and PTM linkages can be either reversible or irreversible in nature. PTMs serve many functions, but reversible PTMs play particularly important roles in signal transduction, protein-protein interactions, subcellular localization of proteins and protein degradation. All reversible PTMs, such as phosphorylation, utilize a writer enzyme that adds the PTM and an eraser enzyme that removes the PTM, and in many cases the modified protein is recognized by a reader protein that binds to the PTM itself in a local sequence-dependent manner, serving as a mechanism to read out the PTM signal.
I will review the major types of PTMs and their functions, focusing on protein phosphorylation, which is the most prominent PTM in eukaryotic cells. I will discuss the 150-year history of protein phosphorylation and why phosphorylation was selected as a PTM during evolution, the serendipitous discovery of tyrosine phosphorylation in 1979, and the development of selective tyrosine kinase inhibitors (TKIs) that target aberrant tyrosine phosphorylation. Currently, over 80 TKIs have been approved for use in cancer therapy and treatment of inflammatory conditions.
In the second half of the lecture, I will talk about the discovery of the Pin1 prolyl isomerase, the characterization of Pin1 as a pSer/Thr.Pro motif reader and its activity as a cis-trans prolyl isomerase. By isomerizing pSer/Thr.Pro sites, Pin1 regulates multiple signaling pathways and processes that utilize proline-directed protein kinases, like the CDKs and MAP kinases, including cell cycle progression and mitotic signaling. Cancer-associated proteins, such p53 and Myc, are important targets for Pin1, and I will discuss the reported role of Pin1 in breast cancer and pancreatic cancer, and efforts to generate Pin1-selective small molecule inhibitors for use in cancer therapy. Finally, I will talk about our unpublished work identifying a role for Pin1 in bladder cancer, which implicates Pin1 in regulating cholesterol biosynthesis.
Tony Hunter
Tony Hunter received his BA and PhD from the University of Cambridge, and did postdoctoral studies there and at the Salk Institute. Since 1975, he has been on the faculty of the Salk Institute, where he is the Renato Dulbecco Chair. In 1979, through his work on tumor viruses, he discovered a new class of protein kinases that phosphorylate tyrosine in proteins, establishing that dysregulated tyrosine phosphorylation by an activated tyrosine kinase can cause cancer. Tyrosine phosphorylation is a reversible protein modification essential for the regulation of a wide variety of cellular processes in multicellular eukaryotes, including transmembrane signal transduction by surface receptors. Hunter's work led to the realization that aberrant tyrosine phosphorylation is causal in several types of human cancer, and this has led to the successful development of small molecule inhibitors that target disease-causing tyrosine kinases, known as TKIs, such as GleevecTM.
Hunter has received many awards for his work on tyrosine phosphorylation, including the Sjöberg Prize for Cancer Research, and the Tang Prize for Biopharmaceutical Science, and is a Fellow of the Royal Society of London and a Member of the US National Academy of Sciences.
In recent work, he has been studying histidine phosphorylation of proteins, generating monoclonal antibodies specific for the two isoforms of ph -
04 - Explorer la réponse thérapeutique in vivo
Hugues de Thé
Collège de France
Oncologie cellulaire et moléculaire
Année 2023-2024
04 - Explorer la réponse thérapeutique in vivo -
03 - Explorer la réponse thérapeutique in vivo
Hugues de Thé
Collège de France
Oncologie cellulaire et moléculaire
Année 2023-2024
03 - Explorer la réponse thérapeutique in vivo -
02 - Explorer la réponse thérapeutique in vivo
Hugues de Thé
Collège de France
Oncologie cellulaire et moléculaire
Année 2023-2024
02 - Explorer la réponse thérapeutique in vivo