Tumor induction by disruption of the Dnmt1, PCNA and UHRF1 interactions.

The low level of DNA methylation in tumors compared to the level of DNA methylation in their normal-tissue counterparts or global DNA hypomethylation was one of the first epigenetic alterations to be found in human cancer^1,2^. While the contribution of genome hypomethylation in cancer development and progression is explained by several mechanisms: chromosomal instability, loss of imprinting, and reactivation of transposable elements^3, 4^, the molecular causes of genome hypomethylation remain unclear. Indeed, despite the central roles of the DNA methyltransferases (Dnmts) in the establishment and maintenance of the DNA methylation, no clear consensus appears between the reduction of the Dnmts expression and the genome hypomethylation in human cancers^5^. Nevertheless, the cancer-associated genome hypomethylation could be explained by the disruption of interactions existing between Dnmts and the DNA replication and DNA repair proteins because these interactions play a crucial role in the DNA methylation in mammalian cells^6-8^. We here demonstrate that the disruption of the Dnmt1/PCNA and Dnmt1/UHRF1 interactions induce the genome hypomethylation and act as oncogenic factors promoting the tumorigenesis. We also identify the Akt- and/or PKC-mediated phosphorylations of Dnmt1 as both initiators of these disruptions and as a hallmark conferring poor prognosis in glioma patients

Disruption of Dnmt1/PCNA/UHRF1 Interactions Promotes Tumorigenesis from Human and Mice Glial Cells

Global DNA hypomethylation is a hallmark of cancer cells, but its molecular mechanisms have not been elucidated. Here, we show that the disruption of Dnmt1/PCNA/UHRF1 interactions promotes a global DNA hypomethylation in human gliomas. We then demonstrate that the Dnmt1 phosphorylations by Akt and/or PKC abrogate the interactions of Dnmt1 with PCNA and UHRF1 in cellular and acelluar studies including mass spectrometric analyses and the use of primary cultured patient-derived glioma. By using methylated DNA immunoprecipitation, methylation and CGH arrays, we show that global DNA hypomethylation is associated with genes hypomethylation, hypomethylation of DNA repeat element and chromosomal instability. Our results reveal that the disruption of Dnmt1/PCNA/UHRF1 interactions acts as an oncogenic event and that one of its signatures (i.e. the low level of mMTase activity) is a molecular biomarker associated with a poor prognosis in GBM patients. We identify the genetic and epigenetic alterations which collectively promote the acquisition of tumor/glioma traits by human astrocytes and glial progenitor cells as that promoting high proliferation and apoptosis evasion

Bcl-2 Family Members and the Mitochondrial Import Machineries: The Roads to Death

The localization of Bcl-2 family members at the mitochondrial outer membrane (MOM) is a crucial step in the implementation of apoptosis. We review evidence showing the role of the components of the mitochondrial import machineries (translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM)) in the mitochondrial localization of Bcl-2 family members and how these machineries regulate the function of pro- and anti-apoptotic proteins in resting cells and in cells committed into apoptosis

Mise en évidence d'un marqueur de bon pronostic dans le glioblastome multiforme, l'enzyme mPGES-1 (identification de son produit PGE2 comme un nouvel activateur direct de la protéine pro-apoptotique Bax )

Dans cette étude, la surexpression de mPGES-1, enzyme terminale de la synthèse de PGE2, dans le glioblastome multiforme (GBM) est corrélée à une survie prolongée des patients. mPGES-1 sensibilise les cellules de GBM à l'apoptose in vitro, spontanée et induite. Paradoxalement, alors que PGE2 favorise la progression tumorale par une signalisation membranaire impliquant ses récepteurs EP, elle induit l'apoptose des cellules cancéreuses par une voie strictement intracellulaire, confe rant à PGE2 une fonction bipolaire dans la tumorogenèse. Nous établissons que PGE2 interagit avec la protéine pro-apoptotique Bax et induit son activation. Enfin, l'interaction de PGE2 avec Bax ainsi que l'activation de Bax induite par PGE2 sont inhibées par la prostaglandine D2, autre prostaglandine majeure dans le système nerveux central. La région des hélices 5- 6, responsable de l'insertion membranaire de Bax, semble fortement impliquée dans l'interaction, avec un rôle particulier de la cystéine 126.In this study, the overexpression of mPGES-1, the terminal enzyme in PGE2 synthesis, in glioblastoma multiforme (GBM) is correlated to a longer survival of patients. mPGES-1 increases the GBM cells sensibility to either spontaneous or induced apoptosis in vitro. Paradoxically, while PGE2 facilitates tumoral progression through its membrane EP receptors, it induces cancerous cells apoptosis through a strict intracellular pathway, attributing a bipolar role to PGE2 in tumorogenesis. We establish here that PGE2 interacts with the proapoptotic protein Bax and activates it. At last, the interaction between Bax and PGE2 and PGE2 -induced Bax activation are inhibited by the prostaglandin D2, also a major prostaglandin in the central nervous system. The region encompassing helix 5- 6, which is responsible for Bax membrane insertion, seems of high importance to the interaction, with a special role played by cystein 126.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

LA MYELOPATHIE CERVICALE COMPRESSIVE CHEZ LE CHEVAL

NANTES-Ecole Nat.Vétérinaire (441092302) / SudocSudocFranceF

Bcl-2 Family Members and the Mitochondrial Import Machineries: The Roads to Death

International audienceThe localization of Bcl-2 family members at the mitochondrial outer membrane (MOM) is a crucial step in the implementation of apoptosis. We review evidence showing the role of the components of the mitochondrial import machineries (translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM)) in the mitochondrial localization of Bcl-2 family members and how these machineries regulate the function of pro- and anti-apoptotic proteins in resting cells and in cells committed into apoptosi

Drug Resistance in Glioblastoma: The Two Faces of Oxidative Stress

International audienceGlioblastomas (GBM) are the most common primary brain tumor with a median survival of 15 months. A population of cells with stem cell properties (glioblastoma stem cells, GSCs) drives the initiation and progression of GBM and is localized in specialized microenvironments which support their behavior. GBM are characterized as extremely resistant to therapy, resulting in tumor recurrence. Reactive oxygen species (ROS) control the cellular stability by influencing different signaling pathways. Normally, redox systems prevent cell oxidative damage; however, in gliomagenesis, the cellular redoxmechanisms are highly impaired. Herein we review the dual nature of the redox status in drug resistance. ROS generation in tumor cells affects the cell cycle and is involved in tumor progression and drug resistance in GBM. However, excess ROS production has been found to induce cell death programs such as apoptosis and autophagy. Since GBM cells have a highmetabolic rate and produce high levels of ROS,metabolic adaptation in these cells plays an essential role in resistance to oxidative stress-induced cell death. Finally, the microenvironment with the stromal components participates in the enhancement of the oxidative stress to promote tumor progression and drug resistance

Targeting Metabolism to Induce Cell Death in Cancer Cells and Cancer Stem Cells

International audienceAbnormal metabolism and the evasion of apoptosis are considered hallmarks of cancers. Accumulating evidence shows that cancer stem cells are key drivers of tumor formation, progression, and recurrence. A successful therapy must therefore eliminate these cells known to be highly resistant to apoptosis. In this paper, we describe the metabolic changes as well as the mechanisms of resistance to apoptosis occurring in cancer cells and cancer stem cells, underlying the connection between these two processes

Optimized protocol for Chelex-based extraction of DNA from historical skeletal remains and forensic trace samples

© 2021 The Author. Published by Research Square. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://protocolexchange.researchsquare.com/article/pex-1652/v1PCR-based analysis of skeletonized human remains is a common aspect in both forensic human identification as well as Ancient DNA research. In this, both areas not merely utilize very similar methodology, but also share the same problems regarding quantity and quality of recovered DNA and presence of inhibitory substances in samples from excavated remains. To enable amplification based analysis of the remains, development of optimized DNA extraction procedures is thus a critical factor in both areas. The method paper here presents an optimized protocol for DNA extraction from ancient skeletonized remains using Chelex-100, with improved effectively in yielding amplifiable extracts from sample material excavated after centuries in a soil environment, which consequently have high inhibitor content and overall limited DNA preservation. Further studies showed that the optimized protocol can likewise be utilized for extraction of DNA from common and trace Forensic sample material

Putative role of Caspase-3 during mesenchymal stem cells differentiation

National audienc