Podcasts about e2f

Oncotarget published "A novel E2F1-regulated lncRNA, LAPAS1, is required for S phase progression and cell proliferation" which reported that long non-coding RNAs are major regulators of many cellular processes, including cell cycle progression and cell proliferation. Inhibition of LAPAS1 expression increases the percentage of S phase cells, and its silencing in synchronized cells delays their progression through S phase. In agreement with its suggested role in cell cycle progression, prolonged inhibition of LAPAS1 attenuates proliferation of human cancer cells. Importantly, knockdown of SPNS2 rescues the effect of LAPAS1 silencing on cell cycle and cell proliferation. Summarily, they identify LAPAS1 as a novel E2F-regulated lncRNA that has a potential role in human cancer and regulates cell-cycle progression and cell proliferation, at least in part, via regulation of SPNS2. Dr. Doron Ginsberg from The Bar-Ilan University said, "The human genome expresses many thousands of long non-coding RNAs (lncRNAs), which are transcripts longer than 200 bases that lack a significant open reading frame." Increasing evidence indicates that lncRNAs are key regulators of important biological processes including cell cycle progression, cell proliferation and apoptosis. Specifically, some lncRNAs function in regulation of cell cycle progression via modulation of critical cell cycle players, such as the cyclins, CDKs, CDK inhibitors, pRB, and p53. Transcription factors that regulate mRNA transcription were shown to also regulate lncRNAs expression. Inhibition of LAPAS1 expression delays progression of cells through S phase and inhibits proliferation of human cancer cells. Thus, the authors identify LAPAS1 as a new E2F-regulated lncRNA that has a potential role in human cancer and regulates cell proliferation and cell-cycle progression, at least in part, via regulation of SPNS2. The Ginsberg Research Team concluded in their Oncotarget Research Output, "this study reports the identification of a novel lncRNA that affects cell cycle progression and cell proliferation and may affect cancer progression. Its initial characterization shows that it is transcriptionally regulated by E2F and it exerts its activity, at least in part, by regulating SPNS2." DOI - https://doi.org/10.18632/oncotarget.27962 Full text - https://www.oncotarget.com/article/27962/text/ Correspondence to - Doron Ginsberg - doron.ginsberg@biu.ac.il Keywords - lncRNA, E2F, cell cycle, cell proliferation About Oncotarget Oncotarget is a bi-weekly, peer-reviewed, open access biomedical journal covering research on all aspects of oncology. To learn more about Oncotarget, please visit https://www.oncotarget.com or connect with: SoundCloud - https://soundcloud.com/oncotarget Facebook - https://www.facebook.com/Oncotarget/ Twitter - https://twitter.com/oncotarget LinkedIn - https://www.linkedin.com/company/oncotarget Pinterest - https://www.pinterest.com/oncotarget/ Reddit - https://www.reddit.com/user/Oncotarget/ Oncotarget is published by Impact Journals, LLC please visit https://www.ImpactJournals.com or connect with @ImpactJrnls Media Contact MEDIA@IMPACTJOURNALS.COM 18009220957x105 Copyright © 2021 Impact Journals, LLC Impact Journals is a registered trademark of Impact Journals, LLC

Type 2 Diabetes (T2D) is a chronic metabolic disease, which is caused by the failure of beta-cells in the pancreas and insulin resistance in peripheral tissue and characterized by high glucose levels in the blood. World-wide 382 Million people suffer from Diabetes which makes up 8,3% of the population. Due to this high proportion it is of high interest to find a cure for this disease. The restoration of β-cell mass and function has therefore become a field of intensive research seeking for the next generation of anti-diabetic drugs. Tremendous efforts have been made on deciphering epigenetic regulations that control metabolic tissue function. For several years, the team led by Dr. Jean-Sebastien Annicotte has dissected the molecular links between insulin producing cells, insulin target tissues and T2D/obesity development. Especially, the team research has been focused on the role of cell cycle regulators and their transcriptional co-regulators in the control of metabolic homeostasis, T2D and obesity.   References Jean-Sébastien Annicotte, Elisabeth Fayard, … Johan Auwerx (2003) Pancreatic-Duodenal Homeobox 1 Regulates Expression of Liver Receptor Homolog 1 during Pancreas Development (Molecular and Cellular Biology) DOI: 10.1128/MCB.23.19.6713-6724.2003  Jean-Sébastien Annicotte, Emilie Blanchet, … Lluis Fajas (2009) The CDK4-pRB-E2F1 pathway controls insulin secretion (Nature Cell Biology) DOI: 10.1038/ncb1915  Emilie Blanchet, Jean-Sébastien Annicotte, … Lluis Fajas (2011) E2F transcription factor-1 regulates oxidative metabolism (Nature Cell Biology) DOI: 10.1038/ncb2309 Nabil Rabhi, Pierre-Damien Denechaud, … Jean-Sébastien Annicotte (2016) KAT2B Is Required for Pancreatic Beta Cell Adaptation to Metabolic Stress by Controlling the Unfolded Protein Response (Cell Reports) DOI: 10.1016/j.celrep.2016.03.079 Albert Giralt, Pierre-Damien Denechaud, … Lluis Fajas (2018) E2F1 promotes hepatic gluconeogenesis and contributes to hyperglycemia during diabetes (Molecular Metabolism) DOI: 10.1016/j.molmet.2018.02.011   Contact https://twitter.com/activemotif https://twitter.com/epigenetics_pod https://www.linkedin.com/company-beta/35651/ https://www.facebook.com/ActiveMotifInc/ https://activemotif.com/blog eurotech@activemotif.com

Neuroendocrine tumors are a heterogeneous group of malignancies with an increasing prevalence. Since there is not much progress in therapy, model systems are urgently needed. We have a CEA424-SV40 TAg transgenic mouse model which develops spontaneous tumors in the antral region of the stomach. In addition, several cell lines derived from the tumor were established. Gene expression analysis of the tumor tissue as well as cell lines revealed neuroendocrine markers. Therefore we further characterized this model with special emphasis on the cells of origin and used it for testing new targeted treatment protocols. To analyze CEA424-SV40 TAg mouse model in more detail, tumor tissue as well as the cell lines derived from the primary tumor were investigated by immunohistochemistry, immunofluorescence, western blot, and ELISA. Antibodies used were directed at SV40 TAg, Ki-67, chromogranin A, chromogranin B, secretin, H+-K+-ATPase, glucagon, and transcription factors NeuroD1 and Nkx2.2. Plasma hormone levels of serotonin and secretin were measured by ELISA. Immunostainings of SV40 TAg and Ki-67 revealed highly proliferative tumors cells. The tumors stained intensively for the neuroendocrine markers chromogranin A, chromogranin B, secretin and glucagon. The tumor tissue as well as the cell lines expressed transcription factors NeuroD and Nkx2.2, which are involved in the differentiation of the neuroendocrine lineage. Hormone levels of serotonin and secretin in the plasma of the transgenic mice were dramatically elevated when compared with normal littermates, thus supporting the neuroendocrine phenotype. As the neuroendocrine phenotype of CEA424-SV40 TAg transgenic mouse was confirmed, molecularly targeted therapies were tested in this model system both in vitro and in vivo. Cell lines were tested for drug sensitivity with mTOR inhibitors (RAD001, NVP-BEZ235), paclitaxel, E2F inhibitor, HSP90 inhibitor, and p53 stabilizer Nutlin-3a. All the drugs tested in vitro could efficiently inhibit cell proliferation in a dose dependent manner. From these drugs the mTOR inhibitor RAD001 was chosen for the in vivo experiment. Daily feeding of 10 mg/kg RAD001 inhibited the tumor development and prolonged the survival time of the CEA424-SV40 TAg transgenic mice dramatically. The effects of the RAD001 treatment on tumor cells were achieved mainly through inactivating mTOR-p70S6K and mTOR-4EBP1 signaling as proven by western blot and immunohistochemistry. Still, some cells must develop escape mechanisms, since the tumor tend to grow. To gain a better understanding of the T antigen transforming mechanisms as well as the possible escape mechanisms, some efforts were made on the tumor originating cells in the CEA424-SV40 Tag transgenic mouse model. Possible candidates for these tumor originating cells in the stomach are the newly described epithelial as well as mesenchymal stem cells. In a first attempt, the expression feature of epithelial and mesenchymal stem cell markers were analyzed. Established cell lines as well as tumor tissue from the tumor bearing mice were investigated by reverse transcription PCR (RT-PCR), immunohistochemistry, immunofluorescence, western blot, and microarray analysis. From several markers analyzed, the tumor cell lines showed a high expression level of the potential epithelial stem cell marker Bmi1 in RT-PCR and cDNA expression array. This could be further substantiated by western-blotting and immunostaining. Consequently, Bmi1 message could also be found in the growing tumors both in mRNA and protein levels. Experiments using siRNA to knock down the SV40-TAg expression showed that the Bmi1 expression went down in the cell lines thus showing the interrelationship. On the other hand, the mesenchymal stem cell marker Etv1 was also found to be expressed in the tumor tissue and cell lines derived from the tumor. More interestingly, Etv1 expression level was up-regulated over the time course of the tumor development. From these, an Etv1 positive mesenchymal cell could be a possible candidate for transformation. Since the CEA-promoter used for the generation of the T-antigen transgenic animals contains Etv1 binding sites, it is tempting to speculate, that this may drive the transcription of the T antigen. In conclusion, our data provide convincing evidence that CEA424-SV40 TAg mice are a clinically relevant model for neuroendocrine tumor. Testing of molecularly targeted therapies both in vitro and in vivo offered promising candidates for further clinical evaluation. Thus, this new model system could be of great value not only for studies on the mechanisms of how SV40 TAg induces neuroendocrine tumors but also for exploring novel targeted therapy in a preclinical setting.

The Retinoblastoma protein (pRb) was the first tumor suppressor protein to be identified. It is the founding member of the so called pRb or pocket protein family, comprising two additional members (p107 and p130) in mammalian cells, and its best characterized function is the regulation of the E2F family of transcription factors. Today, the pRb-E2F network represents one of the best understood pathways implicated in cell cycle regulation and differentiation. Pocket proteins negatively regulate the transactivation properties of E2F proteins by two mechanisms: First, binding of pocket proteins to E2F masks the E2F transactivation domain and thereby impairs transcriptional activation. Second, pocket proteins interact with several chromatin modifying and chromatin binding proteins and recruit these proteins to E2F target genes, where they help to establish a repressive chromatin conformation. In this work, advantage was taken of the relative simplicity of the Drosophila melanogaster pRb-E2F network to purify and functionally characterize native pRb repressor complexes. Two related multisubunit complexes that only differ in their pocket protein subunit (RBF1 or RBF2) have been purified from Drosophila embryo nuclear extract. These complexes contain several novel pocket protein-associated polypeptides and localize to transcriptionally silent regions on Drosophila polytene chromosomes. Moreover, they specifically associate with deacetylated histone tails, which are a hallmark of transcriptionally silent chromatin. In cycling Drosophila S2 cells, the purified complexes redundantly repress the expression of a certain class of E2F target genes implicated in differentiation and development, whereas they do not control the expression of cell cycle-regulated E2F targets. Interestingly, the isolated complexes seem to be highly conserved between different organisms. Genes encoding the Caenorhabditis elegans homologs of the complex subunits act within the same genetic pathway involved in vulval cell fate determination and they functionally cooperate in different developmental processes. Furthermore, a complex with striking homology to the Drosophila complexes also exists in human cells. In the light of the specific repression of developmentally regulated E2F target genes in cycling Drosophila cells, it is conceivable that the complexes prevent the uncontrolled expression of genes important during differentiation. Since the C. elegans homologs of the complex subunits are also involved in cell fate determination, this might be a highly conserved feature of the isolated complexes.

Abläufe in der Zelle eines multizellulären Organismus im Rahmen des Zellzyklus oder beim Vorgang der Differenzierung unterliegen strengen Kontrollmechanismen. Ein prominentes Regulationsprotein dieser Mechanismen ist der Retinoblastoma Tumorsuppressor (pRB). Im Zellzyklus liegt die Hauptfunktion pRBs in der Kontrolle des Übergangs von der G1- in die S-Phase. In der aktiven, nichtphosphorylierten Form reprimiert pRB die Expression von S-Phase Genen durch Inaktivierung des Transkriptionsfaktors E2F. Cyclin-abhängige Kinasen überführen pRB in eine mehrfach phosphorylierte, inaktive Form, wodurch die S-Phase eingeleitet wird. Im Gegensatz dazu übt pRB bei Differenzierungsvorgängen aber auch koaktivierende Funktionen aus und wird im Rahmen dieser Prozesse acetyliert. In der vorliegenden Arbeit konnte gezeigt werden, dass pRB nicht nur phosphoryliert und acetyliert wird, sondern darüber hinaus durch den small ubiquitin-like modifier (SUMO) modifiziert wird. Aktives pRB stellt das bevorzugte Substrat dieser Modifikation dar. Das Akzeptorlysin 720 ist konserviert und liegt in einer für die pRB-Funktion entscheidenden Domäne, der sogenannten pocket B Region. Zusammen mit der pocket A Region bildet sie die pocket Domäne, deren strukturelle Integrität sowohl für die Tumorsuppressorfunktion pRBs als auch für die Modifikation durch SUMO essenziell ist. An die pocket B Region binden neben zellulären Regulationsproteinen des Zellzyklus und der Differenzierung auch virale Onkoproteine, die pRB inaktivieren und dadurch für die Transformation einer Zelle verantwortlich sind. Diese viralen Onkoproteine und bestimmte zelluläre Proteine inhibieren die SUMO-Modifikation pRBs. Umgekehrt steigt die SUMOylierung von pRB an, wenn mutierte pRB-Versionen eingesetzt werden, die keine viralen oder zellulären Proteine mehr über die pocket B Region binden können. Eine Version von pRB, bei der das Lysin 720 zu Arginin ausgetauscht wurde und die somit nicht mehr SUMOyliert werden kann, besitzt ein stärkeres Repressionspotenzial auf die E2F-abhängige Genexpression, wie Reportergenversuche zeigten. Die SUMOylierung vermindert also pRBs Potenzial zur E2F-Reprimierung. Möglicherweise wird durch die SUMO-Modifikation von pRB die Zusammensetzung der Bindungspartner an der wichtigen pocket B Region moduliert.