BIOM-41. LIVE-CELL IMAGING SHOWS UNEVEN SEGREGATION OF EXTRACHROMOSOMAL DNA ELEMENTS AND TRANSCRIPTIONALLY ACTIVE EXTRACHROMOSOMAL DNA CLUSTERS IN CANCER

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi20-vi20
Author(s):  
Eunhee Yi ◽  
Amit Gujar ◽  
Molly Guthrie ◽  
Hoon Kim ◽  
Dacheng Zhao ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Live Cell Imaging ◽  
Direct Evidence ◽  
Extrachromosomal Dna ◽  
Cancer Treatments ◽  
Fluorescent Markers ◽  
Copy Numbers ◽  
Dna Elements ◽  
Underlying Mechanisms

Abstract Oncogenic extrachromosomal DNA elements (ecDNAs) promote intratumoral heterogeneity, creating a barrier for successful cancer treatments. The underlying mechanisms are poorly understood and studies are hampered in part by a lack of adequate tools enabling studies of ecDNA behavior. Here, we show that single-cell ecDNA copy numbers greatly vary between tumor cells, both in vitro and in patient glioblastoma specimens, suggesting uneven ecDNA segregation during mitosis. We established a CRISPR-based approach which leverages unique ecDNA breakpoint sequences to tag ecDNA with fluorescent markers in living cells. Applying this method during mitosis revealed disjointed ecDNA inheritance patterns, providing an explanation for rapid ecDNA accumulation in cancer. Post-mitosis, ecDNAs tended to cluster and clustered ecDNAs colocalized with RNA polymerase II, promoting transcription of cargo oncogenes. Our observations provide direct evidence for uneven segregation of ecDNA and sheds new light on mechanisms through which ecDNAs contribute to oncogenesis.

scholarly journals Live-cell imaging shows uneven segregation of extrachromosomal DNA elements and transcriptionally active extrachromosomal DNA clusters in cancer

2020 ◽  
Author(s):  
Eunhee Yi ◽  
Amit D. Gujar ◽  
Molly Guthrie ◽  
Hoon Kim ◽  
Kevin C. Johnson ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Live Cell Imaging ◽  
Direct Evidence ◽  
Extrachromosomal Dna ◽  
Cancer Treatments ◽  
Fluorescent Markers ◽  
Copy Numbers ◽  
Dna Elements ◽  
Underlying Mechanisms

AbstractOncogenic extrachromosomal DNA elements (ecDNAs) promote intratumoral heterogeneity, creating a barrier for successful cancer treatments. The underlying mechanisms are poorly understood and studies are hampered in part by a lack of adequate tools enabling studies of ecDNA behavior. Here, we show that single-cell ecDNA copy numbers follow a Gaussian distribution across tumor cells in vitro and in patient glioblastoma specimens, suggesting uneven ecDNA segregation during mitosis. We established a CRISPR-based approach which leverages unique ecDNA breakpoint sequences to tag ecDNA with fluorescent markers in living cells. Applying this method during mitosis revealed disjointed ecDNA inheritance patterns, providing an explanation for rapid ecDNA accumulation in cancer. Post-mitosis, ecDNAs tended to cluster and clustered ecDNAs colocalized with RNA polymerase II, promoting transcription of cargo oncogenes. Our observations provide direct evidence for uneven segregation of ecDNA and shed new lights of mechanisms through which ecDNAs contribute to oncogenesis.

scholarly journals Eucaryotic RNA polymerase conditional mutant that rapidly ceases mRNA synthesis.

1987 ◽  
Vol 7 (5) ◽  
pp. 1602-1611 ◽  
Author(s):  
M Nonet ◽  
C Scafe ◽  
J Sexton ◽  
R Young
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Direct Evidence ◽  
Mrna Synthesis ◽  
Wild Type ◽  
Gene Encoding ◽  
Conditional Mutant ◽  
Defective Rna

We have isolated a yeast conditional mutant which rapidly ceases synthesis of mRNA when subjected to the nonpermissive temperature. This mutant (rpb1-1) was constructed by replacing the wild-type chromosomal copy of the gene encoding the largest subunit of RNA polymerase II with one mutagenized in vitro. The rapid cessation of mRNA synthesis in vivo and the lack of RNA polymerase II activity in crude extracts indicate that the mutant possesses a functionally defective, rather than an assembly-defective, RNA polymerase II. The shutdown in mRNA synthesis in the rpb1-1 mutant has pleiotropic effects on the synthesis of other RNAs and on the heat shock response. This mutant provides direct evidence that the RPB1 protein has a functional role in mRNA synthesis.

Live-cell imaging shows uneven segregation of extrachromosomal DNA elements and transcriptionally active extrachromosomal DNA hubs in cancer

2021 ◽  
pp. candisc.1376.2021
Author(s):  
Eunhee Yi ◽  
Amit D Gujar ◽  
Molly Guthrie ◽  
Hoon Kim ◽  
Dacheng Zhao ◽  
...  
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Cell ◽  
Extrachromosomal Dna ◽  
Dna Elements

Eucaryotic RNA polymerase conditional mutant that rapidly ceases mRNA synthesis

1987 ◽  
Vol 7 (5) ◽  
pp. 1602-1611 ◽  
Author(s):  
M Nonet ◽  
C Scafe ◽  
J Sexton ◽  
R Young
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Direct Evidence ◽  
Mrna Synthesis ◽  
Wild Type ◽  
Gene Encoding ◽  
Conditional Mutant ◽  
Defective Rna

We have isolated a yeast conditional mutant which rapidly ceases synthesis of mRNA when subjected to the nonpermissive temperature. This mutant (rpb1-1) was constructed by replacing the wild-type chromosomal copy of the gene encoding the largest subunit of RNA polymerase II with one mutagenized in vitro. The rapid cessation of mRNA synthesis in vivo and the lack of RNA polymerase II activity in crude extracts indicate that the mutant possesses a functionally defective, rather than an assembly-defective, RNA polymerase II. The shutdown in mRNA synthesis in the rpb1-1 mutant has pleiotropic effects on the synthesis of other RNAs and on the heat shock response. This mutant provides direct evidence that the RPB1 protein has a functional role in mRNA synthesis.

scholarly journals Loci-specific phase separation of FET fusion oncoproteins promotes gene transcription

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Linyu Zuo ◽  
Guanwei Zhang ◽  
Matthew Massett ◽  
Jun Cheng ◽  
Zicong Guo ◽  
...  
Keyword(s):  
Phase Separation ◽  
Rna Polymerase Ii ◽  
Gene Transcription ◽  
Single Molecule ◽  
Condensate Formation ◽  
Dna Elements ◽  
Target Binding ◽  
Aberrant Gene ◽  
Specific Phase

AbstractAbnormally formed FUS/EWS/TAF15 (FET) fusion oncoproteins are essential oncogenic drivers in many human cancers. Interestingly, at the molecular level, they also form biomolecular condensates at specific loci. However, how these condensates lead to gene transcription and how features encoded in the DNA element regulate condensate formation remain unclear. Here, we develop an in vitro single-molecule assay to visualize phase separation on DNA. Using this technique, we observe that FET fusion proteins undergo phase separation at target binding loci and the phase separated condensates recruit RNA polymerase II and enhance gene transcription. Furthermore, we determine a threshold number of fusion-binding DNA elements that can enhance the formation of FET fusion protein condensates. These findings suggest that FET fusion oncoprotein promotes aberrant gene transcription through loci-specific phase separation, which may contribute to their oncogenic transformation ability in relevant cancers, such as sarcomas and leukemia.

Dysregulation of DNA methylation during development as a potential mechanisms contributing to obsessive compulsive disorders and autism

2019 ◽  
Author(s):  
German I. Todorov ◽  
Karthikeyan Mayilvahanan ◽  
David Ashurov ◽  
Catarina Cunha
Keyword(s):  
Mouse Model ◽  
Autism Spectrum ◽  
Obsessive Compulsive ◽  
Cancer Treatments ◽  
Knock Out ◽  
Treatment Priority ◽  
Underlying Mechanisms ◽  
Knock Out Mice ◽  
Obsessive Compulsive Disorders ◽  
Compulsive Disorders

Autism Spectrum Disorder (ASD) is a pervasive developmental disorder, that is raising at a concerning rate. However, underlying mechanisms are still to be discovered. Obsessions and compulsions are the most debilitating aspect of these disorders (OCD), and they are the treatment priority for patients. SAPAP3 knock out mice present a reliable mouse model for repetitive compulsive behavior and are mechanistically closely related to the ASD mouse model Shank3 on a molecular level and AMPA receptor net effect. The phenotype of SAPAP3 knock out mice is obsessive grooming that leads to self-inflicted lesions by 4 months of age. Recent studies have accumulated evidence, that epigenetic mechanisms are important effectors in psychiatric conditions such as ASD and OCD. Methylation is the most studied mechanism, that recently lead to drug developments for more precise cancer treatments. We injected SAPAP3 mice with an epigenetic demethylation drug RG108 during pregnancy and delayed the onset of the phenotype in the offspring by 4 months. This result gives us clues about possible mechanism involved in OCD and ASD. Additionally, it shows that modulation of methylation mechanisms during development might be explored as a preventative treatment in the cases of high inherited risk of certain mental health conditions.

Phytosomal Curcumin Elicits Anti-tumor Properties Through Suppression of Angiogenesis, Cell Proliferation and Induction of Oxidative Stress in Colorectal Cancer

2019 ◽  
Vol 24 (39) ◽  
pp. 4626-4638 ◽  
Author(s):  
Reyhaneh Moradi-Marjaneh ◽  
Seyed M. Hassanian ◽  
Farzad Rahmani ◽  
Seyed H. Aghaee-Bakhtiari ◽  
Amir Avan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Colorectal Cancer ◽  
Therapeutic Potential ◽  
Vegf Signaling ◽  
Anticancer Effects ◽  
Inhibition Of Angiogenesis ◽  
Underlying Mechanisms ◽  
Apoptotic Activity

Background: Colorectal cancer (CRC) is one of the most common causes of cancer-associated mortality in the world. Anti-tumor effect of curcumin has been shown in different cancers; however, the therapeutic potential of novel phytosomal curcumin, as well as the underlying molecular mechanism in CRC, has not yet been explored. Methods: The anti-proliferative, anti-migratory and apoptotic activity of phytosomal curcumin in CT26 cells was assessed by MTT assay, wound healing assay and Flow cytometry, respectively. Phytosomal curcumin was also tested for its in-vivo activity in a xenograft mouse model of CRC. In addition, oxidant/antioxidant activity was examined by DCFH-DA assay in vitro, measurement of malondialdehyde (MDA), Thiol and superoxidedismutase (SOD) and catalase (CAT) activity and also evaluation of expression levels of Nrf2 and GCLM by qRT-PCR in tumor tissues. In addition, the effect of phytosomal curcumin on angiogenesis was assessed by the measurement of VEGF-A and VEGFR-1 and VEGF signaling regulatory microRNAs (miRNAs) in tumor tissue. Results: Phytosomal curcumin exerts anti-proliferative, anti-migratory and apoptotic activity in-vitro. It also decreases tumor growth and augmented 5-fluorouracil (5-FU) anti-tumor effect in-vivo. In addition, our data showed that induction of oxidative stress and inhibition of angiogenesis through modulation of VEGF signaling regulatory miRNAs might be underlying mechanisms by which phytosomal curcumin exerted its antitumor effect. Conclusion: Our data confirmed this notion that phytosomal curcumin administrates anticancer effects and can be used as a complementary treatment in clinical settings.

Novel Findings of Anti-cancer Property of Propofol

2018 ◽  
Vol 18 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Jiaqiang Wang ◽  
Chien-shan Cheng ◽  
Yan Lu ◽  
Xiaowei Ding ◽  
Minmin Zhu ◽  
...  
Keyword(s):  
General Anesthesia ◽  
Cancer Progression ◽  
Molecular Mechanisms ◽  
Intravenous Anesthetic ◽  
The Past ◽  
Anti Cancer ◽  
Underlying Mechanisms ◽  
Recent Attention

Background: Propofol, a widely used intravenous anesthetic agent, is traditionally applied for sedation and general anesthesia. Explanation: Recent attention has been drawn to explore the effect and mechanisms of propofol against cancer progression in vitro and in vivo. Specifically, the proliferation-inhibiting and apoptosis-inducing properties of propofol in cancer have been studied. However, the underlying mechanisms remain unclear. Conclusion: This review focused on the findings within the past ten years and aimed to provide a general overview of propofol's malignance-modulating properties and the potential molecular mechanisms.

scholarly journals Cockayne syndrome B protein acts as an ATP-dependent processivity factor that helps RNA polymerase II overcome nucleosome barriers

2020 ◽  
Vol 117 (41) ◽  
pp. 25486-25493 ◽  
Author(s):  
Jun Xu ◽  
Wei Wang ◽  
Liang Xu ◽  
Jia-Yu Chen ◽  
Jenny Chong ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Neurological Diseases ◽  
Transcription Elongation ◽  
Cockayne Syndrome ◽  
Stable Complex ◽  
Loss Of Function ◽  
Pol Ii ◽  
Chromatin Remodelers ◽  
Processivity Factor

While loss-of-function mutations in Cockayne syndrome group B protein (CSB) cause neurological diseases, this unique member of the SWI2/SNF2 family of chromatin remodelers has been broadly implicated in transcription elongation and transcription-coupled DNA damage repair, yet its mechanism remains largely elusive. Here, we use a reconstituted in vitro transcription system with purified polymerase II (Pol II) and Rad26, a yeast ortholog of CSB, to study the role of CSB in transcription elongation through nucleosome barriers. We show that CSB forms a stable complex with Pol II and acts as an ATP-dependent processivity factor that helps Pol II across a nucleosome barrier. This noncanonical mechanism is distinct from the canonical modes of chromatin remodelers that directly engage and remodel nucleosomes or transcription elongation factors that facilitate Pol II nucleosome bypass without hydrolyzing ATP. We propose a model where CSB facilitates gene expression by helping Pol II bypass chromatin obstacles while maintaining their structures.

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