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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

A Thermosensitive, Phase-Variable Epigenetic Switch: pap Revisited

It has been more than a decade since the last comprehensive review of the phase-variable uropathogen-associated pyelonephritis-associated pilus (pap) genetic switch. Since then, important data have come to light, including additional factors that regulate pap expression, better characterization of H-NS regulation, the structure of the Lrp octamer in complex with pap regulatory DNA, the temperature-insensitive phenotype of a mutant lacking the acetyltransferase RimJ, evidence that key components of the regulatory machinery are acetylated, and new insights into the role of DNA binding by key regulators in shaping both the physical structure and regulatory state of the papI and papBA promoters. This review revisits pap, integrating these newer observations with older ones to produce a new model for the concerted behavior of this virulence-regulatory region.

gene silencing↗
DOE OSTI2017

Epigenetic activation of SIN1 promotes NSCLC cell proliferation and metastasis by affecting the epithelial–mesenchymal transition

Stress-activated protein kinase (SAPK) interacting protein 1 (SIN1) is an essential component of mTORC2. Previous studies have shown that SIN1 is a key regulator of Akt pathway which plays an important role in various pathological conditions including cancer. While its effects and mechanisms on the progression of NSCLC remain unknown. In this study, we report that SIN1 is able to promote the growth and migration of NSCLC cells both in vitro and in vivo. Overexpression of SIN1 promoted A549 and H1299 cells proliferation by both MTT and colony formation assays. Consistently, knockdown of SIN1 inhibited the proliferation of these cells. In transwell assay, overexpression of SIN1 increased the migration of A549 and H1299 cells, while SIN1 knockdown reduced their migration. In a tumor xenograft model, overexpression of SIN1 promoted tumor growth of A549 cells in vivo, while SIN1 knockdown suppresses the tumor growth. We also found a mechanistic link between SIN1 and H3K4me3, H3K4me3 is involved in SIN1 upregulation. Moreover, SIN1 can significantly promote the in vitro migration and invasion of NSCLC cells via induction epithelial mesenchymal transition (EMT) process, which subsequently leads to transcriptional downregulation of epithelial marker E-cadherin and upregulation of mesenchymal markers N-cadherin and Vimentin expression. Together, our results reveal that SIN1 plays an important role in NSCLC and SIN1 is a potential biomarker and a promising target in the treatment of NSCLC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Research on epigenetic mechanism of SFRP2 in advanced chronic myeloid leukemia

Secreted frizzled-related protein 2 (SFRP2) has been reported to act as a tumor suppressors. This study aims to detect the biological role of SFRP2 in advanced chronic myeloid leukemia (CML). In this study we examined bone marrow samples from 45 CML patients and 10 healthy donors. K562 and KCL22 cells were cultured and treated with demethylation drug and histone deacetylase inhibitor (HDACi). KCL22 and K562 cells were transfected with lentiviral vector (LV)-SFRP2, LV-control. The cells were then subjected to proliferation and apoptosis assays, real time polymerase chain reaction (PCR), Methylation-specific PCR (MSP), Western blotting, co-immunoprecipitation (CoIP) and Chromatin immunoprecipitation (ChIP), We found that SFRP2 was down-regulated in the accelerated and blast phase of CML, whereas, the levels of WNT1, WNT3 and WNT5A were up-regulated in the accelerated and blast phase of CML. Overexpression SFRP2 inhibited proliferation, promoted apoptosis and activated the WNT pathway. CoIP-MS results showed that SFRP2 interacted with WNT1 and WNT5A. ChIP-seq result indicated that the promoter of H3K4me3 and H3K27me3 were able to interact with SFRP2. In conclusion, our findings demonstrated the SFRP2 act as a potential therapeutic target for advanced CML. Furthermore, our results support the use of demethylation drugs and HDACi as a potential CML treatment strategy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

DPY30 functions in glucose homeostasis via integrating activated histone epigenetic modifications

Highlights: • DPY30 promoted the expression of key glycolytic genes. • DPY30 recruited H3K4me3 on key glycolytic gene promoters. • DPY30 integrated H3K4me3 and H3K9Ac on key glycolytic gene promoters via inhibiting SIRT6 occupancy. Glucose homeostasis is a key event during many physiological and pathological processes. Histone modifications have emerged as vital factors influencing this process. DPY30, a core subunit of SET1/MLL family histone H3K4 methyltransferase complexes, has been reported to be amplified in cancers. However, the role of DPY30 in glucose homeostasis remains unclear. Here we reported that DPY30 regulated H3K4me3 recruitment to control the expression of Hif1α and its targeted glycolytic genes. Specifically, DPY30 promoted H3K9Ac recruitment via inhibiting SIRT6 occupancy on these gene promoters. Finally, we observed significant upregulation of DPY30 mRNA expression in hepatocellular carcinoma samples from datasets. Taken together, our results reveal a critical role of DPY30 in glucose homeostasis and might offer new therapeutic and diagnostic opportunities for cancers.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Epigenetic Regulation of KLHL34 Predictive of Pathologic Response to Preoperative Chemoradiation Therapy in Rectal Cancer Patients

Purpose: Prediction of individual responsiveness to preoperative chemoradiation therapy (CRT) is urgently needed in patients with poorly responsive locally advanced rectal cancer (LARC). Methods and Materials: Candidate methylation genes associated with radiosensitivity were identified using a 3-step process. In the first step, genome-wide screening of methylation genes was performed in correlation with histopathologic tumor regression grade in 45 patients with LARC. In the second step, the methylation status of selected sites was analyzed by pyrosequencing in 67 LARC patients, including 24 patients analyzed in the first step. Finally, colorectal cancer cell clones with stable KLHL34 knockdown were generated and tested for cellular sensitivity to radiation. Results: Genome-wide screening identified 7 hypermethylated CpG sites (DZIP1 cg24107021, DZIP1 cg26886381, ZEB1 cg04430381, DKK3 cg041006961, STL cg00991794, KLHL34 cg01828474, and ARHGAP6 cg07828380) associated with preoperative CRT responses. Radiosensitivity in patients with hypermethylated KLHL34 cg14232291 was confirmed by pyrosequencing in additional cohorts. Knockdown of KLHL34 significantly reduced colony formation (KLHL34 sh#1: 20.1%, P=.0001 and KLHL34 sh#2: 15.8%, P=.0002), increased the cytotoxicity (KLHL34 sh#1: 14.8%, P=.019 and KLHL34 sh#2: 17.9%, P=.007) in LoVo cells, and increased radiation-induced caspase-3 activity and the sub-G1 population of cells. Conclusions: The methylation status of KLHL34 cg14232291 may be a predictive candidate of sensitivity to preoperative CRT, although further validation is needed in large cohorts using various cell types.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

An epigenetic gene silencing pathway selectively acting on transgenic DNA in the green alga Chlamydomonas

Abstract Silencing of exogenous DNA can make transgene expression very inefficient. Genetic screens in the model alga Chlamydomonas have demonstrated that transgene silencing can be overcome by mutations in unknown gene(s), thus producing algal strains that stably express foreign genes to high levels. Here, we show that the silencing mechanism specifically acts on transgenic DNA. Once a permissive chromatin structure has assembled, transgene expression can persist even in the absence of mutations disrupting the silencing pathway. We have identified the gene conferring the silencing and show it to encode a sirtuin-type histone deacetylase. Loss of gene function does not appreciably affect endogenous gene expression. Our data suggest that transgenic DNA is recognized and then quickly inactivated by the assembly of a repressive chromatin structure composed of deacetylated histones. We propose that this mechanism may have evolved to provide protection from potentially harmful types of environmental DNA.

Neupert, Juliane↗