14 research outputs found
Methylation of the KEAP1 gene promoter region in human colorectal cancer
<p>Abstract</p> <p>Background</p> <p>The Keap1-Nrf2 pathway has been reported to be impaired in several cancers. However, the status of Keap1-Nrf2 system in human colorectal cancer (CRC) has not been elucidated.</p> <p>Methods</p> <p>We used colorectal cancer (CRC) cell lines and surgical specimens to investigate the methylation status of the <it>KEAP1 </it>promoter region as well as expression of Nrf2 and its downstream antioxidative stress genes, <it>NQO-1 </it>and <it>AKR1C1</it>.</p> <p>Results</p> <p>DNA sequencing analysis indicated that all mutations detected were synonymous, with no amino acid substitutions. We showed by bisulfite genomic sequencing and methylation-specific PCR that eight of 10 CRC cell lines had hypermethylated CpG islands in the <it>KEAP1 </it>promoter region. HT29 cells with a hypermethylated <it>KEAP1 </it>promoter resulted in decreased mRNA and protein expression but unmethylated Colo320DM cells showed higher expression levels. In addition, treatment with the DNA methyltransferase inhibitor 5-Aza-dC combined with the histone deacetylase inhibitor trichostatin A (TSA) increased <it>KEAP1 </it>mRNA expression. These result suggested that methylation of the <it>KEAP1 </it>promoter regulates its mRNA level. Time course analysis with the Nrf2-antioxidant response element (ARE) pathway activator t-BHQ treatment showed a rapid response within 24 h. HT29 cells had higher basal expression levels of <it>NQO-1 </it>and <it>AKR1C1 </it>mRNA than Colo320DM cells. Aberrant promoter methylation of <it>KEAP1 </it>was detected in 53% of tumor tissues and 25% of normal mucosae from 40 surgical CRC specimens, indicating that cancerous tissue showed increased methylation of the <it>KEAP1 </it>promoter region, conferring a protective effect against cytotoxic anticancer drugs.</p> <p>Conclusion</p> <p>Hypermethylation of the <it>KEAP1 </it>promoter region suppressed its mRNA expression and increased nuclear Nrf2 and downstream ARE gene expression in CRC cells and tissues.</p
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Accurate Estimation of Neural Population Dynamics without Spike Sorting
A central goal of systems neuroscience is to relate an organism's neural activity to behavior. Neural population analyses often reduce the data dimensionality to focus on relevant activity patterns. A major hurdle to data analysis is spike sorting, and this problem is growing as the number of recorded neurons increases. Here, we investigate whether spike sorting is necessary to estimate neural population dynamics. The theory of random projections suggests that we can accurately estimate the geometry of low-dimensional manifolds from a small number of linear projections of the data. We recorded data using Neuropixels probes in motor cortex of nonhuman primates and reanalyzed data from three previous studies and found that neural dynamics and scientific conclusions are quite similar using multiunit threshold crossings rather than sorted neurons. This finding unlocks existing data for new analyses and informs the design and use of new electrode arrays for laboratory and clinical use
Superparamagnetic Nanocomposites Templated with Pyrazole-Containing Diblock Copolymers
Monodisperse maghemite nanoparticles, templated in novel, well-defined pyrazole-containing norbornene-based block copolymers, provided a superparamagnetic nanocomposite with high saturation magnetization at room temperature under an applied magnetic field. The synthesis of the polymer nanocomposites and physical, morphological, and magnetic chracaterization of the nanocomposites are reported. Micelle-encapsulated superparamagnetic nanocomposites were generated for dispersal in aqueous medium. Their stability in water in the presence of a magnetic field was investigated as was their morphology and cell viability, strongly suggesting the potential of these superparamagnetic polymer-based nanocomposites in certain biomedical imaging and associated applications
Dendritic calcium signals in rhesus macaque motor cortex drive an optical brain-computer interface
Surface two-photon imaging of the brain cannot access somatic calcium signals of neurons from deep layers of the macaque cortex. Here, the authors present an implant and imaging system for chronic motion-stabilized two-photon imaging of dendritic calcium signals to drive an optical brain-computer interface in macaques