8-Oxoguanine DNA Glycosylase-1 Augments Proinflammatory Gene Expression by Facilitating the Recruitment of Site-Specific Transcription Factors

Among the insidious DNA base lesions, 8-oxo-7,8-dihydroguanine (8-oxoG) is one of the most abundant, a lesion that arises through the attack by reactive oxygen species on guanine, especially when located in cis-regulatory elements. 8-oxoG is repaired by the 8-oxoguanine glycosylase 1 (OGG1)-initiated DNA base excision repair (BER) pathway. Here we investigated whether 8-oxoG repair by OGG1 in promoter regions is compatible with a prompt gene expression and a host innate immune response. For this purpose, we utilized a mouse model of airway inflammation, supplemented with cell cultures, chromatin immunoprecipitation, siRNA knockdown, real-time PCR, Comet and reporter transcription assays. Our data show that exposure of cells to tumor necrosis factor alpha (TNF-α) altered cellular redox, increased the 8-oxoG level in DNA, recruited OGG1 to promoter sequences and transiently inhibited BER of 8-oxoG. Promoter-associated OGG1 then enhanced NF-êB/RelA binding to cis-elements and facilitated recruitment of Specificity Protein 1 (SP1), transcription initiation factor II-D (TFIID), and phospho-RNA polymerase II, resulting in the rapid expression of chemokines/cytokines and inflammatory cell accumulation in mouse airways. siRNA depletion of OGG1 or prevention of guanine oxidation significantly decreased TNF-α-induced inflammatory responses. Together, these results show that non-productive binding of OGG1 to 8-oxoG in promoter sequences could be an epigenetic mechanism to modulate gene expression for a prompt innate immune response

8-Oxoguanine DNA glycosylase-1-mediated DNA repair is associated with Rho GTPase activation and α-smooth muscle actin polymerization

Reactive oxygen species (ROS) are activators of cell signaling and modify cellular molecules, including DNA. 8-Oxo-7,8-dihydroguanine (8-oxoG) is one of the prominent lesions in oxidatively damaged DNA, whose accumulation is causally linked to various diseases and aging processes, whereas its etiological relevance is unclear. 8-OxoG is repaired by the 8-oxoguanine DNA glycosylase-1 (OGG1)-initiated DNA base excision repair (BER) pathway. OGG1 binds free 8-oxoG and this complex functions as an activator of Ras family GTPases. Here we examined whether OGG1-initiated BER is associated with the activation of Rho GTPase and mediates changes in the cytoskeleton. To test this possibility, we induced OGG1- initiated BER in cultured cells and mouse lungs and used molecular approaches such as active Rho pull- down assays, siRNA ablation of gene expression, immune blotting, and microscopic imaging. We found that OGG1 physically interacts with Rho GTPase and, in the presence of 8-oxoG base, increases Rho–GTP levels in cultured cells and lungs, which mediates α-smooth muscle actin (α-SMA) polymerization into stress fibers and increases the level of α-SMA in insoluble cellular/tissue fractions. These changes were absent in cells lacking OGG1. These unexpected data and those showing that 8-oxoG repair is a lifetime process suggest that, via Rho GTPase, OGG1 could be involved in the cytoskeletal changes and organ remodeling observed in various chronic diseases

Increased Abundance of Plasmacytoid Dendritic Cells and Interferon-Alpha Induces Plasma Cell Differentiation in Patients of IgA Nephropathy

The roles of pDC and IFN-α have not been well defined in IgA nephropathy (IgAN). In this study, we investigated the abundance of pDCs and IFN-α in IgAN patients and the response of peripheral blood mononuclear cells (PBMCs) after stimulation of the pDC-preferred TLR9 ligand CpG2216. The effects of IFN-α on plasma cell differentiation and leukocyte migration were also investigated. Here, we found that the percentages of pDCs were increased in PBMCs of IgAN patients, than in those of healthy controls. Plasma levels of IFN-α proteins and abundance of plasma cells were higher in IgAN patients than in healthy donors. Plasma IFN-α levels were positively associated with proteinuria, renal IgM deposition, and renal tubular atrophy/interstitial fibrosis grade in IgAN patients. Ex vivo activation of TLR9 on pDCs resulted in increased IFN-α production and enhanced plasma cell differentiation in IgAN patients as compared with healthy donors. IFN-α treatment led to increased plasma cell differentiation in vitro. IFN-α also significantly promoted expression of chemokines IP-10 and MCP-1 in human mesangial cells, which subsequently facilitated the transendothelial migration of human CD4+ and CD14+ cells. In conclusion, pDC and its secreted cytokine IFN-α may play important roles in pathological changes of IgA nephropathy

The fragmentomic property of plasma cell-free DNA enables the non-invasive detection of diabetic nephropathy in patients with diabetes mellitus

BackgroundDiabetic nephropathy (DN) is one of the most prevalent complications of diabetes mellitus (DM). However, there is still a lack of effective methods for non-invasive diagnosis of DN in clinical practice. We aimed to explore biomarkers from plasma cell-free DNA as a surrogate of renal biopsy for the differentiation of DN patients from patients with DM.Materials and methodsThe plasma cell-free DNA (cfDNA) was sequenced from 53 healthy individuals, 53 patients with DM but without DN, and 71 patients with both DM and DN. Multidimensional features of plasma DNA were analyzed to dissect the cfDNA profile in the DM and DN patients and identify DN-specific cfDNA features. Finally, a classification model was constructed by integrating all informative cfDNA features to demonstrate the clinical utility in DN detection.ResultsIn comparison with the DM patients, the DN individuals exhibited significantly increased cfDNA concentration in plasma. The cfDNA from the DN patients showed a distinct fragmentation pattern with an altered size profile and preferred motifs that start with “CC” in the cfDNA ending sites, which were associated with deoxyribonuclease 1 like 3 (DNASE1L3) expression in the kidney. Moreover, patients with DM or DN were found to carry more alterations in whole-genome cfDNA coverage when compared with healthy individuals. We integrated DN-specific cfDNA features (cfDNA concentration, size, and motif) into a classification model, which achieved an area under the receiver operating characteristic curve (AUC) of 0.928 for the differentiation of DN patients from DM patients.ConclusionOur findings showed plasma cfDNA as a reliable non-invasive biomarker for differentiating DN patients from DM patients. The utility of cfDNA in clinical practice in large prospective cohorts is warranted

High Prevalence of Extended-Spectrum Beta Lactamases among Salmonella enterica Typhimurium Isolates from Pediatric Patients with Diarrhea in China

We investigated the extended-spectrum beta lactamases among 62 Salmonella enterica Typhimurium isolates recovered from children with diarrhea in a Chinese pediatric hospital. A large proportion of S. enterica Typhimurium isolates were resistant to multiple antimicrobial agents, including ampicillin (90.3%), tetracycline (80.6%), trimethoprim/sulfamethoxazole (74.2%), chloramphenicol (66.1%), cefotaxime (27.4%). Forty-nine (79.0%) of S. enterica Typhimurium isolates were positive for blaTEM-1b and resistant to ampicillin. Thirteen S. enterica Typhimurium isolates (21.0%) were positive for blaCTX-M-1-group and blaCTX-M-9-group, and all isolates harboring blaCTX-M genes were positive for ISEcp1. Two main clones (PFGE type A and D) accounted for nearly 70% of S. enterica Typhimurium isolates, and 7 CTX-M-producing isolates belonged to PFGE type D. Collectively, our data reveal multi-drug resistance and a high prevalence of extended spectrum beta lactamases among S. enterica Typhimurium isolates from children in China. In addition, we report the first identification of blaCTX-M-55 within Salmonella spp. Our data also suggest that clonal spread is responsible for the dissemination of S. enterica Typhimurium isolates

A Crosstalk between the Smad and JNK Signaling in the TGF-β-Induced Epithelial-Mesenchymal Transition in Rat Peritoneal Mesothelial Cells

Transforming growth factor β (TGF-β) induces the process of epithelial-mesenchymal transition (EMT) through the Smad and JNK signaling. However, it is unclear how these pathways interact in the TGF-β1-induced EMT in rat peritoneal mesothelial cells (RPMCs). Here, we show that inhibition of JNK activation by introducing the dominant-negative JNK1 gene attenuates the TGF-β1-down-regulated E-cadherin expression, and TGF-β1-up-regulated α-SMA, Collagen I, and PAI-1 expression, leading to the inhibition of EMT in primarily cultured RPMCs. Furthermore, TGF-β1 induces a bimodal JNK activation with peaks at 10 minutes and 12 hours post treatment in RPMCs. In addition, the inhibition of Smad3 activation by introducing a Smad3 mutant mitigates the TGF-β1-induced second wave, but not the first wave, of JNK1 activation in RPMCs. Moreover, the inhibition of JNK1 activation prevents the TGF-β1-induced Smad3 activation and nuclear translocation, and inhibition of the TGF-β1-induced second wave of JNK activation greatly reduced TGF-β1-induced EMT in RPMCs. These data indicate a crosstalk between the JNK1 and Samd3 pathways during the TGF-β1-induced EMT and fibrotic process in RPMCs. Therefore, our findings may provide new insights into understanding the regulation of the TGF-β1-related JNK and Smad signaling in the development of fibrosis

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Control of BLDC Motor Drive with Single Hall Sensor Considering Angle Compensation

The traditional brushless DC motor uses three position sensors to realise six-step reversing control of the motor. The application of three position sensors increases the cost, whereas the sensorless control method represented by the back electromotive force method has the problem of low control accuracy. Therefore, the present research proposes the method of six-step motor reversing control by using single sensor, corrects the motor running state by using the peak–peak difference of phase current in the control process, and resultantly achieves a good control effect. The experimental results prove the control and correction method